Un progetto per Nowa Huta

Il volume raccoglie i progetti presentati alla IX Biennale Internazionale di Cracovia, 2002, sul tema "Less ideology - more geometry in the space to live the city". Oggetto del concorso sono quegli spazi della città, costruita come città dormitorio durante gli anni del Realismo Socialista, che possono diventare spazi pubblici per la città contemporanea. Progetto vincitore del primo premio. Born from a political will (socialist realism), from a model of urban and territorial organization (a new way of life) that imprinted its processes of conception and construction, Nowa Huta is, like all foundation towns, a city without a past, a city that appears today fixed in the everlasting present of the time (the ideology) which conceived and built it, and projected towards a future balanced between failure of the ideals (which were the very reason for the existance of the city) and the shutting-down of the huge factories to which it was connected (its practical reason). A city without a past and with an uncertain future. But the shape of Nowa Huta, its spatial structure, has an immense debt to the history and the tradition of the architecture and, set free form its political and ideological charge, it represents today an important contribution to urban research, both on a territorial scale (location, means of transport, water supply, production settlements) and on a urban scale (quarters, residential units, public services, collective buildings, green areas, traffic in its different forms). Therefore our reflection starts from the actual reality of the city, from its built structure (the layout of streets and its relationship with architecture, the residential districts and the emerging monuments) which represents the more constant and convincing element: the aggregative systems, the building types and the architectural forms have changed in the course of time, but the plan remained unchanged in its geometrical clearness

An optical quasimonomer

A comprehensive investigation of the luminescent properties of carbon nitride polymers, based on tri-s-triazine units, has been conducted. Steady-state temperature- and excitation-power-dependent as well as time-resolved measurements with near-UV excitation (λ=325 nm and 405 nm) yield strong photoluminescence, covering the visible spectrum. The spectral, thermal, and temporal features of the photoluminescence can be satisfactorily described by the excitation and radiative recombination of molecular excitons, localized at single tri-s-triazine units. The discussed model is in accordance with the recently reported absorption features of carbon nitride polymers. Thus, from the point of view of optical spectroscopy, the material effectively behaves as a monomer

Photophysics of polymeric carbon nitride: An optical quasimonomer

A comprehensive investigation of the luminescent properties of carbon nitride polymers, based on tri-s-triazine units, has been conducted. Steady-state temperature- and excitation-power-dependent as well as time-resolved measurements with near-UV excitation (λ=325 nm and 405 nm) yield strong photoluminescence, covering the visible spectrum. The spectral, thermal, and temporal features of the photoluminescence can be satisfactorily described by the excitation and radiative recombination of molecular excitons, localized at single tri-s-triazine units. The discussed model is in accordance with the recently reported absorption features of carbon nitride polymers. Thus, from the point of view of optical spectroscopy, the material effectively behaves as a monomer

Search for very high energy gamma-ray emission from parts of the Gould belt with the H.E.S.S. ground based Cherenkov telescopes

The Gould belt, a well-known region of enhanced star formation in the solar neighborhood, is observed to be an expanding rim with a diameter of a few hundred parsecs and a width of approximately 100 pc. Most of the nearby OB stellar associations and molecular clouds are found to be aligned with the Gould belt. With the high star formation rate along the Gould belt, the local supernova rate during the last few million years is believed to be three to four times larger than the Galactic average. Under the assumption that supernova remnants are efficient accelerators of cosmic rays, the Gould belt and its environment should show an increased cosmic ray density with respect to the Galactic average. The cosmic rays are expected to interact with the dense molecular gas which results mainly in pi-meson production with subsequent decay in gamma-rays and neutrinos. We have searched for gamma-ray emission from various nearby (d=100-200 pc) parts of the Gould belt with the HESS Cherenkov telescopes. Results will be presented at the conference.D. Horns, G.P. Rowell, F. Aharonian, S. Gabici, A. Santangelo, S. Schwarzburg for The H.E.S.S. Collaboration

The methodology of using a matrix «Control of safety» for the study subjects fgos for unsuring environmental and production safety

In this research, invited to submit control of all kinds of needs in the form of the corresponding matrix, allowing to methodically reflect the different variants of interrelation between the needs and dangers and related of the occupational diseases. Use of the matrix allow to create and analyze a variety of tasks (exercises) for students (students of courses for advanced training) for study of the subjects «Life safety» and «Medical and biological bases of safety» for unsuring environmental and production safetyВ настоящей работе предложено представить управление всеми видами потребностей в виде соответствующей матрицы, позволяющей методично отражать различные варианты взаимосвязи потребностей с соответствующими видами опасностей и связанных с ними профессиональных заболеваний. Использование матрицы позволяет формировать широкий круг задач (упражнений) для студентов (слушателей повышения квалификации) по углубленному изучению дисциплин «Безопасность жизнедеятельности» и «Медико-биологические основы безопасности

H.E.S.S. observations of gamma-ray bursts in 2003-2007

Very-high-energy (VHE; >~100 GeV) gamma-rays are expected from gamma-ray bursts (GRBs) in some scenarios. Exploring this photon energy regime is necessary for understanding the energetics and properties of GRBs. GRBs have been one of the prime targets for the H.E.S.S. experiment, which makes use of four Imaging Atmospheric Cherenkov Telescopes (IACTs) to detect VHE gamma-rays. Dedicated observations of 32 GRB positions were made in the years 2003-2007 and a search for VHE gamma-ray counterparts of these GRBs was made. Depending on the visibility and observing conditions, the observations mostly start minutes to hours after the burst and typically last two hours. Results from observations of 22 GRB positions are presented and evidence of a VHE signal was found neither in observations of any individual GRBs, nor from stacking data from subsets of GRBs with higher expected VHE flux according to a model-independent ranking scheme. Upper limits for the VHE gamma-ray flux from the GRB positions were derived. For those GRBs with measured redshifts, differential upper limits at the energy threshold after correcting for absorption due to extra-galactic background light are also presented.Comment: 9 pages, 4 tables, 3 figure

Discovery of VHE gamma-rays from the high-frequency-peaked BL Lac object RGB J0152+017

Aims: The BL Lac object RGB J0152+017 (z=0.080) was predicted to be a very high-energy (VHE; > 100 GeV) gamma-ray source, due to its high X-ray and radio fluxes. Our aim is to understand the radiative processes by investigating the observed emission and its production mechanism using the High Energy Stereoscopic System (H.E.S.S.) experiment. Methods: We report recent observations of the BL Lac source RGB J0152+017 made in late October and November 2007 with the H.E.S.S. array consisting of four imaging atmospheric Cherenkov telescopes. Contemporaneous observations were made in X-rays by the Swift and RXTE satellites, in the optical band with the ATOM telescope, and in the radio band with the Nancay Radio Telescope. Results: A signal of 173 gamma-ray photons corresponding to a statistical significance of 6.6 sigma was found in the data. The energy spectrum of the source can be described by a powerlaw with a spectral index of 2.95+/-0.36stat+/-0.20syst. The integral flux above 300 GeV corresponds to ~2% of the flux of the Crab nebula. The source spectral energy distribution (SED) can be described using a two-component non-thermal synchrotron self-Compton (SSC) leptonic model, except in the optical band, which is dominated by a thermal host galaxy component. The parameters that are found are very close to those found in similar SSC studies in TeV blazars. Conclusions: RGB J0152+017 is discovered as a source of VHE gamma-rays by H.E.S.S. The location of its synchrotron peak, as derived from the SED in Swift data, allows clearly classification it as a high-frequency-peaked BL Lac (HBL).Comment: Accepted for publication in A&A Letters (5 pages, 4 figures

The exceptionally powerful TeV gamma-ray emitters in the Large Magellanic Cloud

The Large Magellanic Cloud, a satellite galaxy of the Milky Way, has been observed with the High Energy Stereoscopic System (H.E.S.S.) above an energy of 100 billion electron volts for a deep exposure of 210 hours. Three sources of different types were detected: the pulsar wind nebula of the most energetic pulsar known N 157B, the radio-loud supernova remnant N 132D and the largest non-thermal X-ray shell - the superbubble 30 Dor C. The unique object SN 1987A is, surprisingly, not detected, which constrains the theoretical framework of particle acceleration in very young supernova remnants. These detections reveal the most energetic tip of a gamma-ray source population in an external galaxy, and provide via 30 Dor C the unambiguous detection of gamma-ray emission from a superbubble.Comment: Published in Science Magazine (Jan. 23, 2015). This ArXiv version has the supplementary online material incorporated as an appendix to the main pape

3.9 day orbital modulation in the TeV gamma-ray flux and spectrum from the X-ray binary LS 5039

New observations of LS 5039, a High Mass X-ray Binary comprising a massive star and compact object, were carried out with the High Energy Stereoscopic System of Cherenkov Telescopes (H.E.S.S.) in 2005 at very high energy (VHE) gamma-ray energies. These observations reveal that its flux and energy spectrum are modulated with the 3.9 day orbital period of the binary system. This is the first time in gamma-ray astronomy that orbital modulation has been observed, and periodicity clearly established using ground-based gamma-ray detectors. The VHE gamma-ray emission is largely confined to half of the orbit, peaking around the inferior conjunction epoch of the compact object. For this epoch, there is also a hardening of the energy spectrum in the energy range between 0.2 TeV and a few TeV. The flux vs. orbital phase profile provides the first clear indication of gamma-ray absorption via pair production within an astrophysical source, a process which is expected to occur if the gamma-ray production site is situated within ~1 AU of the compact object. Moreover the production region size must be not significantly greater than the binary separation (~0.15 AU). Notably, these constraints are also considerably smaller than the collimated outflows or jets (extending out to ~1000 AU) observed in LS 5039. The spectral hardening could arise from variations with phase in the maximum electron energies, and/or the dominant VHE gamma-ray production mechanism.Comment: 8 pages, 8 figures, accepted for publication in Astronomy & Astrophysic