Multilevel Coded Modulation for Unequal Error Protection and Multistage Decoding—Part I: Symmetric Constellations

In this paper, theoretical upper bounds and computer simulation results on the error performance of multilevel block coded modulations for unequal error protection (UEP) and multistage decoding are presented. It is shown that nonstandard signal set partitionings and multistage decoding provide excellent UEP capabilities beyond those achievable with conventional coded modulation. The coding scheme is designed in such a way that the most important information bits have a lower error rate than other information bits. The large effective error coefficients, normally associated with standard mapping by set partitioning, are reduced by considering nonstandard partitionings of the underlying signal set. The bits-to-signal mappings induced by these partitionings allow the use of soft-decision decoding of binary block codes. Moreover, parallel operation of some of the staged decoders is possible, to achieve high data rate transmission, so that there is no error propagation between these decoders. Hybrid partitionings are also considered that trade off increased intraset distances in the last partition levels with larger effective error coefficients in the middle partition levels. The error performance of specific examples of multilevel codes over 8-PSK and 64-QAM signal sets are simulated and compared with theoretical upper bounds on the error performance

Multilevel Coded Modulation for Unequal Error Protection and Multistage Decoding—Part II: Asymmetric Constellations

In this paper, multilevel coded asymmetric modulation with multistage decoding and unequal error protection (UEP) is discussed. These results further emphasize the fact that unconventional signal set partitionings are more promising than traditional (Ungerboeck-type) partitionings, to achieve UEP capabilities with multilevel coding and multistage decoding. Three types of unconventional partitionings are analyzed for asymmetric 8-PSK and 16-QAM constellations over the additive white Gaussian noise channel to introduce design guidelines. Generalizations to other PSK and QAM type constellations follow the same lines. Upper bounds on the bit-error probability based on union bound arguments are first derived. In some cases, these bounds become loose due to the large overlappings of decision regions associated with asymmetric constellations and unconventional partitionings. To overcome this problem, simpler and tighter approximated bounds are derived. Based on these bounds, it is shown that additional refinements can be achieved in the construction of multilevel UEP codes, by introducing asymmetries in PSK and QAM signal constellations

Modélisation des conditions d’environnement des bocaux de culture in vitro : bocaux avec agar et vitroplants

La présente étude traite de la modélisation des conditions des plantes en culture in vitro. Lorsque des vitroplants sont introduits dans les bocaux,l'humidité de l'air intérieur varie en fonction de leur stade de développementet ce en accord avec les courbes expérimentales. Les variations diurnes du déficit de pression de vapeur (DPV) présentent un maximum pendant laphotopériode et un minimum pendant la nyctipériode. Par ailleurs, grâce à la prise en compte des réservoirs de la plante, le modèle permet de décrire la déshydratation et la réhydratation des tissus, ce qui est potentiellement d'un intérêt pratique. Au cours du cycle diurne, la teneur en eau relative varie entre 75 et 90 %. Les flux d'eau dans la plante concordent bien avec les variations de la teneur en eau du réservoir plante et caractérisent bien les deux types de régimes de circulation de l'eau dans la plante : le régime de flux conservatif et le régime de flux non conservatif.Mots-clés : Modélisation, culture in vitro, humidité de l'air intérieur, réservoir-plante, déshydratation, réhydratatio

Modeling the microclimate inside a vessel in in vitro culture : vessel with agar

Numerical simulations show that variations in vessel internal humidity was sensitive to transfer coefficient, climatic conditions within the growth chamber, evaporation and condensation of water vapor on the walls of the vessel. The variations in water vapor pressure deficits (VPD) (low during the nyctiperiod and high during the photoperiod) were well explained by a free convection model, which took into account temperature differences. Finally, the results show the necessity to construct containers with variable openings and growth chambers in which bioclimatic conditions can be controlled.Les simulations numériques révèlent que les variations de l\'humidité interne ont été sensibles au coefficient d\'échange de vapeur d\'eau, aux conditions climatiques de la chambre de culture et aux phénomènes d\'évaporation et de condensation de vapeur d\'eau sur les parois des bocaux. Par ailleurs, il a été établi que le «créneau» de déficit de pression de vapeur (DPV) de l\'air intérieur (palier de DPV faible en nyctipériode et palier de DPV élevé en photopériode) a été bien imité en mode convectif libre qui tient compte des écarts de températures. Ainsi, ces résultats montrent la nécessité de construire des récipients à ouverture variable et des chambres de culture dans lesquelles les facteurs bioclimatiques des plantes peuvent être maîtrisés. Keywords: Agar, in vitro culture, microclimate, modeling, transfer coefficient./Agar, culture in vitro, microclimat, modélisation, coefficient d\'échange.Sciences & Nature Vol. 4 (1) 2007: pp. 75-8

Mass Transfer by Stellar Wind

I review the process of mass transfer in a binary system through a stellar wind, with an emphasis on systems containing a red giant. I show how wind accretion in a binary system is different from the usually assumed Bondi-Hoyle approximation, first as far as the flow's structure is concerned, but most importantly, also for the mass accretion and specific angular momentum loss. This has important implications on the evolution of the orbital parameters. I also discuss the impact of wind accretion, on the chemical pollution and change in spin of the accreting star. The last section deals with observations and covers systems that most likely went through wind mass transfer: barium and related stars, symbiotic stars and central stars of planetary nebulae (CSPN). The most recent observations of cool CSPN progenitors of barium stars, as well as of carbon-rich post-common envelope systems, are providing unique constraints on the mass transfer processes.Comment: Chapter 7, in Ecology of Blue Straggler Stars, H.M.J. Boffin, G. Carraro & G. Beccari (Eds), Astrophysics and Space Science Library, Springe

Clinical significance of VEGF-A, -C and -D expression in esophageal malignancies

Vascular endothelial growth factors ( VEGF)- A, - C and - D are members of the proangiogenic VEGF family of glycoproteins. VEGF-A is known to be the most important angiogenic factor under physiological and pathological conditions, while VEGF-C and VEGF-D are implicated in the development and sprouting of lymphatic vessels, so called lymphangiogenesis. Local tumor progression, lymph node metastases and hematogenous tumor spread are important prognostic factors for esophageal carcinoma ( EC), one of the most lethal malignancies throughout the world. We found solid evidence in the literature that VEGF expression contributes to tumor angiogenesis, tumor progression and lymph node metastasis in esophageal squamous cell carcinoma ( SCC), and many authors could show a prognostic value for VEGF-assessment. In adenocarcinoma (AC) of the esophagus angiogenic properties are acquired in early stages, particularly in precancerous lesions like Barrett's dysplasia. However, VEGF expression fails to give prognostic information in AC of the esophagus. VEGF-C and VEGF-D were detected in SCC and dysplastic lesions, but not in normal mucosa of the esophagus. VEGF-C expression might be associated with lymphatic tumor invasion, lymph node metastases and advanced disease in esophageal SCC and AC. Therapeutic interference with VEGF signaling may prove to be a promising way of anti-angiogenic co-treatment in esophageal carcinoma. However, concrete clinical data are still pending

Modified Whole-Mount In situ Hybridization Protocol for the Detection of Transgene Expression in Electroporated Chick Embryos

hybridization. hybridization (WISH).Here we describe a modification to the WISH protocol that is essential to prevent DNA cross-hybridization and to specifically detect transgene mRNA transcripts in electroporated embryos. Our optimized WISH procedure can be applied not only to electroporated chick embryos but also to other embryos or adult tissues that have been transfected with large amounts of reporter- or expression construct DNA

Antimicrobial activity and bioactive compounds of portuguese wild edible mushrooms methanolic extracts

The antimicrobial properties of phenolic extracts of Portuguese wild edible mushroom species (Lactarius deliciosus, Sarcodon imbricatus and Tricholoma portentosum) against pathogens were investigated. The minimal inhibitory concentrations (MICs) were evaluated for the entire mushroom, the cap and the stipe, separately; the portion of the mushroom used proved to be influenced in the results obtained, which are directly correlated with the content of total phenols and flavonoids in the extracts. The growth of Grampositive bacteria (Bacillus cereus, B. subtilis,) was well inhibited by these mushrooms, while Escherichia coli (Gramnegative bacteria) was resistant. The study on the antifungal effect of these mushrooms revealed that Candida albicans and Cryptococcus neoformans were differently inhibited for the mushrooms used