Zn K-edge XANES in nanocrystalline ZnO

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Combining scanning probe microscopy and x-ray spectroscopy

A new versatile tool, combining Shear Force Microscopy and X-Ray Spectroscopy was designed and constructed to obtain simultaneously surface topography and chemical mapping. Using a sharp optical fiber as microscope probe, it is possible to collect locally the visible luminescence of the sample. Results of tests on ZnO and on ZnWO4 thin layers are in perfect agreement with that obtained with other conventional techniques. Twin images obtained by simultaneous acquisition in near field of surface topography and of local visible light emitted by the sample under X-Ray irradiation in synchrotron environment are shown. Replacing the optical fibre by an X-ray capillary, it is possible to collect local X-ray fluorescence of the sample. Preliminary results on Co-Ti sample analysis are presented

Зависимость эффективности биологической обратной связи по параметрам ритма сердца от вариаций геомагнитного поля

Протягом багатоденного моніторингу біологічного зворотного зв’язку (БЗЗ) за параметрами варіабельності серцевого ритму встановлено залежність ефективності БЗЗ від геліогеофізичної обстановки. У випробуваних з переважанням симпатичної активності є тенденція до більш ефективного біоуправління в умовах геомагнітної збуреності а також стабільного напряму міжпланетного магнітного поля. Навпаки, у випробуваних з переважанням вагусної активності БЗЗ є ефективнішім за умов відсутності геомагнітних збурювань а також при змінах полярності міжпланетного магнітного поля. Таким чином, геліогеофізичну обстановку слід ураховувати при аналізі ефективності біоуправління.Through days-long monitoring of biofeedback parameters of heart rate variability the dependence of biofeedback effectiveness on the geocosmic factors was established. In subjects whose nervous system is dominated by sympathetic type of reactivity, the biofeedback effectiveness tends to a better biocontrol under conditions of changes in interplanetary magnetic field or conditions of stable orientation of the interplanetary geomagnetic field. Individuals with prevalence of vagal activity usually are more effective in the biofeedback session if there are no geomagnetic disturbances as well as under conditions of changes in the interplanetary magnetic field polarity. Thus, the geocosmic factors should be taken into account when biofeedback effectiveness is analyzed

Applicazione di una Piattaforma Multicast a Sistemi Sensibili all`Ambiente

In questa tesi abbiamo fatto uno studio riguardante una tecnica di integrazione e comunicazione per sistemi di ubiquitous computing sensibili all`ambiente, cioe` sistemi in grado di reagire alla presenza delle persone ed alle loro azioni in un dato ambiente. La tecnica di comunicazione qui presa in considerazione e` il Channeled Multicast ed abbiamo utilizzato LoudVoice come piattaforma ad agenti per l`integrazione e la comunicazione fra le componenti del sistema. L`ambiente usato come caso di studio e` un museo interattivo in fase di sviluppo nell`ambito del progetto PEACH. Le considerazioni che abbiamo fatto in questa tesi non riguardano le parti di front-end del sistema (interfacce, presentazioni multimediali, ecc) o aspetti tecnici sull`hardware da utilizzare, ma l`integrazione e la comunicazione delle componenti con LoudVoice e lo studio di un archittetura adeguata a questo tipo di sistema. Gli obiettivi specifici di questo lavoro sono: verificare sperimentalmente l`adeguatezza delle prestazioni di LoudVoice per valutarne l`effettiva utilizzabilita` e capire dove eventualmente apportare modifiche per migliorarla; individuare un pattern di design per realizzare agenti che sfruttino al meglio le API e le funzionalita` di LoudVoice; definire un pattern architetturale per sistemi sensibili all`ambiente; infine, utilizzare tale pattern in un simulatore allo scopo di verificare concretamente la validita` del Channeled Multicast e, al contempo, l`integrita` e correttezza delle API di LoudVoic

Scheduling in 802.11e: Open-Loop or Closed-Loop?

http://citi.insa-lyon.fr/wons2006/index.htmlScheduling in 802.11e networks is managed by the Hybrid Coordination Function (HCF), located within the access point. HCF has access both to trafc descriptions (TSPEC) and to feedback information sent in every frame by stations. In this paper we discuss the use of open-loop or closed-loop scheduling; the rst one is based only on the TSPECs, while the second one relays also on the feedback information from stations and builds upon classical control theory design. We discuss how closed-loop scheduling can be used to manage both the QoS guaranteed trafc and the best-effort trafc with a non-marginal performance improvement compared to openloop scheduling algorithms. We propose a simple max-min fair scheduling algorithm based on a positional controller which measures buffer levels. The controller is up- and down-clipped to meet strict QoS guarantees, while optimally distributing stochastically guaranteed and spared resources. Simulation results based on ns-2 are presented to support the theory and the design, showing that the proposed scheduler is robust and performs always better than open loop scheduler in presence of trafc uncertainties

Supersonic molecular beams deposition of alpha-quaterthiophene: Enhanced growth control and devices performances

The alpha-quatertiophene is widely considered an interesting material for the realization of organic electronics and opto-electronics. Compared to other oligothiophenes, the performances of transistors based on this compound are limited by its kind of growth on the typical materials used for device realization. Here we show that via seeded supersonic beams we can lead to a nice improvement of both morphological and electrical properties of the film grown, through a better control of the initial state of the precursor in the vapor phase. Using the high kinetic energy achievable in the supersonic beams, we increase the dimensions of the grains and the coalescence of different islands, limiting the grain boundary formation, As consequence, the performance of the realized field effect transistors is enhanced of one order of magnitude. (C) 2009 Elsevier B.V. All rights reserved

Deoxycholate as an efficient coating agent for hydrophilic silicon nanocrystals.

Silicon nanocrystals were made hydrophilic by 10-undecenoic acid grafting and were then coated with sodium deoxycholate, a detergent-like compound belonging to the bile acid class which is crucial for absorption of lipids in the small intestine. The resulting silicon nanocrystals have an average diameter of 3–5 nm, can be dispersed in aqueous solutions and show stable photoluminescence. Coating with non-biological surfactants, which are dangerous for cell safety, was investigated for comparison. Results indicate that deoxycholate is a stabilizer of luminescent silicon nanocrystals. Deoxycholate coated nanocrystals appear suitable for applications as multifunctional probes in biomedicine. Graphical abstract Water soluble, light emitting silicon nanocrystals were obtained by a two-step procedure: a chemical grafting followed by physical coating by deoxycholate which is natural surfactant-like molecule well tolerated by cells. This compound maintained the bright nanocrystal luminescence emission stable for 4–5 days

A new tool for nanoscale X-ray absorption spectroscopy and element-specific SNOM microscopy

Investigations of complex nanostructured materials used in modern technologies require special experimental techniques able to provide information on the structure and electronic properties of materials with a spatial resolution down to the nanometer scale. We tried to address these needs through the combination of X-ray absorption spectroscopy (XAS) using synchrotron radiation microbeams with scanning near-field optical microscopy (SNOM) detection of the X-ray excited optical luminescence (XEOL) signal. The first results obtained with the prototype instrumentation installed at the European Synchrotron Radiation Facility (Grenoble, France) are presented. They illustrate the possibility to detect an element-specific contrast and to perform nanoscale XAS experiments at the Zn K and W L-3-absorption edges in pure ZnO and mixed ZnWO4/ZnO thin films. (C) 2008 Elsevier Ltd. All rights reserved