1,429 research outputs found
Low-temperature rotational relaxation of CO in self-collisions and in-collisions with Ne and He
The low-temperature rotational relaxation of CO in self-collisions and in collisions with the rare-gas atoms Ne and He has been investigated in supersonic expansions with a combination of resonance-enhanced multiphoton ionization (REMPI) spectroscopy and time-of-flight techniques. For the REMPI detection of CO, a novel 2 + 1′ scheme has been employed through the A1 state of CO. From the measured data, average cross sections for rotational relaxation have been derived as a function of temperature in the range 5-100 K. For CO-Ne and CO-He, the relaxation cross sections grow, respectively, from values of ∼20 and 7 Å2 at 100 K to values of ∼65-70 and ∼20 A°2 in the 5-20 K temperature range. The cross section for the relaxation of CO-CO grows from a value close to 40 Å2 at 100 K to a maximum of 60 Å2 at 20 K and then decreases again to 40 Å2 at 5 K. These results are qualitatively similar to those obtained previously with the same technique for N2-N 2, N2-Ne, and N2-He collisions, although in the low-temperature range (T < 20 K) the CO relaxation cross sections are significantly larger than those for N2. Some discrepancies have been found between the present relaxation cross sections for CO-CO and CO-He and the values derived from electron-induced fluorescence experiments. © 2005 American Chemical Society.Financial support through the Ramón y Cajal program. Financial support from the EU Research Training Network “Reaction Dynamics”, Grant HPRNCT-1999-00007.Financial support from the Spanish Ministry of Education through the State Secretary of Education and University. Support from the Plan Andaluz de Investigación (Group FQM-205). Funding by the MEC of Spain under Grants FIS2004-00456 and BQU2002-04627-C02-02Peer Reviewe
1-[2-(4-methyl-7-coumarinyloxy)ethyl]-4-(5-{1-[2-(4-methyl-7-coumarinyloxy)ethyl]-1h-1, 2, 3-triazol-4-yl}pentyl)-1h-1, 2, 3-triazole
Nature often produces compounds with a high degree of symmetry to reduce structural information and complexity. Synthesis of identical twin drugs, through the linkage of two identical pharmacophoric entities, is a classical strategy to produce more potent and/or selective drugs. Herein, two units of the privileged core of the coumarin hymecromone were linked together using “click chemistry”. Synthesis of 1-[2-(4-Methyl-7-coumarinyloxy)ethyl]-4-(5-{1-[2-(4-methyl- 7-coumarinyloxy)ethyl]-1H-1, 2, 3-triazol-4-yl}pentyl)-1H-1, 2, 3-triazole was achieved by coupling of two identical units of an azido coumarin with a symmetrical alkine using copper(I)-catalyzed alkyne-azide cycloaddition reaction, in good yields and with complete regioselectivity. © 2016 by the authors; licensee MDPI, Basel, Switzerland.2016
Molecular and morphological characterization of the grapevine cultivars “Italia” in the Ica and Cañete valleys (Peru)
The denomination of “Uva de Italia” or “Italia” is commonly used by growers to refer to a group of varieties used from the colonial times to making a brandy of Pisco with muscat aroma. Previous work have demonstrated that Uva de Italia corresponds in fact to the variety Muscat of Alexandria, a widely spread variety around the world and in South America. However, the distinction between “Italia Dorada” and “Italia Rosada” is usually made, in allusion to the color variations observed in the berries. Our aim was to characterize 5 samples collected in vineyards from the valleys of Ica and Cañete. The genotypes were identified using 13 molecular markers of nuclear simple sequence repeat, and 23 morphological descriptors according to OIV. Our results showed that four genotypes were identified as Muscat of Alexandria while the other corresponded to variety well-known in Argentina as Moscatel Rosado or Uva Pastilla in Chile respectively. Moscatel Rosado showed functionally female flowers, with variable berries size and color in the range from greenish yellow through pink. This is the first identification of Moscatel Rosado as a variety present in the Peruvian vineyards and would allow its use in the pisco industry with distinctive aromatic characteristics. Keywords: Italia, Muscat of Alexandria, Moscatel Rosado, variety identification, parentage analysis, microsatellites, Pisco
The clustering of ultra-high energy cosmic rays and their sources
The sky distribution of cosmic rays with energies above the 'GZK cutoff'
holds important clues to their origin. The AGASA data, although consistent with
isotropy, shows evidence for small-angle clustering, and it has been argued
that such clusters are aligned with BL Lacertae objects, implicating these as
sources. It has also been suggested that clusters can arise if the cosmic rays
come from the decays of very massive relic particles in the Galactic halo, due
to the expected clumping of cold dark matter. We examine these claims and show
that both are in fact not justified.Comment: 13 pages, 8 figures, version in press at Phys. Rev.
Phantom with Born-Infield type Lagrangian
Recent analysis of the observation data indicates that the equation of state
of the dark energy might be smaller than -1, which leads to the introduction of
phantom models featured by its negative kinetic energy to account for the
regime of equation of state . In this paper, we generalize the idea to
the Born-Infield type Lagrangian with negative kinetic energy term and give the
condition for the potential, under which the late time attractor solution
exists and also analyze a viable cosmological model in such a scheme.Comment: 13 pages, 6 figures, Reference updated, the final version will be
published in Phys. Rev.
Mixing Bandt-Pompe and Lempel-Ziv approaches: another way to analyze the complexity of continuous-states sequences
In this paper, we propose to mix the approach underlying Bandt-Pompe
permutation entropy with Lempel-Ziv complexity, to design what we call
Lempel-Ziv permutation complexity. The principle consists of two steps: (i)
transformation of a continuous-state series that is intrinsically multivariate
or arises from embedding into a sequence of permutation vectors, where the
components are the positions of the components of the initial vector when
re-arranged; (ii) performing the Lempel-Ziv complexity for this series of
`symbols', as part of a discrete finite-size alphabet. On the one hand, the
permutation entropy of Bandt-Pompe aims at the study of the entropy of such a
sequence; i.e., the entropy of patterns in a sequence (e.g., local increases or
decreases). On the other hand, the Lempel-Ziv complexity of a discrete-state
sequence aims at the study of the temporal organization of the symbols (i.e.,
the rate of compressibility of the sequence). Thus, the Lempel-Ziv permutation
complexity aims to take advantage of both of these methods. The potential from
such a combined approach - of a permutation procedure and a complexity analysis
- is evaluated through the illustration of some simulated data and some real
data. In both cases, we compare the individual approaches and the combined
approach.Comment: 30 pages, 4 figure
Bangus fry resource assessment in the Philippines
The report is the result of an investigative study on the scarcity of milkfish fry in the Philippines, a collaborative effort of BFAR, SEAFDEC, PCAMRD and ICLARM. The study aimed to monitor fry production in selected sites in the Philippines for a period of one year; assess the current demand for milkfish fry; and provide on-the-job training on data collection and recommend a system for continuous collection of data on fry production.Milkfish industry, Fishery management, Philippines,
Cosmological Dynamics of Phantom Field
We study the general features of the dynamics of the phantom field in the
cosmological context. In the case of inverse coshyperbolic potential, we
demonstrate that the phantom field can successfully drive the observed current
accelerated expansion of the universe with the equation of state parameter
. The de-Sitter universe turns out to be the late time attractor
of the model. The main features of the dynamics are independent of the initial
conditions and the parameters of the model. The model fits the supernova data
very well, allowing for at 95 % confidence level.Comment: Typos corrected. Some clarifications and references added. To appear
in Physical Review
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