Steps and terraces at quasicrystal surfaces. Application of the 6d-polyhedral model to the analysis of STM images of i-AlPdMn

6-d polyhedral models give a periodic description of aperiodic quasicrystals. There are powerful tools to describe their structural surface properties. Basis of the model for icosahedral quasicrystals are given. This description is further used to interpret high resolution STM images of the surface of i-AlPdMn which surface preparation was followed by He diffraction. It is found that both terrace structure and step-terrace height profiles in STM images can be consistently interpreted by the described model

Découverte des quasicristaux : les premiers pas

International audienceThis paper is a survey of the initial developments of the research on quasicrystals starting from their discovery by Daniel Shechtman (Nobel Prize in Chemistry in 2011) in 1982 at the National Bureau of Standards (now National Institute for Standard and Technology) in Gaithersburg (Maryland, USA) up to the beginning of the early 1990s, a time when the crystallographic methods were well developed and mastered enough to decipher the ultimate atomic structures of quasicrystals. These early works have enlarged our understanding of spatial order in solids through a strong multidisciplinary effort between mathematicians, physicists, chemists and material scientists.Cet article relate le développement initial des recherches sur les quasicristaux depuis leur découverte par Daniel Shechtman (prix Nobel de chimie en 2011) en 1982 au National Bureau of Standards (aujourd'hui National Institute for Standards and Technology) à Gaithersburg (Maryland, États-Unis) jusqu'au début des années 1990, période durant laquelle se sont développées les méthodes cristallographiques adaptées à l'analyse de ces structures atomiques quasicristallines. Ces premiers travaux ont permis d'élargir notre compréhension de l'ordre dans les solides grâce à une forte pluridisciplinarité alliant mathématiciens, physiciens et spécialistes de la science des matériaux

Konsep Penyelamatan dalam Pandangan Paulus

Our human life in this world ends in death. The mystery of this death becomes a scary thing. However, for those who believe in God in Christ, death is the path to complete salvation. Sin causes humans to experience death. However, through Jesus Christ, God saved mankind from the destruction of death. It does not mean that humans will not die, but after going through death, God provides complete salvation

Identification of genes involved in progression of retinoblastoma

Many retinoblastomas (RBs) show genomic alterations in addition to mutational loss of both normal RB1 alleles. The most frequent of these changes are gains on chromosomes 1q and 6p and losses on 16q. To identify the genes targeted by gains on chromosome 1q we used quantitative-multiplex PCR and array-CGH to determine DNA copy number changes in 76 primary tumours and 6 RB cell lines. In addition, in 21 of these tumours gene expression was analyzed by cDNA microarray hybridization. We have used microsatellite analysis and pyrosequencing to further localise the region of allele loss of heterozygosity on chromosome 16. We have also set up a specific methylation assay for the CDH11 gene located on 16p22 that was previously considered to be the target of loss on 16. The results we obtained were compared with expression of the corresponding genes. A novel region of amplification on the short arm of chromosome 1 was determined with array-CGH, and with a combination of genomic results and expression data allowed us to analyse the possibility of a novel oncogene involved in progression of retinoblastoma. Increased copy numbers of loci on chromosome 1q were present in 34 (45%) primary tumours and in all 6 cell lines. Two regions of gain emerged, one in 1q32 and another in 1q21. Tumours with 1q gains showed higher RNA expression of several genes in these two regions. The clinical manifestation of tumours with and without gains was similar with regard to many aspects including size, necrosis and calcification. However, the distribution of age at diagnosis was remarkably distinct with earlier diagnosis in tumours without gains. This suggests that these tumours are either initiated earlier or grow faster than tumours with gains. This association with clinical manifestation indicates that gains on 1q are significant for the biology of retinoblastoma. The genes on 1q with copy number gains and overexpression here are candidates that need to be tested for their individual contribution to the progression of retinoblastoma. The targets of loss on chromosome 16 are not clearly identified, but our results suggest that the CDH11 gene is probably not the tumour suppressor gene involved in progression of retinoblastoma that was proposed before. The results we obtained with our analyses on chromosome 1p suggest a role for MYCL1 in retinoblastoma

The Effects of Candidate Religiosity and Candidate Secularism on Voters\u27 Support for the Political Candidate

This study examines the effects of candidate religiosity, candidate secularism, and voter fundamentalism on voters\u27 support for a political candidate. Seven effects were tested: 1) the religiosity effect, which suggests that a religious candidate will be supported more than a nonreligious candidate; 2) the secularism effect, which suggests that a secular candidate will be supported more than a nonsecular candidate; 3) the JFK effect, which suggests that a secular religious candidate will be supported more than a nonsecular religious candidate; 4) the deviant effect--an opposite of the JFK effect--, which suggests that a secular religious candidate constitutes a group deviant, and thus will be supported less than a nonsecular religious candidate; 5) the moderating effect of voter fundamentalism, which suggests that low fundamentalists will display the secularism and JFK effects whereas high fundamentalists will display the religiosity and deviant effects; 6) the controversial issue effect, which suggests that, since secularism is a controversial issue, neither secular nor nonsecular candidates will be supported more than a candidate who says nothing about secularism; and 7) the relative amount of information effect, which suggests that adding more information about a candidate\u27s issue positions will decrease the relative influence of other issue positions on voters\u27 evaluation of the candidate. The study employed an experimental design. To manipulate candidate religiosity, the candidate was either described or not described as religious. To manipulate secularism, the candidate was described as favoring policies that endorsed religion-state separation, favoring policies that endorsed religion-state blending, or as not possessing any particular secularism policies. The dependent variables were the likelihood of voters to vote for the candidate, voters\u27 attitude toward the candidate, and perceived competence and integrity of the candidate. The findings support the religiosity effect and the secularism effect, which was particularly strong among low fundamentalists--an evidence of the moderating effect of voter fundamentalism. The findings also support the controversial issue effect: neither the pro-blending nor the pro-separation candidate was supported more than the candidate who said nothing about secularism. Lastly, the findings support the relative amount of information effect in predicting voting likelihood: presenting information on secularism decreased the relative influence of voters\u27 agreement with the candidates in other issues on their likelihood to vote for the candidates

Characterization of Brca2-Deficient Plants Excludes the Role of NHEJ and SSA in the Meiotic Chromosomal Defect Phenotype

In somatic cells, three major pathways are involved in the repair of DNA double-strand breaks (DBS): Non-Homologous End Joining (NHEJ), Single-Strand Annealing (SSA) and Homologous Recombination (HR). In somatic and meiotic HR, DNA DSB are 5′ to 3′ resected, producing long 3′ single-stranded DNA extensions. Brca2 is essential to load the Rad51 recombinase onto these 3′ overhangs. The resulting nucleofilament can thus invade a homologous DNA sequence to copy and restore the original genetic information. In Arabidopsis, the inactivation of Brca2 specifically during meiosis by an RNAi approach results in aberrant chromosome aggregates, chromosomal fragmentation and missegregation leading to a sterility phenotype. We had previously suggested that such chromosomal behaviour could be due to NHEJ. In this study, we show that knock-out plants affected in both BRCA2 genes show the same meiotic phenotype as the RNAi-inactivated plants. Moreover, it is demonstrated that during meiosis, neither NHEJ nor SSA compensate for HR deficiency in BRCA2-inactivated plants. The role of the plant-specific DNA Ligase6 is also excluded. The possible mechanism(s) involved in the formation of these aberrant chromosomal bridges in the absence of HR during meiosis are discussed