Zero-term rank of a matrix is the minimum number of lines (rows or columns) needed to cover all the zero entries of the given matrix. We characterize the linear operators that preserve zero-term rank of the
$m \times n$ real matrices. We also obtain combinatorial equivalent condition for the zero-term rank of a real matrix.
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
Část. anglický a německý souběžný text and Památník byl slavnostně odhalen 10. listopadu 2002 při příležitosti šedesátého výročí transportu černovických židů do ghetta Terezín.
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.
At the heart of Krishna Sobti’s novel Zindagīnāmā (A book of life, 1979) is a village of the Gujrat district (western Panjab, now Pakistan), in the Chaj Doab. The setting is contained within three bands: the outermost band is the village, where most people are Muslim but which is dominated by Śāhjī’s Hindu Khatri family, and above all by Śāhjī himself, a landowner and moneylender. Inside this band is the havelī (large walled house) owned by Śāhjī, and inside the havelī band is the large room ( baiṭ hak) where the men gather. Inside the havelī band there are also the rooms belonging to the women’s realm. Additionally there are several external settings. The village is connected to the world at large through news of events, recounted or witnessed by characters who come into contact with Śāhjī. The period covered is 1900-1916. The narrative consists chiefly of dialogue between the various characters. The language is a mixed vocabulary of Hindi, Urdu and Panjabi. The novel is highly complex, rich in incident and in its cast of characters: Hindu, Sikh and Muslim. The first distinction to be drawn is between the women’s and the men’s world. The women’s world is one of emotions. The men’s world is political in the broad sense of the word and includes Śāhjī business dealings with Muslim Jat tenants. The gatherings in the baiṭ hak of Śāhjī are well attended, and many of the guests are Muslims. Interests sometimes converge and more often diverge, but Śāhjī always handles the conversation skillfully, diplomatically changing the subject when delicate issues such as the economy, politics and, indirectly, religion are raised. Śāhjī’s work as a mediator should not be seen purely as a way of protecting his personal interests. In reality, by mediating in different areas – economic, political and religious – he keeps the village united, providing cultural cohesion. Nonetheless, in Zindagīnāmā, the economic factor emerges repeatedly as the cause of the future Partition.