679 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 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
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
Geophysical Monitoring at Laboratory Scale of Aerobic Degradation of Diesel Oil
The study is aimed to monitor bioremediation of hydrocarbon-polluted soils by measuring geophysical electromagnetic parameters. A previous study at lab scale showed that biostimulated indigenous microorganisms can remove diesel oil from soil successfully. Herein, we focused on the result of a laboratory test using Time Domain Reflectometry (TDR) probes to measure electrical conductivity and dielectric permittivity in a column of sandy soil artificially contaminated with diesel oil. To simulate aerobic degradation of hydrocarbons, mesocosms were set-up in two Plexiglas columns (inner diameter = 13.8 cm) with 3.4 kg of soil (layer height = 14 cm) spiked with 0.24 kg of diesel oil and hydrated with 0.4 kg of Mineral Salt Medium for Bacteria. One mesocosm was aerated by air injection from the bottom of the column, while the other had only natural aeration due to air diffusion through the soil itself. In each column, electrical conductivity and dielectric permittivity were monitored by TDR probes for 105 days. TDR measurements were supported by microbiological and gas chromatographic analyses, along with SEM images. The findings showed that air injection heavily influenced the TDR monitoring, probably due to generation of air bubbles around the probe that interfered with probe-soil coupling. Therefore, the measurement accuracy was reduced in an irreversible way. In the non-aerated system, a slight (2%) and linear decrease of dielectric permittivity was observed over time, meanwhile electrical conductivity decreased by about 30%
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
Open-ended coaxial probe measurements of complex dielectric permittivity in diesel-contaminated soil during bioremediation
In the bioremediation field, geophysical techniques are commonly applied, at lab scale and field scale, to perform the characterization and the monitoring of contaminated soils. We propose a method for detecting the dielectric properties of contaminated soil during a process of bioremediation. An open-ended coaxial probe measured the complex dielectric permittivity (between 0.2 and 20 GHz) on a series of six soil microcosms contaminated by diesel oil (13.5% Voil /Vtot ). The microcosms had different moisture content (13%, 19%, and 24% Vw/Vtot ) and different salinity due to the addition of nutrients (22 and 15 g/L). The real and the imaginary component of the complex dielectric permittivity were evaluated at the initial stage of contamination and after 130 days. In almost all microcosms, the real component showed a significant decrease (up to 2 units) at all frequencies. The results revealed that the changes in the real part of the dielectric permittivity are related to the amount of degradation and loss in moisture content. The imaginary component, mainly linked to the electrical conductivity of the soil, shows a significant drop to almost 0 at low frequencies. This could be explained by a salt depletion during bioremediation. Despite a moderate accuracy reduction compared to measurements performed on liquid media, this technology can be successfully applied to granular materials such as soil. The open-ended coaxial probe is a promising instrument to check the dielectric properties of soil to characterize or monitor a bioremediation process
A very promising antibiofilm activity against Candida albicans from an in vitro screening for antimicrobial, antibiofilm and antiproliferative activity of new synthesized 4-cinnamamido- and 2-phenoxyacedamido-1H-pyrazol-5-yl)benzamides
Several new synthesized 4-cinnamamido- and 2-phenoxyacedamido-(1H-pyrazol-5-yl)benzamides were obtained by two
multi step different synthetic routes in order to maximize their yield. The new derivatives were screened to determine the
antiproliferative, antimicrobial and antibiofilm activity. The biological results showed how, respect to the antiproliferative
and antimicrobial activities, the compounds have a low to missing activity. Different are the results obtained concerning the
antibiofilm activity, especially towards Candida albicans. Most of the synthesized compounds showed a good percentage
inhibition of biofilm formation ranging from 60 to 73% with a Biofilm Inhibition Concentration 50% (BIC50) from 0.13 to
0.01 μM. Among the synthesized compounds the ethyl 5-(4-(2-(4-chlorophenoxy)acetamido)benzamido)-1-methyl-1Hpyrazole-
4-carboxylate (27c) resulted the most active molecule with a BIC50 of 0.01 μM. According to the results obtained,
such compound could be considered a lead subject of further studies to obtain novel and more effective antibiofilm agents
against C. albicans
Regional biomechanical characterization of human ascending aortic aneurysms: Microstructure and biaxial mechanical response
: The ascending thoracic aortic aneurysm (ATAA) is a permanent dilatation of the vessel with a high risk of adverse events, and shows heterogeneous properties. To investigate regional differences in the biomechanical properties of ATAAs, tissue samples were collected from 10 patients with tricuspid aortic valve phenotype and specimens from minor, anterior, major, and posterior regions were subjected to multi-ratio planar biaxial extension tests and second-harmonic generation (SHG) imaging. Using the data, parameters of a microstructure-motivated constitutive model were obtained considering fiber dispersion. SHG imaging showed disruptions in the organization of the layers. Structural and material parameters did not differ significantly between regions. The non-symmetric fiber dispersion model proposed by Holzapfel et al. [25] was used to fit the data. The mean angle of collagen fibers was negatively correlated between minor and anterior regions, and the parameter associated with collagen fiber stiffness was positively correlated between minor and major regions. Furthermore, correlations were found between the stiffness of the ground matrix and the mean fiber angle, and between the parameter associated with the collagen fiber stiffness and the out-of-plane dispersion parameter in the posterior and minor regions, respectively. The experimental data collected in this study contribute to the biomechanical data available in the literature on human ATAAs. Region-specific parameters for the constitutive models are fundamental to improve the current risk stratification strategies, which are mainly based on aortic size. Such investigations can facilitate the development of more advanced finite element models capable of capturing the regional heterogeneity of pathological tissues. STATEMENT OF SIGNIFICANCE: Tissue samples of human ascending thoracic aortic aneurysms (ATAA) were collected. Samples from four regions underwent multi-ratio planar biaxial extension tests and second-harmonic generation imaging. Region-specific parameters of a microstructure-motivated model considering fiber dispersion were obtained. Structural and material parameters did not differ significantly between regions, however, the mean fiber angle was negatively correlated between minor and anterior regions, and the parameter associated with collagen fiber stiffness was positively correlated between minor and major regions. Furthermore, correlations were found between the stiffness of the ground matrix and the mean fiber angle, and between the parameter associated with the collagen fiber stiffness and the out-of-plane dispersion parameter in the posterior and minor regions, respectively. This study provides a unique set of mechanical and structural data, supporting the microstructural influence on the tissue response. It may facilitate the development of better finite element models capable of capturing the regional tissue heterogeneity
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