Nuclear Breathing Mode in the Relativistic Mean Field Theory

The breathing-mode giant monopole resonance is studied within the framework of the relativistic mean-field (RMF) theory. Using a broad range of parameter sets, an analysis of constrained incompressibility and excitation energy of isoscalar monopole states in finite nuclei is performed. It is shown that the non-linear scalar self-interaction and the resulting surface properties influence the breathing-mode considerably. It is observed that dynamical surface properties respond differently in the RMF theory than in the Skyrme approach. A comparison is made with the incompressibility derived from the semi-infinite nuclear matter and with constrained nonrelativistic Skyrme Hartree-Fock calculaions.Comment: Latex (12 pages) and 3 figures (available upon request) J. Phys. G (in press

Plasmonic Structures Fabricated By Interference Lithography For Sensor Applications

In this work we demonstrate the use of holographic lithography for generation of large area plasmonic periodic structures. Submicrometric array of holes, with different periods and thickness, were recorded in gold films, in areas of about 1 cm2, with homogeneity similar to that of samples recorded by Focused Ion Beam. In order to check the plasmonic properties, we measured the transmission spectra of the samples. The spectra exhibit the typical surface plasmon resonances (SPR) in the infrared whose position and width present the expected behavior with the period of the array and film thickness. The shift of the peak position with the permittivity of the surrounding medium demonstrates the feasebility of the sample as large area sensors. © 2009 SPIE.7394Ebbesen, T.W., Lezec, H.J., Ghaemy, H.F., Thio, T., Wolff, P.A., Extraordinary optical transmission through sub-wavelenght hole arrays (1998) Nature, 391, pp. 667-669Ghaemy, H.F., Thio, T., Grupp, D.E., Ebbesen, T.W., Lezec, H.J., Surface plasmons enhance optical transmission through subwavelenght holes (1998) Phys. Rev. B, 58, pp. 6779-6782Lal, S., Link, S., Halas, N.J., Nano-optics from sensing to waveguiding (2007) Nature Photonics, 1, pp. 641-648Barnes, W.L., Dereux, A., Ebbesen, T.W., Surface plasmon subwavelength optics (2003) Nature, 424, pp. 824-830Brolo, A.G., Arctander, E., Gordon, R., Leathem, B., Kavanagh, K.L., Nanohole-Enhanced Raman Scattering (2004) Nano Lett, 4, pp. 2015-2018Brolo, A.G., Gordon, R., Leathem, B., Kavanagh, K.L., Surface plasmon sensor based on the enhanced light transmission through arrays of nanoholes in gold films (2004) Langmuir, 20, pp. 4813-4815Brueck, S.R.J., Optical and Interferometric Lithography- Nanotechnology Enablers (2005) Proc. IEEE, 93, pp. 1704-1721Lai, N.D., Liang, W.P., Lin, J.H., Hsu, C.C., Lin, C.H., Fabrication of two- and three-dimensional periodic structures by multi-exposure of two-beam interference technique (2005) Opt. Express, 13, pp. 9605-9611Frejlich, J., Cescato, L., Mendes, G.F., Analysis of an active stabilization system for holographic setup (1988) Appl. Opt, 27, pp. 1967-197

Bulk photochromism in a tungstate-phosphate glass: A new optical memory material?

In this work, we present a new photochromic tungstate based glass which have both absorption coefficient and refractive index modified under laser exposure. The photosensitive effect is superficial under ultraviolet (UV) irradiation but occurs in the entire volume of the glass under visible irradiation. The effect can be obtained in any specific point inside the volume using an infrared femtosecond laser. In addition, the photosensitive phenomenon can be erased by specific heat treatment. This glass can be useful to substitute actual data storage supports and is a promising material for 3-dimensional (3D) and holographic optical storage.1251

Design And Fabrication Of Two-dimensional Hexagonal Photonic Crystals With A Linear Waveguide In Erbium Doped Geo2-bi2o 3-pbo-tio2 Glasses

In this work, we designed and recorded two-dimensional Hexagonal Photonic Crystals (2D-HPC) layers, with a linear waveguide, in erbium doped GeO 2-Bi2O3-PbO-TiO2 glassy films, by combining the techniques of holographic recording and femtosecond (fs) laser micromachining. The 2D-HPC is recorded holographically in a photoresist film coated on a glass substrate by exposing the sample to the same interference pattern twice and rotating the sample of 60° between the exposures. After the development a two dimensional hexagonal array of photoresist columns remain on the glass substrate. The recording of the waveguide is made by a fs laser micromachining system focused at sample surface. The laser spot produces the ablation of the photoresist columns generating a defect line in the periodic hexagonal array. After the recording of the photoresist template, the erbium doped GeO2-Bi2O3-PbO-TiO2 film is evaporated on the photoresist and finally the photoresist template is removed using acetone. The design of the geometrical parameters of the 2D-HPC is performed by calculation of the dispersion mode curves of the photonic crystal using a 2D finite element method. The proper geometrical parameters depend on both the refractive index of the glass film and thickness. Such parameters as well as the period of the 2D-HPC have been defined in order to obtain a photonic band gap in the region of erbium luminescence band. In such condition the erbium luminescence will propagate only through the waveguide. © 2013 SPIE.8776The Society of Photo-Optical Instrumentation Engineers (SPIE)Notomi, M., Shinya, A., Kuramochi, E., Photonic crystals: Towards ultrasmall lightwave circuits (2004) NTTTech. Rev., 2, pp. 36-47Chow, E., Lin, S.Y., Jonhson, S.G., Villeneuve, P.R., Joannopoulos, J.D., Wendt, J.R., Vawter, G.A., Alleman, A., Three-dimensional control of light in a two-dimensional photonic crystal slab (2000) Nature, 407, pp. 983-986Sharp, D.N., Campbell, M., Dedman, E.R., Harrison, M.T., Denning, R.G., Turberfield, A.J., Photoniccrystals for the visible spectrum by holographic lithography (2002) Opt. Quantum Electron, 34, pp. 3-12Carlsson, N., Ikeda, N., Sugimoto, Y., Asakawa, K., Takemori, T., Katayama, Y., Kawai, N., Inoue, K., Design, nano-fabication and analysis of near-infrared 2D photonic crystal air-bridge structures (2002) Opt. Quantum Electron, 34, pp. 123-131Joannopoulos, J.D., Meade, R.D., Winn, J.N., (1995) Photonic Crystals, , Princeton University PressVilleneuve, P.R., Piché, M., Photonic band gaps in two-dimensional square and hexagonal lattices (1992) Phys. Rev. B, 46, pp. 4969-4972Cheng, C.C., Scherer, A., Fabrication of photonic band-gap crystals (1995) J. Vac. Sci. Technol. B, 13, pp. 2696-2700Lai, N.D., Liang, W.P., Lin, J.H., Hsu, C.C., Lin, C.H., Fabrication of two-and three-dimensional periodic structures by multi-exposure of two-beam interference technique (2005) Opt. Express, 13, pp. 9605-9611. , 11O'Brien, J., Kuang, W., Photonic crystal lasers, cavities, and waveguides (2005) Enc. Mod. Optics, 2005, pp. 146-155Gattass, R.R., Mazur, E., Femtosecond laser micromachining in transparent materials (2008) Nat. Photonics, 2 (4), pp. 219-22

Application of the density dependent hadron field theory to neutron star matter

The density dependent hadron field (DDRH) theory, previously applied to isospin nuclei and hypernuclei is used to describe $\beta$-stable matter and neutron stars under consideration of the complete baryon octet. The meson-hyperon vertices are derived from Dirac-Brueckner calculations of nuclear matter and extended to hyperons. We examine properties of density dependent interactions derived from the Bonn A and from the Groningen NN potential as well as phenomenological interactions. The consistent treatment of the density dependence introduces rearrangement terms in the expression for the baryon chemical potential. This leads to a more complex condition for the $\beta$-equilibrium compared to standard relativistic mean field (RMF) approaches. We find a strong dependence of the equation of state and the particle distribution on the choice of the vertex density dependence. Results for neutron star masses and radii are presented. We find a good agreement with other models for the maximum mass. Radii are smaller compared to RMF models and indicate a closer agreement with results of non-relativistic Brueckner calculations.Comment: 28 pages, 11 figure

Density dependent hadron field theory for neutron stars with antikaon condensates

We investigate $K^-$ and $\bar K^0$ condensation in $\beta$-equilibrated hyperonic matter within a density dependent hadron field theoretical model. In this model, baryon-baryon and (anti)kaon-baryon interactions are mediated by the exchange of mesons. Density dependent meson-baryon coupling constants are obtained from microscopic Dirac Brueckner calculations using Groningen and Bonn A nucleon-nucleon potential. It is found that the threshold of antikaon condensation is not only sensitive to the equation of state but also to antikaon optical potential depth. Only for large values of antikaon optical potential depth, $K^-$ condensation sets in even in the presence of negatively charged hyperons. The threshold of $\bar K^0$ condensation is always reached after $K^-$ condensation. Antikaon condensation makes the equation of state softer thus resulting in smaller maximum mass stars compared with the case without any condensate.Comment: 20 pages, 7 figures; final version to appear in Physical Review

A standardised study to compare prostate cancer targeting efficacy of five radiolabelled bombesin analogues

Purpose: Prostate-specific antigen (PSA)-based screening for prostate cancer (PC) has dramatically increased early diagnosis. Current imaging techniques are not optimal to stage early PC adequately. A promising alternative to PC imaging is peptide-based scintigraphy using radiolabelled bombesin (BN) analogues that bind to gastrin-releasing peptide receptors (GRPR) being overexpressed in PC. When labelled to appropriate radionuclides BN targeting of GRPRs may also provide applications for peptide radionuclide receptor therapy (PRRT). Assessment studies under identical experimental conditions allowing a reliable comparison of the potential of such analogues are lacking. This study was performed to evaluate and directly compare five promising radiolabelled BN analogues for their targeting efficacy for PC under standardised conditions. Methods: The BN agonists [111In]DOTA-PESIN, [111In]AMBA, [111In]MP2346 and [111In]MP2653 and one antagonist [99mTc]Demobesin-1 were evaluated in GRPR-overexpressing human PC-3 tumou

Illuminating the life of GPCRs

The investigation of biological systems highly depends on the possibilities that allow scientists to visualize and quantify biomolecules and their related activities in real-time and non-invasively. G-protein coupled receptors represent a family of very dynamic and highly regulated transmembrane proteins that are involved in various important physiological processes. Since their localization is not confined to the cell surface they have been a very attractive "moving target" and the understanding of their intracellular pathways as well as the identified protein-protein-interactions has had implications for therapeutic interventions. Recent and ongoing advances in both the establishment of a variety of labeling methods and the improvement of measuring and analyzing instrumentation, have made fluorescence techniques to an indispensable tool for GPCR imaging. The illumination of their complex life cycle, which includes receptor biosynthesis, membrane targeting, ligand binding, signaling, internalization, recycling and degradation, will provide new insights into the relationship between spatial receptor distribution and function. This review covers the existing technologies to track GPCRs in living cells. Fluorescent ligands, antibodies, auto-fluorescent proteins as well as the evolving technologies for chemical labeling with peptide- and protein-tags are described and their major applications concerning the GPCR life cycle are presented