896 research outputs found
Spontaneous Conversion from Virtual to Real Photons in the Ultrastrong Coupling Regime
We show that a spontaneous release of virtual photon pairs can occur in a
quantum optical system in the ultrastrong coupling regime. In this regime,
which is attracting interest both in semiconductor and superconducting systems,
the light-matter coupling rate {\Omega}R becomes comparable to the bare
resonance frequency of photons {\omega}0. In contrast to the dynamical Casimir
effect and other pair creation mechanisms, this phenomenon does not require
external forces or time dependent parameters in the Hamiltonian.Comment: To appear on Phys. Rev. Let
Molecular Bremsstrahlung Radiation at GHz Frequencies in Air
A detection technique for ultra-high energy cosmic rays, complementary to the
fluorescence technique, would be the use of the molecular Bremsstrahlung
radiation emitted by low-energy ionization electrons left after the passage of
the showers in the atmosphere. In this article, a detailed estimate of the
spectral intensity of photons at ground level originating from this radiation
is presented. The spectral intensity expected from the passage of the
high-energy electrons of the cascade is also estimated. The absorption of the
photons in the plasma of electrons/neutral molecules is shown to be negligible.
The obtained spectral intensity is shown to be W cm
GHz at 10 km from the shower core for a vertical shower induced by a
proton of eV. In addition, a recent measurement of Bremsstrahlung
radiation in air at gigahertz frequencies from a beam of electrons produced at
95 keV by an electron gun is also discussed and reasonably reproduced by the
model.Comment: 20 pages, 9 figures, figures (2,4,7) improved in v2, accepted by
Phys. Rev.
A comparison of the lateral controllability with flap and plug ailerons on a sweptback-wing model
Land and sea BRDF laboratory measurements at 360 nm in view of ground reflected Cherenkov light detection in EUSO
A Tactile Sensor Device Exploiting the Tunable Sensitivity of Copper-PDMS Piezoresistive Composite
Abstract A low cost and highly mechanically flexible 8x8 pressure matrix sensor with dedicated electronics has been fabricated with an innovative metal-elastomer composite material. Under the action of a compressive stress the material exhibits a giant piezoresistive effect varying its electrical resistance of several orders of magnitude. This phenomenon can be tuned by changing the material composition parameters, directly modifying the sensitivity of the sensor. The micro casting fabrication technique, used for the preparation of self standing sheet of functional material, gives the possibility of easily fabricating complex-shaped structure suitable for integration on robot surface for tactile sensing. The sensor has been tested with a customized electronic circuit after an exhaustive characterization of the functional properties of the material
Islet Beta-Cell Apoptosis Triggered in Vivo by Interleukin-1 Is Not Related to the Inducible Nitric Oxide Synthase Pathway: Evidence for Mitochondrial Function Impairment and Lipoperoxidation
Real-Time Monitoring of Temperature-Dependent Structural Transitions in DNA Nanomechanical Resonators: Unveiling the DNA-Ligand Interactions for Biomedical Applications
Despite being widely recognized as of paramount importance in molecular biology, real-time monitoring of structural transitions in DNA complexes is currently limited to complex techniques and chemically modified oligonucleotides. Here, we show that nanomechanical resonators made of different DNA complexes, such as pristine dsDNA, ssDNA, and DNA intercalated with dye molecules or chemotherapeutic agents, are characterized by unique fingerprint curves when their flexural resonance frequency is tracked as a function of temperature. Such frequency shifts can be successfully used to monitor structural variations in DNA complexes, such as B-to-A form and helix-to-coil transitions, thus opening implications in both environmental studies─for example, trucking the effects of heavy metal exposure on human or vegetable DNA molecules─and in vitro experiments for the evaluation of the effects of drugs on patient DNA
Radiometer offsets and count conversion coefficients for the Earth Radiation Budget Experiment (ERBE) spacecraft for the years 1984, 1985, and 1986
A compendium is presented of the ground and inflight scanner and nonscanner offsets and count conversion (gain) coefficients used for the Earth Radiation Budget Experiment (ERBE) production processing of data from the ERBS, NOAA-9, and NOAA-10 satellites for the 1 Nov. 1984 to 31 Dec. 1986
Microenvironment in neuroblastoma: Isolation and characterization of tumor-derived mesenchymal stromal cells
Background: It has been proposed that mesenchymal stromal cells (MSCs) promote tumor progression by interacting with tumor cells and other stroma cells in the complex network of the tumor microenvironment. We characterized MSCs isolated and expanded from tumor tissues of pediatric patients diagnosed with neuroblastomas (NB-MSCs) to define interactions with the tumor microenvironment. Methods: Specimens were obtained from 7 pediatric patients diagnosed with neuroblastoma (NB). Morphology, immunophenotype, differentiation capacity, proliferative growth, expression of stemness and neural differentiation markers were evaluated. Moreover, the ability of cells to modulate the immune response, i.e. inhibition of phytohemagglutinin (PHA) activated peripheral blood mononuclear cells (PBMCs) and natural killer (NK) cytotoxic function, was examined. Gene expression profiles, known to be related to tumor cell stemness, Wnt pathway activation, epithelial-mesenchymal transition (EMT) and tumor metastasis were also evaluated. Healthy donor bone marrow-derived MSCs (BM-MSC) were employed as controls. Results: NB-MSCs presented the typical MSC morphology and phenotype. They showed a proliferative capacity superimposable to BM-MSCs. Stemness marker expression (Sox2, Nanog, Oct3/4) was comparable to BM-MSCs. NB-MSC in vitro osteogenic and chondrogenic differentiation was similar to BM-MSCs, but NB-MSCs lacked adipogenic differentiation capacity. NB-MSCs reached senescence phases at a median passage of P7 (range, P5-P13). NB-MSCs exhibited greater immunosuppressive capacity on activated T lymphocytes at a 1:2 (MSC: PBMC) ratio compared with BM-MSCs (p = 0.018). NK cytotoxic activity was not influenced by co-culture, either with BM-MSCs or NB-MSCs. Flow-cytometry cell cycle analysis showed that NB-MSCs had an increased number of cells in the G0-G1 phase compared to BM-MSCs. Transcriptomic profiling results indicated that NB-MSCs were enriched with EMT genes compared to BM-MSCs. Conclusions: We characterized the biological features, the immunomodulatory capacity and the gene expression profile of NB-MSCs. The NB-MSC gene expression profile and their functional properties suggest a potential role in promoting tumor escape, invasiveness and metastatic traits of NB cancer cells. A better understanding of the complex mechanisms underlying the interactions between NB cells and NB-derived MSCs should shed new light on potential novel therapeutic approaches
ULTRA : Uv Light Transmission and Reflection in the Atmosphere - Technical report - A supporting experiment for the EUSO project
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