Five centuries of Southern Moravian drought variations revealed from living and historic tree rings

Past, present, and projected fluctuations of the hydrological cycle, associated to anthropogenic climate change, describe a pending challenge for natural ecosystems and human civilizations. Here, we compile and analyze long meteorological records from Brno, Czech Republic and nearby tree-ring measurements of living and historic firs from Southern Moravia. This unique paleoclimatic compilation together with innovative reconstruction methods and error estimates allows regional-scale May-June drought variability to be estimated back to ad 1500. Driest and wettest conditions occurred in 1653 and 1713, respectively. The ten wettest decades are evenly distributed throughout time, whereas the driest episodes occurred in the seventeenth century and from the 1840s onward. Discussion emphasizes agreement between the new reconstruction and documentary evidence, and stresses possible sources of reconstruction uncertainty including station inhomogeneity, limited frequency preservation, reduced climate sensitivity, and large-scale constraint

Testing ceramics inserts at irregular interrupted cut on material 14MoV6

This article deals with the test of removable ceramic cutting inserts during machining with an irregular interrupted cut. Tests were performed on a lathe, with a preparation which simulated an interrupted cut for us. By changing the number of slats mounted in the preparation, it simulated a regular or irregular interrupted cut for us. When it had four slats, it was a regular interrupted cut, whereas the remaining three variants were already irregular cuts. This paper examined whether it would have an irregular interrupted cutting effect on the insert and possibly how it would change the life of the inserts during an irregular interrupted cut (a variable delay between shocks).Web of Science371736

Tree-Ring Amplification of the Early Nineteenth-Century Summer Cooling in Central Europe

Les prokinéticines sont des facteurs angiogènic potentiels qui se liant aux récepteurs couplés aux protéines G (PKR1 et PKR2) pour initier leurs effets biologiques. Nous avons montré que le transfert transitoire du gène PKR1 après ligation de l’artère coronaire réduit la mortalité et préserve la fonction du ventricule gauche en favorisant la néovascularisation et protegé des cardiomyocytes. Nous avons montré que des souris transgéniques (TG) surexprimant PKR1 dans le coeur aucune anomalie spontanée dans les cardiomyocytes, mais on observe une augmentation de néovascularization. Cependant des souris TG surexprimant PKR2 dans le coeur ont montré de l'hypertrophie excentrique et la perméabilité vasculaire. Pour la première fois nous avons montré que la balance entre l'activation de la voie de signalisation de PKR1 et de PKR2 pouvait être très importante pour protéger les cardiomyocytes des lésions causées par l'ischémie et/ou d’induire la neovascularisation dans le coeur.Cardiovascular disease is first cause of mortality worldwide. Prokineticins are potent angiogenic factors that bind to two G protein-coupled receptors (PKR1 and PKR2) to initiate their biological effects. We showed that transient PKR1 gene transfer after coronary ligation reduces mortality and preserves left ventricular function by promoting neovascularization and protecting cardiomyocytes. Next we showed that transgenic (TG) mice overexpressing PKR1 in heart exhibit neovascularization without inducing any spontaneous pathology in cardiomyocytes. However TG mice overexpressing PKR2 in heart exhibit eccentric hypertrophy in cardiomyocyte and vascular leakage. As a conclusion, for the first time we have shown that the balance between the activation of PKR1 and PKR2 signaling could be very important to prevent cardiomyocytes from ischemic insult and/or to induce neovascularization in heart

Metoda a ekonomické limity regulace ve finančním právu

Hlavním cílem práce bylo identifikovat metodu regulace ve finančním právu a pojednat o jednotlivých oblastech finančního práva. Dalším cílem bylo vybrat základní ekonomické instituty, kterých stát užívá při plnění svých funkcí nebo které ovlivňují svojí regulací. Třetím cílem bylo určit sociologické metody, konkrétně metody kvantitativního a kvalitativního výzkumu, které lze využít při úvahách de lege ferenda. Publikace je výstupem dvouleté výzkumné činnosti v projektech specifického výzkumu Masarykovy univerzity Metoda a ekonomické limity regulace ve finančním právu (2012) a Metoda a ekonomické limity regulace ve finančním právu II (2013).The main goal of the work has been to identify the method of legal regulation in financial law relations and to discuss certain segments of financial law. The second goal has been to select the basic economic institutes used by the state for fulfilling its tasks or affected by the state through its regulation. The third goal has been to assess the sociological methods including the methods of the quantitative and qualitative research that may be used for de lege ferenda discussions. The publication is the output of the two-years research activities in the specific research projects Method and economic limits of regulation in financial law (2012) and Method and economic limits of regulation in financial law II (2013)

Old World megadroughts and pluvials during the Common Era

Climate model projections suggest widespread drying in the Mediterranean Basin and wetting in Fennoscandia in the coming decades largely as a consequence of greenhouse gas forcing of climate. To place these and other “Old World” climate projections into historical perspective based on more complete estimates of natural hydroclimatic variability, we have developed the “Old World Drought Atlas” (OWDA), a set of year-to-year maps of tree-ring reconstructed summer wetness and dryness over Europe and the Mediterranean Basin during the Common Era. The OWDA matches historical accounts of severe drought and wetness with a spatial completeness not previously available. In addition, megadroughts reconstructed over north-central Europe in the 11th and mid-15th centuries reinforce other evidence from North America and Asia that droughts were more severe, extensive, and prolonged over Northern Hemisphere land areas before the 20th century, with an inadequate understanding of their causes. The OWDA provides new data to determine the causes of Old World drought and wetness and attribute past climate variability to forced and/or internal variability

Tree rings reveal globally coherent signature of cosmogenic radiocarbon events in 774 and 993 CE

This study was funded by the WSL-internal COSMIC project (5233.00148.001.01), the ETHZ (Laboratory of Ion Beam Physics), the Swiss National Science Foundation (SNF Grant 200021L_157187/1), and as the Czech Republic Grant Agency project no. 17-22102s.Though tree-ring chronologies are annually resolved, their dating has never been independently validated at the global scale. Moreover, it is unknown if atmospheric radiocarbon enrichment events of cosmogenic origin leave spatiotemporally consistent fingerprints. Here we measure the 14C content in 484 individual tree rings formed in the periods 770–780 and 990–1000 CE. Distinct 14C excursions starting in the boreal summer of 774 and the boreal spring of 993 ensure the precise dating of 44 tree-ring records from five continents. We also identify a meridional decline of 11-year mean atmospheric radiocarbon concentrations across both hemispheres. Corroborated by historical eye-witness accounts of red auroras, our results suggest a global exposure to strong solar proton radiation. To improve understanding of the return frequency and intensity of past cosmic events, which is particularly important for assessing the potential threat of space weather on our society, further annually resolved 14C measurements are needed.Publisher PDFPeer reviewe

Using of the tree-ring analysis for dating of large scale dieback of dwarf pine (Pinus mugo) in the Giant Mountains

Abrupt growth depressions and high proportion of missing tree-rings was observed on dwarf pine shrub (Pinus mugo) in Krkonoše, Mts. These symptoms were ascribed to strong defoliation of shrub caused by insect outbreaks and confirmed by observed decrease in shrub cover using historical aerial photographs. The study proved the using of dendrochronological methods for detection of historical inasect outbreaks in dwarf pine shrub stands

Global Climate Changes

katedra: KEK; přílohy: 2 CD; rozsah: 83s.With the purpose of describing climate-change effects on our planet and discussing proposed measures to fight against it, the present dissertation addresses the broad topic of climate-change impact. In particular, it covers individual measures and evaluates them in terms of their feasibility, efficacy and cost. The thesis is divided into several chapters. While the introduction provides a definition of the climate system, the following parts are concerned with causes and consequences of climate changes. I characterize the greenhouse effect, sunspots, and the carbon cycle, and refer to the Kyoto Protocol. Further, the effects of climate change are looked at with respect to their impact upon the Czech Republic as well as the whole planet. In the final section, the proposed corrective measures are described and their feasibility assessed.Diplomová práce se zabývá dopady klimatických změn na naší planetu. Cílem práce je dopady formulovat a zjistit navrhovaná opatření v boji proti změnám klimatu. Zaměření bylo především na jednotlivá opatření a jejich zhodnocení z hlediska reálné proveditelnosti, účinnosti a nákladnosti. Struktura práce je rozdělena do několika části. Na úvod charakterizuji co je to klimatický systém. V další části se zabývám příčinami a následky změn klimatu. Charakterizuji zde skleníkový efekt, sluneční skvrny, koloběh uhlíku a poukazuji na Kjótský protokol. Následky změn klimatu jsou dále posuzovány, jak ovlivňují samotnou Českou republiku a celou naší planetu. V závěrečné části popisuji navrhované změny a jejich proveditelnost