The Physics of Cluster Mergers

Clusters of galaxies generally form by the gravitational merger of smaller clusters and groups. Major cluster mergers are the most energetic events in the Universe since the Big Bang. Some of the basic physical properties of mergers will be discussed, with an emphasis on simple analytic arguments rather than numerical simulations. Semi-analytic estimates of merger rates are reviewed, and a simple treatment of the kinematics of binary mergers is given. Mergers drive shocks into the intracluster medium, and these shocks heat the gas and should also accelerate nonthermal relativistic particles. X-ray observations of shocks can be used to determine the geometry and kinematics of the merger. Many clusters contain cooling flow cores; the hydrodynamical interactions of these cores with the hotter, less dense gas during mergers are discussed. As a result of particle acceleration in shocks, clusters of galaxies should contain very large populations of relativistic electrons and ions. Electrons with Lorentz factors gamma~300 (energies E = gamma m_e c^2 ~ 150 MeV) are expected to be particularly common. Observations and models for the radio, extreme ultraviolet, hard X-ray, and gamma-ray emission from nonthermal particles accelerated in these mergers are described.Comment: 38 pages with 9 embedded Postscript figures. To appear in Merging Processes in Clusters of Galaxies, edited by L. Feretti, I. M. Gioia, and G. Giovannini (Dordrecht: Kluwer), in press (2001

Cosmic ray oriented performance studies for the JEM-EUSO first level trigger

JEM-EUSO is a space mission designed to investigate Ultra-High Energy Cosmic Rays and Neutrinos (E > 5 ⋅ 1019 eV) from the International Space Station (ISS). Looking down from above its wide angle telescope is able to observe their air showers and collect such data from a very wide area. Highly specific trigger algorithms are needed to drastically reduce the data load in the presence of both atmospheric and human activity related background light, yet retain the rare cosmic ray events recorded in the telescope. We report the performance in offline testing of the first level trigger algorithm on data from JEM-EUSO prototypes and laboratory measurements observing different light sources: data taken during a high altitude balloon flight over Canada, laser pulses observed from the ground traversing the real atmosphere, and model landscapes reproducing realistic aspect ratios and light conditions as would be seen from the ISS itself. The first level trigger logic successfully kept the trigger rate within the permissible bounds when challenged with artificially produced as well as naturally encountered night sky background fluctuations and while retaining events with general air-shower characteristics

Nanocarriers in medicine

Każdy tradycyjny lek wprowadzony do organizmu powoduje różnorakie skutki uboczne. Zazwyczaj jest to spowodowane niską specyficznością, problemem z osiągnięciem miejsca docelowego oraz zbyt szybkim metabolizmem. Aby temu zapobiec, poprawić biodystrybucję leku, zmniejszyć skutki uboczne a tym samym poprawić jakość życia pacjentów, prowadzi się badania nad wykorzystaniem (zastosowaniem) osiągnięć nanotechnologii w medycynie. Prym wiodą tutaj nanonośniki leków, czyli nanocząstki metali lub kapsuły polimerowe. Jednak aby leczenie było efektywne, równie ważna jest szybka i dokładna diagnostyka medyczna. W tej dziedzinie uwagę przyciągają kropki kwantowe, których szczególne właściwości optyczne są ściśle związane z ich wielkością, rzędu nanometrów.Each traditional drug introduced into the body is causing various side effects. This usually results from low specificity, difficulties in reaching its destination, and fast metabolism. To prevent this, in order to improve the biodistribution of the drug, reduce side effects and thus improve the quality of life of patients, intensive research on the use of nanotechnology developments in medicine is carried out. Drug nanocarriers, metal nanoparticles or polymer capsules are the most commonly used for this purpose. Additionally, to ensure effective treatment, rapid and accurate medical diagnosis is equally important. In this field the quantum dots with their specific optical properties closely connected with the size of the order of nanometers attract specific attention

Synthesis of silver and gold nanoparticles using methods of green chemistry

Wraz z rozwojem różnych dziedzin przemysłu zaczęto zwracać uwagę na degradację środowiska naturalnego przez produkty uboczne, powstające wskutek prowadzonych procesów technologicznych. Rozpoczęto więc badania nad zminimalizowaniem zastosowania substancji toksycznych w różnych dziedzinach gospodarki i zastąpienia ich naturalnymi. Powstał trend zwany zieloną chemią. Zaczęto go stosować również w nanotechnologii, szczególnie w syntezie nanocząstek, i wykorzystywać substancje popularnie występujące w organizmach, zarówno roślinnych jak i zwierzęcych. W artykule przybliżono tematykę syntezy nanocząstek srebra i złota naturalnymi metodami oraz badania dotyczące modyfikacji tak otrzymanych układów.Together with the development of various fields of industry it started to pay attention to environmental degradation by-products formed as a result of technological processes. Thus, research on minimizing the use of toxic substances and replace them with natural ones in various sectors of the economy has been stimulated. In this way, the trend called “green chemistry” was created. Also it had begun to be used in nanotechnology, especially for the synthesis of nanoparticles. Due to that, substances normally occurring in the organisms of plants and animals have been used more often. This article introduces silver and gold nanoparticles synthesis via natural methods followed by modification of their surfaces