All-optical switching device for infrared based on PbTe quantum dots

Multilayers of PbTe quantum dots embedded in SiO2 were fabricated by alternate use of Pulsed Laser Deposition (PLD) and Plasma Enhanced Chemical Vapor Deposition (PECVD) techniques. The morphological properties of the nanostructured material were studied by means of High Resolution Transmission Electron Microscopy (HRTEM), Grazing-Incidence Small-Angle X-ray scattering (GISAXS) and X-ray Reflectometry (XRR) techniques. A preliminary analysis of the GISAXS spectra provided information about the multilayer periodicity and its relationship to the size of the deposited PbTe nanoparticles. Finally multilayers were fabricated inside a Fabry-Perot cavity. The device was characterized by means of Scanning Electron Microscopy (SEM). Transmittance measurements show the device functionality in the infrared region. (C) 2007 Elsevier Ltd. All rights reserved.

The spectrum of an open vertex model based on the U(q)[SU(2)] algebra at roots of unity

We study the exact solution of an N-state vertex model based on the representation of the U(q)[SU(2)] algebra at roots of unity with diagonal open boundaries. We find that the respective reflection equation provides us one general class of diagonal K-matrices having one free-parameter. We determine the eigenvalues of the double-row transfer matrix and the respective Bethe ansatz equation within the algebraic Bethe ansatz framework. The structure of the Bethe ansatz equation combine a pseudomomenta function depending on a free-parameter with scattering phase-shifts that are fixed by the roots of unity and boundary variables. (C) 2010 Elsevier B.V. All rights reserved.

Switching off the reservoir through nonstationary quantum systems

In this paper, we demonstrate that the inevitable action of the environment can be substantially weakened when considering appropriate nonstationary quantum systems. Beyond protecting quantum states against decoherence, an oscillating frequency can be engineered to make the system-reservoir coupling almost negligible. Differently from the program for engineering reservoir and similarly to the schemes for dynamical decoupling of open quantum systems, our technique does not require previous knowledge of the state to be protected. However, differently from the previously-reported schemes for dynamical decoupling, our technique does not rely on the availability of tailored external pulses acting faster than the shortest timescale accessible to the reservoir degree of freedom.

REIDEMEISTER SPECTRUM FOR METABELIAN GROUPS OF THE FORM Q(n) x Z AND Z[1/p](n) x Z, p PRIME

In this paper, we study the Reidemeister spectrum for metabelian groups of the form Q(n) x Z and Z[1/p](n) x Z. Particular attention is given to the R(infinity)-property of a subfamily of these groups.

Fluoxetine and norfluoxetine analysis by direct injection of human plasma in a column switching liquid chromatographic system

A column switching LC method is presented for the analysis of fluoxetine (FLU) and norfluoxetine (NFLU) by direct injection of human plasma using a lab-made restricted access media (RAM) column. A RAM-BSA-octadecyl silica (C-18) column (40 min x 4.6 mm, 10 mu m) is evaluated in both backflush and foreflush elution modes and coupled with a C-18 lab-made (50 mm x 4.6 mm, 3 pm) analytical column in order to perform online sample preparation. Direct injection of 100 mu L, of plasma samples is possible with the developed approach. In addition, reduction of sample handling is obtained when compared with traditional liquid-liquid extraction (LLE) and SPE. The total analysis time is around 20 min. A LOQ of 15 ng/mL is achieved in a concentration range of 15-500 ng/mL, allowing the therapeutic drug monitoring of clinical samples. The precision values achieved are lower than 15% for all the evaluated points with adequate recovery and accuracy. Furthermore, no matrix interferences are found in the analysis and the proposed method shows to be an adequate alternative for analysis of FLU in plasma.

The hand of God is over their hands (Q. 48:10) : on the notion of covenant in al-Ṭabarī’s account of Karbalāʾ

This article is an analysis of the story of the killing of Ḥusayn b. ʿAlī at Karbalāʾ in 61/680, as it is presented by Abū Jaʿfar Muḥammad b. Jarīr al-Ṭabarī (d. 310/923). The main argument is that the notion of the divine covenant, which permeates the Qur’an, constitutes a framework through which al-Ṭabarī views this event. The Qur’anic idea of the covenant is read in structural/thematic continuity with the Hebrew Bible account of the covenant between Yahweh and the Hebrew people, which has, in turn, been traced back in its basic form to Late Bronze Era treaties between rulers and their vassals.   The present study focusses on four speeches ascribed to Ḥusayn during the encounter he and his group had with the vanguard of the Kūfan army led by al-Ḥurr. These are analysed in accordance with their use of Qur’anic covenant vocabulary. They are also categorised within the broader framework of the eight standard characteristics of Ancient West Asian and Biblical covenants, as presented by George Mendenhall and Gary Herion, which have recently been developed in a Qur’anic context by Rosalind Ward Gwynne. This article argues that al-Ṭabarī’s Karbalāʾ narrative presents the pact of loyalty to Ḥusayn as a clear extension of the divine covenant.

Claude Elwood Shannon e a symbolic analysis of relay and switching circuits: tornando o computador uma máquina semiótica.

O nome de Claude Elwood Shannon não é totalmente estranho aos pesquisadores de Comunicação Social. No entanto, parte de sua importância para a história da comunicação no século XX é pouco conhecida. Sua dissertação de mestrado e o artigo dela derivado (A Symbolic Analysis of Relay and Switching Circuits) foram essenciais para que o computador se tornasse uma máquina de comunicação e, conseqüentemente, penetrasse em nossa sociedade na forma como ocorre hoje. Este artigo revisa o primeiro grande trabalho de Shannon e explicita sua participação no contexto atual da comunicação.

Improving mutual fund market timing measures: a markov switching approach

Market timing performance of mutual funds is usually evaluated with linear models with dummy variables which allow for the beta coefficient of CAPM to vary across two regimes: bullish and bearish market excess returns. Managers, however, use their predictions of the state of nature to deÞne whether to carry low or high beta portfolios instead of the observed ones. Our approach here is to take this into account and model market timing as a switching regime in a way similar to Hamilton s Markov-switching GNP model. We then build a measure of market timing success and apply it to simulated and real world data.