18,723 research outputs found
Realization of Universal Optimal Quantum Machines by Projective Operators and Stochastic Maps
Optimal quantum machines can be implemented by linear projective operations.
In the present work a general qubit symmetrization theory is presented by
investigating the close links to the qubit purification process and to the
programmable teleportation of any generic optimal anti-unitary map. In
addition, the contextual realization of the N ->M cloning map and of the
teleportation of the N->(M-N) universal NOT gate is analyzed by a novel and
very general angular momentum theory. An extended set of experimental
realizations by state symmetrization linear optical procedures is reported.
These include the 1->2 cloning process, the UNOT gate and the quantum
tomographic characterization of the optimal partial transpose map of
polarization encoded qubits.Comment: 11 pages, 7 figure
Transient increases in intracellular calcium and reactive oxygen species levels in TCam-2 cells exposed to microgravity
The effects of microgravity on functions of the human body are well described, including alterations in the male and female reproductive systems. In the present study, TCam-2 cells, which are considered a good model of mitotically active male germ cells, were used to investigate intracellular signalling and cell metabolism during exposure to simulated microgravity, a condition that affects cell shape and cytoskeletal architecture. After a 24 hour exposure to simulated microgravity, TCam-2 cells showed 1) a decreased proliferation rate and a delay in cell cycle progression, 2) increased anaerobic metabolism accompanied by increased levels of intracellular Ca(2+), reactive oxygen species and superoxide anion and modifications in mitochondrial morphology. Interestingly, all these events were transient and were no longer evident after 48 hours of exposure. The presence of antioxidants prevented not only the effects described above but also the modifications in cytoskeletal architecture and the activation of the autophagy process induced by simulated microgravity. In conclusion, in the TCam-2 cell model, simulated microgravity activated the oxidative machinery, triggering transient macroscopic cell events, such as a reduction in the proliferation rate, changes in cytoskeleton-driven shape and autophagy activation
Single Superconducting Split-Ring Resonator Electrodynamics
We investigate the microwave electrodynamic properties of a single
superconducting thin film split-ring resonator (SRR). The experiments were
performed in an all-Nb waveguide, with Nb wires and Nb SRRs. Transmission data
showed a high-Q stopband for a single Nb SRR ( at 4.2 K)
below , and no such feature for a Cu SRR, or closed Nb loops, of similar
dimensions. Adding SRRs increased the bandwidth, but decreased the insertion
loss of the features. Placing the Nb SRR into an array of wires produced a
single, elementary negative-index passband ( at 4.2 K).
Changes in the features due to the superconducting kinetic inductance were
observed. Models for the SRR permeability, and the wire dielectric response,
were used to fit the data.Comment: 4 pages, 3 figures, RevTex, submitted to Applied Physics Letters.
Updated version includes mention of bianisotropy, better looking figures, and
different temperature dat
Modifications of the hydrogen bond network of liquid water in a cylindrical SiO_2 pore
We present results of molecular dynamics simulations of water confined in a
silica pore. A cylindrical cavity is created inside a vitreous silica cell with
geometry and size similar to the pores of real Vycor glass. The simulations are
performed at different hydration levels. At all hydration levels water adsorbs
strongly on the Vycor surface; a double layer structure is evident at higher
hydrations. At almost full hydration the modifications of the
confinement-induced site-site pair distribution functions are in qualitative
agreement with neutron diffraction experiment. A decrease in the number of
hydrogen bonds between water molecules is observed along the pore radius, due
to the tendency of the molecules close to the substrate to form hydrogen-bonds
with the hydrophilic pore surface. As a consequence we observe a substrate
induced distortion of the H-bond tetrahedral network of water molecules in the
regions close to the surface.Comment: Talk presented at "Physics of Liquids: Foundations, Highlights,
Challenge", Murau Sept. 1998. To appear in J. Mol. Li
Translation-Rotation Coupling in Transient Grating Experiments : Theoretical and Experimental Evidences
The results of a Transient Grating experiment in a supercooled molecular
liquid of anisotropic molecules and its theoretical interpretation are
presented. These results show the existence of two distinct dynamical
contributions in the response function of this experiment, density and
orientation dynamics. These dynamics can be experimentally disentangled by
varying the polarisation of the probe and diffracted beams and they have been
identified and measured in a Heterodyne Detected experiment performed on
m-toluidine. The results of the theory show a good qualitative agreement with
the measurements at all temperatures.Comment: PDF format, 14 pages including 4 figures, accepted for publication in
EPL. minor modification
What information could the main actors of liquid biopsy provide? A representative case of non-small cell lung cancer (NSCLC)
In non-small cell lung cancer (NSCLC), there is a consensus regarding the use of liquid biopsy, generally, to detect "druggable" mutations and, in particular, to monitor tyrosine kinase inhibitor (TKI) treatments. However, whether circulating tumor cells (CTCs) are better tools than cell-free DNA (cfDNA), is still a matter of debate, mainly concerning which antigen(s) we should use to investigating simultaneously both epithelial and epithelial-to-mesenchymal transient (EMT) phenotype in the same sample of CTCs. To address this item, we exploited here a single-tube liquid biopsy, to detect both epithelial cell adhesion molecule (EpCAM)-positive CTCs and EpCAM-low/negative CTCs, because down-modulation of EpCAM is considered the first step in EMT. Furthermore, we analyzed the DNA from CTCs of four different phenotypes (ctcDNA), according to their EpCAM expression and cytokeratin pattern, and circulating tumor DNA (ctDNA) by droplet digital PCR (ddPCR), in order to disclose activating and resistancedriving mutations. Liquid biopsy reflected spatial and temporal heterogeneity of the tumor under treatment pressure. We provide the proof-of-concept that the complementary use of ctDNA and ctcDNA represents a reliable, minimally invasive and dynamic tool for a more comprehensive view of tumor evolution
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