184 research outputs found
Floristic Checklist From An Atlantic Forest Vegetation Mosaic In Reserva Particular Do PatrimĂ´nio Natural Fazenda Tabatinga, Pernambuco, Brazil
Conselho Nacional de Desenvolvimento CientĂfico e TecnolĂłgico (CNPq)A floristic inventory was made in the Reserva Particular do PatrimĂ´nio Natural Fazenda Tabatinga to show the importance of small forest fragments for conservation of the biodiversity of the Atlantic Forest. The reserve protects a vegetation mosaic typical of coastal habitats in an area of ​ca. 20 ha, located in the northern part of the Brazilian Atlantic Forest. Samples of vascular plants were collected between January 2010 and November 2011, and altogether 329 species were recorded. These are classified in 230 genera and 79 families of angiosperms and two genera and two families of ferns. Among the species found, 28 are endemic to the Atlantic Forest, while others are rare and restricted to the Pernambuco Endemism Center. In addition, three threatened species were detected. The presence of endemic, rare, and threatened species, along with floristic patterns typical of coastal areas of Brazil, reinforce the importance of the area for the conservation. © 2016 Check List and Authors.126BMBF, Bundesministerium fĂĽr Bildung und ForschungCNPq, Conselho Nacional de Desenvolvimento CientĂfico e TecnolĂłgicoDEB-0946618, NSF, National Science FoundationConselho Nacional de Desenvolvimento CientĂfico e TecnolĂłgico (CNPq
Energy relaxation of an excited electron gas in quantum wires: many-body electron LO-phonon coupling
We theoretically study energy relaxation via LO-phonon emission in an excited
one-dimensional electron gas confined in a GaAs quantum wire structure. We find
that the inclusion of phonon renormalization effects in the theory extends the
LO-phonon dominated loss regime down to substantially lower temperatures. We
show that a simple plasmon-pole approximation works well for this problem, and
discuss implications of our results for low temperature electron heating
experiments in quantum wires.Comment: 10 pages, RevTex, 4 figures included. Also available at
http://www-cmg.physics.umd.edu/~lzheng
In vitro inhibition of Helicobacter pylori and interaction studies of lichen natural products with jack bean urease
The interaction of (S)-(-)-usnic acid (2) and fumarprotocetraric acid (3), isolated from Cladonia rappii (lichen), and commercial (R)-(+)-usnic acid (1) with urease was investigated in vitro by molecular spectroscopy at pH 7.4 and kinetics experiments using jack bean type III urease. All lichen compounds tested interact with urease by a statistical quenching mechanism forming non-fluorescent complexes that change the native protein structure. Formation of complexes was spontaneous and stabilized mainly by electrostatic forces, in which the interaction magnitude was determined to be 3 < 2 < 1. Compound 2, whose tridimensional structure is disclosed here, acts as a mixed inhibitor while compounds 1 and 3 function as competitive ones. The (R)-(+)-UA (1) is the most efficient lichen metabolite with respect to impairment of the growth of five H. pylori strains. The minimum inhibitory concentrations (MIC) for the lichen metabolites tested were lower (from 2- to 7.8-fold) than those of omeprazole (reference drug) against all H. pylori strains tested. Overall, the lichen metabolites 1-3 are promising lead compounds for the design of more efficient urease inhibitors for the treatment of H. pylori infections
Challenging SO(10) SUSY GUTs with family symmetries through FCNC processes
We perform a detailed analysis of the SO(10) SUSY GUT model with D3 family
symmetry of Dermisek and Raby (DR). The model is specified in terms of 24
parameters and predicts, as a function of them, the whole MSSM set of
parameters at low energy scales. Concerning the SM subset of such parameters,
the model is able to give a satisfactory description of the quark and lepton
masses, of the PMNS matrix and of the CKM matrix. We perform a global fit to
the model, including flavour changing neutral current (FCNC) processes Bs -->
mu+ mu-, B --> Xs gamma, B --> Xs l+ l- and the B(d,s) - bar B(d,s) mass
differences Delta M(d,s) as well as the flavour changing (FC) process B+ -->
tau+ nu. These observables provide at present the most sensitive probe of the
SUSY mass spectrum and couplings predicted by the model. Our analysis
demonstrates that the simultaneous description of the FC observables in
question represents a serious challenge for the DR model, unless the masses of
the scalars are moved to regions which are problematic from the point of view
of naturalness and probably beyond the reach of the LHC. We emphasize that this
problem could be a general feature of SUSY GUT models with third generation
Yukawa unification and weak-scale minimal flavour violation.Comment: 1 + 37 pages, 5 figures, 11 tables. v3: minor typos fixed. Matches
JHEP published versio
Search for W' bosons decaying to an electron and a neutrino with the D0 detector
This Letter describes the search for a new heavy charged gauge boson W'
decaying into an electron and a neutrino. The data were collected with the D0
detector at the Fermilab Tevatron proton-antiproton Collider at a
center-of-mass energy of 1.96 TeV, and correspond to an integrated luminosity
of about 1 inverse femtobarn. Lacking any significant excess in the data in
comparison with known processes, an upper limit is set on the production cross
section times branching fraction, and a W' boson with mass below 1.00 TeV can
be excluded at the 95% C.L., assuming standard-model-like couplings to
fermions. This result significantly improves upon previous limits, and is the
most stringent to date.Comment: submitted to Phys. Rev. Let
Measurement of the ratios of the Z/G* + >= n jet production cross sections to the total inclusive Z/G* cross section in ppbar collisions at sqrt(s) = 1.96 TeV
We present a study of events with Z bosons and jets produced at the Fermilab
Tevatron Collider in ppbar collisions at a center of mass energy of 1.96 TeV.
The data sample consists of nearly 14,000 Z/G* -> e+e- candidates corresponding
to the integrated luminosity of 0.4 fb-1 collected using the D0 detector.
Ratios of the Z/G* + >= n jet cross sections to the total inclusive Z/G* cross
section have been measured for n = 1 to 4 jet events. Our measurements are
found to be in good agreement with a next-to-leading order QCD calculation and
with a tree-level QCD prediction with parton shower simulation and
hadronization.Comment: 7 pages, 2 figures, slightly modified, submitted to Phys. Lett.
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