23,730 research outputs found
Trophonella (Gastropoda: Muricidae), a New Genus from Antarctic Waters, with the Description of a New Species
The new genus Trophonella is described from the outer shelf and upper continental slope of Antarcticaand islands within the Antarctic Convergence. Four previously known species that had been attributed to the genusTrophon (Trophon scotianus Powell, 1951; T. echinolamellatus Powell, 1951; T. enderbyensis Powell, 1958; and T.eversoni Houart, 1997) are included in Trophonella, as is one new species (Trophonella rugosolamellata) describedherein. Trophonella resembles Trophon in gross shell morphology: the members of both genera have large, globoseshells, paucispiral protoconchs, prominent axial lamellae, and short siphonal canals. Trophonella differs fromTrophon in having shells with evenly rounded whorls that lack a well-defined shoulder; rachidian teeth withdistinctive, broadly triangular central cusps, but that lack the marginal cusps of Trophon; characteristic sphericalaccessory salivary glands; and a circumpapillar fold on the penis that is absent in Trophon. Relationships of thegenera Trophon and Trophonella, as well as of the subfamily Trophoninae are reexamined by supplementing the datamatrix of Kool (1993b, Table 3) with data for additional taxa. Results support the segregation of Trophonella fromTrophon at the generic level. Based on the relationships of the type species of their respective nominotypical genera,Trophoninae is either the sister taxon of a narrowly circumscribed Ocenebrinae, or both are part of a larger clade. Abetter resolved phylogeny containing a much broader sampling of the more than 50 genus-level taxa that have beenattributed to these two subfamilies will be required in order to delineate more precisely the membership of the cladeand to identify its diagnostic synapomorphies.Fil: Harasewych, M. G.. National Museum of Natural History; Estados UnidosFil: Pastorino, Roberto Santiago Guido. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentin
The Transition to College Process in PR-CETP Scholars
This article describes a study about the experiences of a group of students during the transition from high school to college. The students are future teachers who evidenced a high level of academic achievement in high school and received merit scholarships from the Puerto Rico Collaborative for Excellence in Teacher Preparation (PR-CETP). Two groups of students were compared: those who sustained a high GPA during their freshman year, and those who did not and, therefore, no longer qualified for the scholarship. The study was carried out through focused interviews with eight students, from three universities, four of whom maintained the scholarship and four who did not. Findings indicate that the main problems encountered were academic and social, and that the students received support from their families during the entire process. Regarding formal support, they pointed out that they felt highly satisfied with the services provided by PR-CETP and the universities, but they also pointed out (particularly those who lost the scholarship) that they needed additional services from the universities. They suggested, for example, better tutoring, and social activities among the scholars. The interviewed students, in general, consider that they faced the transition successfully since most of them described their academic, emotional, and social status as satisfactory at the time of the interviews
Physics of Brane Kinetic Terms
Models with extra dimensions may give new effects visible at future
experiments. In these models, bulk fields can develop localized corrections to
their kinetic terms which can modify the phenomenological predictions in a
sizeable way. We review the case in which both gauge bosons and fermions
propagate in the bulk, and discuss the limits on the parameter space arising
from electroweak precision data.Comment: Presented at Matter To The Deepest: Recent Developments In Physics of
Fundamental Interactions, XXVII International Conference of Theoretical
Physics, Ustron 15-21 September 2003, Polan
Bulk fields with brane terms
In theories with branes, bulk fields get in general divergent corrections
localized on these defects. Hence, the corresponding brane terms are
renormalized and should be included in the effective theory from the very
beginning. We review the phenomenology associated to brane kinetic terms for
different spins and backgrounds, and point out that renormalization is required
already at the classical level.Comment: Presented at HEP2003, International Europhysics Conference on High
Energy Physics (July 17-23, 2003) Aachen, German
Observable contributions of new exotic quarks to quark mixing
Models with new vector-like quarks can produce observable quark mixing
effects which are forbidden in the Standard Model. We classify all such models
and write down the effective Lagrangian that results from integrating out the
new quarks. We study the relations between neutral and charged currents and
discuss how to distinguish among the different possibilities.Comment: 15 pages, 1 figure, typos corrected, version to appear in JHE
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