Photosynthetic induction responses to a sudden increase in photosynthetic photon flux density (PPFD) from lower background PPFD (0, 25, 50, and 100 μmol m-2 s-1) to 1 000 μmol m-2 s-1 were measured in leaves of Fagus crenata, Acer rufinerve Siebold & Zucc., and Viburnum furcatum growing in a gap and understory of a F. crenata forest in the Naeba mountains. In the gap, A. rufinerve exhibited more than 1.2-fold higher maximum net photosynthetic rate (PNmax) than F. crenata and V. furcatum. Meanwhile, in the understory F. crenata exhibited the highest PNmax among the three species. The photosynthetic induction period required to reach PNmax was 3-41 min. The photosynthetic responses to increase in PPFD depended on the background PPFD before increase in PPFD. The induction period required to reach PNmax was 2.5-6.5-fold longer when PPFD increased from darkness than when PPFD increased from 100 μmol m-2 s-1. The induction period was correlated with initial PN and stomatal conductance (gs) relative to maximum values before increase in PPFD. The relationship was similar between the gap and the understory. As the background PPFD increased, the initial PN and gs increased, indicating that the degrees of biochemical and stomata limitations to dynamic photosynthetic performance decreased. Therefore, photosynthetic induction responses to increase in PPFD became faster with the increasing background PPFD. The differences in time required to reach induction between species, as well as between gap and understory, were mainly due to the varying of relative initial induction states in PN and gs at the same background PPFD. and M. Naramoto, Q. Han, Y. Kakubari.
The correlation between serum gastrin levels and gastric acid secretion during 4 weeks of cimetidine administration (once daily) was investigated. Serum gastrin levels and gastric acid secretion were estimated on the 7th, 14th, 21st and 28th day after cimetidine administration (25 mg.kg'1, intragastrically). At the mentioned time intervals gastric acid secretion stimulated by histamine and pentagastrin was also studied. It was found that on the 14th and 21th day after cimetidine administration serum gastrin levels were significantly elevated. Basal gastric acid secretion after cimetidine administration was significantly decreased at all the observed time intervals. Histamine-stimulated gastric acid secretion was increased on the 14th, 21st and 28th day after cimetidine administration Hypoacidity was not followed at all time intervals by hypergastrinaemia (only on day 14 and 21 after cimetidine).
We compared graft outcome between two types of a novel
composite three-layer carp-collagen-coated vascular graft in
low-flow conditions in a sheep model. Collagen in group A
underwent more cycles of purification than in group B in order to
increase the ratio between collagen and residual fat. The grafts
were implanted end-to-side in both carotid arteries in sheep
(14 grafts in 7 sheep in group A, 18 grafts in 9 sheep in group B)
and artificially stenosed on the right side. The flow in the grafts
in group A decreased from 297±118 ml/min to 158±159 ml/min
(p=0.041) after placement of the artificial stenosis in group A,
and from 330±164ml/min to 97±29 ml/min (p=0.0052) in
group B (p=0.27 between the groups). From the five surviving
animals in group A, both grafts occluded in one animal 3 and 14
days after implantation. In group B, from the six surviving
animals, only one graft on the left side remained patent
(p=0.0017). Histology showed degradation of the intimal layer in
the center with endothelization from the periphery in group A
and formation of thick fibrous intimal layer in group B. We
conclude that the ratio between collagen and lipid content in the
novel three-layer graft plays a critical role in its patency and
structural changes in vivo.
Toxoplasma gondii, a parasite infecting 20-60% of humans in various countries, influences the behaviour of infected animal and human hosts. Infected human subjects have changes in several of Cattell's and Cloninger's personality factors. Recently, three independent studies have shown that Rh-positive subjects are protected against the T. gondii-induced changes of reaction times and increased risk of traffic accidents. Here we searched for evidence of similar effects of RhD phenotype on toxoplasmosis- or aging-associated changes in the personality profile of about 302 blood donors. We found that Rh-positive and Rh-negative subjects responded differently to toxoplasmosis. In addition to the already known effects of toxoplasmosis on novelty seeking, self transcendence, superego strength and protension, we also found effects of RhD phenotype on ego strength, protension, and praxernia, as well as opposite effects of toxoplasmosis on ego strength, praxernia, ergic tension and cooperativeness in Rh-positive and Rh-negative subjects. Moreover, our results indicate that RhD phenotype might influence not only the effect of toxoplasmosis but also the effect of aging on specific personality traits.
The use of environmentally-friendly materials in hydraulic engineering (e.g. the stone lining of weirs at levees) calls for the more accurate estimation of the discharge coefficient for broad-crested weirs with a rough crest surface. However, in the available literature sources the discharge coefficient of broad-crested weirs is usually expressed for a smooth crest. The authors of this paper have summarized the theoretical knowledge related to the effect of weir crest surface roughness on the discharge coefficient. The method of determination of the head-discharge relation for broad-crested weirs with a rough crest surface is proposed based on known discharge coefficient values for smooth surfaces and on the roughness parameters of the weir. For selected scenarios the theoretical results were compared with experimental research carried out at the Laboratory of Water Management Research, Faculty of Civil Engineering (FCE), Brno University of Technology (BUT). and Používání přírodě blízkých materiálů ve vodním hospodářství (např. kamenná opevnění povrchu přelivů v ochranných hrázích) vyvolává požadavek přesnějšího stanovení součinitele průtoku pro přelivy se širokou a hydraulicky drsnou korunou. V dostupných literárních pramenech je součinitel průtoku přelivů se širokou korunou obvykle vyjádřen pouze pro hladký povrch koruny přelivu. Autoři článku shrnuli teoretické poznatky týkající se vlivu drsnosti povrchu koruny přelivu na součinitel průtoku a navrhli metodu pro stanovení způsobu hydraulického výpočtu konzumční křivky přepadu přes přeliv se širokou a drsnou korunou. Postup vychází ze znalosti součinitele průtoku přelivu s hladkou korunou a charakteristik drsnosti. Pro vybrané scénáře byly teoreticky vypočítané hodnoty porovnány s výsledky experimentálního výzkumu uskutečněného v Laboratoři vodohospodářského výzkumu Ústavu vodních staveb, Fakulty stavební, Vysokého učení technického v Brně.
Smoking is the most widespread substance dependence in the world. Nicotine and some other components of the cigarette smoke cause various endocrine imbalances, and have negative effects on pituitary, thyroid, adrenal, testicular and ovarian functions. Here, we examined studies that describe the influence of smoking and smoking cessation on the male and female reproductive systems. We also focused on studies providing an account of differences in cessation success rates between men and women. In men, the most common effects associated with smoking are erectile dysfunction and decreasing spermiogram quality. Several groups have studied the effects of cigarette smoking on testosterone levels in men. However, the results have been conflicting. In women, nicotine has an antiestrogen effect and increases the ratio of androgens to estrogens throughout life. Beside nicotine, other cigarette toxins also cause dysregulation of reproductive and hormonal system, and essentially influence the probability of a successful pregnancy not only in cases of assisted reproduction but also in healthy women. Tobacco addiction is one of the forms of addiction that are generally thought to be different for men and for women. Women are less successful than men in quitting smoking, and nicotine replacement therapy is less effective in female smokers. We also summarize recent studies that have indicated possible reasons., H. Jandíková, M. Dušková, L. Stárka., and Obsahuje bibliografii
The correct determination of material properties of construction materials from experiments is important not only during their development, but also during final verification. Specimens for testing mechanical properties of fiber-reinforced composites with a quasi-brittle matrix are usuall prepared by casting into a sutable mold. But they can be also prepared by cutting to desired shape from large body of material. The method of preparation may affect the measured values of material characteristics. In the case of sawed specimens, the fibers in surface layer are damaged, while in the case of casted specimens, fibers in surface layer tended to align with mold surface. The purpose of this article is to clarify the influence of these phenomena using numerical simulations. and Obsahuje seznam literatury
Stony soils are composed of two fractions (rock fragments and fine soil) with different hydrophysical characteristics. Although stony soils are abundant in many catchments, their properties are still not well understood. This manuscript presents an application of the simple methodology for deriving water retention properties of stony soils, taking into account a correction for the soil stoniness. Variations in the water retention of the fine soil fraction and its impact on both the soil water storage and the bottom boundary fluxes are studied as well. The deterministic water flow model HYDRUS-1D is used in the study. The results indicate that the presence of rock fragments in a moderate-to-high stony soil can decrease the soil water storage by 23% or more and affect the soil water dynamics. Simulated bottom fluxes increased or decreased faster, and their maxima during the wet period were larger in the stony soil compared to the non-stony one.
The influence of hormonal superovulation preparations of FSH (450 IU) or PMSG (1500 IU), on the levels of catecholamines (dopamine, norepinephrine and epinephrine) was studied in the oestrus period using radioenzymatic methods. The administration of FSH caused a significant increase in the concentrations of norepinephrine (NE) and epinephrine (EPI) in eminentia mediana (EM) of sheep (p<0.001 and p<0.01, respectively). The pituitary gland exhibited an increase in the level of norepinephrine after administration PMSG while no marked changes were recorded for epinephrine and dopamine (DA). The administration of FSH affected the increase in pituitary epinephrine (p<0.01). The hormonal stimulation by FSH resulted in a marked decrease of dopamine (p<0.05) as well as in , a significant increase of norepinephrine (p<0.05) and epinephrine (p<0.05) in the epiphysis. The comparison of the effect of hormonal preparations on the changes in catecholamine levels showed that the effect of FSH was observed mostly in eminentia mediana and the pituitary gland while that of PMSG was recorded in the epiphysis.
The development of Adalia bipunctata larvae feeding on the grain aphid Sitobion avenae was investigated at 15, 20 and 25°C and two different levels of food supply. Increased temperatures accelerated development and reduced mortality rates. A reduced food supply slowed down development and increased mortality at all life stages. The total food intake of larvae ranged from 24-65 mg, which is equivalent to up to 190 aphids. Larvae compensated for low food supply by reducing development rates, high prey exploitation efficiencies, reaching up to 100%, and by high prey-biomass conversion efficiencies, reaching over 40%. The findings are discussed under the aspect of suitability of A. bipunctata as a biological control agent for greenhouse-specific aphid pest species.