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The P2X7 receptor (P2X7R) is a cation membrane channel activated by extracellular adenosine 5′-triphosphate. Activation of this receptor results in numerous downstream events including the modulation of neurotransmission, release of pro-inflammatory mediators, cell proliferation or cell death. While the expression of P2X7Rs is well documented on microglia and oligodendrocytes, the presence of functional P2X7Rs on neurons and astrocytes remains debated. Furthermore, to date, functional studies on the P2X7R are mostly limited to studies in cells from rodents and immortalised cell lines expressing human P2X7Rs. To assess the functional expression of P2X7Rs in human neurons and astrocytes, we differentiated human-induced pluripotent stem cells (hiPSCs) into forebrain cortical neurons that co-express FOXG1 and βIII-tubulin as well as S100 β-expressing astrocytes. Immunostaining revealed prominent punctate P2X7R staining on the soma and processes of hiPSC-derived neurons and astrocytes. In addition, our data show that stimulation with the potent nonselective P2X7R agonist BzATP induces robust calcium rises in hiPSC-derived neurons and astrocytes, which were blocked by the selective P2X7R antagonist AFC-5128. Together, our findings provide evidence for the functional expression of P2X7Rs in hiPSC-derived forebrain cortical neurons and astrocytes demonstrating that these cells offer the potential for investigating P2X7R-mediated pathophysiology and drug screening in vitro.

38th European Photovoltaic Solar Energy Conference and Exhibition; 334-338, Completing our investigations on different melt removal techniques presented at previous PVSEC we installed an appliance in our SCU-G1 furnace for pouring the impurity-enriched silicon melt at the top of the ingot at the end of crystallization. With this method any amount of silicon melt between 0 and 25% (compared to the original mass of the G1 ingot) can be removed completely within a few seconds. Thus, the top surface of the growing crystal can be freed from the impurity enriched melt immediately and completely before the end of the regular crystallization process. This can be detected by optical investigation of the ingot’s top surface. However, in all of our experiments a top red-zone of at least 1.7 cm thickness in the mc-Si ingot remained. Compared to reference ingots, where no melt was removed, no significant thickness reduction was achieved. A deeper analysis of the minority charge carrier lifetime by a diffusion model [9] revealed that, typically, the Fei content in the ingot’s top region was reduced by a factor of about 3 compared to reference ingots. Yet, this seems to be not enough to affect the thickness of the top red zone. We suppose additional contamination of the ingot via the gas phase to be a reason for this behavior.

OA platinum Research on sentiment analysis is in its ma- ture status. Studies on this topic have pro- posed various solutions and datasets to guide machine-learning approaches. However, so far the sentiment scoring is restricted to the level of short textual units such as sentences. Our comparison shows that there is a huge gap between machines and human judges when the task is to determine sentiment scores of a longer text such as a news article. To close this gap, we propose a new human-annotated dataset containing 250 news articles with sen- timent labels at article level. Each article is annotated by at least 10 people. The articles are evenly divided into fake and non-fake cate- gories. Our investigation on this corpus shows that fake articles are significantly more senti- mental than non-fake ones. The dataset will be made publicly available.

Two directly-modulated GaInAsP/InP micro-rings with different radii vertically-coupled on a common bus are assessed for both independent and simultaneous operation. A device area

The phase and intensity noise of microring lasers coupled with passive waveguides are examined through linewidth and relative intensity noise measurements. Laser linewidth down to 500 KHz was measured through the self-homodyne technique and a direct association is established between the linewidth and the two main structural parameters of a microring, the ring radius and coupling efficiency with the bus waveguide. Coupling efficiency is estimated through waveguiding analysis by means of 3-D finite difference in time domain techniques. © 2006 IEEE.

The relation between the structural parameters and the operating characteristics of microring lasers is examined through theoretical estimations, waveguiding simulations, and experimental measurements. The effects of ring radius, waveguide profile, and overall geometry on the coupling efficiency and subsequently on threshold and spectral characteristics are thoroughly investigated. Coupling efficiency is calculated through 3-D finite difference in time domain methods. Fabricated devices consist of active microrings integrated with passive bus waveguides using wafer bonding techniques.

The relation between the structural parameters and the operating characteristics of microring lasers is examined through theoretical estimations, waveguiding simulations, and experimental measurements. The effects of ring radius, waveguide profile, and overall geometry on the coupling efficiency and subsequently on threshold and spectral characteristics are thoroughly investigated. Coupling efficiency is calculated through 3-D finite difference in time domain methods. Fabricated devices consist of active microrings integrated with passive bus waveguides using wafer bonding techniques. © 2011 IEEE.

Data streams with bit rates of up to 1 Gbit/s have been applied though the subcarrier modulation technique in an experimentally deployed optical communication system based on chaos data encryption and have been recovered efficiently. By shifting the spectral components of the encrypted data in regions where the chaotic carrier is powerful, a more efficient encryption and final message recovery is recorded with respect to the baseband modulation technique, improving the up-to-date performance of analogous systems. © 2010 Optical Society of America.

Security in information exchange plays a central role in the deployment of modern communication systems. Besides algorithms, chaos is exploited as a real-time high-speed data encryption technique which enhances the security at the hardware level of optical networks. In this work, compact, fully controllable and stably operating monolithic photonic integrated circuits (PICs) that generate broadband chaotic optical signals are incorporated in chaos-encoded optical transmission systems. Data sequences with rates up to 2.5 Gb/s with small amplitudes are completely encrypted within these chaotic carriers. Only authorized counterparts, supplied with identical chaos generating PICs that are able to synchronize and reproduce the same carriers, can benefit from data exchange with bitrates up to 2.5Gb/s with error rates below 10 -12. Eavesdroppers with access to the communication link experience a 0.5 probability to detect correctly each bit by direct signal detection, while eavesdroppers supplied with even slightly unmatched hardware receivers are restricted to data extraction error rates well above 10-3. ©2010 Optical Society of America.

A widely tunable laser source based on double microrings is presented which exhibits tuning range up to 46 nm. Two microrings consisting of active GalnAsP/InP material are vertically coupled with a straight transparent waveguide using full wafer bonding techniques. Wafer bonding allows the fabrication of ultra short couplers where the critical coupling gap can be epitaxially controlled. The microrings are operated above threshold and act as laser sources forming a coupled cavity system. Their respective radii are chosen to be slightly different, greatly extending the coupled cavity free spectral range (FSR) providing sufficiently high mode suppression ratio (MSR > 30 dB). The isolation of adjacent rings allows an individual electrical control and enables a wavelength tuning with pm accuracy. The tuning mechanism benefits from the Vernier effect resulting in a broad range of achievable wavelengths in a systematic and repeatable way. © 2010 IEEE.

A novel photonic integrated device has been designed and evaluated as a transmitter for chaos applications in optical communications. The device consists of a semiconductor laser integrated with a semiconductor optical amplifier, a phase section and a waveguide, forming thus all integrated external cavity laser with adjustable optical feedback and phase. Under diverse operating parameters the: device behaves in different modes, from stable operation to limit cycles and hyperchaotic broadband behavior. Chaos data analysis from experimental data is performed in order to quantify the complexity of the: experimental reconstructed attractors under the influence of noise. Calculation of the correlation dimension and Kolmogorov entropy are compared with numerical predictions from well-known theoretical models.

Two different configurations of compact optical chaos generators, based either on fiber or monolithic photonic integration, have been designed, fabricated, and experimentally characterized in terms of their potential to generate a broadband chaotic optical spectrum. The architectures considered have the potential to offer various types of dynamics depending on the design and operational conditions-from periodic states to complex chaos. Their application in an optical chaos communication scheme is also studied, through the capability of such complex carriers to synchronize with the appropriate receiver and regenerate the carrier locally. Numerical simulations confirm the behavior of these emitters in terms of chaos generation and identify the preferable operating conditions and limitations for the optimum performance. © 2009 IEEE.

Two directly-modulated GalnAsP/InP micro-rings with different radii vertically-coupled on a common bus are assessed for both independent and simultaneous operation. A device area

We summarize the results of a European Project entitled WAPITI (Waferbonding and Active Passive Integration Technology and Implementation) dealing with the fabrication and investigation of active/passive vertically coupled ring resonators, wafer bonded on GaAs, and based on full wafer technology. The concept allows for the integration of an active ring laser vertically coupled to a transparent bus waveguide. All necessary layers are grown in a single epitaxial run so that the critical coupling gap can be precisely controlled with the high degree of accuracy of epitaxial growth. One key challenge of the project was to establish a reliable wafer bonding technique using BCB as an intermediate layer. In intensive tests we investigated and quantified the effect of unavoidable shrinkage of the BCB on the overall device performance. Results on cw-operation, low threshold currents of about 8 mA, high side-mode suppression ratios in the range of 40 dB and large signal modulation bandwidths of up to 5 GHz for a radius of 40 pin shows the viability of the integration process.

Ensuring the security of information transmitted over the Internet is an urgent priority in the increasingly digital world. A unique approach to safeguarding data transmission by embedding messages with optical chaos is described, that is known as Optical Chaotic Cryptography. The approach makes use of a pair of lasers that generate chaos, a behavior of a large class of nonlinear systems. A standard DFB telecommunication laser routed to chaos exhibits a widened spectrum, typically on the order of 10-100 GHz, showing a non-periodic and complex behavior. The transmitter produces an optical carrier with an extremely broadened spectrum. Synchronization is usually obtained by injecting a part of chaotic output of the transmitting laser into the receiver laser, to extract the hidden signal. One notable characteristic of the chaotic regime is its strong sensitivity to starting conditions and systems parameters.

A novel photonic monolithic integrated device consisting of a distributed feedback laser, a passive resonator, and active elements that control the optical feedback properties has been designed, fabricated, and evaluated as a compact potential chaotic emitter in optical communications. Under diverse operating parameters, the device behaves in different modes providing stable solutions, periodic states, and broadband chaotic dynamics. Chaos data analysis is performed in order to quantify the complexity and chaoticity of the experimental reconstructed attractors by applying nonlinear noise filtering.

A novel photonic monolithic integrated device consisting of a distributed feedback laser, a passive resonator, and active elements that control the optical feedback properties has been designed, fabricated, and evaluated as a compact potential chaotic emitter in optical communications. Under diverse operating parameters, the device behaves in different modes providing stable solutions, periodic states, and broadband chaotic dynamics. Chaos data analysis is performed in order to quantify the complexity and chaoticity of the experimental reconstructed attractors by applying nonlinear noise filtering. © 2008 The American Physical Society.

Microring resonators are excellent candidates for very large scale photonic integration due to their compactness, and fabrication simplicity. Moreover a wide range of all-optical signal processing functions can be realized due to the resonance effect. Possible applications include filtering, add/drop of optical beams and power switching, as well as more complex procedures including multiplexing, wavelength conversion, and logic operations. All-active ring components based in InGaAsP/InP are possible candidates for laser sources, lossless filters, wavelength converters, etc. Our work is based on measurement, characterization and proposal of possible exploitation of such devices in a variety of applications. We investigate the spectral characteristics of multi-quantum well InGaAsP(lambda=1.55 mu m)/InP microring structures of various ring diameters and different configurations including racetracks with one or two bus waveguides and MMI couplers. The latter configuration has recently exhibited the possibility to obtain tunable active filters as well as tunable laser sources based on all-active ring-bus-coupler structures. In the case of tunable lasers single mode operation has been achieved by obtaining sufficiently high side mode suppression ratio. The timing capability is attributed to a coupled cavities effect, resembling the case of multi-section DBR lasers. However, in contrast to the latter, the fabrication of microring resonators is considered an easier task, due to a single step growth procedure, although further investigation must be carried out in order to achieve wide range tunability. Detailed mappings of achievable wavelengths are produced for a wide range of injection current values.

An enhanced low frequency relative intensity noise due to mode hopping induced from the asymmetric gain suppression in InGaAsP-InP microring lasers, is observed experimentally for the first time. The experimental results are in good agreement to those predicted by a multimode model based on the rate equation approximation accounting for both symmetric and asymmetric nonlinear gain suppression. © IEEE.

A tunable laser based on an InGaAsP-InP microring resonator with multimode interference coupler is demonstrated. Tuning ranges from 18 to 30 nm are achieved and mappings of the tunable operation are experimentally produced and analyzed. The observed tunability is the result of the interaction between counterpropagating ring modes through back-reflection from the device facets.

A novel integrated polarization converter based on ultra short bends is presented, which has a potential for low loss and small device size. A conversion value of 85% was experimentally measured with excess loss of 2.7 dB and overall dimensions of 975*83 mu m. Also 45% conversion was measured with extremely low excess loss of 0.4 dB for a device size of 760*86 mu m

The MOMBE growth of Ga0.11In0.89As0.23P0.77 material with a band gap equivalent emission wavelength of 1.05 mu m carried out in the growth temperature range of 465-500 degrees C provided material of high structural and optical quality as well as high lateral uniformity and reproducibility of the alloy composition. The low-temperature photoluminescence linewidth below 5 meV and the X-ray diffraction linewidth approaching the theoretical limit have been obtained at the growth temperature of 465 degrees C. Rib waveguides fabricated by dry etching techniques on MOMBE GaInAsP layers grown at this temperature exhibit optical propagation losses down to 0.1 dB/cm at lambda =1.55 mu m.

A novel type of polarisation converter has been realised using deeply etched narrow InP-InGaAsP ridge waveguide bends with small bending radius. It combines low loss (2.7 dB) with compact device size (975*83 mu m) and high polarisation conversion (>85%). It is realized using curved waveguides with small bending radii. Strong polarization conversion (>85%) is measured with excess loss of only 2.7 dB