Thomas-forbidden particle capture

At high energies, in particle-capture processes between ions and atoms, classical kinematic requirements show that generally double collision Thomas processes dominate. However, for certain mass-ratios these processes are kinematically forbidden. This paper explores the possibility of capture for such processes by triple or higher order collision processes.Comment: 34 pages and three figure

The Polymerases for V(D)J Recombination

DNA transactions of a wide variety generally require three major types of enzymatic activities: nucleases, polymerases, and ligases. V(D)J recombination is no exception. In this issue, Bertocci et al. (2006) have provided new insight by generating mice deficient in one or more of the polymerases

Toward a New Paradigm for the Evolution of Developmental and Growth-Pattern Systems in Plants and Animals

Genetically controlled and environmentally responsive mutation as a significant feature of evolution has very likely occurred on different genomic levels. The evolution of developmental and growth-pattern systems in plants and animals could have occurred through a karyotypic mutator system creating controlled, frequent genomic changes on the karyotypic level in response to environmental stresses, such as temperature changes. Such a mutator system generating controlled karyotypic changes at very high frequency in response to stress was discovered. in the fungus, Aspergillus nidulans, once classified within the plant kingdom. This mutator system is itself representative of a basic, responsive developmental system producing changes in growth-pattern, morphology, and changes ensuing in a new pattern of differentiation, which are adaptive. Such a developmental, karyotypic mutator system may itself have evolved, through its own self-controlled evolution, into types of complex developmental systems that, through controlled, specific, and minute karyotypic changes during ontogeny, could control patterns of development in plants and animals, integrating different levels of organization. The deeper implications for development and evolution are illustrated, suggesting a new paradigm

Functional significance of sequences following the TATA box of an immunoglobulin promoter studied by random mutagenesis

AbstractWe have investigated the importance of sequences downstream to the TATA box or an immunoglobulin promoter by transfection and in vitro transcription assays. A sequence from −11 to +10 with respect to the transcriptional start site was synthsised by a procedure allowing for random misincorporation of nucleotides. The pool of mutant oligonucleotides was cloned into the respective position of a vector carrying a fusion of a synthetic immunoglobulin heavy chain promoter with the human growth hormone gene. From 200 clones sequenced, 115 were mutants with at least one nucleotide exchange in every position. Whereas most mutations are of minor functional importance, changes at or near the transcriptional start site reduce the promoter activity considerably

Physical Characteristics and Classification of the Large Amplitude Variable Star V1719 Cygni

Pulsating stars are used as standard candles which are helpful in determining distances to stellar objects along with the relationship between their period and apparent luminosity. The focus of this study was the variable star, V1719 Cygni, which is often classified as a Delta (δ) Scuti star, but there exists debate that it should be classified as a RR Lyrae star due to its abnormal light curve and similar characteristics between the two variable star categories. Observational data was taken in 2019 using the Las Cumbres Observatory international telescope network. The resulting data were calibrated using comparison stars in the field of known magnitude. We performed aperture photometry in the V-, B-, i- and z- photometric bands. The period was then found using the string method which determines the most probable period. The average period was found to be 0.269 days with an error of 0.0005. The distance was calculated using the previously established period-luminosity relation for both δ Scuti and RR Lyrae stars to determine which classification fits our data best. The distance calculation was more closely aligned with previous results when using the δ Scuti relationship as compared to the RR Lyrae relationship. Based on these results, we conclude that V1719 Cygni should be classified as a high-amplitude δ Scuti variable star. It is important to note that period-luminosity relationships have not been established in all photometric bands, but the period measurements obtained in the B-, i-, and z- bands will help to establish that relationship

Impact of DNA ligase IV on the fidelity of end joining in human cells

A DNA ligase IV (LIG4)‐null human pre‐B cell line and human cell lines with hypomorphic mutations in LIG4 are significantly impaired in the frequency and fidelity of end joining using an in vivo plasmid assay. Analysis of the null line demonstrates the existence of an error‐prone DNA ligase IV‐independent rejoining mechanism in mammalian cells. Analysis of lines with hypomorphic mutations demonstrates that residual DNA ligase IV activity, which is sufficient to promote efficient end joining, nevertheless can result in decreased fidelity of rejoining. Thus, DNA ligase IV is an important factor influencing the fidelity of end joining in vivo. The LIG4‐defective cell lines also showed impaired end joining in an in vitro assay using cell‐free extracts. Elevated degradation of the terminal nucleotide was observed in a LIG4‐defective line, and addition of the DNA ligase IV–XRCC4 complex restored end protection. End protection by DNA ligase IV was not dependent upon ligation. Finally, using purified proteins, we demonstrate that DNA ligase IV–XRCC4 is able to protect DNA ends from degradation by T7 exonuclease. Thus, the ability of DNA ligase IV–XRCC4 to protect DNA ends may contribute to the ability of DNA ligase IV to promote accurate rejoining in vivo

Exiles and Migrants in Oceania

Humanities Open Book Program, a joint initiative of the National Endowment for the Humanities and the Andrew W. Mellon FoundationThe cultural and social consequences of uprooting island populations are the principal concerns of the anthropologists contributing to this first comparative study of resettled communities. The ten communities chosen for study include migrant groups like the Rotumans in Fiji as well as relocated ones like the people of Bikini Atoll or the Tikopia in the Russell Islands