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Energy harvesting from human motion is a research field under rapid development. In this tutorial review we address the main physical and physico-chemical processes which can lead to energy generation, including electromagnetism, piezoelectricity, and electrostatic generation. Emphasis is put on the relationships among material properties and device efficiency. Some new and relatively less known approaches, such as triboelectric nanogeneration (TENG) and reverse electrowetting (REWOD), are reported in more detail. [ABSTRACT FROM AUTHOR]

We demonstrate photoluminescence excitation enhancement in an all-polymer flexible onedimensional photonic crystal structure capped with a fluorescent organic ultrathin film. When optical matching conditions between the excitation beam and the Bloch Surface Wave mode supported by the photonic structure are achieved, a ten times enhancement of the photoluminescence is observed. We notice that in these systems luminescence signal reinforcement is achieved by increasing the pump efficiency with no need of spectral resonance to the emission of the chosen fluorophore. All these features make these systems suitable candidates for easy, flexible, and cheap fluorescent sensing. [ABSTRACT FROM AUTHOR]

This work deals with the strain relaxation mechanism in InGaAs metamorphic buffers (MBs) grown on GaAs substrates and overgrown by InAs quantum dots (QD). The residual strain is measured by using Raman scattering and X-ray diffraction, both in Reciprocal Space Map and in single ω-2θ scan modes (ω and θ being the incidence angles on the sample surface and on the scattering planes, respectively). By relating the GaAs-like longitudinal optical phonon frequency ωLO of InGaAs MBs to the in-plane residual strain ε measured by means of photoreflectance (PR), the linear ε-vs.-ωLO working curve is obtained. The results of Raman and XRD measurements, as well as those obtained by PR, are in a very satisfactory agreement. The respective advantages of the techniques are discussed. The measurements confirm that strain relaxation depends on the thickness t of the buffer layer following a ~t-1/2 power law, that can be explained by an energy-balance model. [ABSTRACT FROM AUTHOR]

Enhanced third harmonic (TH) generation from Silicon-On-Insulator (SOI) planar waveguides as well as SOI photonic crystal (PhC) slabs is studied in different angular configurations, both in the visible and infrared energy ranges. In the SOI planar waveguide, the multilayer structure causes the optical properties such as TH reflection to be different from those of bulk silicon samples. This behavior is well reproduced by calculations of TH reflectance. Measurements of third-harmonic reflection and diffraction from one-dimensional PhC slabs etched in the SOI waveguide are also reported. The angular positions of TH peaks at various diffraction orders agree well with those calculated from a nonlinear grating equation. Both reflection and diffraction processes contribute to enhanced TH generation efficiency in the PhC slabs. TH reflectance measurements performed on PhC slabs in the near infrared show a resonant interaction between the incident beam and the photonic structure, dependent on the angle of incidence. This leads to a nonlinear conversion efficiency which is strongly enhanced with respect to that of the SOI waveguide, due to the excitation of strong local fields associated with the presence of photonic modes in the PhC slab. [ABSTRACT FROM AUTHOR]

We report on the fabrication and optical measurements of Silicon On Insulator (SOI) nanostructures designed for photonic applications. Patterning was carried out by either electron beam lithography or nanoimprint lithography, followed by reactive ion etching with a SF6 and CHF3 gas mixture. The two-dimensional photonic lattices obtained were studied by scanning electron microscopy and by measuring photonic band dispersion above the light cone with Astratov coupling technique, showing a good agreement with the theoretical calculations. [Copyright &y& Elsevier]

Recent experimental and theoretical work on two-dimensional (2D) and waveguide-embedded photonic crystals is reviewed. The investigated systems are 2D macroporous silicon and photonic crystal slabs based on silicon-on-insulator as well as GaAs/AlGaAs. In all these structures, reflectance at varying angles of incidence allows to determine the dispersion of photonic modes above the light line. For macroporous silicon, reflectance from the side yields a complementary measurement of the photonic gaps. In the GaAs-based system, second-harmonic generation in reflection shows a resonant enhancement when the pump beam is frequency- and momentum-matched to a photonic mode in the slab. A theory of photonic states in waveguide-embedded photonic crystals leads to a determination of mode dispersion and diffraction losses for leaky photonic modes. [Copyright &y& Elsevier]

We report on Raman scattering experiments on InAs/AlxGa1-xAs quantum dot heterostructures with 0≤x≤0.6. The samples were prepared by using molecular beam epitaxy (MBE) and atomic layer MBE for the growth of different layers. For x>0, we detected several lines originating from the AlxGa1-xAs alloy. These can be related to scattering from GaAs-like and AlAs-like phonons with q≅0, and weaker scattering from disorder-activated phonons with q≠0. In particular, we identified a line at ∼250 cm-1 as due to disorder-activated longitudinal optical phonons in the alloy. This conclusion is different than the attribution of this line to scattering from dots and, consequently, we do not recognize the possibility of deriving any information about the actual composition of the dots from an analysis of this line as proposed by other authors. [ABSTRACT FROM AUTHOR]

GaAs/AlGaAs photonic crystal waveguides with unconventional tilted-square lattices and different filling factors are fully investigated by means of variable angle reflectance spectroscopy, which yields the photonic band dispersion, and theoretical calculation of both reflectance spectra and photonic band structure. [Copyright &y& Elsevier]

Pain assessment in patients with disorders of consciousness (DoC) is a controversial issue for clinicians, who require tools and standardised procedures for testing nociception in non-communicative patients. The aims of the present study were, first, to analyse the psychometric properties of the Italian version of the Nociception Coma Scale and, second, to evaluate pressure pain thresholds in a group of patients with DoC. The authors conducted a multi-centre study on 40 healthy participants and 60 DoC patients enrolled from six hospitals in Italy. For each group an electronic algometer was used to apply all nociceptive pressure stimuli. Our results show that the Italian version of the NCS retains the good psychometric properties of the original version and is therefore suitable for standardised pain assessment in clinical practice. In our study, pressure pain thresholds measured in a group of patients in vegetative and minimally conscious state were relatively lower than pain threshold values found in a group of healthy participants. Such findings motivate additional investigation on possible pain sensitisation in patients with severe brain injury and multiple co-morbidities, and on application of tailored therapeutic approaches useful for pain management in patients unable verbally to communicate their feelings.

We report the synthesis and characterization of a MASnxPb1-xBr3 (MA = methylammonium; nominal x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, 1) solid solution. The original synthetic method developed allowed one to obtain single-phase materials with homogeneous Sn/Pb distribution. All of the samples prepared are cubic, and the unit cell linearly decreases with increasing x value. The optical response indicates a linear trend (Vegard's law) of the band gap with increasing Sn content from 2.20 eV (x = 0) to 1.33 eV (x = 1), thus extending light absorption into the near-IR.

The first Italian experiences of HTA are born inside single hospitals and, lately, regional health care systems. In Italy, anyway, no agency had health technology assessment as an institutional duty until 2007, the year of the founding of the Italian Society of Health Technology Assessment (SIHTA). In times of "spending review", the HTA, whose purpose is to make decisions about health technologies rational and consistent with a context of scarce resources, is increasingly emerging as a priority need of the National Health System. The objective of this paper is to analyze if and how the librarian is involved in the process of health technology assessment, analyzing the results of a survey performed at a selection of Italian research organizations. The analysis of the results shows that the Italian situation is still very varied, from the point of view of HTA, and health technologies are often introduced without any preliminary analysis. The librarian is almost never represented within the HTA evaluation group and his/her knowledge of HTA should be improved.

We present the first demonstration of frequency conversion by simultaneous second- and third-harmonic generation in a silicon photonic crystal nanocavity using continuous-wave optical excitation. We observe a bright dual wavelength emission in the blue/green (450-525 nm) and red (675-790 nm) visible windows with pump powers as low as few microwatts in the telecom bands, with conversion efficiencies of ∼ 10 (-5) /W and ∼ 10/ W(2) for the second- and third-harmonic, respectively. Scaling behaviors as a function of pump power and cavity quality-factor are demonstrated for both second- and third order processes. Successful comparison of measured and calculated emission patterns indicates that third-harmonic is a bulk effect while second-harmonic is a surface-related effect at the sidewall holes boundaries. Our results are promising for obtaining practical low-power, continuous-wave and widely tunable multiple harmonic generation on a silicon chip.

We report on experimental demonstration of all-optical switching in a silicon-on-insulator photonic wire nanocavity operating at telecom wavelengths. The switching is performed with a control pulse energy as low as approximately 0.1 pJ on a cavity device that presents very high signal transmission, an ultra-high quality-factor, almost diffraction-limited modal volume and a footprint of only 5 microm(2). High-speed modulation of the cavity mode is achieved by means of optical injection of free carriers using a nanosecond pulsed laser. Experimental results are interpreted by means of finite-difference time-domain simulations. The possibility of using this device as a logic gate is also demonstrated.

We report on a photoluminescence and photoreflectance study of metamorphic InAs/InGaAs quantum dot strain-engineered structures with and without additional InAlAs barriers intended to limit the carrier escape from the embedded quantum dots. From: (1) the substantial correspondence of the activation energies for thermal quenching of photoluminescence and the differences between wetting layer and quantum dot transition energies and (2) the unique capability of photoreflectance of assessing the confined nature of the escape states, we confidently identify the wetting layer states as the final ones of the process of carrier thermal escape from quantum dots, which is responsible for the photoluminescence quenching. Consistently, by studying structures with additional InAlAs barriers, we show that a significant reduction of the photoluminescence quenching can be obtained by the increase of the energy separation between wetting layers and quantum dot states that results from the insertion of enhanced barriers. These results provide useful indications on the light emission quenching in metamorphic quantum dot strain-engineered structures; such indications allow us to obtain light emission at room temperature in the 1.55 microm range and beyond by quantum dot nanostructures grown on GaAs substrates.

We report on a technique for measuring the refractive indices of nonabsorbing media over a broad spectral range from 0.5 to 5 microm. White-light interferometry based on a double-interferometer system consisting of a fixed Mach-Zehnder interferometer and a Fourier-transform spectrometer is used for direct measurement of the absolute rotation-dependent phase shift induced by an optical element. Refractive index n(lambda) over the whole investigated spectral range is thus obtained directly to an accuracy of 10(-4) without the need for any specific assumption about dispersion. Results for synthetic fused silica are presented and discussed.

The recording of olfactory evoked potentials in healthy humans, using a continuous flow olfactory stimulator, is described. A stimulator pushed inert gas (N2) in a continuous flow through the nose at a rate of 4 l/min. At fixed 30-second intervals, (32 times) the flow was replaced by an equal amount of CO2, a trigeminal stimulant. Each pulse lasted 200 ms. An electronic timing circuit triggered both the stimulator and the recorder. Signal acquisition was performed using an Evoked Potential Recorder (Nicolet Compact Four by Nicolet Biomedical Instruments), triggered by the stimulator. Using this stimulator device reliable olfactory evoked potentials can be recorded in a clinical setting. Since this is a non invasive technique which can be used to test olfactory function whether or not the patient cooperates, it is expected to become widely used, particularly in non collaborating patients and in those suspected of malingering.