Influence of photo-initiator concentration on residual mechanical stress in SU-8 thin films

In this paper, experimental results on the residual mechanical stress generated during the different steps of the photolithography process of SU-8 thin films using different photo-initiator concentrations are presented. The main aim of the reported research work has been firstly to investigate and identify the causes for the generation of residual stresses and secondly to optimise the fabrication process in order to minimise the residual stresses. It was found that the major parameters that influence the generation of internal stresses were the exposure time, the post-baking temperature and time and the concentration of the photoinitiator which is used (Cyracure UVI). At lower concentrations of the photo-initiator, the measured stress levels after the post-baking step were consistently found to be significantly lower than the ones corresponding to higher photo-initiator concentrations. In addition, there was an additional improvement by using a ramping hot-plate. Finally, preliminary experiments were carried out in order to encapsulate nanoparticles in these low stress SU-8 thin films

The role of seaweed extracts, Ascophyllum nodosum, in the reduction in fecundity of Meloidogyne javanica

Les effets d'extraits commerciaux de l'algue marine #Ascophyllum nodosum sur la fécondité du nématode #Meloidogyne javanica, élevé sur tomate (#Lycopersicon esculentum$ cv. Ailsa Craig) sont évalués. Après une génération, le nombre d'oeufs du nématode récupérés sur les plantes traitées diminue considérablement en comparaison avec les plantes témoins, traitées avec de l'eau pure. Un plus faible nombre d'oeufs sont récupérés sur les plantes infestées par des juvéniles ayant incubé dans des extraits d'algue en comparaison avec les plantes infestées par des juvéniles ayant incubé dans de l'eau pure. (Résumé d'auteur

The role of betaines in alkaline extracts of Ascophyllum nodosum in the reduction of Meloidogyne javanica and M. incognita infestations of tomato plants

L'application sur les racines de plants de tomates d'un extrait alcalin de l'algue brune #Ascophyllum nodosum, disponible dans le commerce, produit une réduction significative du nombre de juvéniles de deuxième stade de #Meloidogyne javanica et #M. incognita$ pénétrant dans les racines, en comparaison avec des plants de tomates traités uniquement avec de l'eau. Le nombre d'oeufs récupérés sur les plants traités par l'extrait d'algue est également significativement plus faible. Lorsque les trois bétaïnes essentielles (bétaïne d'acide-gamma-aminobutyrique, bétaïne d'acide delta-aminovalérique, glycine bétaïne) présentes dans l'extrait d'algue sont appliquées - à des concentrations équivalent à celles de l'extrait - on observe également une réduction significative de l'infestation par les nématodes et du nombre d'oeufs récupérés. Il peut donc être conclu que les bétaïnes présentes dans l'extrait d'algue jouent un rôle important dans le processus occasionnant les effets observés. Lorsque le sol est humidifée par une application des constituants inorganiques de l'extrait, on observe également une réduction significative du nombre d'oeufs récupérés, cette réduction étant plus faible que celle produite par application de bétaïnes. (Résumé d'auteur

Entanglement of remote atomic qubits

We report observations of entanglement of two remote atomic qubits, achieved by generating an entangled state of an atomic qubit and a single photon at site A, transmitting the photon to site B in an adjacent laboratory through an optical fiber, and converting the photon into an atomic qubit. Entanglement of the two remote atomic qubits is inferred by performing, locally, quantum state transfer of each of the atomic qubits onto a photonic qubit and subsequent measurement of polarization correlations in violation of the Bell inequality |S|?2. We experimentally determine Sexp?=2.16±0.03. Entanglement of two remote atomic qubits, each qubit consisting of two independent spin wave excitations, and reversible, coherent transfer of entanglement between matter and light represent important advances in quantum information scienc

Storing light with subradiant correlations in arrays of atoms

We show how strong light-mediated resonant dipole-dipole interactions between atoms can be utilized in a control and storage of light. The method is based on a high-fidelity preparation of a collective atomic excitation in a single correlated subradiant eigenmode in a lattice. We demonstrate how a simple phenomenological model captures the qualitative features of the dynamics and sharp transmission resonances that may find applications in sensin

Coherent scattering of near-resonant light by a dense microscopic cold atomic cloud

We measure the coherent scattering of light by a cloud of laser-cooled atoms with a size comparable to the wavelength of light. By interfering a laser beam tuned near an atomic resonance with the field scattered by the atoms, we observe a resonance with a redshift, a broadening, and a saturation of the extinction for increasing atom numbers. We attribute these features to enhanced light-induced dipole-dipole interactions in a cold, dense atomic ensemble that result in a failure of standard predictions such as the “cooperative Lamb shift”. The description of the atomic cloud by a mean-field model based on the Lorentz-Lorenz formula that ignores scattering events where light is scattered recurrently by the same atom and by a microscopic discrete dipole model that incorporates these effects lead to progressively closer agreement with the observations, despite remaining difference

Polarized deep inelastic scattering at high energies and parity violating structure functions

A comprehensive analysis of deep inelastic scattering of polarized charged leptons on polarized nucleons is presented; weak interaction contributions, both in neutral and charged current processes, are taken into account and the parity violating polarized nucleon structure functions are studied. Possible ways of their measurements and their interpretations in the parton model are discussed.Comment: (slightly modified version, includes a few new references and corrects few misprints for publication), 14 pages in TeX (needs harvmac) no figure, DFTT 80/9

Leading Chiral Logarithms to the Hyperfine Splitting of the Hydrogen and Muonic Hydrogen

We study the hydrogen and muonic hydrogen within an effective field theory framework. We perform the matching between heavy baryon effective theory coupled to photons and leptons and the relevant effective field theory at atomic scales. This matching can be performed in a perturbative expansion in alpha, 1/m_p and the chiral counting. We then compute the O(m_{l_i}^3 alpha^5/m_p^2 x logarithms) contribution (including the leading chiral logarithms) to the Hyperfine splitting and compare with experiment. They can explain about 2/3 of the difference between experiment and the pure QED prediction when setting the renormalization scale at the rho mass. We give an estimate of the matching coefficient of the spin-dependent proton-lepton operator in heavy baryon effective theory.Comment: 17 pages, LaTeX, minor changes, one reference adde

Projected shell model study of odd-odd f-p-g shell proton-rich nuclei

A systematic study of 2-quasiparticle bands of the proton-rich odd-odd nuclei in the mass A ~ 70-80 region is performed using the projected shell model approach. The study includes Br-, Rb-, and Y-isotopes with N = Z+2, and Z+4. We describe the energy spectra and electromagnetic transition strengths in terms of the configuration mixing of the angular-momentum projected multi-quasiparticle states. Signature splitting and signature inversion in the rotational bands are discussed and are shown to be well described. A preliminary study of the odd-odd N = Z nucleus, 74Rb using the concept of spontaneous symmetry breaking is also presented.Comment: 14 pages, 7 figures, final version accepted by Phys. Rev.

Collective resonance fluorescence in small and dense atom clouds:Comparison between theory and experiment

We study the emergence of a collective optical response of a cold and dense Rb87 atomic cloud to a near-resonant low-intensity light when the atom number is gradually increased. Experimental observations are compared with microscopic stochastic simulations of recurrent scattering processes between the atoms that incorporate the atomic multilevel structure and the optical measurement setup. We analyze the optical response of an inhomogeneously broadened gas and find that the experimental observations of the resonance line shifts and the total collected scattered light intensity in cold atom clouds substantially deviate from those of thermal atomic ensembles, indicating strong light-induced resonant dipole-dipole interactions between the atoms. At high densities, the simulations also predict a significantly slower decay of light-induced excitations in cold than in thermal atom clouds. The role of dipole-dipole interactions is discussed in terms of resonant coupling examples and the collective radiative excitation eigenmodes of the system