Classical behaviour of Q-balls in the Wick-Cutkosky model

In this paper, we continue discussing Q-balls in the Wick--Cutkosky model. Despite Q-balls in this model are composed of two scalar fields, they turn out to be very useful and illustrative for examining various important properties of Q-balls. In particular, in the present paper we study in detail (analytically and numerically) the problem of classical stability of Q-balls, including the nonlinear evolution of classically unstable Q-balls, as well as the behaviour of Q-balls in external fields in the non-relativistic limit.Comment: 21 pages, 12 figures, LaTeX; v2: section 3.3 slightly enlarged, typos corrected, minor changes in the tex

Effect of α-Hgl_2 epitaxial growth on the defect structure of CdTe:Ge substrates

The aα-HgI_2/CdTe:Ce heterostructures have been studied by cathodoluminescence (CL) in the scanning electron microscope. The alpha-HgI2 expitaxial growth was shown to cause an enhancement of the CL intensity in a layer of the substrate extending up to about 500 mu m from the α-Hgl_2 /CdTe:Ge interface. CL spectra of the layer reveal the appearance of a band related to tellurium vacancies as well as the decrease of the emission attributed to defect complexes involving Ge. The data obtained indicate that Ge-impurity gettering and V-Te generation at the interface take place during α-Hgl_2 epitaxial growth

Application of cathodoluminescence microscopy to the study of native acceptors in gallium antimonide

Cathodoluminescence in the scanning electron microscope is used to ivestigate growth and prosess induced defects in GaSb crystals. In particular, luminescence emission has been used to study the nature of acceptor defects present after different annealing and irradiation treatments

Gas and hydrate occurences in the western Black Sea

Here we present the preliminary results of the ongoing project ¸SAssessment of the gas-bearing sediments in the north-western Black Sea?T supported through a EC Marie Curie Fellowship. The project aims to integrate information from geophysical and geomorphological data in order to define a general characterization of the gas accumulations in the recent sediments of the Black Sea. Investigation is based mainly on high-resolution seismic reflection data and swath bathymetry acquired during the BlaSON and BlaSON 2 surveys by IFREMER (France) in cooperation with GeoEcomar (Romania). Sub-bottom profiles (3,5 KHz) acquired by GeoEcoMar have been also used, as well as seismic and bathymetric data from the CRIMEA EC project.The western margin of the Black Sea contains evidence of abundant subsurface gas accumulations that appear in a complete suite of settings from the coastal zone to the deep basin. Considering the variation of their features from one setting to another, we defined several distinct gas provinces:- the coastal zone in front of the Danube Delta and along the Bulgarian shore is marked by the presence of a shallow gas accumulation that causes a widespread acoustic mask up to 1-3 m depth below the seafloor.- on the shelf the typical gas facies is represented by acoustic columns from a deep source (below the penetration limit of our profiles), either reaching the seafloor or being buried under the upper shelf deposits.- the shelf-edge zone (including the external shelf and the upper slope down to about 750 m water depth) shows significant gas discharge and numerous gas seeps have already been mapped. Gas escape zones are commonly associated with subsurface acoustic turbidity and acoustic columns.- on the slope below 750 m depth, bottom simulating reflectors (BSR) were detected and indicate the probable presence of gas hydrates. A remarkable BSR pattern consisting of multiple BSR-type reflectors occurs in the Danube fan.Zones of significant gas accumulation (especially the coastal zone and the shelf edge) seem to be associated with high sedimentation rates, which may indicate a possible biogenic origin for this gas. Nevertheless, there is evidence that deep thermogenic gas sources could have contributed as well

Xenobiotic-induced activation of human aryl hydrocarbon receptor target genes in Drosophila is mediated by the epigenetic chromatin modifiers

Aryl hydrocarbon receptor (AHR) is the key transcription factor that controls animal development and various adaptive processes. The AHR\u27s target genes are involved in biodegradation of endogenous and exogenous toxins, regulation of immune response, organogenesis, and neurogenesis. Ligand binding is important for the activation of the AHR signaling pathway. Invertebrate AHR homologs are activated by endogenous ligands whereas vertebrate AHR can be activated by both endogenous and exogenous ligands (xenobiotics). Several studies using mammalian cultured cells have demonstrated that transcription of the AHR target genes can be activated by exogenous AHR ligands, but little is known about the effects of AHR in a living organism. Here, we examined the effects of human AHR and its ligands using transgenic Drosophila lines with an inducible human AhR gene. We found that exogenous AHR ligands can increase as well as decrease the transcription levels of the AHR target genes, including genes that control proliferation, motility, polarization, and programmed cell death. This suggests that AHR activation may affect the expression of gene networks that could be critical for cancer progression and metastasis. Importantly, we found that AHR target genes are also controlled by the enzymes that modify chromatin structure, in particular components of the epigenetic Polycomb Repressive complexes 1 and 2. Since exogenous AHR ligands (alternatively - xenobiotics) and small molecule inhibitors of epigenetic modifiers are often used as pharmaceutical anticancer drugs, our findings may have significant implications in designing new combinations of therapeutic treatments for oncological diseases. © Akishina et al

Electron beam induced current and scanning tunnelling spectroscopy correlative study of Cd-xHg_(1-x)Te and CdTe crystals

A combined scanning electron microscope-scanning tunnelling microscope (SEM-STM) system has been used to characterize CdxHg1-xTe and CdTe crystals, The electron beam induced current (EBIC) mode of the SEM shows the existence of inhomogeneities in the electronic behaviour of the samples, mainly related to the presence of subgrain boundaries and precipitates. Current imaging tunnelling spectroscopy images and the related normalized differential conductance curves, obtained with the STM, reveal the electronic inhomogeneities at a finer scale. In particular, local variations of the band gap were shown by the conductance curves in regions with strong EBIC contrast. SEM-and STM-based techniques in a combined instrument appear to be complementary characterization techniques