The inertia set of a symmetric sign pattern $A$ is the set $i(A)=\lbrace i(B) \mid B=B^T \in Q(A)\rbrace $, where $i(B)$ denotes the inertia of real symmetric matrix $B$, and $Q(A)$ denotes the sign pattern class of $A$. In this paper, a complete characterization on the inertia set of the nonnegative symmetric sign pattern $A$ in which each diagonal entry is zero and all off-diagonal entries are positive is obtained. Further, we also consider the bound for the numbers of nonzero entries in the nonnegative symmetric sign patterns $A$ with zero diagonal that require unique inertia.
A decrease in quality and quantity of sleep has a negative impact on efficiency during wakefulness, which shows particularly in case of people who interact with technological systems, for example system operators, vehicle drivers, etc. Day sleep can positively influence the following vigilance but in the time immediately after the sleep, the psychomotor performance is influenced by sleep inertia whose intensity depends on time and length of sleep.
The aim of the study was to compare day psychomotor performances of people suffering from sleep disorders and a control group of healthy people, and to test the hypothesis that a short, 15 minute long sleep causes more important sleep inertia at 3 p.m. than at 1 p.m.
Sleepiness was objectively evaluated on a group of 35 tested probands, consisting of 29 patients (13 women and 16 men) with given excessive daytime sleepiness accompanying sleep disorder, and of a control group of 6 healthy subjects, with help of Multiple Sleep Latency Test (MSLT) and subjectively with help of Alertness Visual Analogue Scale (VAS). Psychomotor performance was examined by Psychomotor Vigilance Task (PVT).
We found out an unimportant difference in the intensity of sleep inertia after a sleep at 1 p.m. and 3 p.m. We proved significant prolongation of a reaction time and an increase in number of lapses on the group with pathologically shortened sleep latency in MSLT compared to the group with the normal sleep latency. Our work also shows the difference between the subjective and objective evaluation of sleepiness of subjects. Our results show that the prolonged reaction time and increase in number of lapses of the patient group are significant in all PVT examinations compared to the control group. Further, it is obvious that the PVT test is a more sensitive method for judging psychomotor performance and indirectly for judging sleepiness than the MSLT.
These facts seem to be important especially from the two following reasons:
- They can be a help for recommendation of improved regime for driver relaxation.
- They can help in search for deeper understanding of mechanisms of attention decreases.
The role of age in the development of two-kidney, one-clip (2K1C) renal hypertension was evaluated. Blood pressure response to aortic constriction was more pronounced in young rats although the alterations of renal renin activity and body fluid volumes were greater in adult ones. Obtained results suggested that 2K1C renal hypertension is maintained by reciprocal interaction of renin-angiotensin system and body fluid volume alterations only in adult rats. In young rats other factors might be more important.
The growth response to angiotensin II (Ang II) was studied using cultured vascular smooth muscle cells (VSMC) isolated from the aortae of male and female spontaneously hypertensive rats (SHR). Systolic and mean arterial blood pressure of 10-week-old males was significantly higher when compared to age-matched females. The specific growth rate of male VSMC was significantly higher on the third and sixth day after synchronisation. Angiotensin II in concentration 10~7 M stimulated the specific growth rate only in male VSMC during the exponential phase of growth. Moreover, doubling time was 3 hours shorter in male VSMC in comparison with the females. Our results suggest that both the increased specific growth rate and augmented growth-response of male VSMC to Ang II may explain the higher sensitivity of males to hypertensive stimuli.
The purpose of the current investigation was to evaluate the influence of antimycin A (AA) as an activator of the alternative respiratory pathway (AP) on photosynthetic pigment composition and functional activity of the photosynthetic apparatus of wheat seedlings (Triticum aestivum L.) under exposure to high temperature as well as their acclimation. Our results indicated that a significant decrease (44-74%) of photosynthetic pigment contents was caused by a long-term exposure to high temperature (42°C), while the short-term exposure resulted in 20-46% decline. However, a combined effect of AA and long-term high temperature reduced the total pigment contents by 28-41%. Our results demonstrated that the reduction of the chlorophyll a/b ratio was less significant under the combined effect of AA and high temperature than that under the stressful condition without AA. We observed that short-term and long-term high temperature modified PSII functionality of the first leaves in wheat seedlings, which was manifested by the low maximal quantum yield of PSII photochemistry, maximum fluorescence yield in the dark-adapted state, and by high minimum fluorescence yield in the dark-adapted state. The quantum yield of PSII photochemistry decreased rapidly by 16-24% under the combination of AA and high temperature. Overall, these results suggest that the activation of the alternative pathway, induced by AA, contributed to the stabilization of the photosynthetic apparatus in wheat seedlings under high temperature., A. Batjuka, N. Škute, A. Petjukevičs., and Obsahuje bibliografii
Chlorophenols, mainly used as biocides, are compounds with a wide spectrum of toxic effects including teratogenic and carcinogenic actions. In this study, the effects of 2,4-dichlorophenol (2,4-DCP) on hepatic microsomal cytochrome P-450, NADPH-cytochrome c reductase activity, liver ascorbic acid (AA) and glutathione (GSH) content were studied in guinea-pigs with a low (2 mg/day/animal) or a high (50 mg/day/animal) ascorbic acid intake. The high AA intake significantly increased liver AA and GSH levels. There was a clear-cut correlation between liver AA and GSH levels. Administration of 2,4-DCP significantly decreased cytochrome P-450 and f iADPH-cytochrome c reductase activity in hepatic microsomes isolated from guinea-pigs with the low AA intake. Such a reduction was not observed in intoxicated guinea-pigs with the high AA intake. The results suggest that AA can play a protective role in 2,4-DCP toxicity.
This research is a follow-up to the previous research which was dealing with the creation of the simulation of the vocal cords function using FEM. This paper focuses on how the vocal cords function is affected by Bernoulli's effect, while using model [1] is used. It is well known, that Bernoulli's effect is connected with the suction in the air space between the vocal cords. This is caused by the high air flow in glottis. The fastest and easiest way how to eliminate the influence of this effect is the change of every negative air pressure on the vocal cords to zero (i.e. the pressure applied as the loads on the vocal cords). Authors of some vocal cords models presume that Bernoulli's effect is the main force causing vocal cords vibrations. Changing the negative pressures to zero should cause that the vocal cords would not vibrate. However, the results of this research show the opposite. and Obsahuje seznam literatury
Viticulture is one of the most intensively managed agricultural ecosystems in Europe. Therefore, the conservation problems of vineyards and the ecological benefits of increasing the amount of fallow land are addressed using butterflies as a model group. We established 43 transects, each 100 m long, in a vineyard region in the vicinity of Trier (Rhineland-Palatinate, Germany) and recorded the butterflies observed along these transects on 20 occasions from late May to early August 2003. Transects crossed vineyards, fallow land and transitional areas of land. 4041 individuals of 34 species showed the typical pattern of relative abundance with few common and many relatively rare species. Fallow land had more individuals and species and a higher Shannon species diversity index than vineyards. Community evenness and average butterfly dispersal ability were highest in the vineyards. Principal Factor Analyses and UPGMA cluster analysis distinguished between fallow land and vineyards. The difference between early meadow and late forest fallow land areas was not strong, but the former tended to have a higher diversity than the latter. Vineyards thus might act as a sink for butterflies. Therefore, a clear separation between vineyards and fallow land is best for nature conservation. As young fallow land tends to have a higher diversity than older fallow land in this study, it is likely that the conservation value of vineyards for butterflies could be increased by active management of fallow land areas.
In order to utilize the absolute gravity ( AG) measurements in terms of tectonic study it is necessary to reduce all disturbing environmental and instrumental effects. Many of those can be easily modelled and this step is done routinely during measurements (i.e. tide, polar motion, ocean tidal loading). Other remains in data and there is a lack of conventional models for them. Significant gravity variation is associated with changes of soil water at global scale. We study this effect for the Lower Silesia (South-western Poland) territory. Computed gravity changes can reach up to 2 μgal peak-to-peak amplitude with seasonal time scale. This effect is beyond of accuracy of modern ballistic gravimeter. Using real data collected with FG5 gravimeter we show here that neglecting of this phenomenon can lead to serious misinterpretation in term of secular gravity changes. This is emphasized especially when only sparse data of a few year time span is at our disposal. No attempt of modelling of local hydrology impact on effect was made, while in this study we concentrate on large scale water storage influence on measured gravity., Marcin Rajner, Tomasz Olszak, Jerzy Rogowski and Janusz Walo., and Obsahuje bibliografické odkazy
Test stand for investigation of the influence of bearing bushing movement control on behaviour of a rigid rotor supported in sliding journal bearings was designed. The stand was equipped with two pairs of piezoactuators, enabling to move each bearing bushing in two directions, and with two pairs of relative sensors tracing shaft movement at both bearings. The initial tests showed quite unexpected phenomena, which should be cleared up, before experiments with controlled bearing bushing movement could be started. Finally the system began to operate according to predictions and it was possible to start intended experiments. Some results of the rotor behaviour with and without piezoactuator action are presented.