Determination of continuous variable entanglement by purity measurements

We classify the entanglement of two--mode Gaussian states according to their degree of total and partial mixedness. We derive exact bounds that determine maximally and minimally entangled states for fixed global and marginal purities. This characterization allows for an experimentally reliable estimate of continuous variable entanglement based on measurements of purity.Comment: 4 pages, 3 EPS figures. Final versio

Preparation of polyimides from mixtures of monomeric diamines and esters of polycarboxylic acids

Polyimides having high thermal and oxidative stability are prepared by the reaction of a mixture of monomers comprising (1) a dialkyl or tetraalkyl ester of an aromatic tetracarboxylic acid; (2) an aromatic diamine; and (3) a monoalkyl or dialkyl ester of a dicarboxylic acid where in the ratio of a:b:c is n:(n+1):2, wherein n has a value from 1 to 20. The mixture of monomers is prepared in a 30 to 70 percent by weight solution of an organic solvent, a substrate impregnated with the solution and heated at 50 to 205 C to remove said solvent and form a low molecular weight prepolymer, and thereafter heated at 275 to 350 C to cure to a high molecular weight polyimide

Thermally stable polyimides from solutions of monomeric reactants

Monomer solutions have high solubility and low solution viscosity. Since monomers are shipped in powder form and reaction to polyimide-acid prepolymer is omitted, the cost is low and handling is easy

A compact high-flux source of cold sodium atoms

We present a compact source of cold sodium atoms suitable for the production of quantum degenerate gases and versatile for a multi-species experiment. The magnetic field produced by permanent magnets allows to simultaneously realize a Zeeman slower and a two-dimensional MOT within an order of magnitude smaller length than standard sodium sources. We achieve an atomic flux exceeding 4x10^9 atoms/s loaded in a MOT, with a most probable longitudinal velocity of 20 m/s, and a brightness larger than 2.5x10^(12) atoms/s/sr. This atomic source allowed us to produce a pure BEC with more than 10^7 atoms and a background pressure limited lifetime of 5 minutes.Comment: 8 pages, 6 figures, submitted to Phys. Rev.

Effects of post-translational modifications catalysed by pollen transglutaminase on the functional properties of microtubules and actin filaments

TGases (transglutaminases) are a class of calcium-dependent enzymes that catalyse the interactions between acyl acceptor glutamyl residues and amine donors, potentially making crosslinks between proteins. To assess the activity of apple (Malus domestica) pollen TGase on the functional properties of actin and tubulin, TGase was prepared from apple pollen by hydrophobic interaction chromatography and assayed on actin and tubulin purified from the same cell type. The enzyme catalysed the incorporation of putrescine in the cytoskeleton monomers. When tested on actin filaments, pollen TGase induced the formation of high-molecular-mass aggregates of actin. Use of fluorescein– cadaverine showed that the labelled polyamine was incorporated into actin by pollen TGase, similar to with guinea pig liver TGase. The pollen TGase also reduced the enzyme activity and the binding of myosin to TGase-treated actin filaments. Polymerization of tubulin in the presence of pollen TGase also yielded the formation of high molecular mass aggregates. Furthermore, the pollen TGase also affected the binding of kinesin to microtubules and reduced the motility of microtubules along kinesincoated slides. These results indicate that the pollen tube TGase can control different properties of the pollen tube cytoskeleton (including the ability of actin and tubulin to assemble and their interaction with motor proteins) and consequently regulate the development of pollen tubes

Quantum cooling and squeezing of a levitating nanosphere via time-continuous measurements

With the purpose of controlling the steady state of a dielectric nanosphere levitated within an optical cavity, we study its conditional dynamics under simultaneous sideband cooling and additional time-continuous measurement of either the output cavity mode or the nanosphere's position. We find that the average phonon number, purity and quantum squeezing of the steady-states can all be made more non-classical through the addition of time-continuous measurement. We predict that the continuous monitoring of the system, together with Markovian feedback, allows one to stabilize the dynamics for any value of the laser frequency driving the cavity. By considering state-of-the-art values of the experimental parameters, we prove that one can in principle obtain a non-classical (squeezed) steady-state with an average phonon number $n_{\sf ph}\approx 0.5$.Comment: 10 pages, 9 figures; v2: close to published versio

Indicatori della lavorazione tessile nel Veneto preromano

Among the grave goods of the ancient Veneto burials, ceramic spindle whorls, reels and counterweights are quite common: they are related to the female world, of which the textile manufacturing was an important element. Some years ago, in a paper written for the catalougue of the exhibition Le ore e I giorni delle donne, Verucchio 2007, we started an analysis aimed at recognizing the specific indicators of weaving, such as distaffs, spindles, thread spacers, needles, buttons, along with the recently discovered weaving tablets from Este. The goal of that work was to understand the various levels of specialization involved in the different phases of the production process. We discussed some tool associations that could be considered as “toolkits”, along with some clear diachronic changes in these sets. In this paper we continued this analysis by approaching old and new data from a numerical and ponderal point of view, in order to better understand the specific function of some classes of artifacts, and be able to make hypoteses about the “invisible” tools (wooden spindles, typology and typometry of the looms…). Furthermore, a complete reconstruction of the textiles production process could help us understanding the change (from an individual, domestic activity to a large-scale production) the textile manufacturing underwent during the 1st millennium BC

Observation of a Spinning Top in a Bose-Einstein Condensate

Boundaries strongly affect the behavior of quantized vortices in Bose-Einstein condensates, a phenomenon particularly evident in elongated cigar-shaped traps where vortices tend to orient along a short direction to minimize energy. Remarkably, contributions to the angular momentum of these vortices are tightly confined to the region surrounding the core, in stark contrast to untrapped condensates where all atoms contribute $\hbar$. We develop a theoretical model and use this, in combination with numerical simulations, to show that such localized vortices precess in an analogous manner to that of a classical spinning top. We experimentally verify this spinning-top behavior with our real-time imaging technique that allows for the tracking of position and orientation of vortices as they dynamically evolve. Finally, we perform an in-depth numerical investigation of our real-time expansion and imaging method, with the aim of guiding future experimental implementation, as well as outlining directions for its improvement.Comment: 10 pages, 7 figure