A multiple-beam CLEAN for imaging intra-day variable radio sources

The CLEAN algorithm, widely used in radio interferometry for the deconvolution of radio images, performs well only if the raw radio image (dirty image) is, to good approximation, a simple convolution between the instrumental point-spread function (dirty beam) and the true distribution of emission across the sky. An important case in which this approximation breaks down is during frequency synthesis if the observing bandwidth is wide enough for variations in the spectrum of the sky to become significant. The convolution assumption also breaks down, in any situation but snapshot observations, if sources in the field vary significantly in flux density over the duration of the observation. Such time-variation can even be instrumental in nature, for example due to jitter or rotation of the primary beam pattern on the sky during an observation. An algorithm already exists for dealing with the spectral variation encountered in wide-band frequency synthesis interferometry. This algorithm is an extension of CLEAN in which, at each iteration, a set of N `dirty beams' are fitted and subtracted in parallel, instead of just a single dirty beam as in standard CLEAN. In the wide-band algorithm the beams are obtained by expanding a nominal source spectrum in a Taylor series, each term of the series generating one of the beams. In the present paper this algorithm is extended to images which contain sources which vary over both frequency and time. Different expansion schemes (or bases) on the time and frequency axes are compared, and issues such as Gibbs ringing and non-orthogonality are discussed. It is shown that practical considerations make it often desirable to orthogonalize the set of beams before commencing the cleaning. This is easily accomplished via a Gram-Schmidt technique.Comment: 9 pages, 7 figures. Accepted for publication in A&

Influence of some fractions isolated from red wine on oxygen cellular consumption

In this study, we carried out the analyse of some polyphenolic fractions obtained from a sample of red wine by solid-liquid repartition. The wine selected sample was obtained by mixing noble wine varieties, with the purpose of realising a great concentration of phenolic compounds. The fractions obtained from this special sample were firstly chemically analysed (total quantity of polyphenols, total quantity of anthocyans, Folin-Ciocâlteu index and permanganate index), and then were correlated with their specific effects on the intensity of oxygen respiratory consumption of the batracian muscle and hepatic cells, carried out by the Warburg micromanometrical method. Different biological effects (values of oxygen cellular consumption) were recorded, according to the type of cells, composition of fractions (polyphenol quantity) and duration of records. The obtained results evidenced a specific influence of the studied fractions on the respiratory and energetic cellular processes, indicating a series of useful pharmacological properties of some wine fractions

Antioxidant activity and photochromic properties of 2,6-bis (2,4- dihydroxybenzylidene) cyclohexanone

Xanthylium derivatives have attracted considerable interest due to their potential health effects and replacement of synthetic pigments. Moreover, these type of compounds exhibit versatile photochromic properties by switching from a variety of colors when submitted to external stimuli (light, temperature, pH). Generally, all these compounds hold the same xanthylium core and follow the same pH-dependent network of reversible chemical reactions as structurally related families such as flavylium [1-4]. In the present study we focused the attention on the isolation and characterisation of of the species involved in the network of chemical reactions of 2,6-bis(2,4- dihydroxybenzylidene)cyclohexanone. The pH-dependent photochromic behavior of the xanthylium derivative has been investigated. In order to identify the species, the NMR spectra were recorded in acidic and basic media. The antioxidant activity was also determined using DPPH assay [5]. The IC50 values of radical scavenging activity for DPPH were found to be 133.68 μg/mL

VLBI observations of SN2011dh: imaging of the youngest radio supernova

We report on the VLBI detection of supernova SN2011dh at 22GHz using a subset of the EVN array. The observations took place 14 days after the discovery of the supernova, thus resulting in a VLBI image of the youngest radio-loud supernova ever. We provide revised coordinates for the supernova with milli-arcsecond precision, linked to the ICRF. The recovered flux density is a factor 2 below the EVLA flux density reported by other authors at the same frequency and epoch of our observations. This discrepancy could be due to extended emission detected with the EVLA or to calibration problems in the VLBI and/or EVLA observations.Comment: Letter. Accepted in A&

Homoleptic and heteroleptic pt(II) complexes with potential biological activity

Metal complexes used as pharmaceuticals have received great attention because of their potential biological activity. The chemistry of platinum(II) complexes has been widely developed since the cytostatic activity of cis-diaminodichloroplatinum(II) (cisplatin) has been discovered [1]. Moreover, transition metal complexes containing planar polycyclic aromatic systems intercalate between the stacked base pairs of DNA. The biological activity of both cis- and trans-diamine Pt(II) complexes is dramatically enhanced by the presence of aromatic intercalator ligands, due to the influence on both kinetics and thermodynamics of DNA binding [2,3]. The chemistry of Pt(II) complexes is highly versatile, permitting the design and synthesis of a large variety of different structures. By ‘smart’ molecular engineering, new structures are programmed and obtained continuously, in an attempt to overcome the drawbacks of the cisplatinum like tumor resistance, or to lessening unpredictable and severe nephrotoxicity and/or providing oral bioavailability. Herein, new Pt(II) complexes as DNA intercalators were synthesized and characterized aiming to follow their structure – activity relationships. The synthesis and characterization of the complexes will be presented

Elliptical Squeezed States and Rydberg Wave Packets

We present a theoretical construction for closest-to-classical wave packets localized in both angular and radial coordinates and moving on a keplerian orbit. The method produces a family of elliptical squeezed states for the planar Coulomb problem that minimize appropriate uncertainty relations in radial and angular coordinates. The time evolution of these states is studied for orbits with different semimajor axes and eccentricities. The elliptical squeezed states may be useful for a description of the motion of Rydberg wave packets excited by short-pulsed lasers in the presence of external fields, which experiments are attempting to produce. We outline an extension of the method to include certain effects of quantum defects appearing in the alkali-metal atoms used in experiments.Comment: published in Phys. Rev. A, vol. 52, p. 2234, Sept. 199

A doublet of cosmic-ray events with primary energies >10^20 eV

The Telescope Array Collaboration has observed a cosmic-ray event with estimated primary energy of 1.38*10^20 eV whose arrival direction coincides (see arxiv:1205.5984), given the angular resolution of 1.5 deg, with that of an event with estimated primary energy of 1.23*10^20 eV observed by the Pierre Auger Observatory. The total number of events with energies >10^20 eV published by both experiments is six. I estimate the statistical significance of the doublet, which is rather weak, and point out that the arrival directions of events in the doublet coincide with the Galactic X-ray source Aql X-1.Comment: 4 pages, 3 figures, submitted to JETP Letters; v.2: a misprint correcte

Cercetări privind producerea băuturilor de tip bitter

The present study has as main objective the evaluation of the methods of obtaining a bitter type curative beverage to evaluate the possibility of superior utilization of the medicinal plants. Aromatic and condimentary plants have been used. Among the plants used: Angelica archangelica, artichoke (Cynara scolymus), basil (Ocimum basilicum), Thymus serpyllum, Achillea millefolium, Juniperus communis, Hyssopus officinalis, Salvia officinalis, Origanum vulgare, Glycyrrhiza glabra, Mentha piperita, Melissa officinalis and Fir resin. The variants used were V1 -sweetening sugar, V2 -sweetening with liquorice V3 -unsweetened and V4 -alcohol of 50 %vol. The analyzes were performed according to scientific literature. Alcoholic strength, pH, phenolic compounds and sensory analysis were evaluated. The study shows that it is appropriate to prepare an herbal beverage. The medicinal plants used imprinted the beverage with hints of wild flowers, coniferous trees and other aromaticplants. The liquorice sweetened variant was the most appreciated by the taster

Keplerian Squeezed States and Rydberg Wave Packets

We construct minimum-uncertainty solutions of the three-dimensional Schr\"odinger equation with a Coulomb potential. These wave packets are localized in radial and angular coordinates and are squeezed states in three dimensions. They move on elliptical keplerian trajectories and are appropriate for the description of the corresponding Rydberg wave packets, the production of which is the focus of current experimental effort. We extend our analysis to incorporate the effects of quantum defects in alkali-metal atoms, which are used in experiments.Comment: accepted for publication in Physical Review

Minimum-Uncertainty Angular Wave Packets and Quantized Mean Values

Uncertainty relations between a bounded coordinate operator and a conjugate momentum operator frequently appear in quantum mechanics. We prove that physically reasonable minimum-uncertainty solutions to such relations have quantized expectation values of the conjugate momentum. This implies, for example, that the mean angular momentum is quantized for any minimum-uncertainty state obtained from any uncertainty relation involving the angular-momentum operator and a conjugate coordinate. Experiments specifically seeking to create minimum-uncertainty states localized in angular coordinates therefore must produce packets with integer angular momentum.Comment: accepted for publication in Physical Review