234 results on '"Velebil, P"'
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2. Varieties of Quantitative or Continuous Algebras (Extended Abstract)
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Adámek, Jiří, Dostál, Matěj, and Velebil, Jiří
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Mathematics - Category Theory - Abstract
Quantitative algebras are algebras enriched in the category $\mathsf{Met}$ of metric spaces so that all operations are nonexpanding. Mardare, Plotkin and Panangaden introduced varieties (aka $1$-basic varieties) as classes of quantitative algebras presented by quantitative equations. We prove that they bijectively correspond to strongly finitary monads $T$ on $\mathsf{Met}$. This means that $T$ is the Kan extension of its restriction to finite discrete spaces. An analogous result holds in the category $\mathsf{CMet}$ of complete metric spaces. Analogously, continuous algebras are algebras enriched in $\mathsf{CPO}$, the category of $\omega$-cpos, so that all operations are continuous. We introduce equations between extended terms, and prove that varieties (classes presented by such equations) correspond bijectively to strongly finitary monads $T$ on $\mathsf{CPO}$. This means that $T$ is the Kan extension of its restriction to finite discrete cpos. (The two results have substantially different proofs.) An analogous result is also presented for monads on $\mathsf{DCPO}$. We also characterize strong finitarity in all the categories above by preservations of certain weighted colimits. As a byproduct we prove that directed colimits commute with finite products in all cartesian closed categories.
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- 2023
3. Quantitative Algebras and a Classification of Metric Monads
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Adámek, J., Dostál, M., and Velebil, J.
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Mathematics - Category Theory - Abstract
Quantitative algebras are $\Sigma$-algebras acting on metric spaces, where operations are nonexpanding. Mardare, Panangaden and Plotkin introduced 1-basic varieties as categories of quantitative algebras presented by quantitative equations. We prove that for the category $\mathsf{UMet}$ of ultrametric spaces such varieties bijectively correspond to strongly finitary monads on $\mathsf{UMet}$. The same holds for the category $\mathsf{Met}$ of metric spaces, provided that strongly finitary endofunctors are closed under composition. For uncountable cardinals $\lambda$ there is an analogous bijection between varieties of $\lambda$-ary quantitative algebras and monads that are strongly $\lambda$-accessible. Moreover, we present a bijective correspondence between $\lambda$-basic varieties as introduced by Mardare et al and enriched, surjections-preserving $\lambda$-accesible monads on $\mathsf{Met}$. Finally, for general enriched $\lambda$-accessible monads on $\mathsf{Met}$ a bijective correspondence to generalized varieties is presented.
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- 2022
4. Comparative Experimental Assessment of Pollutant Emission Behavior in Combustion of Untreated and Thermally Treated Solid Biofuels from Spruce Chips and Rapeseed Straw
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Jan Malaťák, Jan Velebil, Jiří Bradna, Marián Kučera, Arkadiusz Gendek, Monika Aniszewska, and Tatiana Alexiou Ivanova
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biomass ,biochar ,combustion ,carbon monoxide ,nitrogen oxides ,torrefaction ,Meteorology. Climatology ,QC851-999 - Abstract
Biomass energy for heating is going to be part of the spectrum of renewable energy sources. However, biomass combustion produces emissions of various pollutants with negative effects at both local and global scales. To reduce some of the locally important pollutant load, thermally treated biomass fuels may offer a partial solution. In this study, two biomass feedstocks, i.e., spruce chips and rapeseed straw, were thermally treated at 300 °C to produce biochars. Subsequently, both original materials and biochars were burned in a 25 kW retort combustion device. In both cases, the biochar showed lower emissions of carbon monoxide and nitrogen oxides, usually almost across the whole range of tested combustion conditions. In total, for the emission production per unit of net calorific value, the spruce biochar showed reductions in CO and NOx productions of 10.8% and 14.5%, respectively. More importantly, in rapeseed straw biochar, the difference was more pronounced. The total production was reduced by 28% and 42%, again in CO and NOx emissions, respectively.
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- 2024
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5. A categorical view of varieties of ordered algebras
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Adámek, J., Dostál, M., and Velebil, J.
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Mathematics - Category Theory ,18C15 - Abstract
It is well known that classical varieties of $\Sigma$-algebras correspond bijectively to finitary monads on $\mathsf{Set}$. We present an analogous result for varieties of ordered $\Sigma$-algebras, i.e., classes presented by inequations between $\Sigma$-terms. We prove that they correspond bijectively to strongly finitary monads on $\mathsf{Pos}$. That is, those finitary monads which preserve reflexive coinserters. We deduce that strongly finitary monads have a coinserter presentation, analogous to the coequaliser presentation of finitary monads due to Kelly and Power. We also show that these monads are liftings of finitary monads on $\mathsf{Set}$.
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- 2020
6. Physico-Mechanical and Energy Properties of Pine (Pinus sylvestris) and Beech (Fagus sylvatica) Wood from Railroad Ties
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Monika Aniszewska, Arkadiusz Gendek, Barbora Tamelová, Jan Malaťák, Jan Velebil, Jozef Krilek, Iveta Čabalová, Ireneusz Mikłaszewicz, Witold Zychowicz, Michał Drożdżek, and Andrzej Mazurek
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railroad ties ,wood hardness ,wood strength ,static compression ,static three-point bending ,calorific value ,Plant ecology ,QK900-989 - Abstract
The objective of the present work was to determine the physico-mechanical and energy properties of pine (Pinus sylvestris) and beech (Fagus sylvatica) wood from railroad ties. The ties were divided into internal and external parts as well as into parts impregnated and unimpregnated with creosote oil. The effects of creosote impregnation on wood hardness, compressive strength parallel to the grain, static bending strength, and calorific value were studied. The obtained results show that the parameters of the analyzed samples meet the standard requirements (EN 338) for construction wood (compressive and bending strength class: C50—pine; D70—beech). Depending on the particular property being studied, both pine and beech samples belong to the highest or one of the highest wood quality classes. Creosote oil considerably increased wood density (by 9% for beech and 19% for pine) but did not affect its hardness. Creosote impregnation significantly improved the compressive strength parallel to the grain of both wood species (beech: σc=51.99 MPa (IN); σc=57.78 MPa (OUT); pine: σc=36.56 MPa (IN); σc=42.45 MPa (OUT)); in the case of static bending strength, its value was increased for beech wood (σg=106.13 MPa (IN); σg=113.18 MPa (OUT)) and reduced for pine wood (σg=66.34 MPa (IN); σg=82.62 MPa (OUT)). The oil contained in wood from ties significantly elevated its calorific value (by 25% for beech and 10% for pine). Unfortunately, the presence of creosote oil currently prevents wood from railroad ties from being reused as the oil is deemed hazardous and carcinogenic. However, if it were possible to isolate the unimpregnated parts of railroad ties, they could be reapplied for construction or other uses.
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- 2024
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7. Rubus atroroseus (Rosaceae), a new species of the section Corylifolii from the Czech Republic
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Lepší, Martin, Lepší, Petr, and Velebil, Jiří
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- 2022
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8. Substituting Solid Fossil Fuels with Torrefied Timber Products
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Jan Malaťák, Martin Jankovský, Jitka Malaťáková, Jan Velebil, Arkadiusz Gendek, and Monika Aniszewska
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renewable fuels ,torrefaction ,spruce ,biochar ,economic analysis ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
As a push towards alternative and renewable resources for heat and power generation, biomass and thermally treated fuels from biomass may be viable options in the upcoming economic reality. This study the verified mass and energy balance of spruce woody biomass after low temperature pyrolysis between 250 and 550 °C. The results showed that low-temperature pyrolysis can yield high-grade biochar suitable for substitution of fossil fuels. Crucially, the net calorific value of biochar processed at 350 °C substantially exceeded that of brown coal. An economic analysis was carried out on the assumption of the current economic reality in the Czech Republic. It was shown that even if the price of the biochar slightly increased, it would still be beneficial to invest in torrefaction technology over paying carbon credits.
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- 2023
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9. Extending set functors to generalised metric spaces
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Balan, Adriana, Kurz, Alexander, and Velebil, Jiří
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Mathematics - Category Theory ,Computer Science - Logic in Computer Science ,18B35, 18D20 - Abstract
For a commutative quantale $\mathcal{V}$, the category $\mathcal{V}-cat$ can be perceived as a category of generalised metric spaces and non-expanding maps. We show that any type constructor $T$ (formalised as an endofunctor on sets) can be extended in a canonical way to a type constructor $T_{\mathcal{V}}$ on $\mathcal{V}-cat$. The proof yields methods of explicitly calculating the extension in concrete examples, which cover well-known notions such as the Pompeiu-Hausdorff metric as well as new ones. Conceptually, this allows us to to solve the same recursive domain equation $X\cong TX$ in different categories (such as sets and metric spaces) and we study how their solutions (that is, the final coalgebras) are related via change of base. Mathematically, the heart of the matter is to show that, for any commutative quantale $\mathcal{V}$, the `discrete' functor $D:\mathsf{Set}\to \mathcal{V}-cat$ from sets to categories enriched over $\mathcal{V}$ is $\mathcal{V}-cat$-dense and has a density presentation that allows us to compute left-Kan extensions along $D$., Comment: 57 pages; extended version of the paper presented at CALCO 2015; accepted for publication in LMCS; Sections 2.4 and 3.3 were added
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- 2018
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10. Spruce and Barley Elemental and Stochiometric Analysis Affected by the Impact of Pellet Production and Torrefaction
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Jeníček Lukáš, Neškudla Michal, Malaťák Jan, Velebil Jan, and Passian Luboš
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biomass ,biofuel ,carbon footprint ,greenhouse gas ,calorific value ,Agriculture (General) ,S1-972 - Abstract
Biomass is a potential biofuel which may help fighting high carbon dioxide emissions and negative impacts of global warming. Analysis of Norway spruce (Picea abies) and barley (Hordeum vulgare) were performed at the laboratory of Czech University of Life Sciences. Material was torrefied in an inert nitrogen atmosphere at the temperatures of 250 °C and 280 °C for 45 minutes. Elementary and stoichiometric parameters were monitored and impact of torrefaction and pellet production on carbon footprint was determined. Torrefied and pelleted material showed better fuel properties in comparison to the original material. Calorific value of the torrefied spruce wood chip increased by 12.27% when torrefied at the temperature of 250 °C, and by 25.41% when torrefied at the temperature of 280 °C.
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- 2021
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11. CO2 power cycle chemistry in the CV Řež experimental loop
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Jan Berka, Jakub Vojtěch Ballek, Ladislav Velebil, Eliška Purkarová, Alice Vagenknechtová, and Tomáš Hlinčík
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supercritical carbon dioxide ,sc-co2 ,power cycle chemistry ,materials ,purification ,purity control ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
Power cycles using carbon dioxide in a supercritical state (sc-CO2) can be used in both the nuclear and non-nuclear power industry. These systems are characterized by their advantages over steam power cycles, e. g., the sc-CO2 turbine is more compact than the steam turbine with a similar performance. The parameters and lifespan of the system are influenced by the purity of the CO2 in the circuit, especially the admixtures, such as O2, H2O, etc., cause the enhanced structural materials to degrade. Therefore, gas purification and purity control systems for the sc-CO2 power cycles should be proposed and developed. The inspiration for the proposal of these systems could stem from the gas, especially the CO2-cooled nuclear reactors operation. The first information concerning the CO2 and sc-CO2 power cycle chemistry was gathered in the first period of the project and it is summarized in the paper.
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- 2021
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12. The Effect of Reservoir Cultivation on Conventional Maize in Sandy-Loam Soil
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Daniel Vejchar, Jan Velebil, Karel Kubín, Jiří Bradna, and Jan Malaťák
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diking ,tied ridging ,surface runoff ,inter-row cultivation ,corn ,erosion ,Agriculture (General) ,S1-972 - Abstract
Maize grown on sloped areas is susceptible to surface runoff and soil erosion, especially if traditional technology with tillage is employed. As a result, other solutions are being sought that address this risk and are acceptable to farmers. The combination of inter-row cultivation with the formation of small reservoirs appears to be a suitable alternative solution applicable in traditional corn cultivation. In the years 2020, 2021, and 2022, three plots of land in southern Bohemia, Czech Republic, were selected for testing, on which this approach was tested. During the field experiments, three variants were compared each year: inter-row cultivation with reservoirs, inter-row cultivation only, and a control without any mechanical intervention. All variants were subjected to rain simulation, from which the surface runoff was evaluated. The highest retention of runoff was manifested with reservoir cultivation by 2.4–4.2 min, compared to the cultivated variant, and 2–4.2 min compared to the control. This result would correspond to a difference of 5.7–9.8 mm retained precipitation and 4.6 to 7.3 mm, respectively. The hydraulic conductivity of the soil was evaluated after canopy closure. The lowest values were invariably reached in the reservoirs, up to 88% lower than with the cultivated variant and 79% lower than the control. The fresh matter yield of forage maize was shown to be inconclusively higher by up to 10% in 2020 and 2022 in cultivation with reservoirs. However, the dry matter yield was always lower in the variant with reservoirs compared to inter-row cultivation only. Overall, reservoir cultivation appears to be an effective method for the retention of rainwater on agricultural land with a slope up to 6° without a significant effect on the yield of maize.
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- 2023
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13. The Impact of Nutshell Biochar on the Environment as an Alternative Fuel or as a Soil Amendment
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Lukáš Jeníček, Barbora Tunklová, Jan Malaťák, Jan Velebil, Jitka Malaťáková, Michal Neškudla, and František Hnilička
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biomass ,biofuel ,biochar ,calorific value ,nut shells ,phytotoxicity ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Walnut, pistachio, and peanut nutshells were treated by pyrolysis to biochar and analyzed for their possible usage as fuels or soil fertilizers. All the samples were pyrolyzed to five different temperatures, i.e., 250 °C, 300 °C, 350 °C, 450 °C, and 550 °C. Proximate and elemental analyses were carried out for all the samples, as well as calorific value and stoichiometric analysis. For sample usage as a soil amendment, phytotoxicity testing was performed and the content of phenolics, flavonoids, tannin, juglone, and antioxidant activity were determined. To characterize the chemical composition of walnut, pistachio, and peanut shells, lignin, cellulose, holocellulose, hemicellulose, and extractives were determined. As a result, it was found that walnut shells and pistachio shells are best pyrolyzed at the temperature of 300 °C and peanut shells at the temperature of 550 °C for their use as alternative fuels. The highest measured net calorific value was in pistachio shells, which were biochar pyrolyzed at 550 °C, of 31.35 MJ kg−1. On the other hand, walnut biochar pyrolyzed at 550 °C had the highest ash share of 10.12% wt. For their use as soil fertilizers, peanut shells were the most suitable when pyrolyzed at 300 °C, walnut shells at 300 and 350 °C, and pistachio shells at 350 °C.
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- 2023
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14. Micropropagation as a Tool for the Conservation of Autochthonous Sorbus Species of Czechia
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Jana Šedivá, Jiří Velebil, and Daniel Zahradník
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endemic species ,micropropagation ,ex vitro rooting ,substrate ,Sorbus ,Botany ,QK1-989 - Abstract
Members of the genus Sorbus are the only endemic tree species that occur in Czechia. They are important components of endangered plant communities. Their natural regeneration is usually problematic because of their mode of reproduction and because they can survive in rare populations with small numbers of individuals. The aim of this study was to develop a successful micropropagation protocol for selected Sorbus species, of which two are endemic (S. gemella and S. omissa) and two are hybrid (S. × abscondita and S. × kitaibeliana). We found significant differences in shoot induction and rooting ability between the Sorbus species under study. With the exception of S. × abscondita, N6-benzyladenine had a significantly greater effect on shoot regeneration, both in terms of shoot number and total shoot length, than meta-topolin. Root induction was key to the successful micropropagation of the Sorbus species studied. Our results show that four Sorbus species can be successfully rooted under ex vitro conditions, without a rooting powder treatment in a steamed peat-perlite substrate. Auxin-untreated microcuttings of S. gemella, S. × kitaibeliana and S. omissa, but not S. × abscondita, rooted better than ones treated with indole-3-butyric acid. This is the first time a micropropagation protocol for S. omissa, S. × abscondita and S. × kitaibeliana has been published.
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- 2023
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15. Are differences in caesarean section rates between countries in Europe decreasing or increasing?
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Velebil, P, primary, Tica, V, additional, Durox, M, additional, Nijhuis, J, additional, Alexander, S, additional, Zeitlin, J, additional, and Gissler, M, additional
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- 2023
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16. An elementary characterisation of sifted weights
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Dostál, Matěj and Velebil, Jiří
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Mathematics - Category Theory - Abstract
Sifted colimits (those that commute with finite products in sets) play a major role in categorical universal algebra. For example, varieties of (many-sorted) algebras are precisely the free cocompletions under sifted colimits of (many-sorted) Lawvere theories. Such a characterisation does not depend on the existence of finite products in algebraic theories, but on the above fact that these products commute with sifted colimits and another condition: finite products form a sound class of limits. In this paper we study the notion of soundness for general classes of weights in enriched category theory. We show that soundness of a given class of weights is equivalent to having a `nice' characterisation of flat weights for that class. As an application, we give an elementary characterisation of sifted weights for the enrichment in categories and in preorders. We also provide a number of examples of sifted weights using our elementary criterion., Comment: An erroneous definition of saturated classes of weights was corrected on page 2
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- 2014
17. Positive fragments of coalgebraic logics
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Balan, Adriana, Kurz, Alexander, and Velebil, Jiří
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Mathematics - Category Theory ,Computer Science - Logic in Computer Science - Abstract
Positive modal logic was introduced in an influential 1995 paper of Dunn as the positive fragment of standard modal logic. His completeness result consists of an axiomatization that derives all modal formulas that are valid on all Kripke frames and are built only from atomic propositions, conjunction, disjunction, box and diamond. In this paper, we provide a coalgebraic analysis of this theorem, which not only gives a conceptual proof based on duality theory, but also generalizes Dunn's result from Kripke frames to coalgebras for weak-pullback preserving functors. To facilitate this analysis we prove a number of category theoretic results on functors on the categories $\mathsf{Set}$ of sets and $\mathsf{Pos}$ of posets: Every functor $\mathsf{Set} \to \mathsf{Pos}$ has a $\mathsf{Pos}$-enriched left Kan extension $\mathsf{Pos} \to \mathsf{Pos}$. Functors arising in this way are said to have a presentation in discrete arities. In the case that $\mathsf{Set} \to \mathsf{Pos}$ is actually $\mathsf{Set}$-valued, we call the corresponding left Kan extension $\mathsf{Pos} \to \mathsf{Pos}$ its posetification. A $\mathsf{Set}$-functor preserves weak pullbacks if and only if its posetification preserves exact squares. A $\mathsf{Pos}$-functor with a presentation in discrete arities preserves surjections. The inclusion $\mathsf{Set} \to \mathsf{Pos}$ is dense. A functor $\mathsf{Pos} \to \mathsf{Pos}$ has a presentation in discrete arities if and only if it preserves coinserters of `truncated nerves of posets'. A functor $\mathsf{Pos} \to \mathsf{Pos}$ is a posetification if and only if it preserves coinserters of truncated nerves of posets and discrete posets. A locally monotone endofunctor of an ordered variety has a presentation by monotone operations and equations if and only if it preserves $\mathsf{Pos}$-enriched sifted colimits., Comment: 51 pages; accepted for publication; expanded and improved version of the previous submission. Proposition 4.15 is new; Section 6 was rewritten in view of new results (theorem 6.9, proposition 6.14, paragraphs A-D); references added
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- 2014
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18. Kan injectivity in order-enriched categories
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Adamek, Jiri, Sousa, Lurdes, and Velebil, Jiri
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Computer Science - Logic in Computer Science ,Mathematics - Category Theory - Abstract
Continuous lattices were characterised by Martin Escardo as precisely the objects that are Kan-injective w.r.t. a certain class of morphisms. We study Kan-injectivity in general categories enriched in posets. For every class H of morphisms we study the subcategory of all objects Kan-injective w.r.t. H and all morphisms preserving Kan-extensions. For categories such as Top_0 and Pos we prove that whenever H is a set of morphisms, the above subcategory is monadic, and the monad it creates is a Kock-Zoeberlein monad. However, this does not generalise to proper classes: we present a class of continuous mappings in Top_0 for which Kan-injectivity does not yield a monadic category., Comment: 23 pages
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- 2013
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19. Evaluation of Co and Nox Emissions in Real-Life Operating Conditions of Herbaceous Biomass Briquettes Combustion
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Malaťák Jan, Velebil Jan, Bradna Jiří, Gendek Arkadiusz, and Tamelová Barbora
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calorific value ,elementary analysis ,stoichiometry ,coefficient of excess air ,flue gas ,Agriculture (General) ,S1-972 - Abstract
The issue of carbon monoxide and nitrogen oxides emissions into the atmosphere is very current. This article thus focuses on the assessment of elemental composition of selected herbal biomass species and emission concentrations during combustion in a commonly available grate combustion device for briquetted fuel. In tests, emission concentrations were evaluated in contrast to the oxygen concentration in flue gas and flue gas temperatures. Samples of camelina (Camelina sativa), giant miscanthus (Miscanthus gigantheus), reed canary grass (Phalaris arundinacea L.) and sorghum (Sorghum bicolor) were used. Elementary and stoichiometric combustion analyses were conducted for these samples (LECO AC-600 semi-automatic calorimeter, CHN628 + S elemental analyser and LECO TGA-701 analyser). Analyses of C, H, N and S concentrations and calorific values showed that samples of briquetted herb biomass had insignificant differences and could be used for energy purposes without limitation. The limiting factor was the high amount of ash, which amounted to 6.59% of dry weight in reed canary grass briquette sample. Furthermore, a high percentage (1.91% wt.) of nitrogen was observed in reed canary grass briquettes. Such a high amount of nitrogen during combustion tests resulted in an increase in NOx emission levels in flue gas of the Phalaris arundinacea L. sample, in which it reached the maximum concentration of 375.20 mg·m−3. The combustion tests showed that even under steady-state conditions, high concentrations of carbon monoxide could not be avoided for tested briquetted biofuels without active regulation of the combustion process.
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- 2020
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20. Properties of Biochar Derived from Tea Waste as an Alternative Fuel and Its Effect on Phytotoxicity of Seed Germination for Soil Applications
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Barbora Tunklová, Lukáš Jeníček, Jan Malaťák, Michal Neškudla, Jan Velebil, and František Hnilička
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biomass ,biofuel ,biochar ,calorific value ,tea waste ,phytotoxicity ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Tea waste as a potential biofuel and bio fertilizer was analyzed. Samples were collected from various tea species and torrefied to five different temperatures. All samples were analyzed for their proximal composition and calorific value. From the results, stoichiometric properties were calculated. A phytotoxicity test was performed, and the germination index was measured. Tea waste torrefied at 350 °C may be suitable biofuel reaching the calorific value of 25–27 MJ kg−1, but with quite a high share of ash, up to 10%, which makes its use technically challenging and may lead to operating issues in a combustion chamber. The same biochar may be a suitable fertilizer for increasing the germination index, therefore, applicable to the soil. The non-torrefied sample and the sample treated at 250 °C are not suitable as fertilizers for being toxic. The total phenolic content in waste black tea was reduced from 41.26 to 0.21 mg g−1, depending on the torrefaction temperature. The total flavonoid content was also reduced from 60.49 to 0.5 mg g−1. The total antioxidant activity in the non-torrefied sample was 144 mg g−1, and after torrefaction at 550 °C, it was 0.82 mg g−1. The results showed that black tea waste residues have the potential for further use, for example, in agriculture as a soil amendment or as a potential biofuel.
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- 2022
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21. Reducing Emissions from Combustion of Grape Residues in Mixtures with Herbaceous Biomass
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Jan Malaťák, Jan Velebil, Jitka Malaťáková, Luboš Passian, Jiří Bradna, Barbora Tamelová, Arkadiusz Gendek, and Monika Aniszewska
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grape pomace ,stems ,Miscanthus sinensis ,carbon monoxide ,nitrogen oxides ,combustion test ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
The use of grape residues as a renewable energy source for combustion presents various problems. One of these is the excessive production of carbon monoxide and nitrogen oxides. Analyses and combustion tests were performed on white and red grape pomace as well as grape stems. To verify the possibility of a reduction in emissions, straw of Miscanthus sinensis was added to mixtures with red grape pomace. Emission concentrations of carbon monoxide and nitrogen oxides were determined on a grate combustion device with a nominal thermal output of 8 kW under steady-state conditions. In addition to these emission concentrations, the excess air factor and the flue gas temperature were monitored. The results show a high energy content in grape residues. In red grape pomace, the gross calorific value of dry matter reached 22.17 MJ kg−1. Unfavourable properties included high ash and nitrogen contents. During combustion tests on all types of grape residue, the emission concentrations of carbon monoxide were above the legal limit for the combustion of solid fuels. The addition of Miscanthus straw improved the behaviour during combustion. The maximum content of grape pomace in the mixture capable of meeting legislative emission requirements was 50% wt.
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- 2022
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22. Impact of Torrefaction on Fuel Properties of Aspiration Cleaning Residues
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Barbora Tamelová, Jan Malaťák, Jan Velebil, Arkadiusz Gendek, and Monika Aniszewska
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biochar ,torrefaction ,calorific potential ,fuel properties ,stoichiometry ,agricultural residues ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
To maximise the use of biomass for energy purposes, there are various options for converting biomass to biofuels through thermochemical conversion processes, one of which is torrefaction. Higher utilisation of waste from the aspiration cleaning of grains, such as wheat or maize, could be one of the means through which the dependence on fossil fuels could be reduced in the spirit of a circular economy. In this study, the effect of torrefaction on fuel properties of agricultural residues was investigated. The tested materials were waste by-products from the aspiration cleaning of maize grains and waste from wheat. The materials were treated by torrefaction under a nitrogen atmosphere (225 °C, 250 °C, and 275 °C), over a residence time of 30 min. During the treatment, weight loss was monitored as a function of time. Proximate and elemental composition, as well as calorific values, were analysed before and after torrefaction. Torrefaction has a positive effect on the properties of the fuels in the samples studied, as shown by the results. The carbon content increased the most between temperatures of 250 °C and 275 °C, i.e., by 11.7% wt. in waste from maize. The oxygen content in the maize waste samples decreased by 38.99% wt. after torrefaction, and in wheat waste, it decreased by 37.20% wt. compared to the original. The net calorific value increased with increasing temperatures of process and reached a value of 23.56 MJ·kg−1 at a peak temperature of 275 °C in by-products from maize. To express the influence of the treatments on combustion behaviour, stoichiometric combustion calculations were performed. Differences of up to 20% in stoichiometric combustion parameters were found between the two types of waste. A similar case was found for fuel consumption, where a difference of 19% was achieved for torrefaction at a temperature of 275 °C, which fundamentally differentiated these fuels.
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- 2022
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23. Relation lifting, with an application to the many-valued cover modality
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Bilkova, Marta, Kurz, Alexander, Petrisan, Daniela, and Velebil, Jiri
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Computer Science - Logic in Computer Science - Abstract
We introduce basic notions and results about relation liftings on categories enriched in a commutative quantale. We derive two necessary and sufficient conditions for a 2-functor T to admit a functorial relation lifting: one is the existence of a distributive law of T over the "powerset monad" on categories, one is the preservation by T of "exactness" of certain squares. Both characterisations are generalisations of the "classical" results known for set functors: the first characterisation generalises the existence of a distributive law over the genuine powerset monad, the second generalises preservation of weak pullbacks. The results presented in this paper enable us to compute predicate liftings of endofunctors of, for example, generalised (ultra)metric spaces. We illustrate this by studying the coalgebraic cover modality in this setting., Comment: 48 pages, accepted for publication in LMCS
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- 2013
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24. Relation Liftings on Preorders and Posets
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Bilkova, Marta, Kurz, Alexander, Petrisan, Daniela, and Velebil, Jiri
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Computer Science - Logic in Computer Science ,Mathematics - Category Theory - Abstract
The category Rel(Set) of sets and relations can be described as a category of spans and as the Kleisli category for the powerset monad. A set-functor can be lifted to a functor on Rel(Set) iff it preserves weak pullbacks. We show that these results extend to the enriched setting, if we replace sets by posets or preorders. Preservation of weak pullbacks becomes preservation of exact lax squares. As an application we present Moss's coalgebraic over posets.
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- 2012
25. Use of Spent Coffee Ground as an Alternative Fuel and Possible Soil Amendment
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Lukáš Jeníček, Barbora Tunklová, Jan Malaťák, Michal Neškudla, and Jan Velebil
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biomass ,biofuel ,calorific value ,spent coffee ground ,phytotoxicity ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Spent coffee ground is a massively produced coffee industry waste product whose reusage is beneficial. Proximate and ultimate and stochiometric analysis of torrefied spent coffee ground were performed and results were analyzed and compared with other research and materials. Spent coffee ground is a material with high content of carbon (above 50%) and therefore high calorific value (above 20 MJ·kg−1). Torrefaction improves the properties of the material, raising its calorific value up to 32 MJ·kg−1. Next, the phytotoxicity of the aqueous extract was tested using the cress test. The non-torrefied sample and the sample treated at 250 °C were the most toxic. The sample treated at 250 °C adversely affected the germination of the cress seeds due to residual caffeine, tannins and sulfur release. The sample treated at 350 °C performed best of all the tested samples. The sample treated at 350 °C can be applied to the soil as the germination index was higher than 50% and can be used as an alternative fuel with net calorific value comparable to fossil fuels.
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- 2022
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26. Semantics of Higher-Order Recursion Schemes
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Adamek, Jiri, Milius, Stefan, and Velebil, Jiri
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Computer Science - Logic in Computer Science ,Mathematics - Category Theory ,math.CT - Abstract
Higher-order recursion schemes are recursive equations defining new operations from given ones called "terminals". Every such recursion scheme is proved to have a least interpreted semantics in every Scott's model of \lambda-calculus in which the terminals are interpreted as continuous operations. For the uninterpreted semantics based on infinite \lambda-terms we follow the idea of Fiore, Plotkin and Turi and work in the category of sets in context, which are presheaves on the category of finite sets. Fiore et al showed how to capture the type of variable binding in \lambda-calculus by an endofunctor H\lambda and they explained simultaneous substitution of \lambda-terms by proving that the presheaf of \lambda-terms is an initial H\lambda-monoid. Here we work with the presheaf of rational infinite \lambda-terms and prove that this is an initial iterative H\lambda-monoid. We conclude that every guarded higher-order recursion scheme has a unique uninterpreted solution in this monoid.
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- 2011
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27. Algebraic Theories over Nominal Sets
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Kurz, Alexander, Petrişan, Daniela, and Velebil, Jiří
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Computer Science - Logic in Computer Science ,Mathematics - Category Theory - Abstract
We investigate the foundations of a theory of algebraic data types with variable binding inside classical universal algebra. In the first part, a category-theoretic study of monads over the nominal sets of Gabbay and Pitts leads us to introduce new notions of finitary based monads and uniform monads. In a second part we spell out these notions in the language of universal algebra, show how to recover the logics of Gabbay-Mathijssen and Clouston-Pitts, and apply classical results from universal algebra., Comment: 16 pages
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- 2010
28. Final coalgebras in accessible categories
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Karazeris, Panagis, Matzaris, Apostolos, and Velebil, Jiri
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Mathematics - Category Theory ,18C35 - Abstract
We give conditions on a finitary endofunctor of a finitely accessible category to admit a final coalgebra. Our conditions always apply to the case of a finitary endofunctor of a locally finitely presentable (l.f.p.) category and they bring an explicit construction of the final coalgebra in this case. On the other hand, there are interesting examples of final coalgebras beyond the realm of l.f.p. categories to which our results apply. We rely on ideas developed by Tom Leinster for the study of self-similar objects in topology., Comment: 23 pages
- Published
- 2009
29. MONITORING AND PROTECTION OF TIMBER-CONCRETE BRIDGES
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Petr Kuklík, Lukáš Velebil, Anna Gregorová, and Petr Svora
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bridges, concrete, timber, timber-concrete composite, monitoring, durability ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
The majority of timber bridges for ordinary road traffic are often made as timber-concrete composite structures. Concrete slab is something like as umbrella for timber. The reason for problems in timber-concrete bridges is nearly always poor detailing for durability and neglected maintenance. Mainly all aspects of timber protection and maintenance should therefore be considered even during the planning phase of bridge. Paper deals with evaluation of timber properties, system of opto-fiber sensors for monitoring and diagnostics of mechanical stress of timber-concrete bridges, and degradation of timber due to UV radiation, atmospheric conditions and biological agents after application of photocatalytic materials on surface.
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- 2019
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30. Decolorization and Oxidation of Acid Blue 80 in Homogeneous and Heterogeneous Phases by Selected AOP Processes
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Jiří Palarčík, Olga Krupková, Petra Peroutková, Jan Malaťák, Jan Velebil, Jaromíra Chýlková, and Libor Dušek
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Acid Blue 80 ,Fenton oxidation ,dye photolysis ,photocatalytic oxidation ,Chemical technology ,TP1-1185 ,Chemistry ,QD1-999 - Abstract
This paper is a kinetic study that compares the rate of decolorization and subsequently the mineralization of Acid Blue 80 in model dyeworks wastewater, both in the homogeneous phase using the Fenton and photo-Fenton reactions, UV-C and UVC/H2O2 processes, and in the heterogeneous phase, where the proven commercial photocatalysts P25, P90, and AV01 based on TiO2 were used. The influence of pH of the environment was studied and in the case of the Fenton reaction, the influence of the concentration of catalyzing Fe2+ ions on the rate of decolorization of the model wastewater was also studied. The optimal molar ratio of H2O2/Fe2+ was 10:1. For describing the reaction kinetics, first-order speed constants were best-suited. In all applied processes, the dye chromophore degraded, which was accompanied by a quantitative decolorization of the model wastewater. Subsequently, the mineralization of colorless intermediate products was studied through a decrease in COD or, more precisely, TOC. The mineralization efficiency in the homogeneous phase ranged between 18.6 and 97.1% after 24 h. In the case of heterogeneous photocatalysis, it ranged between 79.6 and 97.3% after 24 h, with efficiency declining in the order P90 > P25 > AV01.
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- 2022
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31. Elgot Algebras
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Adamek, Jiri, Milius, Stefan, and Velebil, Jiri
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Computer Science - Logic in Computer Science ,Mathematics - Category Theory ,F.3.2 - Abstract
Denotational semantics can be based on algebras with additional structure (order, metric, etc.) which makes it possible to interpret recursive specifications. It was the idea of Elgot to base denotational semantics on iterative theories instead, i.e., theories in which abstract recursive specifications are required to have unique solutions. Later Bloom and Esik studied iteration theories and iteration algebras in which a specified solution has to obey certain axioms. We propose so-called Elgot algebras as a convenient structure for semantics in the present paper. An Elgot algebra is an algebra with a specified solution for every system of flat recursive equations. That specification satisfies two simple and well motivated axioms: functoriality (stating that solutions are stable under renaming of recursion variables) and compositionality (stating how to perform simultaneous recursion). These two axioms stem canonically from Elgot's iterative theories: We prove that the category of Elgot algebras is the Eilenberg-Moore category of the monad given by a free iterative theory.
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- 2006
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32. On coalgebra based on classes
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Adamek, J., Milius, S., and Velebil, J.
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Computer Science - Logic in Computer Science ,F.4.1 - Abstract
Every endofunctor of the category of classes is proved to be set-based in the sense of Aczel and Mendler, therefore, it has a final coalgebra. Other basic properties of these endofunctors are proved, e.g. the existence of a free completely iterative theory.
- Published
- 2003
33. Evaluation of Small-Scale Gasification for CHP for Wood from Salvage Logging in the Czech Republic
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Jitka Malaťáková, Martin Jankovský, Jan Malaťák, Jan Velebil, Barbora Tamelová, Arkadiusz Gendek, and Monika Aniszewska
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spruce ,gasifier ,salvage logging ,bark beetle ,net present value ,internal rate of return ,Plant ecology ,QK900-989 - Abstract
This study focused on small gasification units for combined heat and power generation (CHP) up to 200 kW of electric power, which can use wood from salvage logging, and assessed the current feasibility of running commercially available units in the conditions of the Czech Republic. In total, the technical and economic parameters of 21 gasification units from ten major international producers were compiled. One of the most important parameters assessed was the net calorific value, which in the analysed samples of spruce wood was determined at 18.37 MJ kg−1 on a dry basis. This complies to the requirements for fuel quality for these units. The economic profitability was determined for three investment variants with electric power of 10, 100, and 200 kWel in an operating mode of constant power at 20 and 30 wt.% input moisture level of the wood. Economic analysis showed that smaller alternatives with an output of 10 and 100 kWel produce economic losses. On the other hand, the 200-kWel alternative produced operating profit and positive cash flow at both fuel moisture levels in the first year of operation. The evaluation of individual alternatives using dynamic investment evaluation methods also showed that only the alternative with an output of 200 kWel with both fuel moistures was able to produce a positive net present value.
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- 2021
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34. Mass yield of biochar from hydrothermal carbonization of sucrose
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J. Velebil, J. Malaťák, and J. Bradna
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htc ,wet torrefaction ,reaction time ,mixing ,process liquid ,Agriculture (General) ,S1-972 - Abstract
In this article, the effect of increasing dry matter content and reaction time of hydrothermal carbonization on mass yield of biochar was studied. Carbonization took place in batch experiments in a pressure vessel. Results have confirmed the assumption that the mass yield of biochar would increase with growing dry matter content in the initial solution and also with reaction time at reaction temperature of 200°C. It was found that components of the liquid product that remain in the biochar have a measurable impact on its mass yield. Mixing of the reactor proved to have a considerable effect on the mass yield as well. Biochar produced in absence of mixing had higher pore volume and higher yield. This was evident even after subtracting the equivalent liquid phase dry matter in the biochar after drying.
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- 2016
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35. Extending set functors to generalised metric spaces
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Adriana Balan, Alexander Kurz, and Jiří Velebil
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mathematics - category theory ,computer science - logic in computer science ,18b35, 18d20 ,Logic ,BC1-199 ,Electronic computers. Computer science ,QA75.5-76.95 - Abstract
For a commutative quantale $\mathcal{V}$, the category $\mathcal{V}-cat$ can be perceived as a category of generalised metric spaces and non-expanding maps. We show that any type constructor $T$ (formalised as an endofunctor on sets) can be extended in a canonical way to a type constructor $T_{\mathcal{V}}$ on $\mathcal{V}-cat$. The proof yields methods of explicitly calculating the extension in concrete examples, which cover well-known notions such as the Pompeiu-Hausdorff metric as well as new ones. Conceptually, this allows us to to solve the same recursive domain equation $X\cong TX$ in different categories (such as sets and metric spaces) and we study how their solutions (that is, the final coalgebras) are related via change of base. Mathematically, the heart of the matter is to show that, for any commutative quantale $\mathcal{V}$, the `discrete' functor $D:\mathsf{Set}\to \mathcal{V}-cat$ from sets to categories enriched over $\mathcal{V}$ is $\mathcal{V}-cat$-dense and has a density presentation that allows us to compute left-Kan extensions along $D$.
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- 2019
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36. Energy Utilization of Torrefied Residue from Wine Production
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Barbora Tamelová, Jan Malaťák, Jan Velebil, Arkadiusz Gendek, and Monika Aniszewska
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biochar ,torrefaction ,elemental analysis ,energy properties ,bioenergy ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
A significant amount of waste is generated in the food industry, which is both an environmental and an economic problem. The recycling of this waste has become an important area of research. The processing of grapes produces 20–30% of the waste in the form of grape pomace and stalks. This article assesses the fuel values of these materials before and after torrefaction. The input materials were grape pomace samples from the varieties Riesling (Vitis vinifera “Welschriesling”) and Cabernet Sauvignon (Vitis vinifera “Cabernet Sauvignon”) from the South Moravia region and stalks from the variety Welschriesling. The torrefaction process was performed using a LECO TGA 701 thermogravimetric analyzer under nitrogen atmosphere at set temperatures of 225 °C, 250 °C, and 275 °C. The residence time was 30 min. Elemental analysis, calorific value, and gross calorific value were determined for all samples. The analyses show a positive effect of torrefaction on fuel properties in the samples. Between temperatures 250 °C and 275 °C, the carbon content increased by 4.29 wt.%, and the calorific value increased with the increase in temperature reaching a value of 25.84 MJ·kg−1 at a peak temperature of 275 °C in the sample grape pomace from blue grapevine.
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- 2021
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37. Changes in the Composition and Surface Properties of Torrefied Conifer Cones
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Monika Aniszewska, Arkadiusz Gendek, Štěpán Hýsek, Jan Malaťák, Jan Velebil, and Barbora Tamelová
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torrefaction ,weight loss ,lower heating value ,elemental composition ,SEM ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
The paper investigated the torrefaction of cones from three tree species: Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies L.), and European larch (Larix decidua Mill.). The objective was to determine the effects of torrefaction temperature on the properties of cones with a view to their further use as a renewable energy source. Torrefaction was conducted at 200, 235, 275, and 320 °C for 60 min under an inert gas atmosphere. Elemental composition, ash content, and lower heating value (LHV) were measured for the original and torrefied samples. Torrefaction performance was evaluated using formulas for solid yield, higher heating value (HHV), HHV enhancement factor, as well as energy yield. Scanning electron microscopy (SEM) was used to assess elemental composition and structural changes at the surface of the torrefied material. For all the studied conifer species, the higher the torrefaction temperature, the greater the carbon and ash content and the higher the LHV (a maximum of 27.6 MJ·kg−1 was recorded for spruce and larch cones torrefied at 320 °C). SEM images showed that an increase in process temperature from 200 to 320 °C led to partial decomposition of the scale surface as a result of lignin degradation. Cone scales from all tree species revealed C, O, N, Mg, K, and Si at the surface (except for pine scales, which did not contain Si). Furthermore, the higher the temperature, the higher the enhancement factor and the lower the energy yield of the torrefied biomass. Under the experimental conditions, spruce cones were characterized by the lowest weight loss, the highest HHV, and the highest energy yield, and so they are deemed the best raw material for torrefaction among the studied species.
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- 2020
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38. Achieving more with less: lessons from country-level analyses of caesarean delivery and perinatal outcomes in Europe
- Author
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Zeitlin, J, primary, Mortensen, L, additional, Nijhuis, JG, additional, Recio Alcaide, A, additional, Velebil, P, additional, Tica, V, additional, Mierzejewska, E, additional, Klungsoyr, K, additional, Donati, S, additional, and Macfarlane, A, additional
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- 2022
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39. Laboratory and In-Situ Testing of Integrated FBG Sensors for SHM for Concrete and Timber Structures
- Author
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Kristýna Čápová, Lukáš Velebil, and Jan Včelák
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mechanical strain monitoring ,shm ,fbg sensors ,concrete ,bridge structure ,testing ,Chemical technology ,TP1-1185 - Abstract
Long-term structural health monitoring (SHM) plays an important role in the safety of public transport infrastructure such as bridges or tunnels and warns in the event of any emerging problem. This article describes development and testing of system based on fiber Bragg grating (FBG) sensors that can detect changes in strain and temperature. The first phase of the research has been focused on the development of new fiber optic sensors for the monitoring of concrete structures and their investigation in laboratory conditions. The work also shows novel applicability of the same FBG technology for glulam structures. Mechanical loading tests of the concrete beam as well as glulam beam with embedded sensors were carried out. Data measured by developed fiber optic sensors were compared with the readings from reference sensors as well as with the analytically calculated values. The achieved results proved good agreement between the measured data, analytical data and reference methods. In second phase of the research, the pilot installation of the sensors was carried out on the newly constructed prestressed-concrete bridge. The bridge was monitored throughout pre-stressing phase and monitoring continued after the completion of the construction works. Problems with the fragility of the sensors occurred during the measurements, but the obtained results provide a good basis for further improvement of the system.
- Published
- 2020
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40. Morita Equivalence for Many-Sorted Enriched Theories
- Author
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Dostál, Matĕj and Velebil, Jiří
- Published
- 2016
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41. Using Robson's Ten‐Group Classification System for comparing caesarean section rates in Europe: an analysis of routine data from the Euro‐Peristat study
- Author
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Zeitlin, J., Durox, M., Macfarlane, A. J., Alexander, S., Heller, G., Loghi, M., Nijhuis, J., Sól Ólafsdóttir, H., Mierzejewska, E., Gissler, M., Blondel, B., Haidinger, G., Klimont, J., Vandervelpen, G., Zhang, W-H., Jordanova, E., Kolarova, R., Filipovic‐Grcic, B., Drausnik, Z., Rodin, U., Kyprianou, T., Scoutellas, V., Velebil, P., Mortensen, L., Sakkeus, L., Heino, A., Chantry, A., Deneux Tharaux, C., Lack, N., Antsaklis, A., Berbik, I., Bonham, S., Kearns, K., Sikora, I., Cuttini, M., Misins, J., Zile, I., Isakova, J., Billy, A., Couffignal, S., Lecomte, A., Weber, G., Gatt, M., Achterberg, P., Broeders, L., Hindori‐Mohangoo, A., Akerkar, R., Klungsøyr, K., Szamotulska, K., Barros, H., Horga, M., Tica, V., Cap, J., Tul, N., Verdenik, I., Bolumar, F., Jané, M., Alcaide, A. R., Vidal, M. J., Zurriaga, O., Kallen, K., Nyman, A., Berrut, S., Riggenbach, M., Rihs, T. A., Smith, L., Woods, R., Delnord, M., Hocquette, A., RS: GROW - R4 - Reproductive and Perinatal Medicine, MUMC+: MA Obstetrie Gynaecologie (3), Obstetrie & Gynaecologie, and Instituto de Saúde Pública da Universidade do Porto
- Subjects
medicine.medical_specialty ,ten-group classification system ,Epidemiology ,RJ ,medicine.medical_treatment ,Population ,RT ,03 medical and health sciences ,0302 clinical medicine ,Pregnancy ,RA0421 ,medicine ,Humans ,Caesarean section ,Ten‐Group Classification System ,education ,perinatal health indicators ,reproductive and urinary physiology ,education.field_of_study ,030219 obstetrics & reproductive medicine ,Cesarean Section ,Singleton ,business.industry ,Obstetrics ,Obstetrics and Gynecology ,Gestational age ,Original Articles ,Corrigenda ,Robson classification ,Ten group classification system ,Europe ,Caesarean Birth ,Data quality ,health information systems ,Female ,Original Article ,Caesarean birth ,Observational study ,RG ,business ,Live Birth - Abstract
Objective Robson's Ten Group Classification System (TGCS) creates clinically relevant sub‐groups for monitoring caesarean birth rates. This study assesses whether this classification can be derived from routine data in Europe and uses it to analyse national caesarean rates. Design Observational study using routine data. Setting Twenty‐seven EU member states plus Iceland, Norway, Switzerland and the UK. Population All births at ≥22 weeks of gestational age in 2015. Methods National statistical offices and medical birth registers derived numbers of caesarean births in TGCS groups. Main outcome measures Overall caesarean rate, prevalence and caesarean rates in each of the TGCS groups. Results Of 31 countries, 18 were able to provide data on the TGCS groups, with UK data available only from Northern Ireland. Caesarean birth rates ranged from 16.1 to 56.9%. Countries providing TGCS data had lower caesarean rates than countries without data (25.8% versus 32.9%, P = 0.04). Countries with higher caesarean rates tended to have higher rates in all TGCS groups. Substantial heterogeneity was observed, however, especially for groups 5 (previous caesarean section), 6, 7 (nulliparous/multiparous breech) and 10 (singleton cephalic preterm). The differences in percentages of abnormal lies, group 9, illustrate potential misclassification arising from unstandardised definitions. Conclusions Although further validation of data quality is needed, using TGCS in Europe provides valuable comparator and baseline data for benchmarking and surveillance. Higher caesarean rates in countries unable to construct the TGCS suggest that effective routine information systems may be an indicator of a country's investment in implementing evidence‐based caesarean policies. Tweetable abstract Many European countries can provide Robson's Ten‐Group Classification to improve caesarean rate comparisons., Tweetable abstract Many European countries can provide Robson's Ten‐Group Classification to improve caesarean rate comparisons.
- Published
- 2021
42. Cross-Country Individual Participant Analysis of 4.1 Million Singleton Births in 5 Countries with Very High Human Development Index Confirms Known Associations but Provides No Biologic Explanation for 2/3 of All Preterm Births.
- Author
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David M Ferrero, Jim Larson, Bo Jacobsson, Gian Carlo Di Renzo, Jane E Norman, James N Martin, Mary D'Alton, Ernesto Castelazo, Chris P Howson, Verena Sengpiel, Matteo Bottai, Jonathan A Mayo, Gary M Shaw, Ivan Verdenik, Nataša Tul, Petr Velebil, Sarah Cairns-Smith, Hamid Rushwan, Sabaratnam Arulkumaran, Jennifer L Howse, and Joe Leigh Simpson
- Subjects
Medicine ,Science - Abstract
BACKGROUND:Preterm birth is the most common single cause of perinatal and infant mortality, affecting 15 million infants worldwide each year with global rates increasing. Understanding of risk factors remains poor, and preventive interventions have only limited benefit. Large differences exist in preterm birth rates across high income countries. We hypothesized that understanding the basis for these wide variations could lead to interventions that reduce preterm birth incidence in countries with high rates. We thus sought to assess the contributions of known risk factors for both spontaneous and provider-initiated preterm birth in selected high income countries, estimating also the potential impact of successful interventions due to advances in research, policy and public health, or clinical practice. METHODS:We analyzed individual patient-level data on 4.1 million singleton pregnancies from four countries with very high human development index (Czech Republic, New Zealand, Slovenia, Sweden) and one comparator U.S. state (California) to determine the specific contribution (adjusting for confounding effects) of 21 factors. Both individual and population-attributable preterm birth risks were determined, as were contributors to cross-country differences. We also assessed the ability to predict preterm birth given various sets of known risk factors. FINDINGS:Previous preterm birth and preeclampsia were the strongest individual risk factors of preterm birth in all datasets, with odds ratios of 4.6-6.0 and 2.8-5.7, respectively, for individual women having those characteristics. In contrast, on a population basis, nulliparity and male sex were the two risk factors with the highest impact on preterm birth rates, accounting for 25-50% and 11-16% of excess population attributable risk, respectively (p
- Published
- 2016
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43. Variations in Multiple Birth Rates and Impact on Perinatal Outcomes in Europe.
- Author
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Anna Heino, Mika Gissler, Ashna D Hindori-Mohangoo, Béatrice Blondel, Kari Klungsøyr, Ivan Verdenik, Ewa Mierzejewska, Petr Velebil, Helga Sól Ólafsdóttir, Alison Macfarlane, Jennifer Zeitlin, and Euro-Peristat Scientific Committee
- Subjects
Medicine ,Science - Abstract
OBJECTIVE:Infants from multiple pregnancies have higher rates of preterm birth, stillbirth and neonatal death and differences in multiple birth rates (MBR) exist between countries. We aimed to describe differences in MBR in Europe and to investigate the impact of these differences on adverse perinatal outcomes at a population level. METHODS:We used national aggregate birth data on multiple pregnancies, maternal age, gestational age (GA), stillbirth and neonatal death collected in the Euro-Peristat project (29 countries in 2010, N = 5 074 643 births). We also used European Society of Human Reproduction and Embryology (ESHRE) data on assisted conception and single embryo transfer (SET). The impact of MBR on outcomes was studied using meta-analysis techniques with random-effects models to derive pooled risk ratios (pRR) overall and for four groups of country defined by their MBR. We computed population attributable risks (PAR) for these groups. RESULTS:In 2010, the average MBR was 16.8 per 1000 women giving birth, ranging from 9.1 (Romania) to 26.5 (Cyprus). Compared to singletons, multiples had a nine-fold increased risk (pRR 9.4, 95% Cl 9.1-9.8) of preterm birth (
- Published
- 2016
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44. Small babies, big risks: global estimates of prevalence and mortality for vulnerable newborns to accelerate change and improve counting
- Author
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Lawn, Joy E, Ohuma, Eric O, Bradley, Ellen, Idueta, Lorena Suárez, Hazel, Elizabeth, Okwaraji, Yemisrach B, Erchick, Daniel J, Yargawa, Judith, Katz, Joanne, Lee, Anne C C, Diaz, Mike, Salasibew, Mihretab, Requejo, Jennifer, Hayashi, Chika, Moller, Ann-Beth, Borghi, Elaine, Black, Robert E, Blencowe, Hannah, Ashorn, Per, Black, Robert E, Lawn, Joy E, Ashorn, Ulla, Klein, Nigel, Hofmeyr, G Justus, Temmerman, Marleen, Askari, Sufia, Ohuma, Eric O, Moller, Ann-Beth, Bradley, Ellen, Chakwera, Samuel, Hussain-Alkhateeb, Laith, Lewin, Alexandra, Okwaraji, Yemisrach B, Retno Mahanani, Wahyu, White Johansson, Emily, Lavin, Tina, Estevez Fernandez, Diana, Gatica Domínguez, Giovanna, de Costa, Ayesha, Cresswell, Jenny A, Krasevec, Julia, Lawn, Joy E, Blencowe, Hannah, Requejo, Jennifer, Moran, Allisyn C, Pingray, Veronica, Cormick, Gabriela, Gibbons, Luz, Belizan, José, Guevel, Carlos, Warrilow, Kara, Gordon, Adrienne, Flenady, Vicki, Sexton, Jessica, Lawford, Harriet, Paixao, Enny S., Rocha Falcão, Ila, Lima Barreto, Mauricio, Lisonkova, Sarka, Wen, Qi, Mardones, Francisco, Caulier-Cisterna, Raúl, Acuña, José, Velebil, Petr, Jirova, Jitka, Horváth-Puhó, Erzsébet, Sørensen, Henrik Toft, Sakkeus, Luule, Abuladze, Liili, Gissler, Mika, Moradi-Lakeh, Maziar, Heidarzadeh, Mohammad, Khalili, Narjes, A. Yunis, Khalid, Al Bizri, Ayah, Nakad, Pascale, Devi Karalasingam, Shamala, R Jeganathan, J Ravichandran, binti Baharum, Nurakman, Suárez-Idueta, Lorena, Barranco Flores, Arturo, Gonzalez Roldan, Jesus F, Lopez Alvarez, Sonia, van Dijk, Aimée E., Broeders, Lisa, Huicho, Luis, Quezada Pinedo, Hugo G, Cajachagua-Torres, Kim N, Carrillo-Larco, Rodrigo M, Tarazona Meza, Carla Estefania, Guzman-Vilca, Wilmer Cristobal, Olukade, Tawa O., Ali, Hamdy A., Alyafei, Fawziya, AlQubaisi, Mai, Alturk, Mohamad R, Kim, Ho Yeon, Cho, Geum Joon, Razaz, Neda, Söderling, Jonas, Smith, Lucy K, Kurinczuk, Jennifer J, Matthews, Ruth J, Manktelow, Bradley N, Draper, Elizabeth S, Fenton, Alan C, Lowry, Estelle, Rowland, Neil, Wood, Rachael, Monteath, Kirsten, Pereyra, Isabel, Pravia, Gabriella, Davis, Celina, Clarke, Samantha, Wu, Lee S.F., Yoshida, Sachiyo, Bahl, Rajiv, Grandi, Carlos, Labrique, Alain B, Rashid, Mabhubur, Ahmed, Salahuddin, Roy, Arunangshu D., Haque, Rezwanul, Shaikh, Saijuddin, Baqui, Abdullah H., Saha, Samir K., Khanam, Rasheda, Rahman, Sayedur, Shapiro, Roger, Zash, Rebecca, Silveira, Mariângela F., Buffarini, Romina, Kolsteren, Patrick, Lachat, Carl, Huybregts, Lieven, Roberfroid, Dominique, Zeng, Lingxia, Zhu, Zhonghai, He, Jianrong, Qui, Xiu, Gebreyesus, Seifu H., Tesfamariam, Kokeb, Bekele, Delayehu, Chan, Grace, Baye, Estifanos, Workneh, Firehiwot, Asante, Kwaku P., Boanmah-Kaali, Ellen, Adu-Afarwuah, Seth, Dewey, Kathryn G., Gyaase, Stephaney, Wylie, Blair J., Kirkwood, Betty R., Manu, Alexander, Thulasiraj, Ravilla D, Tielsch, James, Chowdhury, Ranadip, Taneja, Sunita, Babu, Giridhara R, Shriyan, Prafulla, Ashorn, Per, Maleta, Kenneth, Ashorn, Ulla, Mangani, Charles, Acevedo-Gallegos, Sandra, Rodriguez-Sibaja, Maria J., Khatry, Subarna K., LeClerq, Steven C., Mullany, Luke C., Jehan, Fyezah, Ilyas, Muhammad, Rogerson, Stephen J., Unger, Holger W., Ghosh, Rakesh, Musange, Sabine, Ramokolo, Vundli, Zembe-Mkabile, Wanga, Lazzerini, Marzia, Mohamed, Rishard, Wang, Dongqing, Fawzi, Wafaie W., Minja, Daniel T.R., Schmiegelow, Christentze, Masanja, Honorati, Smith, Emily, Lusingu, John P.A., Msemo, Omari A., Kabole, Fathma M., Slim, Salim N., Keentupthai, Paniya, Mongkolchati, Aroonsri, Kajubi, Richard, Kakuru, Abel, Waiswa, Peter, Walker, Dilys, Hamer, Davidson H., Semrau, Katherine E.A., Chaponda, Enesia B., Chico, R. Matthew, Banda, Bowen, Musokotwane, Kebby, Manasyan, Albert, Pry, Jake M., Chasekwa, Bernard, Humphrey, Jean, Shamim, Abu Ahmed, Christian, Parul, Ali, Hasmot, Klemm, Rolf D.W., Massie, Alan B., Mitra, Maithili, Mehra, Sucheta, Schulze, Kerry J., Shamim, Abu Amed, Sommer, Alfred, Ullah, Barkat, West, Keith P., Begum, Nazma, Chowdhury, Nabidul Haque, Islam, Shafiqul, Mitra, Dipak Kumar, Quaiyum, Abdul, Diseko, Modiegi, Makhema, Joseph, Cheng, Yue, Guo, Yixin, Yuan, Shanshan, Roro, Meselech, Shikur, Bilal, Goddard, Frederick, Haneuse, Sebastien, Hunegnaw, Bezawit, Berhane, Yemane, Worku, Alemayehu, Kaali, Seyram, Arnold, Charles D., Jack, Darby, Amenga-Etego, Seeba, Hurt, Lisa, Shannon, Caitlin, Soremekun, Seyi, Bhandari, Nita, Martines, Jose, Mazumder, Sarmila, Ana, Yamuna, R, Deepa, Hallamaa, Lotta, Pyykkö, Juha, Lumbreras-Marquez, Mario I., Mendoza-Carrera, Claudia E., Hussain, Atiya, Karim, Muhammad, Kausar, Farzana, Mehmood, Usma, Nadeem, Naila, Nisar, Muhammad Imran, Sajid, Muhammad, Mueller, Ivo, Ome-Kaius, Maria, Butrick, Elizabeth, Sayinzoga, Felix, Mariani, Ilaria, Urassa, Willy, Theander, Thor, Deloron, Phillippe, Nielsen, Birgitte Bruun, Muhihi, Alfa, Noor, Ramadhani Abdallah, Bygbjerg, Ib, Moeller, Sofie Lykke, Aftab, Fahad, Ali, Said M., Dhingra, Pratibha, Dhingra, Usha, Dutta, Arup, Sazawal, Sunil, Suleiman, Atifa, Mohammed, Mohammed, Deb, Saikat, Kamya, Moses R., Nakalembe, Miriam, Mulowooz, Jude, Santos, Nicole, Biemba, Godfrey, Herlihy, Julie M., Mbewe, Reuben K., Mweena, Fern, Yeboah-Antwi, Kojo, Bruce, Jane, Chandramohan, Daniel, and Prendergast, Andrew
- Abstract
Small newborns are vulnerable to mortality and lifelong loss of human capital. Measures of vulnerability previously focused on liveborn low-birthweight (LBW) babies, yet LBW reduction targets are off-track. There are two pathways to LBW, preterm birth and fetal growth restriction (FGR), with the FGR pathway resulting in the baby being small for gestational age (SGA). Data on LBW babies are available from 158 (81%) of 194 WHO member states and the occupied Palestinian territory, including east Jerusalem, with 113 (58%) having national administrative data, whereas data on preterm births are available from 103 (53%) of 195 countries and areas, with only 64 (33%) providing national administrative data. National administrative data on SGA are available for only eight countries. Global estimates for 2020 suggest 13·4 million livebirths were preterm, with rates over the past decade remaining static, and 23·4 million were SGA. In this Series paper, we estimated prevalence in 2020 for three mutually exclusive types of small vulnerable newborns (SVNs; preterm non-SGA, term SGA, and preterm SGA) using individual-level data (2010–20) from 23 national datasets (∼110 million livebirths) and 31 studies in 18 countries (∼0·4 million livebirths). We found 11·9 million (50% credible interval [Crl] 9·1–12·2 million; 8·8%, 50% Crl 6·8–9·0%) of global livebirths were preterm non-SGA, 21·9 million (50% Crl 20·1–25·5 million; 16·3%, 14·9–18·9%) were term SGA, and 1·5 million (50% Crl 1·2–4·2 million; 1·1%, 50% Crl 0·9–3·1%) were preterm SGA. Over half (55·3%) of the 2·4 million neonatal deaths worldwide in 2020 were attributed to one of the SVN types, of which 73·4% were preterm and the remainder were term SGA. Analyses from 12 of the 23 countries with national data (0·6 million stillbirths at ≥22 weeks gestation) showed around 74% of stillbirths were preterm, including 16·0% preterm SGA and approximately one-fifth of term stillbirths were SGA. There are an estimated 1·9 million stillbirths per year associated with similar vulnerability pathways; hence integrating stillbirths to burden assessments and relevant indicators is crucial. Data can be improved by counting, weighing, and assessing the gestational age of every newborn, whether liveborn or stillborn, and classifying small newborns by the three vulnerability types. The use of these more specific types could accelerate prevention and help target care for the most vulnerable babies.
- Published
- 2023
- Full Text
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45. WHO Statement on Caesarean Section Rates
- Author
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Betran, A P, Torloni, M R, Zhang, J J, Gülmezoglu, A M, Aleem, H A, Althabe, F, Bergholt, T, de Bernis, L, Carroli, G, Deneux-Tharaux, C, Devlieger, R, Debonnet, S, Duan, T, Hanson, C, Hofmeyr, J, Pérez, Gonzalez R, de Jonge, A, Khan, K, Lansky, S, Lazdane, G, Lumbiganon, P, Mackeen, D, Mahaini, R, Manyame, S, Mathai, M, Mikolajczyk, R, Mori, R, De Mucio, B, Oladapo, O T, Ortiz-Panozo, E, Ouedraogo, L, Parker, C, Robson, M, Serruya, S, Souza, J P, Spong, C Y, Stanton, C, Stanton, M E, Sullivan, E A, Temmerman, M, Tita, A, Tunçalp, Ö, Velebil, P, Vogel, J P, Weber, M, Wojdyla, D, Ye, J, Yunis, K, Zamora, J, and Zongo, A
- Published
- 2016
- Full Text
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46. Positive fragments of coalgebraic logics
- Author
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Adriana Balan, Alexander Kurz, and Jiří Velebil
- Subjects
mathematics - category theory ,computer science - logic in computer science ,Logic ,BC1-199 ,Electronic computers. Computer science ,QA75.5-76.95 - Abstract
Positive modal logic was introduced in an influential 1995 paper of Dunn as the positive fragment of standard modal logic. His completeness result consists of an axiomatization that derives all modal formulas that are valid on all Kripke frames and are built only from atomic propositions, conjunction, disjunction, box and diamond. In this paper, we provide a coalgebraic analysis of this theorem, which not only gives a conceptual proof based on duality theory, but also generalizes Dunn's result from Kripke frames to coalgebras for weak-pullback preserving functors. To facilitate this analysis we prove a number of category theoretic results on functors on the categories $\mathsf{Set}$ of sets and $\mathsf{Pos}$ of posets: Every functor $\mathsf{Set} \to \mathsf{Pos}$ has a $\mathsf{Pos}$-enriched left Kan extension $\mathsf{Pos} \to \mathsf{Pos}$. Functors arising in this way are said to have a presentation in discrete arities. In the case that $\mathsf{Set} \to \mathsf{Pos}$ is actually $\mathsf{Set}$-valued, we call the corresponding left Kan extension $\mathsf{Pos} \to \mathsf{Pos}$ its posetification. A $\mathsf{Set}$-functor preserves weak pullbacks if and only if its posetification preserves exact squares. A $\mathsf{Pos}$-functor with a presentation in discrete arities preserves surjections. The inclusion $\mathsf{Set} \to \mathsf{Pos}$ is dense. A functor $\mathsf{Pos} \to \mathsf{Pos}$ has a presentation in discrete arities if and only if it preserves coinserters of `truncated nerves of posets'. A functor $\mathsf{Pos} \to \mathsf{Pos}$ is a posetification if and only if it preserves coinserters of truncated nerves of posets and discrete posets. A locally monotone endofunctor of an ordered variety has a presentation by monotone operations and equations if and only if it preserves $\mathsf{Pos}$-enriched sifted colimits.
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- 2015
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47. Endometrióza v postmenopauze.
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Hanáček, J., Drahoňovský, J., Heřman, H., Eminger, M., Křepelka, P., Velebil, P., Macková, K., and Dibonová, M.
- Published
- 2022
48. Enriched Logical Connections
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Kurz, Alexander and Velebil, Jiří
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- 2013
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49. Relation lifting, with an application to the many-valued cover modality
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Marta Bilkova, Alexander Kurz, Daniela Petrisan, and Jiri Velebil
- Subjects
computer science - logic in computer science ,Logic ,BC1-199 ,Electronic computers. Computer science ,QA75.5-76.95 - Abstract
We introduce basic notions and results about relation liftings on categories enriched in a commutative quantale. We derive two necessary and sufficient conditions for a 2-functor T to admit a functorial relation lifting: one is the existence of a distributive law of T over the "powerset monad" on categories, one is the preservation by T of "exactness" of certain squares. Both characterisations are generalisations of the "classical" results known for set functors: the first characterisation generalises the existence of a distributive law over the genuine powerset monad, the second generalises preservation of weak pullbacks. The results presented in this paper enable us to compute predicate liftings of endofunctors of, for example, generalised (ultra)metric spaces. We illustrate this by studying the coalgebraic cover modality in this setting.
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- 2013
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50. TVT-S for surgical treatment of stress urinary incontinence: prospective trial, 1-year follow-up
- Author
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Krofta, Ladislav, Feyereisl, Jaroslav, Velebil, Petr, Otčenášek, Michal, Kašíková, Eva, and Krčmář, Michal
- Published
- 2010
- Full Text
- View/download PDF
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