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The recently developed photothermal technique of quadrature photopyroelectric spectroscopy (Q-PPES) has been applied to measurements of amorphous Si thin films deposited on crystalline Si substrates. Direct, meaningful comparisons have been made between purely optical transmission in-phase (IP-PPES) spectra, and purely thermal-wave sub-gap spectra with the use of a novel noncontacting PPES instrument to record lock-in in-phase and quadrature spectra, respectively. FT-IR transmission spectra have also been obtained for a comparison with this IP-PPES optical method. The results of the present work showed that the FT-IR method performs the worst in terms of spectral resolution of thin films and sub-bandgap defect/impurity absorptions inherent in the Si wafer substrate. The optical IP-PPES channel, however, albeit more sensitive than the FT-IR technique, fails to resolve spectra from surface films thinner than 2100 Å, but is sensitive to sub-bandgap absorptions. The thermal-wave Q-PPES channel is capable of resolving thin-film spectra well below 500 Å thick and exhibits strong signal levels from the crystalline Si sub-bandgap absorptions. Depending on the surface thin-film orientation toward, or away from, the direction of the incident radiation, the estimated minimum mean film thickness resolvable spectroscopically by Q-PPES is either 40 Å or 100 Å, respectively.

PbS quantum dots (QDs) of different sizes capped with short (NH4)(3)AsS3 inorganic ligands are produced via ligand exchange processes from oleate-capped PbS QDs. The solid-state photophysical properties of the control organic-capped and the inorganic-ligand-capped QDs are investigated to determine their potential for optoelectronic applications. Ultrafast transient transmission shows that in the oleate-capped QDs, carrier recombination at sub-nanosecond scales occurs via Auger recombination, traps, and surface states. At longer times, intense signals associated with radiative recombination are obtained. After ligand exchange, the QDs become decorated with (NH4)(3)AsS3 complexes and relaxation is dominated by efficient carrier transfer to the ligand states on timescales as fast as approximate to 2 ps, which competes with carrier thermalization to the QD band edge states. Recombination channels present in the oleate-capped QDs, such as radiative and Auger recombination, appear quenched in the inorganic-capped QDs. Evidence of efficient carrier trapping at shallow ligand states, which appears more intense under excitation above the (NH4)(3)AsS3 gap, is provided. A detailed band diagram of the various relaxation and recombination processes is proposed that comprehensively describes the photophysics of the QD systems studied. 4 7 1301547 1301547 PT: J TC: 8 J9: ADV ENERGY MATER

Results Phylogenetic analyses of the obtained viral sequences showed genetic diversity. In the eastern European cohort, subtype F1 was the dominant subtype (40%), followed by subtype C (20%), A1, A2, CRF02_AG, and CRF03_AB (10% each). In the young MSM cohort subtype B was the main subtype (50%), followed by subtype A1 (25%), CRF01_AE (12.5%) and one HIV-1 isolate that was not classified in any known subtype or recombinant form (12.5%). Complete recombination analysis revealed that this isolate had a new recombinant pattern, comprising segments of subtypes A1 and B, and is distinct from any reported recombinant. Conclusions These findings exhibit an influx of infrequent HIV-1 genetic forms from eastern European countries in Cyprus, and a stable circulation of B and A1 subtype among the young Cypriot MSM cohort. A unique recombination event between A1 and B subtypes has occurred and the parental strains seem to be formerly characterized Cypriot MSM patients. For the first time, these data show an impact on the evolutionary progress of HIV-1 epidemic of the island. The significance of this study along with the earlier variable epidemiological status of HIV-1 infection in Cyprus reflects the contribution to HIV classification, and the important implications for HIV-1 disease control and surveillance.

Ion implantation is a key technological process in modern microelectronics introduced as an alternative to diffusion for the semiconductor doping process [1]. However, disadvantages result from ion implantation such as defect damage to the wafer. Therefore, ion implantation has to be followed by the annealing process in order for the semiconductor to recover its crystallinity and for the doping impurity to become electrically active [2]. In recent years, layers doped by ion implantation have been studied via numerous techniques such as ... 4

Aim To investigate whether incorrect order of draw of blood samples during phlebotomy causes in vitro potassium ethylenediaminetetraacetic acid EDTA (kEDTA) contamination of blood samples. Methods Serum kEDTA, potassium, calcium, magnesium, alkaline phosphatase, zinc and iron concentrations were measured in blood samples drawn before and after collecting blood into kEDTA containing sample tubes by an experienced phlebotomist using the Sarstedt Safety Monovette system. Results EDTA was undetectable in all samples. The concentrations of other analytes were similar in blood samples drawn before and after collection of the EDTA blood sample. Conclusion Order of draw of blood samples using the Sarstedt Safety Monovette system has no effect on serum biochemistry results, when samples are taken by an experienced phlebotomist.

A 60 year old South Asian woman with a one year history of lethargy and anorexia, and 3 kg weight loss was referred by her general practitioner to a medical outpatient department. Medical history included pulmonary tuberculosis, hypothyroidism, psoriasis, and Raynaud’s phenomenon. She was taking levothyroxine 100 μg daily, amlodipine 5 mg daily, and applying Polytar liquid 250 ml twice weekly to her scalp. Clinical examination was unremarkable. Chest radiograph, abdominal ultrasound, and serum tissue transglutaminase antibodies, glucose, and thyroid function tests excluded active tuberculosis, coeliac disease, diabetes mellitus, and thyroxine overtreatment. Apart from persisting mild hyponatraemia (serum sodium concentration 128-135 mmol/L), routine haematology, biochemistry, and serum inflammatory markers were normal. The patient was not oedematous or dehydrated. Further investigations showed: Given these results, a short Synacthen test was performed using 0.25 mg Synacthen given intravenously at 0 minutes.⇓ View this table: Table 1 Results of the short Synacthen test

Experimental spectroscopic and time-resolved luminescence measurements of the ${\mathrm{Ti}}^{3+}$:${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ crystalline system have been performed. The absorption and fluorescence spectra obtained have led to a reconsideration of prevailing theoretical models for the radiative relaxation process in Ti:sapphire crystals. A realistic, two-dimensional configuration-coordinate space model has been constructed to describe the Jahn-Teller distortion of the system. Consideration of the nonlinear contributions to the electron-lattice coupling potential was found to contribute little to the second luminescence emission maximum, thus indicating that the electron-phonon interaction is essentially linear in the ground state. The main effect of the nonlinearity was found to be in the value of the nonradiative activation energy. The spin-orbit coupling was also incorporated in the model and was shown to be responsible for the nonradiative transitions in ${\mathrm{Ti}}^{3+}$:${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$, while the phonon structure of the ground ${(}^{2}$${\mathit{T}}_{2}$) state of the system results from both spin-orbit and nonlinear coupling with the lattice.

Photopyroelectric spectroscopy (PPES) was used in a noncontact experimental configuration to obtain high-resolution absolute spectra of the optical-to-thermal energy-conversion efficiency (nonradiative coefficient), η NR (λ), of Ti:sapphire laser crystals with widely different figures of merit. Optical-absorption-coefficient β(λ) spectra were obtained from the PPES signal in the purely optical transmission mode. These were subsequently used self-consistently in a theoretical model along with PPES-signal quadrature spectra (purely thermal transmission mode) to extract η NR (λ) spectra. These spectra were found to depend on the optical quality of the bulk and of the polished surfaces of the Ti:sapphire material

The sensitivity of various thicknesses of optically thin film Pd layers evaporated into a silicon oxide substrate is investigated in the presence of a hydrogen/air atmosphere at room temperature. The magnitude of the resulting reflectivity change is measured using an excite-probe technique, through laser excited photothermal modulation of a probe beam. Data indicates that concentrations of 0.1% hydrogen in a balanced air mixture and at room temperature may be measured with an 8nm Pd film. Inhomogeneities in the Pd layers lead ... 463 1 220 222

The properties of thin palladium films on silicon dioxide/silicon substrates are investigated. As the electrical properties of very thin palladium films cannot be measured, due to highly discontinuous nature of the films resulting from the low level of surface coverage, simple laser diagnostic techniques are used. Results showed the changes in the absolute reflectivity of Pd-SiO2 films upon exposure to various concentrations of hydrogen gas as a function of temperature. 43 4 155 157 Cited By :2

Photothermal radiometric measurements were performed on metal contaminated silicon wafers. Data were collected over modulation frequencies ranging from 0.1 to 100kHz, with a Kr-Ar ion laser used as the excitation source. The sensitivity of this technique to different forms of metallic contamination is examined. A qualitative comparison is made between theory and experiment. 463 1 386 388

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CY-NiUL UCY-LIB PELEGARIS TA1800.O84 1999 $7 10203598 000248890 2 ΧΡΗΣΤΟΣ ΠΕΤΡΩΝΔΑΣ In Library CYPR ID: 94 87nam 2200337 i 450 hbk. 20040109d1999 y0engy0105 ba ill. 24 cm. Includes bibliogra 1 Artech House optoelectronics library Optical fibers Diffraction gratings Optical detectors 0 CY University of Cyprus AACR2 CY-NiUL UCY-LIB KEN TA1800.O84 1999 $7 10046940 000139856 1 In Library CYPR

A study of a thermal wave hydrogen sensor characterized using transverse optical beam deflection measurements is presented, including a comparison of experimental data with a simple theoretical model. The sensor consists of a thin film polyvinylidene fluoride (PVDF) film coated with a thin Pd layer. Changes in the thermal boundary conditions at the gas-film interface lead to sensitivity to hydrogen gas that depends upon the thermo-physical properties of the gas. Concentrations of 4% to 100ppm hydrogen in balanced air and at ... 463 1 247 249

Thesis (Master) -- University of Cyprus, Faculty of Pure and Applied Sciences, Department of Computer Science, 2009. Databases are the main component of modern systems. We may find Database Management Systems (DBMS) in the backend of many software systems, such as Enterprise Resource Systems (ERPs), websites, accounting systems, scientific applications and many others. DBMS systems are responsible for storing, analyzing, managing and querying large volumes of data. Querying of data forms is the most time-consuming workload of DBMS systems. The querying comprises of different operations, mostly aggregations, selections and join operations. The most known queries and also the most time-consuming are the Decision Support System (DSS) queries. DSS queries are designed to process large data sets and use large-scale multiprocessors. For this work we decided to analyze the benefits of accelerating DSS queries on different GPU and the CELL processors. Both architectures, aside from promising high-performance, are of low-cost. We use Rapidmind to implement the parallel version of three representative DSS queries found in the TPC-H Benchmark. As a baseline for our comparisons we use a single-core native C++ code execution on a Core 2 Duo 2.13GHz CPU. We compare the execution of the three queries with two different GPU models of the same generation (NVidia Geforce 8500GT and 8800GT) and with the CELL processor found on Playstation 3. Results show that GPUs are very promising as far as exploiting parallelism in database queries. The speedup observed was up to 21x compared to the single processor CPU execution.

Decision Support System (DSS) workloads are known to be one of the most time-consuming database workloads that processes large data sets. Traditionally, DSS queries have been accelerated using large-scale multiprocessor. The topic addressed in this work is to analyze the benefits of using high-performance/low- cost processors such as the GPUs and the Cell/BE to accelerate DSS query execution. In order to overcome the programming effort of developing code for different architectures, in this work we explore the use of a platform, Rapidmind, which offers the possibility of executing the same program on both Cell/BE and GPUs. To achieve this goal we propose data-parallel versions of the original database scan and join algorithms. In our experimental results we compare the execution of three queries from the standard DSS benchmark TPC-H on two systems with two different GPU models, a system with the Cell/BE processor, and a system with dual quad-core Xeon processors. The results show that parallelism can be well exploited by the GPUs. The speedup values observed were up to 21× compared to a single processor system. Copyright 2009 ACM. 117 126 Sponsors: ACM SIGMicro Conference code: 100066 Cited By :12

The optical properties of several thin metal film palladium-silicon oxide structures are examined at room temperature before and after annealing to 200 degrees C and also at 90 degrees C-in all cases in the presence of hydrogen gas. Multicycling sample activation is shown to occur iii the presence of hydrogen at room temperature with an increase in reflectivity on exposure to hydrogen, in contrast to thicker 80 Angstrom films. The reflectivity change increases with increasing film thickness (1-10 Angstrom). The surface activation at room temperature, before and after annealing to 200 degrees C, is compared with the performance at 90 degrees C, where it is shown that heat treatment strongly influences the behavior of the metal film. (C) 1998 American Institute of Physics. [S0034-6748(98)03809-X]. 69 9 3331 3338 PT: J TC: 9 J9: REV SCI INSTRUM

Over the past 2 decades there has been tremendous advancements in the field of ultrafast carrier dynamics in semiconductors. The driving force behind this movement other than the basic fundamental interest is the direct application of semiconductor devices and the endless need for faster response and faster processing of information. To improve and develop microelectronics devices and address these needs, there must be a basic understanding of the various dynamical processes in the semiconductors which have to be studied in detail. Therefore, the excitation of semiconductors out of their equilibrium and the subsequent relaxation processes with various rates has become a key area of semiconductor research. With the development of lasers that can generate pulses as short as a few femtoseconds the excitation and subsequent probing of semiconductors on an ultrashort timescale have become routine. Processes such as carrier momentum randomization, carrier thermalization, and energy relaxation have been studied in detail using excite-and-probe novel techniques. This article reviews the status of ultrafast carrier and phonon dynamics in semiconductors. Experimental techniques such as excite-and-probe transmission, time-resolved up-conversion luminescence, and pump-probe Raman scattering along with some of the significant experimental findings from probing semiconductors are discussed. Finally, a selfconsistent theoretical model, which correlates the carrier and phonon dynamics in germanium on an ultrashort time scale, is described in detail. © 1998 American Institute of Physics. 83 4 1789 1830 Cited By :266

An improved model of wavelength division multiplexing (WDM) by superimposed gratings in planar waveguides has been developed. Based on this theory, principal design rules of N-channel WDM are established and a fanout capacity of 100 is estimated. Finally, fourchannel WDM at 840 nm has been demonstrated on a Ge:SiO2/SiO2/Si planar waveguide, which was hydrogenated to enhance its photosensitivity. The superimposed gratings were written using a narrow linewidth KrF excimer laser in an interferometric setup used in inscribing fiber Bragg gratings. © 1998 Society of Photo-Optical Instrumentation Engineers. 37 2 717 720 Cited By :5

Photothermal radiometry (PTR) is applied to characterize nickel-pigmented aluminium oxide solar absorbing coatings. A modulated laser beam is used to heat the solar samples. The subsequent emission of thermal radiation is measured as a function of modulated frequency in the range of 10 Hz to 10 kHz. A simple one-dimensional model is used to fit the experimental PTR results, allowing for the extraction of some thermal parameters for the solar absorbing coatings. Finally, comparison of the emissivity measured by traditional technique and the photothermal radiometry is made. © 1998 Elsevier Science B.V. All rights reserved. 51 2 171 179 Cited By :13

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Laser-induced, frequency-scanned IR photothermal radiometry was used to investigate the thermophysical properties of the paper on which several genuine and counterfeit British (pound 10) and U.S. ($50, $100) currency bills were printed. The radiometric photothermal amplitudes and phases were further compared with a theoretical model, which yielded simultaneous quantitative measurements of the thermal diffusivities and conductivities of the bills. Both statistical and single-specimen results demonstrated the excellent thermophysical resolution of the technique with prospects for its use in the nonintrusive, on-line identification of counterfeit banknotes. (C) 1997 Society of Photo-Optical Instrumentation Engineers. 36 2 400 407 PT: J TC: 4 J9: OPT ENG

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Since the discovery of photosensitivity in optical fibers there has been great interest in the fabrication of Bragg gratings within the core of a fiber. The ability to inscribe intracore Bragg gratings in these photosensitive fibers has revolutionized the field of telecommunications and optical fiber based sensor technology. Over the last few years, the number of researchers investigating fundamental, as well as application aspects of these gratings has increased dramatically. This article reviews the technology of Bragg gratings in optical fibers. It introduces the phenomenon of photosensitivity in optical fibers, examines the properties of Bragg gratings, and presents some of the important developments in devices and applications. The most common fabrication techniques (interferometric, phase mask, and point by point) are examined in detail with reference to the advantages and the disadvantages in utilizing them for inscribing Bragg gratings. Reflectivity, bandwidth, temperature, and strain sensitivity of the Bragg reflectors are examined and novel and special Bragg grating structures such as chirped gratings, blazed gratings, phase-shifted gratings, and superimposed multiple gratings are discussed. A formalism for calculating the spectral response of Bragg grating structures is described. Finally, devices and applications for telecommunication and fiber-optic sensors are described, and the impact of this technology on the future of the above areas is discussed. © 1997 American Institute of Physics. 68 12 4309 4341 Cited By :481

The common feature of all previous photothermal studies of semiconductors is that only electronically homogeneous materials have been assumed. Correspondingly, both carrier lifetime (τ) and diffusivity (D n) values have been usually taken to be the bulk characteristics of semiconductor and no experimental works or theoretical models have addressed the problem of τ and D n depth profile reconstructions. For continuously inhomogeneous solids the treatment of the thermal-wave propagation problem using a ... 371 378

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Laser-induced, frequency-scanned infrared photothermal radiometry (PTR) was used successfully in a noncontacting manner to characterize commercial-quality xerographic paper, which was impossible to characterize optically because of its large optical scattering coefficient. A theoretical photothermal mode was developed and applied to the frequency-domain data, thus yielding simultaneous measurements of the thermophysical properties (thermal diffusivity and conductivity) of as-received and xerographically processed sheets of paper. 23 3 J108 J112 PT: J TC: 5 J9: J PULP PAP SCI

The dynamics of photoexcitations in hybrid blends of poly(3-hexylthiophene) (P3HT) conjugated polymer donor and oleic-acid capped lead sulfide (PbS) quantum dot (QD) acceptors of different concentrations - for light harvesting applications - were investigated using time-resolved transmission and photoluminescence spectroscopies. Following excitation at 400 nm and probing in the 500-1000 nm region, we find that geminate excitation recombination in the blend of P3HT/PbS QDs dominates the transient decays at sub-ns times while intermaterial interactions such as charge transfer processes appear at longer times in the 1-50 ns regime. For the hybrid blend films with lower QD concentrations (Cited By :4

Photothermal radiometric measurements were performed on phosphorus implanted and annealed silicon wafers. Data were collected over modulation frequencies ranging between 0.1 and 100 kHz with the 488 nm Ar ion laser line as the excitation source. The sensitivity of this technique on implantation dose and annealing temperature is discussed. A semiquantitative analysis of the data is also carried out. © 1996 American Institute of Physics. 69 6 821 823 Cited By :21

We present the results of a study of the subpicosecond dynamic behavior of optically induced absorption changes in low-temperature-grown GaAs. We show that the observed behavior is dominated by mid-gap trap states, and can be accurately modeled by the rate equations previously developed to describe quasi-cw results. Our data give the first approximate values for trap emptying times in this material. © 1996 American Institute of Physics. 68 18 2544 2546 Cited By :73

A method of extracting the strain profile along a fiber Bragg grating from the intensity reflection spectrum is described. The procedure is based on a filter synthesis theory that relates the aperiodicity of a grating with its reflection spectrum. To illustrate the approach, we measured the strain profile near a hole in a plate and obtained a strain resolution of 80 μ∈. The spatial resolution depends on the strain gradient i.e., the higher the gradient, the better the resolution. A resolution of 0.8 mm was achieved for a 5-mm grating with a gradient of 250 μ∈/mm. © 1996 Optical Society of America. 21 17 1405 1407 Cited By :98

The authors design and demonstrate a high-reflector broadband Bragg mirror for a fiber laser system. A T-matrix formalism was used to design a broadband intracore mirror consisting of a series of Bragg gratings. Ultraviolet light from a KrF excimer laser was used in an interferometric setup to inscribe these Bragg gratings in a photosensitive fiber. This resulted in a broadband Bragg mirror covering a wavelength range of approximately 3.5 nm. An all-Bragg grating, erbium-doped fiber laser cavity is demonstrated using this Bragg mirror as the high reflector and a single narrowband Bragg grating centered at 1550 nm as the output coupler. Tunability of the fiber laser was achieved over the range of the high reflector using strain-induced changes on the output coupler. © 1996 Society of Photo-Optical Instrumentation Engineers. 35 4 1088 1092 Cited By :11

Atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM) were used to study optical fiber structures. The refractive index profile of fiber was disclosed by surface topography of etched fiber endface using a AFM. The difference of refractive index was resolved to 1 × 10 -6. Near-field optical intensity distribution at fiber endface has been successfully measured by a tapping-mode force regulated SNOM. Combination of tapping-mode AFM and SNOM allowed us to image both refractive index and near-field intensity structures of fibers simultaneously. The correlation between waveguide structures and near-field propagating modes was directly provided by this novel method. Results of single mode fibers and fibers with anisotropic structures illustrated the usefulness of this technique. 2695 204 210 Sponsors: SPIE - Int Soc for Opt Engineering, Bellingham, WA USA Conference code: 22478 Cited By :1

Wavelength-division multiplexed (WDM) devices are becoming increasingly important for fiber-optics communication and sensing systems. Large-channel fanout, low loss, and compatibility with fiber connection, laser sources and detectors are desired. This article reports the theoretical analysis and experimental demonstration of a new type of WDM device - Supergrating WDM on planar waveguide. Anaheim, CA, USA 513 514 Sponsors: IEEE Optical Society of America Conference code: 45129 Cited By :1

The authors demonstrate the importance of spatial coherence of the writing beam for inscribing Bragg gratings with a phase mask. Bragg gratings were written using a normal excimer laser with the fiber placed at various distances away from the phase mask. This was repeated with an excimer laser that was modified to improve the beam spatial coherence showing dramatic improvement in the ability to inscribe gratings. ‘Tunability of the inscribed Bragg grating wavelength, utilizing a single phase mask in conjunction with the improved spatial coherence of the excitation source, is demonstrated. © 1995 IEEE 7 10 1183 1185 Cited By :35

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Fiber Bragg gratings are attracting increasing attention as sensors for the measurement of strain, temperature, and pressure. They are equally important as wavelength selective reflectors for fiber, and to a lesser extent, semiconductor lasers. This paper describes results from a hybrid laser comprising of a semiconductor optical amplifier coupled to a Bragg grating, and investigates the characteristics of such a laser system as a discrete strain sensor. 2509 48 56 Sponsors: SPIE - Int Soc for Opt Engineering, Bellingham, WA USA Conference code: 22351 Cited By :1

A spectrally narrow linewidth KrF excimer laser has been developed for the application of writing Bragg gratings in optical fibers. Two air spaced etalons 80 and 6 cm-1 have been incorporated within the laser cavity resulting in a laser line with a linewidth of approximately 4 pm. A stable wavelength setting for writing Bragg gratings has been achieved without the necessity of a feedback mechanism. A study of the formation of Bragg grating in optical fibers with this narrow linewidth KrF excimer laser has been carried out. High quality gratings have been demonstrated in hydrogen sensitized fibers with a pulse energy density as low as 20 mJ/cm2. Limitations and various problems encountered in inscribing Bragg gratings (such as two simultaneous grating lines) with the narrow linewidth excimer laser source are also discussed. © 1995 American Institute of Physics. 66 5 3112 3115 Cited By :11

This work examines the effects of different manufacturing techniques of fiber optic intracore Bragg gratings on their sensing and system parameters. Specifically, we have looked at tolerance with respect to center wavelength, strain, and temperature sensitivity. Our test results indicate a slight variation in the strain and temperature sensitivity of different gratings. In an attempt to quantify the effect of transverse loading on fiber gratings, three differently manufactured sensors were diametrically loaded and their spectrums studied. Our experimental results indicate a splitting of the grating spectrum with small loads for an optical fiber grating manufactured in either boron doped fiber or hydrogen loaded fibers. On the other hand, very small transverse sensitivity was observed for a fiber optic grating formed in a bend insensitive fiber suggesting some degree of control on the transverse sensitivity of these sensors. 2444 528 535 Sponsors: SPIE - Int Soc for Opt Engineering, Bellingham, WA USA Conference code: 22245 Cited By :12