CONTRIBUTION OF RESONANCE RAMAN EXCITATION SPECTROSCOPY FOR PROBING ELECTRONICALLY EXCITED-STATES - NATURE OF A PORPHYRIN-DNA EXCIPLEX

The resonance Raman spectra of a water-soluble metalloporphyrin Cu(TMpy-P4), complexed with a synthetic nucleic acid, poly(dA-dT), were measured by using excitation wavelengths located within the B (Soret) transition of the porphyrin (417-470 nm), while its excited state was synchronously pumped with 545-nm pulsed excitation corresponding to the Q transition. In the presence of pump pulses, the aqueous solution of the Cu(TMpy-P4).poly(dA-dT) complex exhibits resonance Raman bands at 1558 and 1353 cm-1 that are not observed in the absence of pump pulses. These new features were previously assigned to electronically excited Cu(TMpy-P4), stabilized by forming an exciplex with the A-T sites of the nucleic acid. Here we present resonance Raman excitation profiles (RREP) of both the excited and ground states of the complex, and we experimentally confirm the very short lifetime of the exciplex. To our knowledge this is the first time that a RREP of a very short lived (ca. 20 ps) intermediate excited state has been obtained with a two-color experiment. We use this to help to characterize the nature of the porphyrin-AT specific complex formed in the porphyrin excited state.

Electronically Reconfigurable Liquid Crystal Based Mm-Wave Polarization Converter

An electronically tunable reflection polarizer which exploits the dielectric anisotropy of nematic liquid crystals (LC) has been designed, fabricated and measured in a frequency band centered at 130 GHz. The phase agile polarizing mirror converts an incident slant 45° signal upon reflection to right hand circular (RHCP), orthogonal linear (-45 °) or left hand circular (LHCP) polarization depending on the value of the voltage biasing the LC mixture. In the experimental set-up this is achieved by applying a low frequency bias voltage of 0 V, 40 V and 89 V respectively, across the cavity containing the LC material.

Electronically Scanned Rotman Lens Antenna with Liquid Crystal Phase Shifters

The performance of a Rotman lens, which forms fixed beams at 0°, ±15° and ±30°, is augmented using liquid crystal phase shifters to simultaneously steer each beam by up to ±7.5°. Measured results are used to demonstrate that the true time delay property of the antenna and voltage controlled phase shifters can be exploited to provide continuously scanned beams with full coverage over an angular range of ±37.5°, and with operation over the band 6-10 GHz.

Design and Demonstration of an Electronically Scanned Reflectarray Antenna at 100 GHz using Multiresonant Cells Based on Liquid Crystals

The design, fabrication, and measured results are presented for a reconfigurable reflectarray antenna based on liquid crystals (LCs)which operates above 100 GHz. The antenna has been designed to provide beam scanning capabilities over a wide angular range, a large bandwidth,and reduced side-lobe level (SLL). Measured radiation patterns are in good agreement with simulations, and show that the antenna generates an electronically steerable beam in one plane over an angular range of 55◦ in the frequency band from 96 to 104 GHz. The SLL is lower than −13 dB for all the scan angles and −18 dB is obtained over 16% of the scan range. The measured performance is significantly better than previously published results for this class of electronically tunable antenna, and moreover, veri-fies the accuracy of the proposed procedure for LC modeling and antenna design.

A Compact Electronically Reconfigurable Dual Frequency Microstrip Antenna for L-Band Applications

A novel design of a computer electronically reconfigurable dual frequency dual polarized single feed hexagonal slot loaded microstrip antenna in L-band is introduced in this chapter. pin diodes are used to switch the operating frequencies considerably without much affecting the radiation characteristics and gain. the antenna can work with a frequency ratio varying in the wide range from 1.2 to 1.4. the proposed design has an added advantage of size reduction up to 72.21% and 46.84% for the two resonating frequencies compared to standard rectangular patches. the design also gives considerable bandwidth of up to 2.82% and 2.42 % for the operating frequencies.

Electronically Querying for the Provenance of Entities

The provenance of entities, whether electronic data or physical artefacts, is crucial information in practically all domains, including science, business and art. The increased use of software in automating activities provides the opportunity to add greatly to the amount we can know about an entityâ??s history and the process by which it came to be as it is. However, it also presents difficulties: querying for the provenance of an entity could potentially return detailed information stretching back to the beginning of time, and most of it possibly irrelevant to the querier. In this paper, we define the concept of provenance query and describe techniques that allow us to perform scoped provenance queries.

Professionals' perceptions of electronically recorded interviews with vulnerable witnesses

This study presents a qualitative evaluation of the Video and Audio Taped Evidence (VATE) process involving vulnerable witnesses, introduced by Victoria Police in 1996. Specifically, this study presents an analysis of individual in-depth interviews with a diverse group of 25 key Victorian stakeholders (police officers, prosecutors, solicitors, defence lawyers, and members of the judiciary). The aim of the interviews was to provide an overview of the stakeholders' perceptions of the VATE system, with particular focus on the usefulness of VATE interviews viewed or used in the stakeholders' practice. The findings revealed unanimous support for electronic recording of witness statements. However, the stakeholders also perceived that the effectiveness of the system was impeded by several factors. These include: (a) frequent absence within the interviews of a coherent account and detail needed to prove the various offences, (b) inability to scrutinise questions asked prior to the VATE interview, (c) lack of feedback regarding how well the VATE system is working, and (d) the recording medium itself which produced statements of poor sound and visual quality. Three broad recommendations arising from the interviews are discussed.

Is e-governance a function of government or media? Some directions for future research and development of electronically mediated citizen participation

Citizen participation, enabled by electronic means, grows, in parallel with government's apparent failure to promote it. Organisations such as Getup and Moveon flourish; the BBC announced in 2003 that 'Internet-based political activism is happening...The BBC wants to help a wider audience find their voice by tackling obstacles to greater participation' (http://www.opendemocracy.net). (Kevill, 2003). Such actions echo, perhaps, the enthusiastic adoption of the Internet by activist media groups, particularly Indymedia. This paper presents a response to this situation. It provides a richer account of the contradictory rise of e-government without e-governance, and examines the potential for media-based participatory engagement to complement e-government. It presents two models of the future of electronically mediated citizen engagement: the first involving agonistic relations between government and citizenry, with civic participation occurring outside of government-approved forums; the second involving the intimate linking of governmental transactions to participation by those citizens engaged in them. Finally it will outline mechanisms for researching the capacity of either or both models to sustain effective participation.

Low energy elastic and electronically inelastic electron scattering from biomolecules.

Reactions initiated by collisions with low-energy secondary electrons has been found to be the prominent mechanism toward the radiation damage on living tissues through DNA strand breaks. Now it is widely accepted that during the interaction with these secondary species the selective breaking of chemical bonds is triggered by dissociative electron attachment (DEA), that is, the capture of the incident electron and the formation of temporary negative ion states [1,2,3]. One of the approaches largely used toward a deeper understanding of the radiation damage to DNA is through modeling of DEA with its basic constituents (nucleotide bases, sugar and other subunits). We have tried to simplify this approach and attempt to make it comprehensible at a more fundamental level by looking at even simple molecules. Studies involving organic systems such as carboxylic acids, alcohols and simple ¯ve-membered heterocyclic compounds are taken as starting points for these understanding. In the present study we investigate the role played by elastic scattering and electronic excitation of molecules on electron-driven chemical processes. Special attention is focused on the analysis of the in°uence of polarization and multichannel coupling e®ects on the magnitude of elastic and electronically inelastic cross-sections. Our aim is also to investigate the existence of resonances in the elastic and electronically inelastic channels as well as to characterize them with respect to its type (shape, core-excited or Feshbach), symmetry and position. The relevance of these issues is evaluated within the context of possible applications for the modeling of discharge environments and implications in the understanding of mutagenic rupture of DNA chains. The scattering calculations were carried out with the Schwinger multichannel method (SMC) [4] and its implementation with pseudopotentials (SMCPP) [5] at di®erent levels of approximation for impact energies ranging from 0.5 eV to 30 eV. References [1] B. Boudai®a, P. Cloutier, D. Hunting, M. A. Huels and L. Sanche, Science 287, 1658 (2000). [2] X. Pan, P. Cloutier, D. Hunting and L. Sanche, Phys. Rev. Lett. 90, 208102 (2003). [3] F. Martin, P. D. Burrow, Z. Cai, P. Cloutier, D. Hunting and L. Sanche, Phys. Rev. Lett. 93, 068101 (2004). [4] K. Takatsuka and V. McKoy, Phys. Rev. A 24, 2437 (1981); ibid. Phys. Rev. A 30, 1734 (1984). [5] M. H. F. Bettega, L. G. Ferreira and M. A. P. Lima, Phys. Rev. A 47, 1111 (1993).

Implementation of a VLSI amplifier interfaced with biomedical sensors for ultra wide band data transmission

This thesis presents a CMOS Amplifier with High Common Mode rejection designed in UMC 130nm technology. The goal is to achieve a high amplification factor for a wide range of biological signals (with frequencies in the range of 10Hz-1KHz) and to reject the common-mode noise signal. It is here presented a Data Acquisition System, composed of a Delta-Sigma-like Modulator and an antenna, that is the core of a portable low-complexity radio system; the amplifier is designed in order to interface the data acquisition system with a sensor that acquires the electrical signal. The Modulator asynchronously acquires and samples human muscle activity, by sending a Quasi-Digital pattern that encodes the acquired signal. There is only a minor loss of information translating the muscle activity using this pattern, compared to an encoding technique which uses astandard digital signal via Impulse-Radio Ultra-Wide Band (IR-UWB). The biological signals, needed for Electromyographic analysis, have an amplitude of 10-100μV and need to be highly amplified and separated from the overwhelming 50mV common mode noise signal. Various tests of the firmness of the concept are presented, as well the proof that the design works even with different sensors, such as Radiation measurement for Dosimetry studies.

Design and demonstration of an electronically scanned reflectarray antenna at 100 GHz using multiresonant cells based on liquid crystals

The design, fabrication and measured results are presented for a reconfigurable reflectarray antenna based on liquid crystals (LC) which operates above 100 GHz. The antenna has been designed to provide beam scanning capabilities over a wide angular range, a large bandwidth and reduced Side-Lobe Level. Measured radiation patterns are in good agreement with simulations, and show that the antenna generates an electronically steerable beam in one plane over an angular range of 55º in the frequency band from 96 to 104 GHz. The Side Lobes Level is lower than -13 dB for all the scan angles and -18 dB is obtained over 16% of the scan range. The measured performance is significantly better than previously published results for this class of electronically tunable antenna, and moreover verifies the accuracy of the proposed procedure for LC modeling and antenna design.