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3102. Bedform characteristics in a gravel-bed river
- Creator:
- Afzalimehr, Hossein, Maddahi, Mohammad Reza, and Sui, Jueyi
- Type:
- article, model:article, and TEXT
- Subject:
- bedform characteristics, gravel-bed river, field measurements, and form friction factor
- Language:
- Slovak
- Description:
- Estimation of hydraulic and geometric parameters of a gravel-bed river such as dimensions of bedforms is very difficult task, although they play a fundamental role in river engineering projects. One of the methods to get essential information regarding the bedform characteristics is to find the relations between the flow parameters and bedform dimensions. We conducted this field study in the Babolroud River in northern Iran to investigate the application of double averaged method in unspecific gravel bedforms to evaluate friction factor. Using data collected from several river reaches with total length of 356 m of a gravel-bed river, the relationship between bedform geometry (height and the length of bedforms) and flow parameters including shear velocity, transport stage parameter with friction factor is investigated. Different methods for estimating bedforms dimensions are examined to assess the ability of predicting bedform parameters (length and height) in a gravel-bed river. Using bedform parameters, the contribution of particle and form friction is estimated. Results confirm the application of the double averaged method and existing bedform parameters for unspecific bedforms. There exists a similar trend between aspect ratio and friction factor in gravel bedforms.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3103. Bedload equation analysis using bed load-material grain size
- Creator:
- Haddadchi, Arman, Omid, Mohammad H., and Dehghani, Amir A.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- sediment transport, grain size, gravel-bed river, and evaluation
- Language:
- Slovak
- Description:
- Twelve predictive bedload sediment transport equations are rated against 14 sets of gravel-bed river field data collected by handheld bedload sampler in Narmab River, northeastern Iran. To evaluate these formulas two types of grain size namely bedload and bed material were used. The results show that the equations of Engelund and Hansen, Van Rijn and Einstein perform well with bed material grain size, while Shocklitsch, Meyer-Peter and Mueller, and Frijlink yield the best results using the bedload grain size.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3104. Bedload transport and morphological effects of high-magnitude floods in small headwater streams - Moravskoslezské Beskydy Mts. (Czech Republic)
- Creator:
- Galia, Tomáš and Hradecký, Jan
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- incipient motion, bedload transport, headwater stream, Moravskoslezské Beskydy Mts., počátek pohybu, dnový transport, pramenný tok, and Moravskoslezské Beskydy
- Language:
- Slovak
- Description:
- Bedload transport observed during a flood in May 2010 gave rise to several forms of accumulations in small headwater basins located in the Western Flysch Carpathian Mountains, Czech Republic. We have investigated critical conditions of incipient motion of the largest boulders deposited during a c. Q100 flood event (flood competence method). We have tested several formulas designed for high gradient streams in two small basins in the conditions of local mid-mountain relief. The results show that a flood of such a magnitude is able to transport almost all surface bed material and that bedload transport in steep headwater streams (A ≤ 1 km2 ) is probably less selective as for the grain size than that in lower gradient gravel-bed streams. The authors discuss the importance of local basin predispostion factors in order to determine critical conditions for the onset of bedload transport. and Dnový transport sedimentů zapříčinil během květnových povodní v roce 2010 vznik různých typů akumulací v malých pramenných tocích nacházejících se ve flyšových pohořích Západních Karpat. Studie se zaměřuje na určení kritických podmínek nutných pro uvedení největších klastů do pohybu, jež byly následně uloženy do akumulací během této cca Q100 povodně (metoda účinnosti povodně). V rámci výzkumu byly ověřeny některé rovnice vytvořené pro vysokogradientové toky na dvou malých povodích v podmínkách reliéfu hornatin. Výsledky ukazují, že povodeň takové intenzity je schopna transportovat téměř celou povrchovou vrstvu sedimentů a dnový transport je na malých povodích pravděpodobně méně velikostně selektivní než v tocích s nižším gradientem dna. Důraz byl kladen také na lokální predizpoziční faktory ovlivňující kritické podmínky pro uvedení určité velikostní frakce sedimentů do pohybu.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3105. Bedřich Loewenstein, Milan Hlavačka, František Šístek a kol., Násilí. Jiná moderna
- Creator:
- Mrňka, Jaromír
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- political history, violence, and Bedřich Loewenstein
- Language:
- Czech
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3106. Bedřich Loewenstein, Víra v pokrok. Dějiny jedné evropské ideje
- Creator:
- Pullmann, Michal
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- human thinking and faith
- Language:
- Czech
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3107. Behavior of aluminum complexes in the altered coal and low temperature coal ashes
- Creator:
- Pavel Straka
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, uhlí, coal, aluminum complexes, altered coal, low temperature ashes, 7, and 551
- Language:
- English
- Description:
- An occurrence of tetra-coordinated aluminum in altered coal and low temperature coal ashes was investigated. As altered coal a sample from the Lazy mine (Upper Silesian Coal Basin) was tested, further, low-temperature ashes from different coals were prepared and measured. During preparation the selected coal samples were intensively air-oxidized; 27Al MAS NMR spectra of obtained ashes were then acquired and compared against those for initial coals. A reference wood ash and Al standards were used for identification of Al-forms. It was found that chemical shift at 4 ppm with coals corresponds to that for triaquo-hydroxo-diphenoxido-aluminum(III) complex (THDA), further, the shift at 72 ppm with altered coal and resulting ashes agrees with that for Al tetra-coordinated with oxygen. So, in the presence of coal organics the tetra-coordinated Al is formed under low temperature conditions, because during low temperature ashing the THDA complex is transformed to Al tetra-coordinated with oxygen only at 350 °C. A similar process occurred in the case of oxidation of coal substance under low temperature conditions in the nature at temperatures below 150 °C., Pavel Straka., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3108. Behavioral and antinociceptive effects of different psychostimulant drugs in prenatally methamphetamine-exposed rats
- Creator:
- Anna Yamamotová and Romana Šlamberová
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, antinociception, plantar test, prenatal methamphetamine, psychostimulant drugs, morphine, 14, and 612
- Language:
- English
- Description:
- Prenatal exposure to methamphetamine (METH) increases nociceptive sensitivity in adult rats. As the strong analgesics have high abuse potential and drugs of abuse are known to have analgesic properties, the aim was to study analgesic effect of different psychostimulants in control and prenatally METHexposed rats. Latencies of withdrawal reflexes of hind limbs and the tail on thermal nociceptive stimuli were repeatedly measured in 15-min intervals after the application of 5 mg/kg s.c. of amphetamine (AMPH), methamphetamine (METH), cocaine (COC), 3,4-methylenedioxymethamphetamine (MDMA) or morphine (MOR). In all groups, AMPH induced on hind limbs stronger analgesia than METH and MDMA whereas COC and MOR were practically without any effect. On the tail, effect of AMPH did not differ from that of MOR. All psychostimulants increased defecation in comparison with MOR and in all groups the number of defecation boluses positively correlated with analgesia of the hind limbs. We did not confirm that prenatal exposure to METH makes adult rats more sensitive either to same drug or to other psychostimulants. The different analgesic potencies of psychostimulants and MOR at different body sites indicate the possible existence of a somatotopic organization of pain inhibition, which is controlled by different mechanisms., A. Yamamotová, R. Šlamberová., and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3109. Behavioural responses of grey herons Ardea cinerea and great egrets Ardea alba to human-caused disturbance
- Creator:
- Novčić, Ivana
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- anthropogenic disturbance, vigilance, flight response, behaviour, and IBA
- Language:
- English
- Description:
- This study examined the effects of different types on anthropogenic disturbance on behaviours of grey herons Ardea cinerea, and great egrets Ardea alba, that gather in an Important Bird Area near Belgrade (Serbia), during their autumn migration, with the goal of assessing how diverse human-caused stimuli affect the behaviours of foraging and resting birds. I obtained behavioural data through scan sampling, with six categories of behaviour distinguished: vigilant, flying, feeding, comfort, inactive and other. In total, I collected 5,065 observations of individual birds: 1,293 for grey herons and 3,772 for great egrets. Significantly more birds were vigilant or in flight when they were disturbed by construction vehicles, military jets, and rural free-ranging dogs, whereas no statistical significance was associated with shooting and passing cars. Using a linear mixed model, it was shown that a greater proportion of birds was vigilant during disturbance than following disturbance or in the absence of disturbance, whereas air temperature and wind speed were not statistically significant. This study demonstrates that anthropogenic disturbance can alter the behaviour of the study species, which could aid future management and conservation planning.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3110. Behavioural study of polyandrous spawning in Blicca bjoerkna under a controlled environment
- Creator:
- Poncin, Pascal, Termol, Christel, Nzau Matondo, Billy, Philippart, Jean-Claude, and Kestemont, Patrick
- Type:
- article and TEXT
- Subject:
- reproductive activity, mating, silver bream, and cyprinids
- Language:
- English
- Description:
- This study describes the reproductive behaviour of silver bream, Blicca bjoerkna, in an aquarium environment with hormonal injection, constant temperature and natural photoperiod conditions. The results revealed that the reproductive behaviour of silver bream was polyandrous with courting tactics including a high level of tactile stimulation and following behaviour developed by the males, but without territorial or aggressive acts. The individual participation of males in mating acts showed a significant positive correlation with the individual participation of males in following a female. A successful spawning act included trembling movements and violent splashing while eggs and sperm were released on plants. The female mated with one to five males without an active inter- and intra-sexual selection.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/