1,338 research outputs found
Where do bosons actually belong?
We explore a variety of reasons for considering su(1,1) instead of the
customary h(1) as the natural unifying frame for characterizing boson systems.
Resorting to the Lie-Hopf structure of these algebras, that shows how the
Bose-Einstein statistics for identical bosons is correctly given in the su(1,1)
framework, we prove that quantization of Maxwell's equations leads to su(1,1),
relativistic covariance being naturally recognized as an internal symmetry of
this dynamical algebra. Moreover su(1,1) rather than h(1) coordinates are
associated to circularly polarized electromagnetic waves. As for interacting
bosons, the su(1,1) formulation of the Jaynes-Cummings model is discussed,
showing its advantages over h(1).Comment: 9 pages, to appear in J. Phys. A: Math. Theo
Orientation of \u3ci\u3eHylobius Pales\u3c/i\u3e and \u3ci\u3ePachylobius Picivorus\u3c/i\u3e (Coleoptera: Curculionidae) to Visual Cues
Pitfall traps with above-ground silhouettes of various colors and diameters were used in field tests to evaluate the role of vision in host orientation by adult pales weevils, Hylobius pales, and pitch-eating weevils, Pachylobius picivorus. White traps (11 em outer diameter) baited with ethanol and turpentine caught significantly more weevils than similarly baited black or green traps (11 cm outer diameter). Trap diameter (range of 6-22 cm outer diameter) did not affect trap catch. Pitfall traps can be used to monitor root weevil populations in young pine plantations and Christmas tree farms, where they are major pests. These results demonstrate that visual and chemical cues can be integrated to improve trap efficiency
Use of Baited Pitfall Traps for Monitoring Pales Weevil, \u3ci\u3eHylobius Pales\u3c/i\u3e (Coleoptera: Curculionidae)
Pitfall traps baited with ethanol and turpentine serve as an effective tool for monitoring pales weevil (Hylobius pales) populations. Males and females are equally attracted to this bait. Neither component alone showed any attractiveness. The presence of a pine stem for weevil feeding does not affect the number or sex ratio of captured weevils. The potential of using attraction to baited traps as a sampling method for pales weevil is discussed
Quantum Logical States and Operators for Josephson-like Systems
We give a formal algebraic description of Josephson-type quantum dynamical
systems, i.e., Hamiltonian systems with a cos theta-like potential term. The
two-boson Heisenberg algebra plays for such systems the role that the h(1)
algebra does for the harmonic oscillator. A single Josephson junction is
selected as a representative of Josephson systems. We construct both logical
states (codewords) and logical (gate) operators in the superconductive regime.
The codewords are the even and odd coherent states of the two-boson algebra:
they are shift-resistant and robust, due to squeezing. The logical operators
acting on the qubit codewords are expressed in terms of operators in the
enveloping of the two-boson algebra. Such a scheme appears to be relevant for
quantum information applications.Comment: 12 pages in RevTex. In press, Journal of Physics A/Letter
Quantum correlation dynamics in photosynthetic processes assisted by molecular vibrations
During the long course of evolution, nature has learnt how to exploit quantum
effects. In fact, recent experiments reveal the existence of quantum processes
whose coherence extends over unexpectedly long time and space ranges. In
particular, photosynthetic processes in light-harvesting complexes display a
typical oscillatory dynamics ascribed to quantum coherence. Here, we consider
the simple model where a dimer made of two chromophores is strongly coupled
with a quasi-resonant vibrational mode. We observe the occurrence of wide
oscillations of genuine quantum correlations, between electronic excitations
and the environment, represented by vibrational bosonic modes. Such a quantum
dynamics has been unveiled through the calculation of the negativity of
entanglement and the discord, indicators widely used in quantum information for
quantifying the resources needed to realize quantum technologies. We also
discuss the possibility of approximating additional weakly-coupled off-resonant
vibrational modes, simulating the disturbances induced by the rest of the
environment, by a single vibrational mode.
Within this approximation, one can show that the off-resonant bath behaves
like a classical source of noise
Polymeric surfactants for enhanced oil recovery:A review
AbstractChemical enhanced oil recovery (EOR) is surely a topic of interest, as conventional oil resources become more scarce and the necessity of exploiting heavy and unconventional oils increases. EOR methods based on polymer flooding, surfactant-polymer flooding and alkali-surfactant-polymer flooding are well established, but new challenges always emerge, which give impulse to the search for new solutions. Polymeric surfactants represent a very attractive alternative to these techniques, because they can provide simultaneously increase in water viscosity and decrease in interfacial tension, both beneficial for the efficiency of the process. The analysis of the literature shows that the use of polymeric surfactants as displacing fluid has the potential to improve the performances of EOR in some cases. However, the synthesis are often challenging and costly and the available data about the real performances of such systems in oil recovery are still sparse. This holds back the possibility of a significant use of polymeric surfactants for EOR. This review collects the relevant work done in the last decades in developing and testing polymeric surfactants for EOR, with a particular emphasis on the chemical aspects, the patent literature and bio-based systems
Design of a pH-responsive conductive nanocomposite based on MWCNTs stabilized in water by amphiphilic block copolymers
Homogeneouswater dispersions ofmulti-walled carbon nanotubes (MWCNTs)were prepared by ultrasonication in the presence of an amphiphilic polystyrene-block-poly(acrylic acid) (PS-b-PAA) copolymer. The ability of PS-b-PAA to disperse and stabilizeMWCTNs was investigated by UV-vis, SEM and zeta potential. The results show that the addition of a styrene block to PAA enhances the dispersion efficiency of the graphitic filler compared to pure PAA, possibly due to the nanotube affinity with the polystyrene moiety. Notably, the dispersions show an evident pH-responsive behavior, being MWCNTs reaggregation promoted in basic environment. It isworth noting that the responsive character is maintained in solid composites obtained by drop casting, thus indicating potential applications in sensing
Amiodarone-induced pulmonary toxicity with an excellent response to treatment
Amiodarone is an anti-arrhythmic drug widely used, but its administration can be associated with several adverse side-effects. Among these, amiodarone-induced pulmonary toxicity (APT) occurs in 4-17% of cases and, if not early diagnosed and treated, may evolve towards pulmonary fibrosis and respiratory failure. A 76 years-old-man went to the hospital for accidental trauma. The patient did not report respiratory symptoms but was suffering from atrial fibrillation treated with amiodarone 200 mg/day from three years (cumulative dose >150 gr). HRCT showed ground-glass opacities and nodules in both lungs. The patient underwent fibreoptic bronchoscopy with BAL. Cytologic examination of BALF sediment put in evidence foamy macrophages. The electronic microscopy revealed into the alveolar macrophages "… the presence of multilamellar intracytoplasmic bodies and lysosomes, loads of lipid material". LFTs showed a restrictive syndrome and an impairment of DLCO. Amiodarone discontinuation and steroid administration led to the regression of radiological lesions and the recovery of lung function. Patients taking amiodarone can experience APT. They should perform a basal chest x-ray with LFTs before starting therapy. Monitoring could reveal early the pulmonary toxicity, and patients can respond favourably to the treatment
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