Renormalized coordinate approach to the thermalization process

We consider a particle in the harmonic approximation coupled linearly to an environment. modeled by an infinite set of harmonic oscillators. The system (particle--environment) is considered in a cavity at thermal equilibrium. We employ the recently introduced notion of renormalized coordinates to investigate the time evolution of the particle occupation number. For comparison we first present this study in bare coordinates. For a long ellapsed time, in both approaches, the occupation number of the particle becomes independent of its initial value. The value of ocupation number of the particle is the physically expected one at the given temperature. So we have a Markovian process, describing the particle thermalization with the environment. With renormalized coordinates no renormalization procedure is required, leading directly to a finite result.Comment: 16 pages, LATEX, 2 figure

4-Methoxycinnamic acid – An unusual phenylpropanoid involved in phenylphenalenone biosynthesis in Anigozanthos preissii

AbstractIn vitro root cultures of Anigozanthos preissii and Wachendorfia thyrsiflora (Haemodoraceae) are suitable biological systems for studying the biosynthesis of phenylphenalenones. Here we report how we used these root cultures to investigate precursor–product relationships between phenylpropanoids and phenylphenalenones whose phenyl rings share identical substitution patterns. Four phenylpropanoic acids, including ferulic acid and the unusual 4-methoxycinnamic acid, were used in 13C-labeled form as substrates to study their incorporation into phenylphenalenones. In addition to the previously reported 2-hydroxy-9-(4′-hydroxy-3′-methoxyphenyl)-1H-phenalen-1-one (trivial name musanolone F), 2-hydroxy-9-(4′-methoxyphenyl)-1H-phenalen-1-one (proposed trivial name 4′-methoxyanigorufone) was found as a biosynthetic product in A. preissii. The carbon skeleton of 4′-methoxycinnamic acid was biosynthetically incorporated as an intact unit including its 4′-O-methyl substituent at the lateral phenyl ring. 4′-Methoxyanigorufone is reported here for the first time as a natural product

Aphids associated with shrubs, herbaceous plants and crops in the Maltese Archipelago (Hemiptera, Aphidoidea)

A survey of the aphids associated with Maltese shrubs, herbaceous plants and crops was carried out. Sixty six aphid species were recorded from more than 90 species of host plants. Forty eight aphids were recorded from the Maltese islands for the fi rst time bringing the total number of aphid species known from these islands to 99. New records include: Acyrthosiphon lactucae, A. pisum, Anoecia vagans, Aphis alienus, A. euphorbiae, A. hederae, A. lambersi, A. multifl orae, A. nasturtii, A. parietariae, A. picridicola, A. ruborum, A. sedi, Aulacorthum solani, Brachycaudus helichrysi, Capitophorus sp. nr. similis, Clypeoaphis suaedae, Cryptomyzus korschelti, Dysaphis apiifolia, D. foeniculus, D. pyri, D. tulipae, Hyadaphis coriandri, H. foeniculi, H. passerinii, Hyperomyzus lactucae, Idiopterus nephrelepidis, Macrosiphoniella absinthii, M. artemisiae, M. sanborni, Macrosiphum euphorbiae, Ma. rosae, Melanaphis donacis, Metopolophium dirhodum, Pterochloroides persicae, Rectinasus buxtoni, Rhopalosiphum maidis, R. padi, R. rufi abdominale, Schizaphis graminum, Semiaphis dauci, Sipha maydis, Sitobion avenae, S. fragariae, Therioaphis alatina, Uroleucon inulae, U. hypochoeridis and U. sonchi. Of these 99 aphid species, 58 are of economic importance and 16 are alien introductions. For 15 of the aphid species, a total of 22 new host-plant records are made. Ten species of ants were found attending 18 aphid species.peer-reviewe

Diffuse Ionized Gas in the Dwarf Irregular Galaxy DDO 53

The spectral characteristics throughout the dwarf irregular galaxy DDO 53 are studied. The results are very similar to those for other irregular galaxies: high excitation and low values of the [SII]/Halpha ratio. The most likely ionization source is photon leakage from the classical HII regions, without any other source, although the interstellar medium of the galaxy is quite perturbed. Moreover, the physical conditions throughout the galaxy do not change very much because both the photon leakage percentage and the ionization temperature are very similar. In addition, the determined metal content for two HII regions indicates that DDO 53 is a low-metallicity galaxy.Comment: 32 pages, 9 figures, 7 tables. AJ, in pres

Effect of influenza-induced fever on human bioimpedance values

BACKGROUND AND AIMS: Bioelectrical impedance analysis (BIA) is a widely used technique to assess body composition and nutritional status. While bioelectrical values are affected by diverse variables, there has been little research on validation of BIA in acute illness, especially to understand prognostic significance. Here we report the use of BIA in acute febrile states induced by influenza. METHODS: Bioimpedance studies were conducted during an H1N1 influenza A outbreak in Venezuelan Amerindian villages from the Amazonas. Measurements were performed on 52 subjects between 1 and 40 years of age, and 7 children were re-examined after starting Oseltamivir treatment. Bioelectrical Impedance Vector Analysis (BIVA) and permutation tests were applied. RESULTS: For the entire sample, febrile individuals showed a tendency toward greater reactance (p=0.058) and phase angle (p=0.037) than afebrile individuals, while resistance and impedance were similar in the two groups. Individuals with repeated measurements showed significant differences in bioimpedance values associated with fever, including increased reactance (p<0.001) and phase angle (p=0.007), and decreased resistance (p=0.007) and impedance (p<0.001). CONCLUSIONS: There are bioelectrical variations induced by influenza that can be related to dehydration, with lower extracellular to intracellular water ratio in febrile individuals, or a direct thermal effect. Caution is recommended when interpreting bioimpedance results in febrile states

The Dynamics of Nestedness Predicts the Evolution of Industrial Ecosystems

In economic systems, the mix of products that countries make or export has been shown to be a strong leading indicator of economic growth. Hence, methods to characterize and predict the structure of the network connecting countries to the products that they export are relevant for understanding the dynamics of economic development. Here we study the presence and absence of industries at the global and national levels and show that these networks are significantly nested. This means that the less filled rows and columns of these networks' adjacency matrices tend to be subsets of the fuller rows and columns. Moreover, we show that nestedness remains relatively stable as the matrices become more filled over time and that this occurs because of a bias for industries that deviate from the networks' nestedness to disappear, and a bias for the missing industries that reduce nestedness to appear. This makes the appearance and disappearance of individual industries in each location predictable. We interpret the high level of nestedness observed in these networks in the context of the neutral model of development introduced by Hidalgo and Hausmann (2009). We show that, for the observed fills, the model can reproduce the high level of nestedness observed in these networks only when we assume a high level of heterogeneity in the distribution of capabilities available in countries and required by products. In the context of the neutral model, this implies that the high level of nestedness observed in these economic networks emerges as a combination of both, the complementarity of inputs and heterogeneity in the number of capabilities available in countries and required by products. The stability of nestedness in industrial ecosystems, and the predictability implied by it, demonstrates the importance of the study of network properties in the evolution of economic networks.Comment: 26 page

Vortices on demand in multicomponent Bose-Einstein condensates

We present a simple mechanism to produce vortices at any desired spatial locations in harmonically trapped Bose-Einstein condensates (BEC) with multicomponent spin states coupled to external transverse and axial magnetic fields. The vortices appear at the spatial points where the spin-transverse field interaction vanishes and, depending on the multipolar magnetic field order, the vortices can acquire different predictable topological charges. We explicitly demonstrate our findings, both numerically and analytically, by analyzing a 2D BEC via the Gross-Pitaevskii equation for atomic systems with either two or three internal states. We further show that, by an spontaneous symmetry breaking mechanism, vortices can appear in any spin component, unless symmetry is externally broken at the outset by an axial field. We suggest that this scenario may be tested using an ultracold gas of $^{87}$Rb occupying all three $F = 1$ states in an optical trap.Comment: 11 pages, 9 figures, (Accepted in PRA

Modelling non-dust fluids in cosmology

Currently, most of the numerical simulations of structure formation use Newtonian gravity. When modelling pressureless dark matter, or `dust', this approach gives the correct results for scales much smaller than the cosmological horizon, but for scenarios in which the fluid has pressure this is no longer the case. In this article, we present the correspondence of perturbations in Newtonian and cosmological perturbation theory, showing exact mathematical equivalence for pressureless matter, and giving the relativistic corrections for matter with pressure. As an example, we study the case of scalar field dark matter which features non-zero pressure perturbations. We discuss some problems which may arise when evolving the perturbations in this model with Newtonian numerical simulations and with CMB Boltzmann codes.Comment: 5 pages; v2: typos corrected and refs added, submitted version; v3: version to appear in JCA