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The entrainment zone (EZ) capping the convective boundary layer (CBL) is documented using lidar turbulent-scale observations. Sensible and latent heat fluxes have been measured during one hundred hours in CBL temperate and arid regions in free-cloud meteorological conditions. The EZ fluxes have been confronted with scalar gradients, integral scales of turbulence, wind shear, and surface sensible heat flux. In agreement with former observations in stratified surface layer or with EZ large eddy-simulation (LES) studies, Lidar observations show that the buoyant oscillation period associated to the vertical velocity variance are found to be universal relevant parameters for EZ scalar fluxes and gradients. Attempts to introduce non-local CBL scales like the turbulent vertical velocity scale and height, the scalar interfacial layer jumps and the surface sensible heat flux globally increases the scatter of the data. Non-local parametrization particularly failed for EZ latent heat flux compared to sensible heat flux and for weak surface heat flux as it is usually the case in temperate region. Investigating a possible non-local parametrization of EZ vertical velocity variance, it was found that EZ wind shear and then EZ gradient Richardson number play a negligible role. Rather, observations often showed an excess of EZ vertical velocity variance with respect to CBL similarity law that may be explained by a significant contribution of wave-turbulence interaction in the entrainment layer.

By exploiting one-dimensional photonic crystal nanocavities, an ultra-compact indium phosphide-on-silicon laser diode with low current threshold, high wall-plug efficiency and high integrability is demonstrated. The most-awaited convergence of microelectronics and photonics promises to bring about a revolution for on-chip data communications and processing1. Among all the optoelectronic devices to be developed, power-efficient nanolaser diodes able to be integrated densely with silicon photonics and electronics are essential to convert electrical data into the optical domain. Here, we report a demonstration of ultracompact laser diodes based on one-dimensional (1D) photonic crystal (PhC) nanocavities2,3,4 made in InP nanoribs heterogeneously integrated on a silicon-waveguide circuitry. The specific nanorib design enables an efficient electrical injection of carriers in the nanocavity without spoiling its optical properties. Room-temperature continuous-wave (CW) single-mode operation is obtained with a low current threshold of 100 µA. Laser emission at 1.56 µm in the silicon waveguides is obtained with wall-plug efficiencies greater than 10%. This result opens up exciting avenues for constructing optical networks at the submillimetre scale for on-chip interconnects and signal processing.

International audience; The H19 locus controls fetal growth by regulating expression of several genes from the imprinted gene network (IGN). H19 is fully repressed after birth, except in skeletal muscle. Using loss-of-function H19(Delta 3) mice, we investigated the function of H19 in adult muscle. Mutant muscles display hypertrophy and hyperplasia, with increased Igf2 and decreased myostatin (Mstn) expression. Many imprinted genes are expressed in muscle stem cells or satellite cells. Unexpectedly, the number of satellite cells was reduced by 50% in H19(Delta 3) muscle fibers. This reduction occurred after postnatal day 21, suggesting a link with their entry into quiescence. We investigated the biological function of these mutant satellite cells in vivo using a regeneration assay induced by multiple injections of cardiotoxin. Surprisingly, despite their reduced number, the self-renewal capacity of these cells is fully retained in the absence of H19. In addition, we observed a better regeneration potential of the mutant muscles, with enhanced expression of several IGN genes and genes from the IGF pathway.

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The observation of symmetry breaking in a coupled nanolaser system could yield new types of switchable devices.

Heterogeneous integration of III-V semiconductors on silicon has gained considerable momentum fueled by the need to implement fully functional photonic devices and circuits in a CMOS compatible platform. In this communication, we report on a III-V photonic crystal (PhC) nanocavity, heterogeneously integrated on a silicon-on-insulator platform, to form a PhC nanocavity laser capable of exhibiting two elementary static random access memory (SRAM) cell functions individually, namely switching and latching operations under a high-speed, bit-level regime. As such, the PhC nanocavity laser is examined as a generic logic functions building block, suitable toward multiGb/s energy-efficient, optical SRAM cells with minimal device footprint. The proposed device occupies a total area of only 6.2 μm2, rendering in this way the demonstrated memory element the smallest among the integrated optical memories presented so far. Bit-level SRAM cell operation requires two elementary functions: the access gate (AG) switching function and set-reset flip-flop (SR-FF) latching function. At first, AG switching operation is evaluated through successful wavelength conversion at 10 Gb/s, revealing a power penalty of 1 dB at 10-9 BER and a switching energy of only 4.8 fJ/bit. Then, fully functional SR-FF memory operation is successfully demonstrated, exhibiting error-free operation with negative power penalty at 5 Gb/s and switching energies of 6.4 fJ/bit. FF operation at higher speeds of 10 Gb/s with reduced switching energy levels of 3.2 fJ/bit is also experimentally investigated. Both logic operations were demonstrated separately with the same PhC nanocavity laser device exhibiting

Electrically driven CW operation of energy-efficient ultra-compact InP-based nanolasers in a Silicon photonic platform is demonstrated. The nanolaser diode is single mode and emits at 1560 nm with SMSR grater than 20dB. The threshold is low, around 0.1mA at 1 V and the emitted power in the SOI waveguide is of the order of 0.1mW giving a wall-plug efficiency higher than 10 percents.

We experimentally demonstrate wavelength conversion and bit-level memory operation in a hybridly integrated III-V on SOI photonic crystal nanolaser with total footprint of 6.2μm2 and record-energy of 6.4fJ/bit, showing error-free operation at 5Gb/s.

The H19 large intergenic non-coding RNA (lincRNA) is one of the most highly abundant and conserved transcripts in mammalian development, being expressed in both embryonic and extra-embryonic cell lineages, yet its physiological function is unknown. Here we show that miR-675, a microRNA (miRNA) embedded in H19's first exon, is expressed exclusively in the placenta from the gestational time point when placental growth normally ceases, and placentas that lack H19 continue to grow. Overexpression of miR-675 in a range of embryonic and extra-embryonic cell lines results in their reduced proliferation; targets of the miRNA are upregulated in the H19 null placenta, including the growth-promoting insulin-like growth factor 1 receptor (Igf1r) gene. Moreover, the excision of miR-675 from H19 is dynamically regulated by the stress-response RNA-binding protein HuR. These results suggest that H19's main physiological role is in limiting growth of the placenta before birth, by regulated processing of miR-675. The controlled release of miR-675 from H19 may also allow rapid inhibition of cell proliferation in response to cellular stress or oncogenic signals.

In this article we report on ultraslow or fast light propagation, exciting behavior that become achievable thanks to the Coherent Population Oscillations effect (CPO). We show that the group velocity, the speed at which light propagates, can be drastically modified and engineered using the CPO effect in a crystal doped with triply ionized erbium ions, namely: Er3+:Y2SiO5. The steep dispersion of the index of refraction caused by the CPO effect is at the origin of group velocities as low as v g = 3 m / s . By inverting the slope of the index dispersion, we can make, in the same crystal, light go faster than if it was propagating in vacuum. This particular regime is characterized by larger than c or negative group velocities. In the 3-mm-long Er3+:Y2SiO5 crystal, we have achieved a delay of − 0.2 ms corresponding to a group velocity of v g = − 15 m / s . To cite this article: E. Baldit et al., C. R. Physique 10 (2009).

Detrimental surface recombination of carriers in InP-based photonic crystal nanobeams containing quantum wells is reduced by employing chemical treatment followed by silica encapsulation. Carrier lifetime is shown to recover to 2.63ns close to the bulk value. This enables us to obtain optically pumped room-temperature continuous-wave nanolasers at 1.55µm integrated onto Silicon on insulator waveguide platform with a threshold of 8µW.

We experimentally show spontaneous breaking of mirror-symmetry in two evanescently coupled photonic crystal nanocavity-lasers. A transition from a delocalized mode, to two spatially localized states, is observed in the form of a pitchfork bifurcation. Coexistence of these states is demonstrated through short pulse excitation.

Le ralentissement de la lumiere est le resultat d'une forte dispersion de l'indice de refraction. Nous observons un tel effet obtenu par oscillation coherente de population dans un cristal dope aux ions d'Erbium triplement ionises. La lumiere s'y propage avec une vitesse de groupe de 2.7 m/s. La largeur inhomogene de la transition est exploitee comme un parametre additionnel pour controler a la fois cette vitesse de groupe et la transmission.

Thermal properties of InP-based quantum well photonic crystal nanobeam lasers heterogeneously integrated on silicon on insulator waveguides are studied. We show both numerically and experimentally the reduction of the thermal resistance of the III-V cavities by adjusting the composition of the layer which bonds the III-V materials to the silicon wafer and by adding an over-cladding on top of the cavities. Using a bonding layer made of benzocyclobutene and SiO(2) and an over-cladding of MgF(2), we found a decrease by a factor higher than 35 compared to air-suspended photonic crystal nanobeam cavities. Such optimized structures are demonstrated to operate under continuous wave pumping for several 10's of minutes despite the adverse effect of non-radiative surface recombination of carriers.

Fabrication of high Q-factor InP-based Photonic Crystal nanobeam cavities is demonstrated by improving ICP etching. We measure Q-factors as high as ~130,000 for passive cavities by integrating them on to SOI wire waveguides. Nanolasers exhibiting low lasing threshold are then obtained using this technology.

International audience; Ultrafast switching with low energies is demonstrated using InP photonic crystal nanocavities embedding InGaAs surface quantum wells heterogeneously integrated to a silicon on insulator waveguide circuitry. Thanks to the engineered enhancement of surface non radiative recombination of carriers, switching time is obtained to be as fast as 10 ps. These hybrid nanostructures are shown to be capable of achieving systems level performance by demonstrating error free wavelength conversion at 10 Gbit/s with 6 mW switching powers.

Electron paramagnetic resonance spectroscopy of rare earth ions in crystals is an interesting tool to analyze the hyperfine structure of the rare earth ground state. This can be useful for coherent spectroscopy and quantum information applications where the hyperfine structure of the electronic levels is used. In this work, we give a detailed analysis of the hyperfine structure of the ground state ( I 4 15 / 2 ( 0 ) ) of Er3+ ions in Y2SiO5.

The H19 gene controls the expression of several genes within the Imprinted Gene Network (IGN), involved in growth control of the embryo. However, the underlying mechanisms of this control remain elusive. Here, we identified the methyl-CpG-binding domain protein 1 MBD1 as a physical and functional partner of the H19 long noncoding RNA (lncRNA). The H19 lncRNA-MBD1 complex is required for the control of five genes of the IGN. For three of these genes--Igf2 (insulin-like growth factor 2), Slc38a4 (solute carrier family 38 member 4), and Peg1 (paternally expressed gene 1)--both MBD1 and H3K9me3 binding were detected on their differentially methylated regions. The H19 lncRNA-MBD1 complex, through its interaction with histone lysine methyltransferases, therefore acts by bringing repressive histone marks on the differentially methylated regions of these three direct targets of the H19 gene. Our data suggest that, besides the differential DNA methylation found on the differentially methylated regions of imprinted genes, an additional fine tuning of the expressed allele is achieved by a modulation of the H3K9me3 marks, mediated by the association of the H19 lncRNA with chromatin-modifying complexes, such as MBD1. This results in a precise control of the level of expression of growth factors in the embryo.

A standard deviation in lasing wavelength lower than 500pm is characterized on nominally identical and optically-pumped microdisk lasers, heterogeneously integrated on the same SOI circuit. This lasing wavelength uniformity is obtained using electron-beam lithography.

Ring-down temporal measurements of silicon-on-insulator wire racetrack resonators are performed with 150 fs input pulses using a parametric process in a nonlinear crystal to gate and amplify the weak output pulses. We measure the cavity round trip time and the quality factor of these all-pass filters and find excellent agreement with continuous wave spectroscopic measurements as well as with an analytic model built using numerical solutions for the fully vectorial waveguide modes.

Heterogeneous integration of III-V semiconductors on Silicon is one of the key technologies for next-generation on-chip optical interconnects. We extended this approach to nanophotonics by using photonic crystals to demonstrate highly efficient active devices.

Heterogeneous integration of III-V semiconductors on Silicon is a promising technology for next-generation photonic networks. We extended this approach to nanophotonics by using photonic crystals to demonstrate highly efficient active devices.

We perform an experimental time-domain mapping of nonlinear pulse propagation through a two-dimensional photonic-crystal waveguide. Our optical gating method allows for the complete reconstruction of the peculiar propagation behavior in this highly dispersive structure. Temporal soliton formation is accompanied by fast time-scale dynamics within the picosecond pulse regime. For high signal powers, the photonic waveguide band is modified, leading to an acceleration of the propagated pulse.

Chantier qualité GA; International audience; The myogenic regulatory factor Myod and insulin-like growth factor 2 (Igf2) have been shown to interact in vitro during myogenic differentiation. In order to understand how they interact in vivo, we produced double-mutant mice lacking both the Myod and Igf2 genes. Surprisingly, these mice display neonatal lethality due to severe diaphragm atrophy. Alteration of diaphragm muscle development occurs as early as 15.5 days post-coitum in the double-mutant embryos and leads to a defect in the terminal differentiation of muscle progenitor cells. A negative-feedback loop was detected between Myod and Igf2 in embryonic muscles. Igf2 belongs to the imprinted H19-Igf2 locus. Molecular analyses show binding of Myod on a mesodermal enhancer (CS9) of the H19 gene. Chromatin conformation capture experiments reveal direct interaction of CS9 with the H19 promoter, leading to increased H19 expression in the presence of Myod. In turn, the non-coding H19 RNA represses Igf2 expression in trans. In addition, Igf2 also negatively regulates Myod expression, possibly by reducing the expression of the Srf transcription factor, a known Myod activator. In conclusion, Igf2 and Myod are tightly co-regulated in skeletal muscles and act in parallel pathways in the diaphragm, where they affect the progression of myogenic differentiation. Igf2 is therefore an essential player in the formation of a functional diaphragm in the absence of Myod.

Background Although the H19 gene was discovered in 1984, its precise function is still relatively poorly understood. It is located on mouse chromosome 7, close to the Igf2 (insulin-like growth factor 2) gene, in an imprinted locus. The maternal allele expresses a 2.3kb non coding RNA, as well as a micro RNA, the miR-675. We showed that H19 acts as a transregulator of an imprinted gene network (IGN) involved in growth control of the embryo [1]. A recent study described that the miR-675 is exclusively expressed in the placenta during development, where it controls growth probably by downregulating the expression of Igf1r [2]. However, this micro RNA is unable to control the IGN in the embryo, control that appears therefore to be exerted by the full-length form of H19. The main goal of our work was to understand molecular mechanisms that drive this control of the IGN by H19.

CW laser with 4µW threshold and 12ps recovery time ultrafast switching activated with 40fJ is demonstrated with hybrid Photonic crystals on SOI structures bringing III-V semiconductor/silicon photonics to the to nanophotonic world.

We report experimental demonstration of very fast nonlinear response around 1.5μm in an InP-based two-dimensional photonic crystal. The nonlinearity produced by low pump powers via carrier induced nonlinear refractive index, leads to an efficient wavelength shift of a photonic crystal resonance observed in reflectivity. Thus we show that it is possible to obtain round the clock (rise and recovery) switching times shorter than 10ps with contrast ratio higher than 80%.

High-quality (Q) factor indium phosphide (InP)-based 1D photonic crystal nanobeam cavities are fabricated on silicon on insulator waveguides. Through the optimization of the fabrication process, the intrinsic Q factor of these fully encapsulated nanocavities is demonstrated to attain values higher than 100,000. Experimental and numerical investigations are carried out on the impact, on the Q factor, of the strength of the evanescent wave coupling between the cavity and the waveguide. We reveal that this coupling can result in a modification of the electromagnetic field distribution in the resonant mode, which gives rise up to a factor 4 reduction in the intrinsic Q factor for the structures under study.

III–V semiconductor photonic crystal nanolasers are heterogeneously integrated on a SOI waveguides circuitry. We demonstrate this approach constitutes an efficient way to interface these ultimate lasers. Coupling efficiency and optical bistability will be discussed.

We report on optical bistability based on injection locking of hybrid III-V/Silicon-on-Insulator (SOI) nanolaser. Switching power is measured below 40μW. 30ps switching time is deduced from gain recovery time measurement.

We report on the improvement of the thermal dissipation of hybrid III-V/SOI nanolasers by encapsulating the structures in Silica. Careful design was necessary to obtain theoretical quality factor above 106. CW operation was then obtained.

Supplemental materials : www.landesbioscience.com/journals/epigenetics/article/21495; Genomic imprinting characterizes genes with a monoallelic expression, which is dependent on the parental origin of each allele. Approximately 150 imprinted genes are known to date, in humans and mice but, though computational searches have tried to extract intrinsic characteristics of these genes to identify new ones, the existing list is probably far from being comprehensive. We used a high-throughput strategy by diverting the classical use of genotyping microarrays to compare the genotypes of mRNA/cDNA vs. genomic DNA to identify new genes presenting monoallelic expression, starting from human placental material. After filtering of data, we obtained a list of 1,082 putative candidate monoallelic SNPs located in more than one hundred candidate genes. Among these, we found known imprinted genes, such as IPW, GRB10, INPP5F and ZNF597, which contribute to validate the approach. We also explored some likely candidates of our list and identified seven new imprinted genes, including ZFAT, ZFAT-AS1, GLIS3, NTM, MAGI2, ZC3H12Cand LIN28B, four of which encode zinc finger transcription factors. They are, however, not imprinted in the mouse placenta, except for Magi2. We analyzed in more details the ZFAT gene, which is paternally expressed in the placenta (as ZFAT-AS1, a non-coding antisense RNA) but biallelic in other tissues. The ZFAT protein is expressed in endothelial cells, as well as in syncytiotrophoblasts. The expression of this gene is, moreover, downregulated in placentas from complicated pregnancies. With this work we increase by about 10% the number of known imprinted genes in humans.

Nous avons observe la generation de second harmonique accordee en phase dans une structure periodique constituee d'Al 30% Ga 70% As et d'AlOx. D'une part l'accord de phase est realise en utilisant le fait que la dispersion du cristal photonique ainsi constitue est suffisante pour compenser la dispersion naturelle du materiau semi-conducteur. D'autre part la localisation du champ electrique a l'interieur de la structure permet une augmentation de l'efficacite de conversion.

Heterogeneous integration of III–V semiconductor compounds on SOI is one of the key technologies for next generation on chip optical interconnects. The use of photonic crystals nanolasers, within this context, represents a disruptive solution in terms of footprint, activation energy and ultrafast response. In this work, we study the evanescent wave coupling occurring between the nanolasers and a subjacent Si wire and demonstrate that more than 90% of the light is funneled into the Si circuitry.

Heterogeneous integration of III–V semiconductor compounds on Silicon on insulator (SOI) is one the key technologies for next generation on chip optical interconnects. Indeed, this hybrid platform combines the best of both material systems: on one hand, the CMOS compatibility and the predispositions of silicon to be used for fabricating an ultra compact low loss optical circuitry; on the other hand, the versatility of III–V semiconductors for making laser sources and active devices. This approach was recently used for demonstrating laser emission [1,2], light amplification [1], modulation [3] and optical flip-flops [4].

Silicon photonics, enhanced by III–V semiconductors based optical functions, is one of the most promising technologies to achieve large-scale photonic integration taking advantage of the best of both materials. In this work, we study III–V/SOI hybrid structures that combine photonic crystal nanolasers with photonic wires. This approach is particularly interesting as it enables the achievement of compact devices (footprint as small as 5µm2) with low power activation and ultrafast response.

Temporal mapping of 20pJ pulse propagation in a 2DPhC waveguide show of soliton formation. For high signal powers the photonic band is modified influencing the group velocity leading to an acceleration of the pulse propagation.

Diamond Nanoparticles are added to BCB polymer in order to increase the thermal dissipation of InP-based photonic crystal cavity laser bonded on silicon. Optical measurement are performed to evaluate the enhancement of the heat sinking with nanoparticles density.

We demonstrate an easy-to-implement scheme for fluorescence enhancement and observation volume reduction using photonic crystals (PhCs) as substrates for microscopy. By normal incidence coupling to slow 2D-PhC guided modes, a 65 fold enhancement in the excitation is achieved in the near field region (100 nm deep and 1 μm wide) of the resonant mode. Such large enhancement together with the high spatial resolution makes this device an excellent substrate for fluorescence microscopies. Fil: Estrada, Laura Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina Fil: Martínez, Oscar Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina Fil: Brunstein, Maia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Centre National de la Recherche Scientifique; Francia Fil: Bouchoule, S.. Centre National de la Recherche Scientifique; Francia Fil: Le Gratiet, L.. Centre National de la Recherche Scientifique; Francia Fil: Talneau, A.. Centre National de la Recherche Scientifique; Francia Fil: Sagnes, I.. Centre National de la Recherche Scientifique; Francia Fil: Monnier, P.. Centre National de la Recherche Scientifique; Francia Fil: Levenson, J. A.. Centre National de la Recherche Scientifique; Francia Fil: Yacomotti, A. M.. Centre National de la Recherche Scientifique; Francia

We report laser emission from InP-based wire cavities bonded to silicon on insulator wafers. Both, Cavities bonded to unpatterned wafers and bonded to wafers with singlemode waveguides are studied.

We report on the modeling and experimental characterization of an InP-based photonic crystal wire cavity laser bonded to a silicon wafer. Simulations give an insight into the variation of the resonant mode frequency and the dependence of the Q-factor on the geometrical parameters of the laser cavity. Calculated and measured Q-factors are of the order of 104. A low threshold laser operation is demonstrated.

The integration of two-dimensional III-V InP-based photonic crystal and silicon wire waveguides is achieved through an accurate alignment of the two optical levels using mix-and-match deep ultraviolet (DUV)/electron beam lithography. The adhesively bonded structures exhibit an enhancement of light emission at frequencies where low group velocity modes of the photonic crystal line defect waveguides occur. Pulsed laser operation is obtained from these modes at room temperature under optical pumping. The laser light is coupled out of the Si waveguide via grating couplers directly to single mode fiber.

We present continuous-wave laser operation at room temperature at 1.55 μm by optically pumping a photonic crystal structure containing an InGaAs/InP quantum well active layer. The active layer is integrated onto a Silicon chip by means of Au/In bonding technology. This metallic layer provides the reduction of heating by thermal dissipation into the substrate, and increases the quality-factor by reducing the radiative losses.

Electron paramagnetic resonance (EPR) spectroscopy of rare earth ions in crystals is a powerful tool to analyze the hyperfine structure of the rare earth ground state. This can be useful for coherent spectroscopy and quantum information applications where the hyperfine structure of the electronic levels is used. In this work, we give a detailed analysis of the hyperfine structure of the ground state $[^{4}I_{15∕2}(0)]$ of ${\mathrm{Er}}^{3+}$ ions in ${\mathrm{Y}}_{2}\mathrm{Si}{\mathrm{O}}_{5}$. The electronic Zeeman, hyperfine, and quadrupole matrices are obtained from angular variations of the magnetic field in three orthogonal crystal planes. An excellent agreement is obtained between experimental and simulated magnetic field positions and relative intensities of EPR lines.

We experimentally demonstrate excitability in a semiconductor two-dimensional photonic crystal. Excitability is a nonlinear dynamical mechanism underlying pulselike responses to small perturbations in systems possessing one stable state. We show that a band-edge photonic crystal resonator exhibits class II excitability, resulting from the nonlinear coupling between the high-$Q$ optical mode, the charge-carrier density, and the fast (sub-$\ensuremath{\mu}\mathrm{s}$) thermal dynamics. In this context, the critical slowing down of the electro-optical dynamics close to the excitable threshold can delay the optical response by an amount comparable to the duration of the output pulse (5 ns). The latter results from a short thermal dynamical excursion along a high local intensity manifold of the phase space.

Strong dispersion of the refraction index causes slow light propagation. We reported on such phenomenon induced by coherent population oscillations effect in Erbium-doped solids achieving group velocities as low as 2.7 m/s.

We report on the observation of electromagnetically induced transparency using the hyperfine levels of Er3+:Y2SiO5 crystal and on hole burning spectroscopy in order to identify the Lambda-like three-level system over the inhomogeneously broadened distribution.