Constant magnetic field and 2d non-commutative inverted oscillator

We consider a two-dimensional non-commutative inverted oscillator in the presence of a constant magnetic field, coupled to the system in a ``symplectic'' and ``Poisson'' way. We show that it has a discrete energy spectrum for some value of the magnetic field.Comment: 7 pages, LaTeX file, no figures, PACS number: 03.65.-

A Novel Approach for an Integrated Straw tube-Microstrip Detector

We report on a novel concept of silicon microstrips and straw tubes detector, where integration is accomplished by a straw module with straws not subjected to mechanical tension in a Rohacell $^{\circledR}$ lattice and carbon fiber reinforced plastic shell. Results on mechanical and test beam performances are reported on as well.Comment: Accepted by Transactions on Nuclear Science (2005). 11 pages, 9 figures, uses lnfprep.st

Strong Interactions, (De)coherence and Quarkonia

Quarkonia are the central objects to explore the non-perturbative nature of non-abelian gauge theories. We describe the confinement-deconfinement phases for heavy quarkonia in a hot QCD medium and thereby the statistical nature of the inter-quark forces. In the sense of one-loop quantum effects, we propose that the "quantum" nature of quark matters follows directly from the thermodynamic consideration of Richardson potential. Thereby we gain an understanding of the formation of hot and dense states of quark gluon plasma matter in heavy ion collisions and the early universe. In the case of the non-abelian theory, the consideration of the Sudhakov form factor turns out to be an efficient tool for soft gluons. In the limit of the Block-Nordsieck resummation, the strong coupling obtained from the Sudhakov form factor yields the statistical nature of hadronic bound states, e.g. kaons and Ds particles.Comment: 8 pages, Keywords: CPT symmetry, decoherence, Lorentz symmetry breaking; PACS: 02.40.-k; 14.40.Pq; 12.40.Nn; 14.70.Dj; conference proceeding of Discrete 2010, 6-11 December 2010, Roma (Italy); the Symposium proceedings will be published online in a special volume of Journal of Physics: Conference Serie

Two-Center Black Holes Duality-Invariants for stu Model and its lower-rank Descendants

We classify 2-center extremal black hole charge configurations through duality-invariant homogeneous polynomials, which are the generalization of the unique invariant quartic polynomial for single-center black holes based on homogeneous symmetric cubic special Kaehler geometries. A crucial role is played by an horizontal SL(p,R) symmetry group, which classifies invariants for p-center black holes. For p = 2, a (spin 2) quintet of quartic invariants emerge. We provide the minimal set of independent invariants for the rank-3 N = 2, d = 4 stu model, and for its lower-rank descendants, namely the rank-2 st^2 and rank-1 t^3 models; these models respectively exhibit seven, six and five independent invariants. We also derive the polynomial relations among these and other duality invariants. In particular, the symplectic product of two charge vectors is not independent from the quartic quintet in the t^3 model, but rather it satisfies a degree-16 relation, corresponding to a quartic equation for the square of the symplectic product itself.Comment: 1+31 pages; v2: amendments in Sec. 9, App. C added, other minor refinements, Refs. added; v3: Ref. added, typos fixed. To appear on J.Math.Phy

Multi-Centered Black Hole Flows

We describe the systematical construction of the first order formalism for multi-centered black holes with flat three dimensional base-space, within the so-called $T^{3}$ model of N=2, D=4 ungauged Maxwell-Einstein supergravity. The three possible flow classes (BPS, composite non-BPS and almost-BPS) are analyzed in detail, and various solutions, such as single-centered (static or under-rotating) and all known multi-centered black holes, are recovered in this unified framework. We also consider the possibility of obtaining new solutions. The almost-BPS class is proved to split into two general sub-classes, corresponding to a positive or negative value of the duality-invariant polynomial for the total charge; the well known almost BPS system is shown to be a particular solution of the second sub-class.Comment: 17 pages,no figure

A Note on Exact Solutions and Attractor Mechanism for Non-BPS Black Holes

We obtain two extremal, spherically symmetric, non-BPS black hole solutions to 4D supergravity, one of which carries D2-D6 charges and the other carries D0-D2-D4 charges. For the D2-D6 case, rather than solving the equations of motion directly, we assume the form of the solution and then find that the assumption satisfies the equations of motion and the constraint. Our D2-D6 solution is manifestly dual to the solution presented in 0710.4967. The D0-D2-D4 solution is obtained by performing certain $[SL(2,{\bf Z})]^{3}$ duality transformations on the D0-D4 solution in 0710.4967.Comment: 20 pages, LaTe

Rashba effect in 2D mesoscopic systems with transverse magnetic field

We present semiclassical and quantum mechanical results for the effects of a strong magnetic field in Quantum Wires in the presence of Rashba Spin Orbit coupling. Analytical and numerical results show how the perturbation acts in the presence of a transverse magnetic field in the ballistic regime and we assume a strong reduction of the backward scattering interaction which could have some consequences for the Tomonaga-Luttinger transport. We analyze the spin texture due to the action of Spin Orbit coupling and magnetic field often referring to the semiclassical solutions that magnify the singular spin polarization: results are obtained for free electrons in a twodimensional electron gas and for electrons in a Quantum Wire. We propose the systems as possible devices for the spin filtering at various regimes.Comment: 12 pages, 12 figures, to appear in Phys. Rev.

A multibiomarker approach to evaluate the impact of anthropogenic contaminants on the ecotoxicological status of honey bees, Apis mellifera

A rapid decline of Apis mellifera, a keystone pollinator of wild plant species and agricultural crops, was recorded worldwide in recent years. The massive use of insecticides and fungicides in agriculture associated with pollution generated by other human activities and presence of parasites can cause toxicological effects in bees including a decrease of the immune defences, leading to the collapse of the colonies. Effective assessment of the ecotoxicological impacts of anthropogenic contaminants requires an approach that combines different biomarkers that enable a more precise diagnosis of exposure to environmental stressors through a combination of different biological responses. The aim of this study was to develop and apply a set of biomarkers to study the ecotoxicological status of honey bees. In the first phase, we investigated in the laboratory the effects of EMS, cadmium and a commercial fungicide (azoxistrobin 18.2% and ciproconazole 7.3%) in adult honey bees, evaluating eventual variation in glutathione S-transferase (GST), carboxylesterase (CaE), acetylcholinesterase (AChE) activities, alkaline phosphatase (ALP), lysozyme, erythrocyte nuclear abnormalities (ENA) assay and differential haemocytes count (DHC). Genotoxic effects, as well as alteration of the immune system, were found in bees treated with EMS, cadmium or the fungicide. Cadmium and the fungicide also inhibited AChE and CaE activities, GST was induced by all the compounds investigated. In the second phase, adult honey bees were collected from apiaries located in four environments characterized by different chemical input: a wooded environment (low input), an urban site, an orchard and a cultivated countryside site. Honey bees from the urban site were also collected and analyzed before and after treatment for parasites. ENA assay showed that bees taken from the countryside and the orchard had a greater number of abnormalities compared to the forest, confirming the presence of genotoxic substances in agricultural environments compared to control environments. GST activity was induced in bees from the urban environment, AChE was inhibited in the countryside compared to the forest, suggesting the presence of substances with neurotoxic effect in this environment. ALP activity was induced in all sites in comparison to wooded one. The bees collected after the parasites treatment showed an increase for GST activity as well as AChE inhibition

Designing cascades of electron transfer processes in multicomponent graphene conjugates

A novel family of nanocarbon-based materials was designed, synthesized, and probed within the context of charge-transfer cascades. We integrated electron-donating ferrocenes with light-harvesting/electron-donating (metallo)porphyrins and electron-accepting graphene nanoplates (GNP) into multicomponent conjugates. To control the rate of charge flow between the individual building blocks, we bridged them via oligo-p-phenyleneethynylenes of variable lengths by β-linkages and the Prato-Maggini reaction. With steady-state absorption, fluorescence, Raman, and XPS measurements we realized the basic physico-chemical characterization of the photo- and redox-active components and the multicomponent conjugates. Going beyond this, we performed transient absorption measurements and corroborated by single wavelength and target analyses that the selective (metallo)porphyrin photoexcitation triggers a cascade of charge transfer events, that is, charge separation, charge shift, and charge recombination, to enable the directed charge flow. The net result is a few nanosecond-lived charge-separated state featuring a GNP-delocalized electron and a one-electron oxidized ferrocenium

Etching kinetics of nanodiamond seeds in the early stages of CVD diamond growth

We present an experimental study on the etching of detonation nanodiamond (DND) seeds during typical microwave chemical vapor deposition (MWCVD)conditions leading to ultra-thin diamond film formation, which is fundamental for many technological applications. The temporal evolution of the surface density of seeds on the Si(100) substrate has been assessed by scanning electron microscopy (SEM). The resulting kinetics have been explained in the framework of a model based on the effect of the particle size, according to the Young-Laplace equation,on both chemical potential of carbon atoms in DND and activation energy of the reaction with atomic hydrogen. The model describes the experimental kinetics of seeds' disappearance by assuming that nanodiamond particles with a size smaller than a "critical radius", r*, are etched away while those greater than r* can grow. Finally, the model allows to estimate the rate coefficients for growth and etching from the experimental kinetics