9,591 research outputs found
Fisher matrix forecasts for astrophysical tests of the stability of the fine-structure constant
We use Fisher Matrix analysis techniques to forecast the cosmological impact
of astrophysical tests of the stability of the fine-structure constant to be
carried out by the forthcoming ESPRESSO spectrograph at the VLT (due for
commissioning in late 2017), as well by the planned high-resolution
spectrograph (currently in Phase A) for the European Extremely Large Telescope.
Assuming a fiducial model without variations, we show that ESPRESSO
can improve current bounds on the E\"{o}tv\"{o}s parameter---which quantifies
Weak Equivalence Principle violations---by up to two orders of magnitude,
leading to stronger bounds than those expected from the ongoing tests with the
MICROSCOPE satellite, while constraints from the E-ELT should be competitive
with those of the proposed STEP satellite. Should an variation be
detected, these measurements will further constrain cosmological parameters,
being particularly sensitive to the dynamics of dark energy.Comment: Phys. Lett. B (in press
The Asymptotics of Wilkinson's Iteration: Loss of Cubic Convergence
One of the most widely used methods for eigenvalue computation is the
iteration with Wilkinson's shift: here the shift is the eigenvalue of the
bottom principal minor closest to the corner entry. It has been a
long-standing conjecture that the rate of convergence of the algorithm is
cubic. In contrast, we show that there exist matrices for which the rate of
convergence is strictly quadratic. More precisely, let be the matrix having only two nonzero entries and let
be the set of real, symmetric tridiagonal matrices with the same spectrum
as . There exists a neighborhood of which is
invariant under Wilkinson's shift strategy with the following properties. For
, the sequence of iterates exhibits either strictly
quadratic or strictly cubic convergence to zero of the entry . In
fact, quadratic convergence occurs exactly when . Let be
the union of such quadratically convergent sequences : the set has
Hausdorff dimension 1 and is a union of disjoint arcs meeting at
, where ranges over a Cantor set.Comment: 20 pages, 8 figures. Some passages rewritten for clarit
A Nuclear Physics Program at the ATLAS Experiment at the CERN Large Hadron Collider
The ATLAS collaboration has significant interest in the physics of
ultra-relativistic heavy ion collisions. We submitted a Letter of Intent to the
United States Department of Energy in March 2002. The following document is a
slightly modified version of that LOI. More details are available at:
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/SM/ionsComment: Letter of Intent submitted to the United States Department of Energy
Nuclear Physics Division in March 2002 (revised version
Avaliação de duas espécies de fungos entomopatogênicos para o controle de Hedypathes betulinus (KLUG, 1825) (Coleoptera: Cerambycidae), em laboratório.
A broca-da- erva-mate Hedypathes betulinus (Klug), é a principal praga da cultura da erva-mate e para o seu controle, estudou-se em laboratório, a utilização de fungos entomopatogênicos. Foi avaliada a infectividade dos fungos Beauveria bassiana (Bals) Vuill. e Paecilomyces sp. Bainier, em adultos de H. betulinus, em laboratório. Os fungos foram aplicados na concentração de 107esporos/ml, em galhos de erva-mate ofertados como alimento ao inseto adulto. Verificou-se que B. bassiana (CG 716) foi mais infectivo que Paecilomyces sp., apresentando mortalidade de 97,5 e 37,5%, respectivamente. Foi avaliada a eficiência da cepa B. bassiana CG 716 nas concentrações de 106 e 107esporos/ml e verificou-se que não ocorreu diferença significativa entre as concentrações, obtendo-se mortalidade de 100 e 96,6%, na concentração de 106 e 107esporos/ml, respectivamente.Seção: Manejo e Extensão. Feira do Agronegócio da Erva-mate, 1., 2003, Chapecó. Integrar para promover o agronegócio da erva-mate
Multiple versus single arterial grafting in coronary artery bypass grafting:A meta-analysis of randomized controlled trials and propensity score studies
Cambio climatico y plagas forestales: el caso de la procesionaria del pino en el noreste de Portugal
The pine processionary moth, Thaumetopoea pityocampa (Den. & Schiff.) (Lep., Thaumetopoeidae) is known as the most defoliating insect in Pinus and Cedrus in many countries. In the last three decades, climate change has led to a substantial expansion of its range and high attack rates in previously unaffected areas were observed. A 3-year analysis of the effect of several climatic elements on the T. pityocampa adult emergence was made and one climatic change scenario was tested in order to predict the insect’s behaviour in the future. Results showed that mean air temperature was the climatic element with the best single regression fit to adult emergence, whereas minimum air temperature and relative humidity provided the best multiple regression fits. Results also demonstrated that higher emergence of adults is often related to a maximum temperature above 30°C, a mean temperature above 23°C, a minimum temperature above 17°C, relative humidity lower than 60% and precipitation values lower than 10 mm. Using the same thresholds for future climatic conditions simulated by the COSMO-CLM model, the period for pine processionary moth emergence will be expanded, starting much sooner. Contrasting with the actual emergence period, the insect is projected to have favorable climatic conditions to start emerging in May. This might have serious implications in forest ecosystems, concerning not only ecological issues, but also forest management.La procesionaria del pino, Thaumetopoea pityocampa (Den. & Schiff.) (Lep., Thaumetopoeidae), es conocido en muchos
países como el insecto más defoliador de Pinus y Cedrus. En las últimas tres décadas el cambio climático ha originado
una considerable expansión de su rango de distribución y aumentado la proporción de ataques en áreas previamente
no atacadas. Durante tres años fue realizada una monitorización de los efectos de diversos elementos climáticos sobre
la emergencia de los adultos de T. pityocampa y un escenario de cambio climático fue testado con el fin de predecir el
comportamiento de los insectos en el futuro. Los resultados revelan que la temperatura media del aire es el elemento climático
que más contribuye en la regresión simple para explicar la emergencia de adultos, seguidos de la temperatura mínima
del aire y la humedad relativa. Nuestros resultados también demostraron que el aumento de emergencia de adultos
estaba a menudo relacionado con temperaturas máximas superiores a 30°C, temperatura media por encima de los 23°C,
temperatura mínima por encima de 17°C, humedad relativa inferior al 60% y valores de precipitación inferiores a los 10
mm. Atendiendo a los resultados para eses umbrales climáticos y el modelo de CLM, el periodo de emergencia de la procesionaria
de pino se extenderá, comenzando mucho antes. En contraste con el actual periodo de emergencia, el insecto
tendrá condiciones climáticas favorables para comenzar a emerger en Mayo. Esto tendrá consecuencias graves para los
ecosistemas forestales no sólo al nivel de las cuestiones ecológicas, sino también para la gestión forestal
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