53,832 research outputs found
A North American Record for \u3ci\u3eValgus Hemipterus\u3c/i\u3e (Coleoptera: Scarabaeidae) and Information on its Life Cycle
A rotting American elm log containing adults of Valgus hemipterus (L.) was discovered on 6 May 1980, at the Rose Lake Wildlife Experiment Station, Shiawassee County, Michigan. This appears to be the first record of this European species in North America. Larvae were collected in the summer, and pupae and teneral adults in the early fall suggesting a univoltine life cycle with the adults overwintering
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U.S. International Corporate Taxation: Basic Concepts and Policy Issues
Recent deficit reduction and tax reform plans have included broad proposals to reform the U.S. international corporate tax system. These proposals have raised concerns over how changing the way American multi-national corporations are taxed could impact the deficit and debt, domestic job markets, competitiveness, and the use of corporate tax havens, among other things. An informed debate about how to reform the system governing the taxation of U.S. multi-national corporations requires careful consideration of these issues, as well as a basic understanding of several features of the current system.
This report provides a general introduction to the basic concepts and issues relevant to the U.S. international corporate tax system. The explanations provided in this report emphasize the underlying concepts of the international tax system and are intended to be as simplified as possible. There are of course important and complex technical details that would need to be considered carefully if reform of the current system were to be implemented effectively and efficiently. These important technical details, however, are beyond the scope of this report. Where appropriate, references to other CRS products are provided within the report. A list of related CRS products and other suggested readings on international corporate taxation may also be found at the end of the report
Mutations in the PERIANTHIA gene of Arabidopsis specifically alter floral organ number and initiation pattern
An open question in developmental biology is how groups of dividing cells can generate specific numbers of segments or organs. We describe the phenotypic effects of mutations in PERIANTHIA, a gene specifically required for floral organ patterning in Arabidopsis thaliana. Most wild-type Arabidopsis flowers have 4 sepals, 4 petals, 6 stamens, and 2 carpels. Flowers of perianthia mutant plants most commonly show a pentamerous pattern of 5 sepals, 5 petals 5 stamens, and 2 carpels. This pattern is characteristic of flowers in a number of plant families, but not in the family Brassicaceae, which includes Arabidopsis. Unlike previously described mutations affecting floral organ number, perianthia does not appear to affect apical or floral meristem sizes, nor is any other aspect of vegetative or floral development severely affected. Floral organs in perianthia arise in a regular, stereotypical pattern similar to that in distantly related species with pentamerous flowers. Genetic analysis shows that PERIANTHIA acts downstream of the floral meristem identity genes and independently of the floral meristem size and floral organ identity genes in establishing floral organ initiation patterns. Thus PERIANTHIA acts in a previously unidentified process required for organ patterning in Arabidopsis flowers
Fractional Cauchy problems on bounded domains
Fractional Cauchy problems replace the usual first-order time derivative by a
fractional derivative. This paper develops classical solutions and stochastic
analogues for fractional Cauchy problems in a bounded domain
with Dirichlet boundary conditions. Stochastic solutions
are constructed via an inverse stable subordinator whose scaling index
corresponds to the order of the fractional time derivative. Dirichlet problems
corresponding to iterated Brownian motion in a bounded domain are then solved
by establishing a correspondence with the case of a half-derivative in time.Comment: Published in at http://dx.doi.org/10.1214/08-AOP426 the Annals of
Probability (http://www.imstat.org/aop/) by the Institute of Mathematical
Statistics (http://www.imstat.org
CLAVATA3 is a specific regulator of shoot and floral meristem development affecting the same processes as CLAVATA1
We have previously described the phenotype of Arabidopsis thaliana plants with mutations at the CLAVATA1 (CLV1) locus (Clark, S. E., Running, M. P. and Meyerowitz, E. M. (1993) Development 119, 397-418). Our investigations demonstrated that clv1 plants develop enlarged vegetative and inflorescence apical meristems, and enlarged and indeterminate floral meristems. Here, we present an analysis of mutations at a separate locus, CLAVATA3(CLV3), that disrupt meristem development in a manner similar to clv1mutations. clv3 plants develop enlarged apical meristems as early as the mature embryo stage. clv3 floral meristems are also enlarged compared with wild type, and maintain a proliferating meristem throughout flower development. clv3 root meristems are unaffected, indicating that CLV3 is a specific regulator of shoot and floral meristem development. We demonstrate that the strong clv3-2 mutant is largely epistatic to clv1 mutants, and that the semi-dominance of clv1 alleles is enhanced by double heterozygosity with clv3 alleles, suggesting that these genes work in the same pathway to control meristem development. We propose that CLV1 and CLV3 are required to promote the differentiation of cells at the shoot and floral meristem
Some Calculable Contributions to Entanglement Entropy
Entanglement entropy appears as a central property of quantum systems in
broad areas of physics. However, its precise value is often sensitive to
unknown microphysics, rendering it incalculable. By considering parametric
dependence on correlation length, we extract finite, calculable contributions
to the entanglement entropy for a scalar field between the interior and
exterior of a spatial domain of arbitrary shape. The leading term is
proportional to the area of the dividing boundary; we also extract finite
subleading contributions for a field defined in the bulk interior of a
waveguide in 3+1 dimensions, including terms proportional to the waveguide's
cross-sectional geometry; its area, perimeter length, and integrated curvature.
We also consider related quantities at criticality and suggest a class of
systems for which these contributions might be measurable.Comment: 4+ pages, 1 figure. v2: Some clarifications and more references;
updated to resemble version published in PR
TSO1 functions in cell division during Arabidopsis flower development
We describe an Arabidopsis mutant, tso1, which develops callus-like tissues in place of floral organs. The tso1 floral meristem lacks properly organized three cell layers, and the nuclei of these cells are irregular in size and shape. Further analyses reveal partially formed cell walls and increased DNA ploidy in tso1 floral meristem cells, indicating defects in mitosis and cytokinesis. Our finding that TSO1 is required for organ formation in floral tissues but not in other tissues indicates that TSO1 may encode a floral-specific cell division component, or that TSO1 function is redundant in nonfloral tissues
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