3,222 research outputs found
On using Directional Information for Parameter Space Decomposition in Ellipse Detection
No full textIn this paper we use the parametric polar representation to extend the application of edge directional information from circle to ellipse extraction. As a result we obtain a mapping which decomposes the parameter space required for ellipse extraction into two independent sub-spaces and one final histogram accumulator. The mapping includes the tangent of the angle of the first and second directional derivatives. These tangents are computed by considering edge direction at two border points. We show that the use of gradient information for parameter space decomposition avoids the intensive point labelling imposed by geometric constraints used by other approaches
Synthesis of binary transition metal nitrides, carbides and borides from the elements in the laser-heated diamond anvil cell and their structure-property relations
No full textTransition metal nitrides, carbides and borides have a high potential for industrial applications as they not only have a high melting point but are generally harder and less compressible than the pure metals. Here we summarize recent advances in the synthesis of binary transition metal nitrides, carbides and borides focusing on the reaction of the elements at extreme conditions generated within the laser-heated diamond anvil cell. The current knowledge of their structures and high-pressure properties like high-(p; T) stability, compressibility and hardness is described as obtained from experiments
MICRO- AND NANOPLASTIC: FATE IN THE FRESHWATER ECOSYSTEM, FORMATION THROUGH THE USE OF PLASTIC WATER BOTTLES, AND A MODEL FOR HUMAN HEALTH RISK EVALUATION
No full textAlthough the degradation of plastics is desirable, the degradation products of plastic materials,
micro- and nanoplastics, are of increasing concern. These plastic particles are now emerging
pollutants in the environment and are considered potentially hazardous to organisms and
humans. This thesis had the scope of giving further insights into the understanding of these
pollutants by addressing fate, generation, detection and effects on human health.
In detail, the following questions were posed: How do microplastics distribute in a river
ecosystem and does the biotic microplastic pollution reflect that of the abiotic matrices? Can
the use of plastic packaging generate plastic particles? How are nanoplastic particles
chemically modified during secondary formation, and through which analytical approach can
they be identified and quantified? What are the human health effects of inhaled microplastics,
and is the 3D structured human airway organoid model suitable for human risk assessment of
atmospheric plastic particles?
For investigating the occurrence and fate of microplastic in a freshwater ecosystem, two
projects were conducted on the Ticino River (North Italy); one on microplastics extracted from
multiple matrices (water, sediment, fish and macroinvertebrates) simultaneously sampled
along the river and one on microplastic isolated from pellets of an avian freshwater species.
The results demonstrated a high complexity of the distribution of microplastics along the river,
evidenced by the absence of correlation of concentration between the matrices and along the
river, and that a single matrix alone cannot accurately represent the microplastic pollution level
of a river ecosystem. Moreover, the spatial variability and the opposing microplastic
concentrations in water and sediment further indicates a strong role of the pronounced
hydrodynamic conditions of the Ticino River, where microplastics can be deposited, retained
and resuspended. Furthermore, using regurgitated pellets and a tied use of different analytical
techniques, here μ-FTIR and SEM-EDS, were proven to be a suitable approach for identifying
(micro)plastics for avian plastic ingestion studies.
The formation of plastic particles from packaging was investigated in two further
projects focusing on the release of micro- and nanoplastic particles from drinking water plastic
bottles (single-use) under simulated use. The results demonstrate that the bottle lid (made of
high-density polyethylene) was the source of the formation of plastic particles, which were also
detected on bottlenecks and, therefore, available for human exposure via ingestion. In this
context, the modifications of the physical-chemical characteristics of secondary nanoplastic
particles were detected and described. High resolution SEM, XPS, SPES and μ-Raman
analysis, in combination with concentration steps proved to be suitable for quantifying and
identifying nanoplastics in simple matrices like drinking water.
The last project was dedicated to an innovative model for the risk evaluation of inhaled
and deposited atmospheric micro- and nanoparticles on humans. In this work, 3D human
airway organoids were characterised and exposed to synthetic microplastic fibres released by
drying textiles in a tumble dryer. The result shows that the presence of nonbiodegradable fibers
during the repair phase of a damaged lung epithelium may lead to their inclusion in the repaired
tissue with unknown effects on long term perspective. Concluding that human airway
organoids are suitable for testing airborne micro-and nanoplastics to determine the potential
risks of atmospheric particles in developing adverse pulmonary effects, this thesis contributes
to the development of urgently needed human models for assessing the impact of particulate
matter pollutants.
Covering different aspects of micro- and nanoplastic pollution, this thesis contributed
to understanding the complexity of this pollutant and to the optimisation of future micro- and
nanoplastic research regarding the evaluation of environmental concentrations, human
exposure of plastic particles from packaging and human risk evaluation of atmospheric
particulate matter. Also, with a perspective on the future of plastic materials (here packaging
and textiles), the results of this work should stimulate and be taken into consideration for the
re-design of plastic materials
Microplastic detection in freshwater ecosystems and drinking water
No full textMicroplastic contamination of freshwater ecosystems and drinking water is a topical area of plastic
pollution investigations. Considering the potential harmful effects of plastic particles, there is a significant
need to better understand fate and possible sources of microplastic intake by humans to assess quantities
and risks related to their properties. This talk will assess the sampling and extraction techniques of
microplastic from an ongoing case study at the river Ticino, where surface water, sediment, fish and
macroinvertebrate samples were sampled in order to report the fate of microplastic with the length of the
river. Also the results of an analysis of plastic bottled drinking water will be presented. Microplastics were
found in water from all analysed brands. Moreover, chances of microplastic ingestion by humans increase
with frequent use of the same single‐use plastic bottle as a considerable number of particles was detected
on the surface of plastic bottlenecks and caps
The toxicity of polyester fibers in Xenopuslaevis
No full textMicroplastics are practically ubiquitous and pose a serious survival challenge for many species. Most of the exposure experiments for determining the toxicological effects of microplastics were performed with a microplastic varying little in shape and size (often purchased microplastic beads), but few studies deal with non-homogeneous samples. We analyzed the effect on Xenopus laevis larva on the early development of polyester fibers, PEFs, taken from a dryer machine in which 100% polyester fabrics were dried after washing. Three concentrations were tested. The results showed that the gastrointestinal tract, GIT, was the most affected system by PEFs which modified the normal shape of the intestine with an EC50 96 h value of 6.3 μg mL−1 . Fibers were observed to press against the digestive epithelium, deforming the normal architecture of the gut, sometimes pushing deep into the epithelium until piercing it. Physical GIT occlusion was observed in a concentration-dependent manner. However, no other damages were registered. No mortality was observed, but PEF-exposed larvae showed a significant reduction in their mobility. The results of the present paper suggest that environmental samples with their heterogeneity may have adverse effects on X. laevis development
A speech portrait of our contemporary in A.S. Kushner's lyrics
No full textThe article is devoted to the speech image of the author in A.S. Kushner's poetry. Combining various socially marked colloquial units with traditional poetic means forms individual style of the author and creates a vivid image of our time
Product mix of České dráhy, a.s.
No full textBakalářská práce se zaměřuje na společnost České dráhy, a.s. a její služby poskytované v rámci širokého portfolia produktů všem cestujícím. V první části práce se autor zaměří na všeobecné informace o nástrojích marketingového mixu. Ve druhé části tyto nástroje aplikuje na produkty a služby společnosti České dráhy, a.s., zejména pak na prvky marketingového mixu, kterými jsou 4P, 5P, 7P, SWOT analýza a nástroje 4C. V poslední části dojde k vyhodnocení navržených produktů na základě dotazníkového šetření. Navrhované produkty, které budou respondentům prezentovány, vznikly na základě briefingu se zástupcem Českých drah, a.s. a se zaměstnanci cateringové společnosti JLV, a.s.The Bachelor thesis focuses on the company České dráhy, a.s. and on its services, which are promoted in wide portfolio of products to all customers. In the first chapter the author focuses to general information about tools of Marketing Mix. In the next chapter are these tools applicated to products and services of České dráhy, a.s., mainly to the points of Marketing Mix, which are following tools 4P, 5P, 7P, SWOT analysis and tools of 4C. The conclusion deals with proposed products, which are based on questionnaire results. Proposed results, which will be presented to respondents, were created thanks to briefing with the representative of České dráhy, a.s. and with employees of catering company JLV, a.s.Dopravní fakulta Jana PerneraProblematiku řešenou ve své bakalářské práci dokázal student odpovídajícím způsobem obhájit. Prokázal schopnost samostatné práce. Na doplňkové otázky reagoval pohotově, se znalostí věci a bez závažných nepřesností je zodpověděl.Dokončená práce s úspěšnou obhajobo
A Lagrangian sub-grid model for the dispersion of clouds of tracers
No full textTurbulence models are expected to satisfy the conflicting requirements of accuracy and computational efficiency. Here we discuss a new model that was recently developed in order to accurately and efficiently describe the dynamic of a clouds of tracers particles in Large Eddy Simulations of homogeneous and isotropic turbulent flows. The models incorporates the multi-scale nature of time and space turbulent velocity correlations that are essential in order to correctly reproduce the relative dispersion of multi-particle clouds. The model can be seen as an off-grid solver for the Eulerian velocity field at the positions of a given number of Lagrangian tracers that self-consistently move with it. Extensions to non homogeneous and isotropic turbulence as well as to the dynamics of particles will be discussed
Rate of breakup of small inertial aggregates in homogeneous turbulence
No full textThe hydrodynamic breakup of small inertial aggregates in homogenous and isotropic turbulence is studied through numerical simulations. Small inertial aggregates are subject to shear stress caused by the local velocity gradient and drag stress caused by the relative velocity of the aggregate and the fluid flow. In our simulations, we follow aggregates moving through the flow and record the total stress acting on them. Breakup is assumed to occur when the total stress overcomes a predefined threshold representing the aggregate strength. By determining how long it takes for an aggregate to reach a stress exceeding its strength for the first time, we are able to derive a breakup rate. It is found that with increasing aggregate inertia, the drag stress rapidly becomes the dominant stress resulting in an increase of the breakup rate with increasing the aggregate inertia
Complex analysis of T-Mobile Czech Rpeublic a.s. corporate identity
No full textPráce Komplexní analýza Corporate Identity firmy T-Mobile srovnává teoreticky zpracova-né poznatky s Corporate Identitou již zavedené společnosti. Autor nejdříve popisuje vý-znam pojmu Corporate Identity a jeho součástí. V této části jsou zpracovány dostupné teo-retické poznatky o dané problematice a naznačena očekávání těchto poznatků aplikovaných v praxi. Ve druhé části práce se autor zabývá komplexní analýzou corporate identity firmy T-Mobile Czech Republic a.s. a využívá k tomu konkrétní podklady.The work Complex Analysis of T-Mobile Czech Republic a.s. Corporate Identity theoreti-cally describes known facts about corporate identity and compares them with on market already established company. In first part is author presenting the explanation of corporate identity itself and its components. In second part of this work is author describing the cor-porate identity of T-Mobile Czech Republic a.s. in deep analysis.Ústav marketingových komunikacíobhájen
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