Metoda zesilování rozmítnutých pulzů vyvinutá Donnou Stricklandovou a Gérardem Mourouem v roce 1985 a oceněná letošní Nobelovou cenou za fyziku způsobila doslova revoluci v konstrukci laserových systémů s vysokým špičkovým výkonem. Maximální intenzita dnešních laserů je až milionkrát vyšší než před 30 lety a jejich využití je celosvětové. Petawattové laserové systémy se uplatňují v celé řadě experimentů z oblasti biologie, fyziky materiálů, urychlování částic či laboratorní astrofyziky. Českou republiku v této oblasti úspěšně reprezentují laboratoře ELI Beamlines v Dolních Břežanech u Prahy, kde jsou v současnosti v provozu dva unikátní laserové systémy terrawatové a petawattové třídy L1 Allegra a L3 HAPLS., The Chirped Pulse Amplification method, developed by Donna Strickland and Gérard Mourou in 1985, which was awarded this year's Nobel Prize in Physics, has revolutionized the field of high peak power laser systems. The maximum intensity of today's lasers is almost a million times higher than it was 30 years ago and their application is worldwide. Experiments using petawatt laser systems range from biology, material physics, and particle acceleration to laboratory astrophysics. The Czech Republic is successfully represented in this field by the ELI Beamlines facility located in Dolní Břežany near Prague, which houses two unique terawatt and petawatt class laser systems L1 Allegra and L3 HAPLS., Lucia Koubíková., and Obsahuje bibliografické odkazy
This contribution gives a brief description of the characteristics of spectral lines formed in the solar chromosphere in the visual range and its continuum in the visual, millimetre, and sub-millimetre (mm-submm) spectral range. The contribution reviews processes responsible for continuum radiation of the limb in the visual range and continua in the mm-submm spectral range. The spectral lines of sodium doublet Na I D1 and D2 are not genuine chromospheric lines since their cores are formed predominately by resonant scattering of radiation from the upper photosphere. Therefore, the cores of Na I D1 and D2 provide information only about chromospheric velocities. An occurrence of the doublet Na I D1, D2 together with helium lines with large excitation and ionization potential indicates an intricate thermodynamic structure of the chromosphere. As numerical simulations indicate, the chromospheric internetwork comprises of cooler cavities surrounded with hotter sheets allowing the occurrence of spectral lines over a large range of excitation and ionization potentials. The contribution accentuates the large diagnostic potential of the mm-submm continua of the chromospheric spectrum. It will be fully exploited after finishing of the ALMA array for the study of the chromospheric fine structure with large angular and temporal resolution., Príspevok podáva stručnú charakteristiku čiarového spektra slnečnej chromosféry vo vizuálnej oblasti a jej spojitého spektra (kontinua) vo vizuálnej, milimetrovej a submilimetrovej (mm-submm) oblasti. Príspevok predstavuje procesy tvoriace vizuálne kontinuum pozorovatel'né na limbe a kontinuá v mm-submm oblasti. Čiary sodíkového dubletu NA I D1 a D2 nie sú v pravom slova zmysle chromosférické, pretože ich jadrá sú tvorené hlavne rezonančným rozptylom žiarenia hornej fotosféry, a preto poskytujú informáciu iba o rýchlostných poliach v chromosfére. Výskyt dubletu Na I D1 a D2 spolu s čiarami hélia s veľkou excitačnou a ionizačnou energiou naznačuje zložitú termodynamickú štruktúru chromosféry. Ako ukazujú numerické simulácie, chromosféra sa v oblastiach mimo magnetickej siete skládá z chladnejších oblastí obalených horúcou látkou, čo umožňuje vznik spektrálnych čiar vo vel'kom rozsahu excitačných a ionizačných energií. Príspevok poukazuje na vel'ký diagnostický potenciál kontinuí v mm-submm oblasti spektra chromosféry, ktorý bude naplno využitý po dokončení rádioteleskopu ALMA pri štúdiu jemnej štruktúry chromosféry s vel'mi vel'kým uhlovým a časovým rozlíšením., Július Koza., and Obsahuje bibliografii
Cadmium in the dose of 1 mg/animal/day was administered to guinea-pigs in the form of CdCl2 dissolved in drinking water during short-term (5 weeks) and subchronic (12 weeks) experiments. Both the control and cadmium-treated groups were divided into two subgroups, according to low (2 mg/animal/day) and high (100 mg/animal/day) vitamin C intake. Subchronic cadmium treatment caused copper deficiency indicated by a dramatic decrease of copper concentration in the liver and serum and by its moderate decrease in the testes and brain. Cadmium significantly increased zinc concentrations in the kidneys during the whole experiment and decreased the level of zinc in the serum after subchronic cadmium treatment. In the control groups, the levels of zinc and copper in the serum were lowered after 5 weeks of high vitamin C doses. High doses of vitamin C in cadmium-treated guinea-pigs decreased the levels of copper in the testes, brain and serum. These observations suggest that cadmium intake in relatively high doses might potentiate the development of copper deficiency, and high doses of vitamin C aggravate, to a certain extent, copper depletion in some important organs and serum of guinea-pigs.
Holanďan Christiaan Huygens významně přispěl k rozvoji mechaniky a optiky v návaznosti na problémy, které řešila astronomie. Je vynálezcem kyvadlových hodin, nejpřesnějšího časoměrného přístroje doby umožňujícího poprvé stanovení zeměpisné délky plujících lodí., The article deals with the life and work of Dutch astronomer, physicist and mathematician Christiaan Huygens. Describing his extensive scientific work, we start with his activities in the field of observational astronomy (e.g. the discovery of the rings and moon of Saturn and the summary of the existing knowledge of the planets in his publication Cosmotheoros). His discovery and quantitative description of centrifugal force contributed significantly to solving problems describes in Newton´s Principia. Huygens is also well-known as a technician and technical designer. He constructed the first pendulum clocks. Last but not least, we describe his work on the impact of solid bodies, when he reflected on the work of R. Descartes and J. Marek Marci., František Jáchim., and Obsahuje seznam literatury
Sofia Kovalevskaya was not only a great Russian mathematician, but also a writer and advocate of women's rights in the 19th century. After concluding her sexondary schooling, Sofia was determined to continue her education at the university level. She travelled to Heidelberg to study mathematics, but discovered there that as a woman she could not graduate. In 1870 she moved to Berlin to study with Karl Meierstrass, in 1874 she was granted a Ph.D. from the Göttingen University. In 1883 she received an invitation from Gösta Mittag-Leffler to lecture at the University of Stockholm. Sophia's most famous work is on the theory of partial differential equations, and on the rotation of a solid body about a fixed point. Sophia died very young, at the age of 41, from pneumonia., Ivo Kraus., and Obsahuje bibliografii
Fyzikálne vzdelávanie v rámci prírodovedného a technického vzdelávania je vo vyspelých krajinách považované za dôležité. Pritiahnuť mladých ľudí a inšpirovať ich učiteľov pri vzdelávaní v týchto školských predmetoch je viacročnou ambíciou aj autorov tohto článku. V tomto článku sa zameriavame na využitie lacnej vývojovej dosky s jednočipovým mikropočítačom Arduino Uno R3 pri konštrukcii jednoduchého hudobného zariadenia - syntetizátora - a jeho následného využitia vo výučbe. Samotná konštrukcia zariadenia môže byť námetom na časovo náročnejšiu bádateľskú aktivitu (v zmysle IBSE - Inquiry Based Science Education). Súčasťou článku sú aj námety na ďalšie bádateľské aktivity, od časovo náročnejšej, venovanej konštrukcii syntetizátora, až po jednoduchšie, zrealizovateľné v rámci jednej vyučovacej hodiny., Physics education is considered to be important in science and technology education in developed countries. Attracting young people and inspiring their teachers for these subjects is a long-term ambition of the authors of this article. In this paper, we focus on using a low-cost development board with a single-chip microcomputer Arduino Uno R3 in the construction of a simple music device - a synthesizer - and its subsequent use in teaching. The design of the device itself can be the subject of a time-consuming inquiry-based activity (in terms of IBSE - Inquiry Based Science Education). This article also includes suggestions for further inquiry-based activities, from the more time-consuming construction of the synthesizer to simpler ones, that can be achieved within one lesson., Martin Hruška, Miriam Spodniaková Pfefferová, Stanislav Holec., and Obsahuje bibliografické odkazy
Příspěvek je věnován problematice jazyka mládeže. Zkoumaná slovní spojení, vybraná ze dvou slovníků, jsou posuzována z hlediska syntaktického (např. utváření nových obratů podle již existujícího vzoru), sémantického a komunikačního (slova nabývající nový význam jsou často začleňována do ustálených větných forem a postupně se stávají frazeologismy). Samotný jazyk mládeže je pak posuzován jako specifická varieta řečové komunikace.
One of the most abundant immunologic cell types in early decidua is the uterine natural killer (UNK) cell that despite the presence of cytoplasmic granules rich in perforin and granzymes does not degranulate in normal pregnancy. UNK cells are important producers of angiogenic factors that permit normal dilation of uterine arteries to provide increased blood flow for the growing feto-placental unit. Gram-negative bacteria lipopolysaccharide (LPS) administration can trigger an imbalance of pro-inflammatory and anti-inflammatory cytokines impairing the normal immune cells activity as well as uterine homeostasis. The present study aimed to evaluate by immunohistochemistry the reactivity of perforin and α-actin on UNK cell from LPStreated pregnant mice. For the first time, we demonstrate that LPS injection in pregnant mice causes α-actin down regulation, concomitantly with perforin loss in UNK cells. This suggests that LPS alters UNK cell migration and activates cytotoxic granule release., B. Zavan, A. M. do Amarante-Paffaro, V. A. Paffaro Jr., and Obsahuje bibliografii