59 research outputs found
Description of a tetraploid Tomopterna (Anura: Ranidae) from South Africa
A new tetraploid species of sand frog, genus Tomopterna, is described from the eastern Cape. On the basis of mtDNA sequences, allozymes and advertisement calls, it appears to have arisen as a hybrid between the adjacent diploid populations of T. delalandii and T. cryptotis. The hybridization event is estimated to have occurred 1,5 MVA. Excluding Xenopus, this is the only allotetraploid member of an advanced frog family that is known
Measurement of the Charged Multiplicities in b, c and Light Quark Events from Z0 Decays
Average charged multiplicities have been measured separately in , and
light quark () events from decays measured in the SLD experiment.
Impact parameters of charged tracks were used to select enriched samples of
and light quark events, and reconstructed charmed mesons were used to select
quark events. We measured the charged multiplicities:
,
, from
which we derived the differences between the total average charged
multiplicities of or quark events and light quark events: and . We compared
these measurements with those at lower center-of-mass energies and with
perturbative QCD predictions. These combined results are in agreement with the
QCD expectations and disfavor the hypothesis of flavor-independent
fragmentation.Comment: 19 pages LaTex, 4 EPS figures, to appear in Physics Letters
Modeling the Subsurface Structure of Sunspots
While sunspots are easily observed at the solar surface, determining their
subsurface structure is not trivial. There are two main hypotheses for the
subsurface structure of sunspots: the monolithic model and the cluster model.
Local helioseismology is the only means by which we can investigate
subphotospheric structure. However, as current linear inversion techniques do
not yet allow helioseismology to probe the internal structure with sufficient
confidence to distinguish between the monolith and cluster models, the
development of physically realistic sunspot models are a priority for
helioseismologists. This is because they are not only important indicators of
the variety of physical effects that may influence helioseismic inferences in
active regions, but they also enable detailed assessments of the validity of
helioseismic interpretations through numerical forward modeling. In this paper,
we provide a critical review of the existing sunspot models and an overview of
numerical methods employed to model wave propagation through model sunspots. We
then carry out an helioseismic analysis of the sunspot in Active Region 9787
and address the serious inconsistencies uncovered by
\citeauthor{gizonetal2009}~(\citeyear{gizonetal2009,gizonetal2009a}). We find
that this sunspot is most probably associated with a shallow, positive
wave-speed perturbation (unlike the traditional two-layer model) and that
travel-time measurements are consistent with a horizontal outflow in the
surrounding moat.Comment: 73 pages, 19 figures, accepted by Solar Physic
Aspects of gene regulation in the diploid and tetraploid Odontophrynus americanus (Amphibia, Anura, Leptodactylidae)
Two rare aneutriploids in the unisexual <i>Ambystoma</i> (Amphibia, Caudata) identified by GISH indicating two different types of meiotic errors
Intergenomic translocations in unisexual salamanders of the genus <i>Ambystoma</i> (Amphibia, Caudata)
Estimating critical habitat based on year-round movements of the endangered Jefferson salamander (Ambystoma jeffersonianum) and their unisexual dependents
Habitat protection is a key component of endangered species conservation but critical habitat designations are often based on limited data or habitat use during only a portion of a speciesâ life cycle. Protected habitat around breeding pools for the endangered Jefferson salamander (Ambystoma jeffersonianum (Green, 1827)) and their unisexual dependants (Ambystoma laterale - (2) jeffersonianum) is based upon limited movement data from primarily spring and summer seasons. Furthermore, despite their treatment as distinct species under Canadaâs Species at Risk Act, differences in habitat use have not been directly compared in areas where they co-occur. We used radio telemetry to track A. jeffersonianum and A. laterale â jeffersonianum (LJJ and LJJJ) during fall migrations to overwintering sites. We used these data and summarized available movement data from past studies that tracked movements in other periods of the annual cycle to estimate year-round critical habitat. A. jeffersonianum travelled significantly longer distances to overwintering locations than unisexuals. Individuals were more likely to overwinter next to a similar genomotype individual than not. Critical habitat encompassing the entire annual cycle of A. jeffersonianum extends up to 400-450 m from breeding ponds indicating existing regulatory habitat protections in Canada do not currently protect sufficient habitat.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author
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