2,728 research outputs found
Assessing statistical significance of periodogram peaks
The least-squares (or Lomb-Scargle) periodogram is a powerful tool which is
used routinely in many branches of astronomy to search for periodicities in
observational data. The problem of assessing statistical significance of
candidate periodicities for different periodograms is considered. Based on
results in extreme value theory, improved analytic estimations of false alarm
probabilities are given. They include an upper limit to the false alarm
probability (or a lower limit to the significance). These estimations are
tested numerically in order to establish regions of their practical
applicability.Comment: 7 pages, 6 figures, 1 table; To be published in MNRA
Variation and Heritability of Phenology in the Fungus Monilinia vaccinii-corymbosi on Blueberry
The germination of field-collected pseudosclerotia and the development of apothecia from eight New Jersey populations of the mummy berry fungus Monilinia vaccinii-corymbosi were evaluated under controlled conditions in the greenhouse. Development data for apothecia were used to describe the timing of apothecium formation and to estimate broad- and narrow-sense heritabilities of fungal phenology. Mean development times for the formation of apothecia ranged from 35.4 to 54.7 days. The mean development times for populations collected from early-season cv. Weymouth ranged from 35.4 to 39.6 days and were significantly shorter than the development times for three of the four populations collected from late-season cv. Jersey (46.9 to 54.7 days) or for the population collected from mixed stands of cultivated blueberries (42.7 days). The development of populations from late cultivars planted in very close proximity to early cv. Weymouth was early (36.5 to 39.0 days) and not significantly different from the development of populations collected from cv. Weymouth. Phenotypic and genetic variances of apothecium development for individual populations ranged from 18.9 to 44.8 and 7.2 to 30.9, respectively. Broad-sense heritabilities of apothecia development for each fungal population, calculated by partitioning phenotypic variation into genetic and environmental components, ranged from 0.31 to 0.78. Narrow-sense heritabilities of apothecia development, based on parent-offspring regression, ranged from 0.58 to 0.78. These results indicate that populations ofM. vaccinii-corymbosi differ in phenology and that a significant portion of the phenological variation within populations is genetic. Thus, it is plausible to propose that the phenology of apothecium development is a component of fungal fitness and that host phenology can influence the timing of pathogen development
Phenology of Apothecium Production in Populations of Monilinia vaccinii-corymbosi from Early- and Late-Maturing Blueberry Cultivars
Pseudosclerotia were evaluated for differences in timing of apothecium development in four controlled experiments conducted over a 2-year period. In a separate experiment, conidia from 10 randomly selected isolates from both of the fungal populations were used to inoculate open flowers. Germination of pseudosclerotia produced from these artificial inoculations also was evaluated. The timing and rate of shoot elongation for cvs. Weymouth and Jersey were assessed in one greenhouse and two field experiments. Average development times for the fungal population from cv. Weymouth were 8 to 15 days earlier or 33 to 42% less than those for the population from cv. Jersey. The fungal population from Weymouth also exhibited less variation in development times for each developmental stage measured. Similarly, germination of pseudosclerotia produced in artificial inoculations differed between populations. On average, pseudosclerotia derived from the Weymouth population produced apothecia 16 days earlier. During spring 1995 and 1996, vegetative and truss buds on cv. Weymouth developed 4 to 16 days earlier than those on cv. Jersey. These results demonstrate that M. vaccinii-corymbosi exhibits variation in timing of pseudosclerotia germination and apothecium development within and between populations. We hypothesize that differences observed in the timing of apothecium development are related to the fitness of the populations on their original host cultivars and were selected by host phenolog
Host Resistance to Monilinia vaccinii-corymbosi in Flowers and Fruits of Highbush Blueberry
Monilinia vaccinii-corymbosi, the causal agent of mummy berry disease, infects blueberry flowers via the gynoecial pathway. To describe the expression of host resistance in highbush blueberry (Vaccinium corymbosum), fungal growth in the styles and colonization of the locules were compared among five blueberry cultivars in a series of controlled greenhouse experiments. Styles were harvested 1 and 4 days postinoculation, and the length colonized by hyphae was determined using fluorescence microscopy. At 8 weeks after inoculation, fruit were harvested and scored for the presence of hyphae in the locules. The infection frequency of styles ranged from 0.33 to 0.71, and only cv. Weymouth had significantly lower infection frequency than the other cultivars. The mean length of the colonized portion of the stylar canal ranged from 0.126 to 0.434 mm after 1 day and 1.62 to 3.59 mm after 4 days. Hyphae in the styles of cv. Weymouth exhibited the least growth, whereas hyphae in the styles of cultivars Jersey and Rancocas were significantly longer. The distance of style penetrated for cultivars Bluecrop and Coville was intermediate. The mean disease incidence of locules differed significantly. Values for cultivars Weymouth and Jersey were the smallest (0.038 and 0.039) and largest (0.249 and 0.236), respectively. The results demonstrate that a component of resistance to infection by M. vaccinii-corymbosi is expressed during growth in the gynoecial pathway
Transport properties of anyons in random topological environments
The quasi one-dimensional transport of Abelian and non-Abelian anyons is
studied in the presence of a random topological background. In particular, we
consider the quantum walk of an anyon that braids around islands of randomly
filled static anyons of the same type. Two distinct behaviours are identified.
We analytically demonstrate that all types of Abelian anyons localise purely
due to the statistical phases induced by their random anyonic environment. In
contrast, we numerically show that non-Abelian Ising anyons do not localise.
This is due to their entanglement with the anyonic environment that effectively
induces dephasing. Our study demonstrates that localisation properties strongly
depend on non-local topological interactions and it provides a clear
distinction in the transport properties of Abelian and non-Abelian statistics.Comment: 9 pages, 5 figure
Optimal strategies of radial velocity observations in planet search surveys
Applications of the theory of optimal design of experiments to radial
velocity planet search surveys are considered. Different optimality criteria
are discussed, basing on the Fisher, Shannon, and Kullback-Leibler
informations. Algorithms of optimal scheduling of RV observations for two
important practical problems are considered. The first problem is finding the
time for future observations to yield the maximum improvement of the precision
of exoplanetary orbital parameters and masses. The second problem is finding
the most favourable time for distinguishing alternative orbital fits (the
scheduling of discriminating observations).
These methods of optimal planning are demonstrated to be potentially
efficient for multi-planet extrasolar systems, in particular for resonant ones.
In these cases, the optimal dates of observations are often concentrated in
quite narrow time segments.Comment: 8 pages, 2 figures, no tables, Accepted to MNRA
An annotated list of the Lepidoptera of Honduras
A biodiversity inventory of the Lepidoptera of Pico Bonito National Park and vicinity, in the Department of Atlantida of northern Honduras, was initiated in 2009 to obtain baseline data. We present a revised checklist of Honduran butterfly species (updated from the initial 1967 lists), as well as the first comprehensive list of Honduran moths. Our updated list includes 550 species of Papilionoidea, 311 Hesperioidea, and 1,441 moth species
An annotated list of the Lepidoptera of Honduras
A biodiversity inventory of the Lepidoptera of Pico Bonito National Park and vicinity, in the Department of Atlantida of northern Honduras, was initiated in 2009 to obtain baseline data. We present a revised checklist of Honduran butterfly species (updated from the initial 1967 lists), as well as the first comprehensive list of Honduran moths. Our updated list includes 550 species of Papilionoidea, 311 Hesperioidea, and 1,441 moth species
On Hilberg's Law and Its Links with Guiraud's Law
Hilberg (1990) supposed that finite-order excess entropy of a random human
text is proportional to the square root of the text length. Assuming that
Hilberg's hypothesis is true, we derive Guiraud's law, which states that the
number of word types in a text is greater than proportional to the square root
of the text length. Our derivation is based on some mathematical conjecture in
coding theory and on several experiments suggesting that words can be defined
approximately as the nonterminals of the shortest context-free grammar for the
text. Such operational definition of words can be applied even to texts
deprived of spaces, which do not allow for Mandelbrot's ``intermittent
silence'' explanation of Zipf's and Guiraud's laws. In contrast to
Mandelbrot's, our model assumes some probabilistic long-memory effects in human
narration and might be capable of explaining Menzerath's law.Comment: To appear in Journal of Quantitative Linguistic
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