The fluorescence detector array of single-pixel telescopes is a low-cost, large-area, next-generation experiment for the detection of ultrahigh-energy cosmic rays via the atmospheric fluorescence technique. The proposed design involves the deployment of several hundred large field-of-view fluorescence telescopes on a regular grid of several thousand square kilometres in ground area. This paper describes the optical design of the telescope, as well as its mechanical support structure. and Pole fluorescenčních detektorů složené z jednopixelových teleskopů představuje levný experiment nové generace observatoří pro detekci vysokoenergetického kosmického záření snímaného na velké rozloze za použití fluorescence sekundárního záření v atmosféře. Předkládaný projekt počítá s několika sty fluorescenčních teleskopů umístěných v pravidelné síti na ploše několika tisíc čtverečných kilometrů. Příspěvek popisuje optický návrh teleskopu a také podpůrnou mechanickou konstrukci teleskopu.
The paper describes the instrument´s design, technique and some results of measurements of the main solar wind kinetic parameters, made aboard the Prognoz 8 satellite by a Soviet-Czechoslovak energy spectrometer. The aim of this experiment was to test the technique of shock wave detection through readings of the plasma instrument and to measure plasma parameters with high time resolution (up to 1.3 s).
Quasi-periodic oscillations /QPO/, with frequencies in the range between about 1 Hz and 10^2 Hz have been detected in the X-ray flux of 10 low-mass X-ray binaries. A brief overview will be given of the main characteristics of these QPO, and the associated red noise, with emphasis on the following topics:
- The relation between QPO and the spectraL properties of the LMXB;
- The time shift between QPO as observed in different X-ray photon energy bands, and the possible role of comptonization in the formation of X-ray spectra of low-mass X-ray binaries.
This article deal with phase diagnostics of femtosecond laser pulses and with its change to increase a nonlinear optical signal. We introduce a single shot technique of complex diagnostics SPIDER, which works on the base of interference in spectral region. Phase characteristics of investigated fs pulses incoming from oscillator was controlled by a prism pair. There was shown that phase characteristics changes of fs pulses leads to intensity changes of two photon fluorescence of coumarine C522 in ethanol.
Thanks to the development of fiber optic technologies for the Internet, large cities and metropolitan networks are now well connected through the fiber optic technology. Since the mid-nineties of the last century a rapid research in the transmission of stable frequencies via optical fibers has been introduced. It is necessary for mutual remote comparison of optical frequency standards via optical fibers. But in order to transmitting optical frequencies through photonic data networks, the key task is to compensate the Doppler shift that is induced in the fibers by external influences, such as particularly changes in the temperature or acoustic noise and mechanical vibration environment in which the fibers are installed. In this work we present some techniques to compensate these unwanted effects. Furthermore, we present the realization of an optical system and measurement parameters achieved by the phase-coherent optical transmission of the optical frequency standard working at a wavelength of 1540.5 nm. The optical frequency dissemination with the stable transport delay has been established on the fiber optic link leading from the Institute of Scientific Instruments ASCR Brno to headquarters of national provider CESNET in Prague over the optical fiber with the length of 306 km. The work includes the verification and measurement of changes of the transport delays using simultaneous bidirectional transmission of 1PPS signals from the instrument based atomic clocks placed in both ends of the same optical fiber. and Díky rozvoji komunikačních technologií pro internet jsou nyní dobře propojena velká města i metropolitní sítě optickými vlákny, čímž lze zajistit čistě fotonický přenos signálů na vzdálenosti až stovek kilometrů. Od poloviny devadesátých let minulého století probíhá intenzivní výzkum v oblasti přenosu stabilních frekvencí pomocí optických vláken, který je nezbytný pro vzájemná dálková porovnávání normálů optické frekvence. Aby však bylo možné přenášet optické frekvence přes běžné fotonické datové sítě, je nezbytné kompenzovat dopplerovský posuv, který je ve vláknech indukován působením vnějších vlivů, jako jsou zejména změny teploty či akustické a mechanické vibrace prostředí, ve kterém jsou vlákna uložena. V práci představujeme vybrané techniky kompenzace těchto nežádoucích efektů. Dále prezentujeme vlastní realizaci optické soustavy a měření dosažených parametrů fázově koherentního přenosu optické frekvence normálového laseru pracujícího na vlnové délce 1540,5 nm z pracoviště Ústavu přístrojové techniky AV ČR v Brně do ústředí poskytovatele fotonických služeb CESNET v Praze po optickém vlákně délky 306 km. Součástí výsledků je i verifikace měření změn dopravního zpoždění pomocí obousměrného simultánního přenosu signálů 1PPS z přístrojových atomových hodin umístěných v obou lokalitách po stejném optickém vlákně.
Building on historical narrative and social-theoretical analysis, Fraser explores the place of second-wave feminism in relation to three specific moments in the history of capitalism. The first point refers to the movement’s beginnings in the context of ‘state-organized capitalism’. The second point refers to the process of feminism’s evolution in the dramatically changed social context of rising neoliberalism. And the third point refers to a possible reorientation of feminism in the present context of capitalist crisis and US political realignment, which for her could mark the beginning of a shift from neoliberalism to a new form of social organization. Orienting her analysis around four key points of feminist critique-androcentrism, economism, étatism and Westphalianism-Fraser charts a fascinating journey of second-wave feminism since the 1960s to identify a “dangerous liaison” second-wave feminism developed with capitalism. She concludes that in order to reclaim second-wave feminism as a robust critique conjoining both claims for recognition and redistribution- which were unlinked during the period of rising neoliberalism-eminism needs to become more historically self-aware., Nancy Fraser ; přeložila Marcela Linková., and Přeloženo z : New Left Review 56/2009
Since 2017, the International Women’s Strike (IWS) has generated a global wave of protest against patriarchy and capitalism, as well as racism, heteronormativity, extractivism, and imperialism. Th is contribution off ers refl ections on the transnational mobilization around IWS from the perspective of feminist strike as an emerging concept, and considers the current and historical implications of the IWS as feminist action. It argues that the concept of feminist strike allows us to place women’s paid and unpaid labor center stage, while it enables us to weave together multiple systems of oppression in the analysis of women’s struggle for liberation. Drawing on insights from the Turkish context, the paper aims to call attention to the left-feminist engagement with the IWS – and its lack thereof – in Central and Eastern Europe.