Alien species in different habitat types of Slovenia: analysis of vegetation database

Background and purpose: Invasion by alien plant species is considered as one of major threats to biodiversity. Actual invasion of different habitats in particular country is important for understanding processes that are important in invasion ecology as well as for the nature conservation.Materials and methods: Vegetation relevés stored in a database Vegetation of Slovenia were translated into 30 EUNIS habitat types which enables comparison with similar studies in other European countries. Out of the 18 606 plots stored in the database stratified resampling yielded 6 517 relevés. For each vegetation plot we calculated mean relative species richness per plot and total cover of archeophytes, neophytes and native species.Results: Most invaded habitat type with the highest species percentages of alien species (archaeophytes and neophytes) is arable land (I1). In addition, archaeophytes occur in higher percentages in trampled areas, anthropogenic herb stands, mesic grasslands, and moist tall-herb stands. Neophytes are on the other hand highly represented in arable land, trampled areas, but also riverine scrubs and wet and moist tall-herb stands.Conclusions: Pattern across different regions in Europe is very similar with anthropogenous habitats being the most invaded by alien species.</p

Cam-follower contact

Tato práce se zabývá konstrukčním návrhem simulátoru kontaktu vačky a zdvihátka. Na začátku práce je stručný přehled vaček, sil působících v rozvodu a druhům opotřebení vačky a zdvihátka. Dále je zde uveden krátký popis jiných aparatur na simulaci kontaktu vačky a zdvihátka. Hlavní část se věnuje samotnému konstrukčnímu řešení, konstrukčním variantám a potřebným výpočtům.This bachelor thesis deals with construction design of a cam-follower contact simulator. At the beginning of the thesis there is a brief overview of cams, forces acting in valve train system and types of cam-follower contact wear. There is also review of other apparatuses developed for cam-follower contact research. Main part is devoted to construction design, variants of design and calculations.

Experimental study of friction and lubrication in THR

V této práci byla řešena problematika tření a mazání totální endoprotézy kyčelního kloubu. Na simulátoru kyčelního kloubu na principu kyvadla byla nejprve provedena studie součinitele tření pro různé materiálové kombinace, zatížení a teploty. Poté byl proveden experiment, kde bylo pozorováno formování mazacího filmu v kontaktu hlavice kyčelního kloubu a jamky, která byla vyrobena ze skla, ale svojí geometrií a rozměry odpovídala jamce reálné kyčelní náhrady, za použití kolorimetrické interferometruie. Vrbka et al. [25] poukazuje na skutečnost, že se zvyšující se konformitou povrchů se zvyšuje i tloušťka mazacího filmu. Taktéž byla pozorována adsorpce proteinů na kontaktní povrchy. Díky ní byla naměřena tloušťka filmu 80 nm i při nulové relativní rychlosti povrchů. Taktéž byla pozorována agregace proteinů na okrajích kontaktu. Podobné agregace pozoroval i Myant et al. [29] na kontaktu ball-on-disk, nebo Vrbka et al. [25] na kontaktu ball-on-lens, tyto agregace pravděpodobně vznikají při smykovém namáhání kapaliny obsahující proteiny a mohou pozitivně ovlivňovat tloušťku mazacího filmu. Pokud není relativní pohyb hlavice a jamky dostatečný, proteinová vrstva v kontaktu se nemůže obnovovat a dochází ke ztenčování mazacího filmu. Součinitel tření naměřený při pozorování mazacího filmu byl 0,13 nejblíže této hodnotě je z reálných endoprotéz materiálová kombinace MoP.This work analyzes problems of friction and lubrication of total hip replacement (THR). At first, experimental study of friction coefficient under various conditions was conducted using hip joint simulator based on principle of pendulum. After that, lubrication film development was observed, using colorimetric interferometry with head from THR and glass cup with respect of geometry and clearance to cups made originally for THR. With respect to research study [25] it was found that increasing contact conformity leads to increased film thickness. Also protein adsorption on articulating surfaces was observed. Thanks to adsorption 80 nm film thickness was measured even if relative surface speed was zero. Furthermore protein aggregation was observed on the border of contact zone, similar aggregations were observed by Myant et al. [29] or Vrbka et al. [25]. These aggregations are formed when lubricant is under shear stress and it can positively affect film thickness. If the relative motion of articulating surfaces is not sufficient, the protein layer can`t be refreshed enough and film thickness start decreasing. Coefficient of friction 0,13 was measured when lubricating film development was observed. Close to this value are material combinations metal on polyethylene and metal on metal.

Coastal sand dune vegetation of Velika plaža (Montenegro)

Velika plaža (Ulcinj, Montenegro) is the largest sandy beach along the coast of the eastern Adriatic that still has well-developed sand-dune vegetation. Although the characterization of the flora and vegetation of Velika plaža has been addressed by many authors, knowledge on its vegetation remained poor. We made a phytosociological study of sand beach vegetation comprising both dunal and wetland areas to provide a comprehensive survey of sand dune vegetation and habitat typology of Velika plaža. Based on 149 relevés (both from literature and recent field work), and with numerical classification (Flexible beta) and ordination (Non-metric multidimensional scaling) our results show that the vegetation of Velika plaža is much more diverse than previously known. Altogether, 19 plant communities from 6 vegetation classes were identified. Among them we described two new associations: Cuscuto cesatianae-Phyletum nodiflorae and Onobrychido caput-galli-Vulpietum fasciculatae

Phi Mesons from a Hadronic Fireball

Production of $\phi$ mesons is considered in the course of heavy-ion collisions at SPS energies. We investigate the possible difference in momentum distributions of $\phi$ mesons measured via their leptonic ($\mu^+\mu^-$) and hadronic ($K^+K^-$) decays. Rescattering of secondary kaons in the dense hadron gas together with the influence of in-medium kaon potential can lead to a relative decrease of a $\phi$ yield observed in the hadronic channel. We analyze how the in-medium modifications of meson properties affect apparent - reconstructed momentum distributions of $\phi$ mesons. Quantitative results are presented for central Pb+Pb collisions at $E_{beam}=158 GeV/A$.Comment: style Revtex4,9 pages, 5 figures. submitted to Phys. Rev.

AgriWeedClim database: A repository of vegetation plot data from Central European arable habitats over 100 years

Aims: Arable habitats (i.e. fields, orchards, vineyards, and their fallows) were cre- ated by humans and have been essential elements in Central European landscapes for several millennia. In recent decades, these habitats have been drastically altered by changes in land use as well as agricultural practices and, more recently, by climate change. These changes have precipitated substantial changes in vegetation and their spatial and temporal trajectories have not yet been exhaustively studied. Here, we present the AgriWeedClim database —­ a new resource of vegetation plot (relevé) data of arable habitats in Central Europe. Location: Germany, Czech Republic, Slovakia, Switzerland, Liechtenstein, Austria, Hungary, Northern Italy, Slovenia, Croatia. Methods: Vegetation plot data were obtained from large repositories (e.g. European Vegetation Archive), specialized regional databases, colleagues and the literature. Data were then checked for completeness and standardized (e.g. taxonomy, nomenclature, crop types). Species were assigned native, archaeophyte (i.e. alien species introduced before c. 1492 CE) or neophyte (i.e. alien species introduced after c. 1492 CE) status. Results: The AgriWeedClim database version 1.0 contains georeferenced data from 32,889 vegetation plots sampled from 1916 to 2019. Conclusions: We provide an overview of this new resource and present example analyses to show its content and possible applications. We outline potential research questions including analysis of patterns and causes of vegetation changes in arable habitats from the early 20th century to the present

Towards near-permanent CoCrMo prosthesis surface by combining micro-texturing and low temperature plasma carburising

This article will argue that the legal academy has much to learn by recording, transcribing and systematically studying student-client and attorney-client consultations. Clinical faculty can utilize conversation analysis and other social science techniques to do this. Social scientists and medical providers have studied doctor-patient conversations in this way over many years. Through this systematic study researchers have reached conclusions about effective doctor-patient consultations that form the basis for teaching these skills in medical school. This article will highlight some of these studies and their findings. Some have contended that attorney-client conversations simply cannot be recorded and studied in the same way as doctor-patient consultations due to attorney-client privilege. This article will lay out how a law clinic could obtain client informed consent to this procedure, protect client confidentiality and privilege, and gain the necessary approval of the Institutional Review Board. Finally, this article will suggest topics about client consultations that could merit study in the law clinic