Superpropagators for explicitly broken 3D-supersymmetric theories

A systematic algorithm to derive superpropagators in the case of either explicitly or spontaneously broken supersymmetric three-dimensional theories is presented. We discuss how the explicit breaking terms that are introduced at tree-level induce 1-loop radiative corrections to the effective action. We also point out that the renormalisation effects and the breaking-inducing-breaking mechanism become more immediate whenever we adopt the shifted superpropagators discussed in this letter.Comment: 6 pages, LaTex, references added. To appear in Phys.Lett.

Systemic release of volatiles by Brassica oleracea var. acephala induced by Pieris brassicae predation.

Pieris brassicae is a specialist on crucifers and its interactions with some of its host plants have been increasingly studied given their importance in pest management, chemical ecology and entomology. Plants are known to respond to insect attack by releasing volatiles that can either warn neighbour plants to the presence of a predator or attract insect parasitoids, thus reducing the attack efficiency. The influence of P. brassicae feeding on Brassica oleracea L. var. acephala (kale) was investigated, namely, its effect in the volatiles released by the plant through time. Substantial differences, mainly quantitative, were found between the volatiles composition of B. oleracea var. acephala before the attack and after insect feeding. More than 40 compounds were found, between terpenes (monoterpenes and sesquiterpenes) and lipoxygenase pathway byproducts (alcohols and aldehydes), ketones, norisoprenoids, among others. After insect attack, monoterpenes like limonene, eucalyptol, camphor and caryophyllene increased noticeably. These compounds have been regarded as markers in local tissue responses and in this study an increase in their concentration was detected at 1 and 4 hours after feeding, with subsequent reduction after 8 hours. Menthol, menthone, phenol and sabinene were found only in the time following the attack. A considerable increase in hexenyl acetate, a well known semiochemical, was also found, with this compound being the major peak in all experiments, rising with time. These findings provide further knowledge of the ecological interactions between these two species and, given the chemical diversity of these matrices, they may constitute a good source of health promoting compounds.Fundação para a Ciência e Tecnologia for financial support (PTDC/AGRAAM/ 64150/2006). F. Fernandes (SFRH/BD/37963/2007

Metabolic fate of dietary volatile compounds in Pieris brassicae

In this work, the evolution of the qualitative and quantitative profile of the volatile fraction of Pieris brassicae after feeding on Brassica oleracea var. acephala (kale) was monitored through time. HS-SPME/GC-MS was applied to both the host plant and the living insect and its excrements. A total of seventy seven compounds (lipoxygenase pathway by-products, nitrogen compounds, norisoprenoids, sulphur compounds, terpenes, among others) were identified. Thirty eight compounds were identified in insect after 2 h of starvation and forty eight compounds in excrements. Qualitative and quantitative changes were detected along time. Dimethyldisulfide, dimethyltrisulfide, limonene and eugenol were major compounds for all analysed times in both matrices, being limonene an important compound in insect after starvation. The accumulation by P. brassicae of some compounds, such as limonene, was verified, suggesting a mechanism by which the insect can take benefit from bioactive constituents from the diet. Along with accumulation, complete excretion of some compounds, including nitrogen bearing compounds, by-products of glucosinolates was detected. These results reflect one of the strategies used to overcome plant barriers, namely detoxification of toxic compounds. The findings contribute to the knowledge of the metabolization of the volatile compounds in insects and contribute to the body of knowledge of this ecologic system.FC

Determination of low molecular weight volatiles in Ficus carica using HS-SPME and GC/FID

Ficus carica L. is one of the earliest cultivated fruit trees, having an important consumption in Mediterranean countries. In this work, the volatile compound profiles of two characteristic Portuguese white varieties (‘‘Pingo de Mel” and ‘‘Branca Tradicional”) was determined by HS-SPME and GC/FID. Leaves, pulps and peels, submitted to freezing and lyophilisation treatments, were analysed. The two varieties presented a similar profile composed of eight volatile compounds: acetaldehyde, ethyl acetate, methanol, ethanol, hexanal, limonene, (E)-2-hexenal and octanal. The total volatile content was different among the vegetal materials, following the order leaves > peels > pulps. Methanol and ethanol are the major compounds in all samples. The developed procedure revealed to be rapid, sensitive, reproducible and accurate. The detection limit values were low, and the method precise. The recovery values for acetaldehyde, ethyl acetate, methanol and ethanol were generally high, suggesting that it will be most suitable for compounds with low molecular weight. Due to its rapidity and low cost, this technique can be useful in the quality control of fig fruit and leaves

Ohm's Law for Plasma in General Relativity and Cowling's Theorem

The general-relativistic Ohm's law for a two-component plasma which includes the gravitomagnetic force terms even in the case of quasi-neutrality has been derived. The equations that describe the electromagnetic processes in a plasma surrounding a neutron star are obtained by using the general relativistic form of Maxwell equations in a geometry of slow rotating gravitational object. In addition to the general-relativistic effect first discussed by Khanna \& Camenzind (1996) we predict a mechanism of the generation of azimuthal current under the general relativistic effect of dragging of inertial frames on radial current in a plasma around neutron star. The azimuthal current being proportional to the angular velocity $\omega$ of the dragging of inertial frames can give valuable contribution on the evolution of the stellar magnetic field if $\omega$ exceeds $2.7\times 10^{17} (n/\sigma) \textrm{s}^{-1}$ ($n$ is the number density of the charged particles, $\sigma$ is the conductivity of plasma). Thus in general relativity a rotating neutron star, embedded in plasma, can in principle generate axial-symmetric magnetic fields even in axisymmetry. However, classical Cowling's antidynamo theorem, according to which a stationary axial-symmetric magnetic field can not be sustained against ohmic diffusion, has to be hold in the general-relativistic case for the typical plasma being responsible for the rotating neutron star.Comment: Accepted for publication in Astrophysics & Space Scienc

Disorder and thermally driven vortex-lattice melting in La{2-x}Sr{x}CuO{4} crystals

Magnetization measurements in La{2-x}Sr{x}CuO{4} crystals indicate vortex order-disorder transition manifested by a sharp kink in the second magnetization peak. The transition field exhibits unique temperature dependence, namely a strong decrease with temperature in the entire measured range. This behavior rules out the conventional interpretation of a disorder-driven transition into an entangled vortex solid phase. It is shown that the transition in La{2-x}Sr{x}CuO{4} is driven by both thermally- and disorder-induced fluctuations, resulting in a pinned liquid state. We conclude that vortex solid-liquid, solid-solid and solid to pinned-liquid transitions are different manifestations of the same thermodynamic order-disorder transition, distinguished by the relative contributions of thermal and disorder-induced fluctuations.Comment: To be published in phys. Rev. B Rapid Com