11,886,520 research outputs found
Genetic and morphological studies of Trichosirocalus species introduced to North America, Australia and New Zealand for the biological control of thistles
Trichosirocalus horridus sensu lato has been used as a biological control agent of several invasive thistles (Carduus spp., Cirsium spp. and Onopordum spp.) since 1974. It has been recognized as a single species until 2002, when it was split into three species based on morphological characters: T. horridus, Trichosirocalus briesei and Trichosirocalus mortadelo, each purported to have different host plants. Because of this taxonomic change, uncertainty exists as to which species were released in various countries; furthermore, there appears to be some exceptions to the purported host plants of some of these species. To resolve these questions, we conducted an integrative taxonomic study of the T. horridus species complex using molecular genetic and morphological analyses of specimens from three continents. Both mitochondrial cytochrome c oxidase subunit I and nuclear elongation factor 1α markers clearly indicate that there are only two distinct species, T. horridus and T. briesei. Molecular evidence, morphological analysis and host plant associations support the synonymy of T. horridus (Panzer, 1801) and T. mortadelo Alonso-Zarazaga & Sánchez-Ruiz, 2002. We determine that T. horridus has been established in Canada, USA, New Zealand and Australia and that T. briesei is established in Australia. The former species was collected from Carduus, Cirsium and Onopordum spp. in the field, whereas the latter appears to be specific to Onopordum
Monolithic zirconia and digital impression: case report
The aim of this study is to present a clinical case of a full arch prosthetic rehabilitation on natural teeth, combining both digital work-flow and monolithic zirconi
Weak order for the discretization of the stochastic heat equation driven by impulsive noise
Considering a linear parabolic stochastic partial differential equation
driven by impulsive space time noise, dX_t+AX_t dt= Q^{1/2}dZ_t, X_0=x_0\in H,
t\in [0,T], we approximate the distribution of X_T. (Z_t)_{t\in[0,T]} is an
impulsive cylindrical process and Q describes the spatial covariance structure
of the noise; Tr(A^{-\alpha})0 and A^\beta Q is bounded
for some \beta\in(\alpha-1,\alpha]. A discretization
(X_h^n)_{n\in\{0,1,...,N\}} is defined via the finite element method in space
(parameter h>0) and a \theta-method in time (parameter \Delta t=T/N). For
\phi\in C^2_b(H;R) we show an integral representation for the error
|E\phi(X^N_h)-E\phi(X_T)| and prove that
|E\phi(X^N_h)-E\phi(X_T)|=O(h^{2\gamma}+(\Delta t)^{\gamma}) where
\gamma<1-\alpha+\beta.Comment: 29 pages; Section 1 extended, new results in Appendix
Understanding ,
I briefly review the experimental observations concerning the charmed mesons
, and survey on some of the interpretations
proposed in order to understand their nature. I present an analysis of their
decay modes in the hypothesis that they can be identified with the scalar and
axial vector states of spectrum
(, ). The method is based on heavy quark symmetries
and Vector Meson Dominance ansatz. Comparison with present data supports the
interpretation.Comment: LaTex, 10 pages. Invited talk at Continuous Advances in QCD 2004,
Minneapolis, Minnesota, May 13-16 200
Measurement of the multi-TeV neutrino cross section with IceCube using Earth absorption
Neutrinos interact only very weakly, so they are extremely penetrating.
However, the theoretical neutrino-nucleon interaction cross section rises with
energy such that, at energies above 40 TeV, neutrinos are expected to be
absorbed as they pass through the Earth. Experimentally, the cross section has
been measured only at the relatively low energies (below 400 GeV) available at
neutrino beams from accelerators \cite{Agashe:2014kda, Formaggio:2013kya}. Here
we report the first measurement of neutrino absorption in the Earth, using a
sample of 10,784 energetic upward-going neutrino-induced muons observed with
the IceCube Neutrino Observatory. The flux of high-energy neutrinos transiting
long paths through the Earth is attenuated compared to a reference sample that
follows shorter trajectories through the Earth. Using a fit to the
two-dimensional distribution of muon energy and zenith angle, we determine the
cross section for neutrino energies between 6.3 TeV and 980 TeV, more than an
order of magnitude higher in energy than previous measurements. The measured
cross section is (stat.) (syst.)
times the prediction of the Standard Model \cite{CooperSarkar:2011pa},
consistent with the expectation for charged and neutral current interactions.
We do not observe a dramatic increase in the cross section, expected in some
speculative models, including those invoking new compact dimensions
\cite{AlvarezMuniz:2002ga} or the production of leptoquarks
\cite{Romero:2009vu}.Comment: Preprint version of Nature paper 10.1038/nature2445
The gamma-ray burst monitor for Lobster-ISS
Lobster-ISS is an X-ray all-sky monitor experiment selected by ESA two years
ago for a Phase A study (now almost completed) for a future flight (2009)
aboard the Columbus Exposed Payload Facility of the International Space
Station. The main instrument, based on MCP optics with Lobster-eye geometry,
has an energy passband from 0.1 to 3.5 keV, an unprecedented daily sensitivity
of 2x10^{-12} erg cm^{-2}s$^{-1}, and it is capable to scan, during each orbit,
the entire sky with an angular resolution of 4--6 arcmin. This X-ray telescope
is flanked by a Gamma Ray Burst Monitor, with the minimum requirement of
recognizing true GRBs from other transient events. In this paper we describe
the GRBM. In addition to the minimum requirement, the instrument proposed is
capable to roughly localize GRBs which occur in the Lobster FOV (162x22.5
degrees) and to significantly extend the scientific capabilities of the main
instrument for the study of GRBs and X-ray transients. The combination of the
two instruments will allow an unprecedented spectral coverage (from 0.1 up to
300/700 keV) for a sensitive study of the GRB prompt emission in the passband
where GRBs and X-Ray Flashes emit most of their energy. The low-energy spectral
band (0.1-10 keV) is of key importance for the study of the GRB environment and
the search of transient absorption and emission features from GRBs, both goals
being crucial for unveiling the GRB phenomenon. The entire energy band of
Lobster-ISS is not covered by either the Swift satellite or other GRB missions
foreseen in the next decade.Comment: 6 pages, 4 figures. Paper presented at the COSPAR 2004 General
Assembly (Paris), accepted for publication in Advances in Space Research in
June 2005 and available on-line at the Journal site
(http://www.sciencedirect.com/science/journal/02731177), section "Articles in
press
The nonexistence of regular near octagons with parameters (s, t, t(2), t(3)) = (2,24,0,8)
Let S be a regular near octagon with s + 1 = 3 points per line, let t + 1 denote the constant number of lines through a given point of S and for every two points x and y at distance i is an element of {2, 3} from each other, let t(i) + 1 denote the constant number of lines through y containing a (necessarily unique) point at distance i - 1 from x. It is known, using algebraic combinatorial techniques, that (t(2), t(3), t) must be equal to either (0, 0, 1), (0, 0, 4), (0, 3, 4), (0, 8, 24), (1, 2, 3), (2, 6, 14) or (4, 20, 84). For all but one of these cases, there is a unique example of a regular near octagon known. In this paper, we deal with the existence question for the remaining case. We prove that no regular near octagons with parameters (s, t, t(2), t(3)) = (2, 24, 0, 8) can exist
Antimicrobials: a global alliance for optimizing their rational use in intra-abdominal infections (AGORA)
Intra-abdominal infections (IAI) are an important cause of morbidity and are frequently associated with poor prognosis, particularly in high-risk patients. The cornerstones in the management of complicated IAIs are timely effective source control with appropriate antimicrobial therapy. Empiric antimicrobial therapy is important in the management of intra-abdominal infections and must be broad enough to cover all likely organisms because inappropriate initial antimicrobial therapy is associated with poor patient outcomes and the development of bacterial resistance. The overuse of antimicrobials is widely accepted as a major driver of some emerging infections (such as C. difficile), the selection of resistant pathogens in individual patients, and for the continued development of antimicrobial resistance globally. The growing emergence of multi-drug resistant organisms and the limited development of new agents available to counteract them have caused an impending crisis with alarming implications, especially with regards to Gram-negative bacteria. An international task force from 79 different countries has joined this project by sharing a document on the rational use of antimicrobials for patients with IAIs. The project has been termed AGORA (Antimicrobials: A Global Alliance for Optimizing their Rational Use in Intra-Abdominal Infections). The authors hope that AGORA, involving many of the world's leading experts, can actively raise awareness in health workers and can improve prescribing behavior in treating IAIs
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