On the unconstrained expansion of a spherical plasma cloud turning collisionless : case of a cloud generated by a nanometer dust grain impact on an uncharged target in space

Nano and micro meter sized dust particles travelling through the heliosphere at several hundreds of km/s have been repeatedly detected by interplanetary spacecraft. When such fast moving dust particles hit a solid target in space, an expanding plasma cloud is formed through the vaporisation and ionisation of the dust particles itself and part of the target material at and near the impact point. Immediately after the impact the small and dense cloud is dominated by collisions and the expansion can be described by fluid equations. However, once the cloud has reached micro-m dimensions, the plasma may turn collisionless and a kinetic description is required to describe the subsequent expansion. In this paper we explore the late and possibly collisionless spherically symmetric unconstrained expansion of a single ionized ion-electron plasma using N-body simulations. Given the strong uncertainties concerning the early hydrodynamic expansion, we assume that at the time of the transition to the collisionless regime the cloud density and temperature are spatially uniform. We do also neglect the role of the ambient plasma. This is a reasonable assumption as long as the cloud density is substantially higher than the ambient plasma density. In the case of clouds generated by fast interplanetary dust grains hitting a solid target some 10^7 electrons and ions are liberated and the in vacuum approximation is acceptable up to meter order cloud dimensions. ..

Comparison of three domestications and wild-harvested plants for nutraceutical properties and sensory profiles in five wild edible herbs: Is domestication possible?

In this study, five wild edible herbs traditionally consumed in the Tuscany region (Italy) were evaluated for their potential in human nutrition. The nutraceutical characterization of Rumex acetosa, Cichorium intybus, Picris hieracioides, Sanguisorba minor, and Plantago coronopus, as well as their sensory profile were reported. Additionally, a preliminary assessment of completely different domestication of the wild species (named "soilless", pot, and open field) was conducted to verify the possibility of their marketability, which is impossible if the plants are only gathered as wild. The open field domestication allowed to obtain plants with nutraceutical and sensory profiles similar to those of the wild species, especially in C. intybus, P. hieracioides, and S. minor. The pot domestication allow to obtain plants with chlorophyll and carotenoid contents close to those of the wild species, as well as a lower total phenolic and flavonoid content and ascorbic acid content than wild species. In the "soilless"method, R. acetosa and P. coronopus exhibited a high quality in terms of phytochemicals and antioxidant activity. Afterward, the sensory profile was strongly affected by the domestication in terms of the palatability, except for R. acetosa and P. coronopus, which displayed Hedonic Index (HI) values close to the consumer acceptability limit (HI = 6). A sensory profile similar to that of wild species was reported in open field domestication, whereas a worse sensory profile was reported in P. hieracioides and C. intybus domesticated using the soilless method. Finally, according to the preliminary assessment carried out in this study through an analysis of the general nutraceutical properties, S. minor was shown to be the most promising species thanks to its intrinsically highest nutraceutical properties considering the marketability of wild edible herbs as "new"functional food. However, further research on the bioavailability and bioactivity tests of nutraceutical compounds present in this species are required to confirm the findings of this study

Scattering polarization of hydrogen lines from electric-induced atomic alignment

We consider a gas of hydrogen atoms illuminated by a broadband, unpolarized radiation with zero anisotropy. In the absence of external fields, the atomic J-levels are thus isotropically populated. While this condition persists in the presence of a magnetic field, we show instead that electric fields can induce the alignment of those levels. We also show that this electric alignment cannot occur in a two-term model of hydrogen (e.g., if only the Ly-alpha transition is excited), or if the level populations are distributed according to Boltzmann's law.Comment: 10 pages, 4 figures. Accepted by J.Phys.B: At.Mol.Opt.Phy

Algebraic description of spacetime foam

A mathematical formalism for treating spacetime topology as a quantum observable is provided. We describe spacetime foam entirely in algebraic terms. To implement the correspondence principle we express the classical spacetime manifold of general relativity and the commutative coordinates of its events by means of appropriate limit constructions.Comment: 34 pages, LaTeX2e, the section concerning classical spacetimes in the limit essentially correcte

QoS management and control for an all-IP WiMAX network architecture: Design, implementation and evaluation

The IEEE 802.16 standard provides a specification for a fixed and mobile broadband wireless access system, offering high data rate transmission of multimedia services with different Quality-of-Service (QoS) requirements through the air interface. The WiMAX Forum, going beyond the air interface, defined an end-to-end WiMAX network architecture, based on an all-IP platform in order to complete the standards required for a commercial rollout of WiMAX as broadband wireless access solution. As the WiMAX network architecture is only a functional specification, this paper focuses on an innovative solution for an end-to-end WiMAX network architecture offering in compliance with the WiMAX Forum specification. To our best knowledge, this is the first WiMAX architecture built by a research consortium globally and was performed within the framework of the European IST project WEIRD (WiMAX Extension to Isolated Research Data networks). One of the principal features of our architecture is support for end-to-end QoS achieved by the integration of resource control in the WiMAX wireless link and the resource management in the wired domains in the network core. In this paper we present the architectural design of these QoS features in the overall WiMAX all-IP framework and their functional as well as performance evaluation. The presented results can safely be considered as unique and timely for any WiMAX system integrator

Genetic susceptibility to malignant pleural mesothelioma and other asbestos-associated diseases.

Exposure to asbestos fibers is a major risk factor for malignant pleuralmesothelioma (MPM), lung cancer, and other non-neoplastic conditions, such as asbestosis and pleural plaques. However, in the last decade many studies have shown that polymorphism in the genes involved in xenobiotic and oxidative metabolism or in DNA repair processes may play an important role in the etiology and pathogenesis of these diseases. To evaluate the association between diseases linked to asbestos and genetic variability we performed a review of studies on this topic included in the PubMed database. One hundred fifty-nine citations were retrieved; 24 of them met the inclusion criteria and were evaluated in the review. The most commonly studied GSTM1 polymorphism showed for all asbestos-linked diseases an increased risk in association with the null genotype, possibly linked to its role in the conjugation of reactive oxygen species. Studies focused on GSTT1 null and SOD2 Ala16Val polymorphisms gave conflicting results, while promising results came from studies on a1-antitrypsin in asbestosis and MPO in lung cancer. Among genetic polymorphisms associated to the risk of MPM, the GSTM1 null genotype and two variant alleles of XRCC1 and XRCC3 showed increased risks in a subset of studies. Results for the NAT2 acetylator status, SOD2 polymorphism and EPHX activity were conflicting. Major limitations in the study design, including the small size of study groups, affected the reliability of these studies. Technical improvements such as the use of high-throughput techniques will help to identify molecular pathways regulated by candidate genes