Cavity-assisted squeezing of a mechanical oscillator

We investigate the creation of squeezed states of a vibrating membrane or a movable mirror in an opto-mechanical system. An optical cavity is driven by squeezed light and couples via radiation pressure to the membrane/mirror, effectively providing a squeezed heat-bath for the mechanical oscillator. Under the conditions of laser cooling to the ground state, we find an efficient transfer of squeezing with roughly 60% of light squeezing conveyed to the membrane/mirror (on a dB scale). We determine the requirements on the carrier frequency and the bandwidth of squeezed light. Beyond the conditions of ground state cooling, we predict mechanical squashing to be observable in current systems.Comment: 7.1 pages, 3 figures, submitted to PR

Continuous mode cooling and phonon routers for phononic quantum networks

We study the implementation of quantum state transfer protocols in phonon networks, where in analogy to optical networks, quantum information is transmitted through propagating phonons in extended mechanical resonator arrays or phonon waveguides. We describe how the problem of a non-vanishing thermal occupation of the phononic quantum channel can be overcome by implementing optomechanical multi- and continuous mode cooling schemes to create a 'cold' frequency window for transmitting quantum states. In addition, we discuss the implementation of phonon circulators and switchable phonon routers, which rely on strong coherent optomechanical interactions only, and do not require strong magnetic fields or specific materials. Both techniques can be applied and adapted to various physical implementations, where phonons coupled to spin or charge based qubits are used for on-chip networking applications.Comment: 33 pages, 8 figures. Final version, a few minor changes and updated reference

Exciton-assisted optomechanics with suspended carbon nanotubes

We propose a framework for inducing strong optomechanical effects in a suspended carbon nanotube based on deformation potential exciton-phonon coupling. The excitons are confined using an inhomogeneous axial electric field which generates optically active quantum dots with a level spacing in the milli-electronvolt range and a characteristic size in the 10-nanometer range. A transverse field induces a tunable parametric coupling between the quantum dot and the flexural modes of the nanotube mediated by electron-phonon interactions. We derive the corresponding excitonic deformation potentials and show that this interaction enables efficient optical ground-state cooling of the fundamental mode and could allow us to realise the strong and ultra-strong coupling regimes of the Jaynes-Cummings and Rabi models.Comment: 25 pages, 2 figure

Master Equation for the Motion of a Polarizable Particle in a Multimode Cavity

We derive a master equation for the motion of a polarizable particle weakly interacting with one or several strongly pumped cavity modes. We focus here on massive particles with complex internal structure such as large molecules and clusters, for which we assume a linear scalar polarizability mediating the particle-light interaction. The predicted friction and diffusion coefficients are in good agreement with former semiclassical calculations for atoms and small molecules in weakly pumped cavities, while the current rigorous quantum treatment and numerical assessment sheds a light on the feasibility of experiments that aim at optically manipulating beams of massive molecules with multimode cavities.Comment: 30 pages, 5 figure

Overexpression of sphingosine kinase 1 is associated with salivary gland carcinoma progression and might be a novel predictive marker for adjuvant therapy

<p>Abstract</p> <p>Background</p> <p>Overexpression of sphingosine kinase-1 (SPHK1) has been demonstrated to be associated with the development and progression in various types of human cancers. The current study was to characterize the expression of SPHK1 in salivary gland carcinomas (SGC) and to investigate the association between SPHK1 expression and progression of SGC.</p> <p>Methods</p> <p>The expression of SPHK1 was examined in 2 normal salivary gland tissues, 8 SGC tissues of various clinical stages, and 5 pairs of primary SGC and adjacent salivary gland tissues from the same patient, using real-time PCR and western blot analysis. Furthermore, the SPHK1 protein expression was analyzed in 159 clinicopathologically characterized SGC cases by immunohistochemistry. Statistical analyses were performed to determine the prognostic and diagnostic associations.</p> <p>Results</p> <p>SPHK1 expression was found to be markedly upregulated in SGC tissues than that in the normal salivary gland tissues and paired adjacent salivary gland tissues, at both mRNA and protein levels. Statistical analysis revealed a significant correlation of SPHK1 expression with the clinical stage (<it>P </it>= 0.005), T classification (<it>P </it>= 0.017), N classification (<it>P </it>= 0.009), M classification (<it>P </it>= 0.002), and pathological differentiation (<it>P </it>= 0.013). Patients with higher SPHK1 expression had shorter overall survival time, whereas patients with lower SPHK1 expression had better survival. Importantly, patients in the group without adjuvant therapy who exhibited high SPHK1 expression had significantly lower overall survival rates compared with those with low SPHK1 expression. Moreover, multivariate analysis suggested that SPHK1 expression might be an independent prognostic indicator for the survival of SGC patients.</p> <p>Conclusions</p> <p>Our results suggest that SPHK1 expression is associated with SGC progression, and might represent as a novel and valuable predictor for adjuvant therapy to SGC patients.</p

Pcdh19 loss-of-function increases neuronal migration in vitro but is dispensable for brain development in mice

Protocadherin 19 (Pcdh19) is an X-linked gene belonging to the protocadherin superfamily, whose members are predominantly expressed in the central nervous system and have been implicated in cell-cell adhesion, axon guidance and dendrite self-avoidance. Heterozygous loss-of-function mutations in humans result in the childhood epilepsy disorder PCDH19 Girls Clustering Epilepsy (PCDH19 GCE) indicating that PCDH19 is required for brain development. However, understanding PCDH19 function in vivo has proven challenging and has not been studied in mammalian models. Here, we validate a murine Pcdh19 null allele in which a β-Geo reporter cassette is expressed under the control of the endogenous promoter. Analysis of β-Geo reporter activity revealed widespread but restricted expression of PCDH19 in embryonic, postnatal and adult brains. No gross morphological defects were identified in Pcdh19(+/β-Geo) and Pcdh19(Y/β-Geo) brains and the location of Pcdh19 null cells was normal. However, in vitro migration assays revealed that the motility of Pcdh19 null neurons was significantly elevated, potentially contributing to pathogenesis in patients with PCDH19 mutations. Overall our initial characterization of Pcdh19(+/β-Geo), Pcdh19(β-Geo/β-Geo) and Pcdh19(Y/β-Geo)mice reveals that despite widespread expression of Pcdh19 in the CNS, and its role in human epilepsy, its function in mice is not essential for brain development.Daniel T. Pederick, Claire C. Homan, Emily J. Jaehne, Sandra G. Piltz, Bryan P. Haines, Bernhard T. Baune, Lachlan A. Jolly, James N. Hughes, Jozef Gecz, Paul Q. Thoma

Patient survival after D 1 and D 2 resections for gastric cancer: long-term results of the MRC randomized surgical trial

Controversy still exists on the optimal surgical resection for potentially curable gastric cancer. Much better long-term survival has been reported in retrospective/non-randomized studies with D 2 resections that involve a radical extended regional lymphadenectomy than with the standard D 1 resections. In this paper we report the long-term survival of patients entered into a randomized study, with follow-up to death or 3 years in 96% of patients and a median follow-up of 6.5 years. In this prospective trial D 1 resection (removal of regional perigastric nodes) was compared with D 2 resection (extended lymphadenectomy to include level 1 and 2 regional nodes). Central randomization followed a staging laparotomy

Electrical Conductivity of Electrospun Polyaniline and Polyaniline-Blend Fibers and Mats

Submicrometer fibers of polyaniline (PAni) doped with (+)-camphor-10-sulfonic acid (HCSA) and blended with poly(methyl methacrylate) (PMMA) or poly(ethylene oxide) were electrospun over a range of compositions. Continuous, pure PAni fibers doped with HCSA were also produced by coaxial electrospinning and subsequent removal of the PMMA shell polymer. The electrical conductivities of both the fibers and the mats were characterized. The electrical conductivities of the fibers were found to increase exponentially with the weight percent of doped PAni in the fibers, with values as high as 50 ± 30 S/cm for as-electrospun fibers of 100% doped PAni and as high as 130 ± 40 S/cm upon further solid state drawing. These high electrical conductivities are attributed to the enhanced molecular orientation arising from extensional deformation in the electrospinning process and afterward during solid state drawing. A model is proposed that permits the calculation of mat conductivity as a function of fiber conductivity, mat porosity, and fiber orientation distribution; the results agree quantitatively with the independently measured mat conductivities.United States. Army Research Office (Institute for Soldier Nanotechnologies, Contract ARO W911NF-07-D- 0004