The effect of moisture on significant mechanical characteristics of masonry

Experimental and laboratory research into residual physical and mechanical characteristics of historical masonry structures (GAČR 2008; Witzany 2008), in particular the determination of residual strength and modulus of elasticity in compression, included research oriented towards the effect of moisture and porosity on the respective characteristics of masonry units – bricks, sandstone and arenaceous marl. Partial results published in (Witzany et al. 2008) and in this paper testify to the need for further research into the effects of porosity, moisture and chemism on the development of characteristics of building materials applied on historical structures. Drėgmės įtaka svarbiausioms mechaninėms mūro charakteristikoms Santrauka Straipsnyje pateikti eksperimentiniai ir laboratoriniai tyrimai nustatant tokias fizines ir mechanines istorinių pastatų mūro charakteristikas (GAČR 2008; Witzany, Čejka, Zigler 2008), kaip faktinis (liekamasis) mūro gniuždomasis stipris bei gniuždomojo tamprumo modulis, įvertinant drėgmės ir poringumo įtaką mūrui (plytoms, smiltainiui ir mergeliui). Dalis rezultatų publikuota Witzany, Čejka, Zigler (2008) straipsnyje. Jame aiškiai parodytas tolesnių tyrimų tikslingumas siekiant išplėtoti istorinių pastatų mūro svarbiausių charakteristikų nustatymo metodus, įvertinant drėgmės, cheminių medžagų (pvz., druskų kristalizacijos) ir poringumo įtaką. First Published Online: 16 May 2013 Reikšminiai žodžiai: mūrinės konstrukcijos, drėgmė, poringumas, faktinis (liekamasis) gniuždomasis stipris, tamprumo modulis, plytos, smiltainis, mergeli

Present knowledge of distribution of Tandonia budapestensis (Hazay, 1881) in the Czech and Slovak Republics (Gastropoda: Milacidae)

All published and known unpublished data on Tandonia budapestensis (Hazay, 1881) from the territory of the Czech and Slovak Republics are summarised. This species occurs rarely in both states in altitudes up to ca. 420 m. and is closely bound to anthropogenous habitats

Risk and reward of the global truffle sector under predicted climate change

Climate change has been described as the main threat for the cultivation and growth of truffles, but hydroclimate variability and model uncertainty challenge regional projections and adaptation strategies of the emerging sector. Here, we conduct a literature review to define the main Périgord truffle growing regions around the world and use 20 global climate models to assess the impact of future trends and extremes in temperature, precipitation and soil moisture on truffle production rates and price levels in all cultivation regions in the Americas, Europe, South Africa, and Australasia. Climate model simulations project 2.3 million km2 of suitable land for truffle growth will experience 50% faster aridification than the rests of the global land surface, with significantly more heat waves between 2070 and 2099 CE. Overall, truffle production rates will decrease by 15%, while associated price levels will increase by 36%. At the same time, a predicted increase in summer precipitation and less intense warming over Australasia will likely alleviate water scarcity and support higher yields of more affordable truffles. Our findings are relevant for truffle farmers and businesses to adapt their irrigation systems and management strategies to future climate change.Publishe

Validation of distinct pathogenic patterns in a cohort of membranoproliferative glomerulonephritis patients by cluster analysis

Background: A novel data-driven cluster analysis identified distinct pathogenic patterns in C3-glomerulopathies and immune complex-mediated membranoproliferative glomerulonephritis. Our aim was to replicate these observations in an independent cohort and elucidate disease pathophysiology with detailed analysis of functional complement markers. ----- Methods: A total of 92 patients with clinical, histological, complement and genetic data were involved in the study, and hierarchical cluster analysis was done by Ward method, where four clusters were generated. ----- Results: High levels of sC5b-9 (soluble membrane attack complex), low serum C3 levels and young age at onset (13 years) were characteristic for Cluster 1 with a high prevalence of likely pathogenic variations (LPVs) and C3 nephritic factor, whereas for Cluster 2-which is not reliable because of the small number of cases-strong immunoglobulin G staining, low C3 levels and high prevalence of nephritic syndrome at disease onset were observed. Low plasma sC5b-9 levels, decreased C3 levels and high prevalence of LPV and sclerotic glomeruli were present in Cluster 3, and patients with late onset of the disease (median: 39.5 years) and near-normal C3 levels in Cluster 4. A significant difference was observed in the incidence of end-stage renal disease during follow-up between the different clusters. Patients in Clusters 3-4 had worse renal survival than patients in Clusters 1-2. ----- Conclusions: Our results confirm the main findings of the original cluster analysis and indicate that the observed, distinct pathogenic patterns are replicated in our cohort. Further investigations are necessary to analyse the distinct biological and pathogenic processes in these patient groups

C4 nephritic factor in patients with immune-complex-mediated membranoproliferative glomerulonephritis and C3-glomerulopathy

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Reliability and failure resistance of the stone bridge structure of Charles bridge during floods

The most frequent damage and collapse of some of the spans of Charles Bridge during floods occurred namely in its central part which was exposed to an intense flow of backwater and erosion of the bridge pier footing bottom, which the originally relatively shallow foundations of the piers on boxes were not able to resist for a longer time (the floods of 1432, 1496, 1784, 1890). The stone vault bridge structure was damaged due to scouring of the bridge piers foundations, their successive tilting and settlement accompanied by degradation, and finally collapse of the adjoining bridge vaults. The foundation of piers on caissons and execution of caisson rings in 1892 and 1902 to 1904 in this part of the bridge, together with measures avoiding the piling up of objects in front of the bridge, enabled the bridge to withstand the impact of more than a hundred‐year flood during the events of August 2002. The numerical analysis proved an extreme sensitivity of the stone vault bridge structure to the effects of changes in the footing bottom shape. Due to the changes in the footing bottom (angular rotation, subsidence, shifting), normal and shear stresses arise in the stone vault bridge structure, and exceed the load‐bearing capacity of the masonry causing its disintegration. The fundamental measure to prevent the bridge vaults from failure due to the changes in the footing bottom shape is to secure reliably the bridge piers foundations. The increased rigidity of the stone bridge structure achieved by the interaction with the additionally inserted reinforcing structure and by bracing the bridge body filler does not ensure the reliability and safety of the bridge structure from flood‐related failures. Karolio tilto mūrinių konstrukcijų patikimumas ir atsparumas per potvynius Santrauka Potvynių metu Karolio (angl. Charles) tilte Čekijoje didžiausios pažaidos ir suirimai atsirado centrinėje dalyje, kuri buvo paveikta intensyvia vandens tėkme. Potvynių metu taip pat vyko pagrindo po tilto tarpine atrama erozija, dėl kurios atramos pamato tolesnė eksploatacija buvo negalima (1432, 1496, 1784, 1890 metų potvyniai). Arkinė mūrinė tilto konstrukcija buvo pažeista dėl pagrindų po atramų pamatais išplovimo. Dėl to atsirado pamato posvyris bei nuosėdis, o tai, sukėlė tilto mūrinių skliautų pažaidas, o vėliau – ir suirimą. Šioje tilto dalyje 1892 m. ir 1902–1904 metais įrengti kesoniniai pamatai sustiprino tilto konstrukciją, kuri atlaikė 2002 m. rugpjūtį vykusį potvynį. Atliktas skaitinis eksperimentas parodė, kad arkinė mūrinio tilto konstrukcija yra labai jautri pagrindo deformacijoms. Dėl pagrindo deformacijų (pasisukimo, nuosėdžio, pasislinkimo) padidėja normaliniai ir tangentiniai įtempiai arkų konstrukcijose. Kritiniais atvejais šie įtempiai viršija mūro stiprumo ribą, o tai sukelia mūro suirimą. Klasikinė mūrinių arkinių tiltų apsaugos nuo suirimo dėl pamato deformacijų priemonė, yra patikimas pamatų po tarpinėmis tilto atramomis stiprinimas. Bendrasis tilto standumas buvo padidintas įrengus papildomą laikančiąją gelžbetoninę konstrukciją bei sutvirtinus anstato užpildymą, tačiau tai neužtikrino tilto konstrukcijų patikimumo ir saugos potvynių metu. First Published Online: 14 Oct 2010 Reikšminiai žodžiai: potvyniai, arkinis mūrinis tiltas, pažaida, horizontalusis ir vertikalusis poslinkis, pamato pagrindas, pasisukimas, nuosėdis, poslinkis, tilto skliautų suirimas, antstato užpildymas, normaliniai ir tangentiniai tempimo įtempiai, standumas, antstatas, klimatiniai poveikiai, sąveika

Evaluation of the Limit of Detection in Network Dataset Quality Assessment with PerQoDA

Machine learning is recognised as a relevant approach to detect attacks and other anomalies in network traffic. However, there are still no suitable network datasets that would enable effective detection. On the other hand, the preparation of a network dataset is not easy due to privacy reasons but also due to the lack of tools for assessing their quality. In a previous paper, we proposed a new method for data quality assessment based on permutation testing. This paper presents a parallel study on the limits of detection of such an approach. We focus on the problem of network flow classification and use well-known machine learning techniques. The experiments were performed using publicly available network datasets.This work is partially funded by the European Union’s Horizon 2020 research, innovation programme under the Marie Sk lodowska-Curie grant agreement No 893146, by the Agencia Estatal de Investigaci´on in Spain, grant No PID2020- 113462RB-I00, and by the Ministry of Interior of the Czech Republic (Flow- Based Encrypted Traffic Analysis) under grant number VJ02010024. The authors would like to thank Szymon Wojciechowski for his support on the Weles tool

Vliv vlhkosti na fyzikalne mechanicke vlastnosti stavebnich materialu.

Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi