Search results for "Tree"
showing 10 items of 1841 documents
An Efficient Distributed Algorithm for Generating Multicast Distribution Trees
2005
Multicast transmission may use network resources more efficiently than multiple point-to-point messages; however, creating optimal multicast trees (Steiner Tree Problem in Networks) is prohibitively expensive. For this reason, heuristic methods are generally employed. Conventional centralized Steiner heuristics provide effective solutions, but they are unpractical for large networks, since they require complete knowledge of the network topology. This paper proposes a distributed algorithm for the heuristic solution of the Steiner Tree Problem. The algorithm allows the construction of effective distribution trees using a coordination protocol among the network nodes. The algorithm has been i…
Aging in Sponges
2003
The sponges (phylum Porifera) are the lowest and phylogenetically oldest, still extant phylum of Metazoa [1, 2]. These animals are considered as the evolutionary earliest living relicts of the successful transition from the (perhaps) unicellular to the multicellular state [2]. Evidence has been presented by molecular phylogenetic analysis that sponges share a common ancestor with the other metazoan phyla, the hypothetical Urmetazoa [2, 3].
Standardizing the analysis of conditioned fear in rodents: a multidimensional software approach
2013
Data comparability between different laboratories strongly depends on the individually applied analysis method. This factor is often a critical source of variation in rodent phenotyping and has never been systematically investigated in Pavlovian fear conditioning paradigms. In rodents, fear is typically quantified in terms of freezing duration via manual observation or automated systems. While manual analysis includes biases such as tiredness or inter-personal scoring variability, computer-assisted systems are unable to distinguish between freezing and immobility. Consequently, the novel software called MOVE follows a semi-automatized approach that prefilters video sequences of interest for…
Effect of water level and climatic factors on the radial growth of black alder
2011
Effect of water level and climatic factors on the radial growth of black alder Black alder (Alnus glutinosa (L.) Gaertn.) is a widespread tree species in Europe and the western part of the temperate climate zone. The area of forest in Latvia dominated by this tree species has substantially decreased due to wide-spread forest drainage. To predict future changes due to environmental change, it is extremely important to understand the function of ecosystems with black alder and their dynamics. Tree rings can be used as a proxy of past environmental factors. The aim of the study was to determine the effects of meteorological and hydrological factors on radial growth of black alder at two study …
New insights into non-avian dinosaur reproduction and their evolutionary and ecological implications: linking fossil evidence to allometries of extan…
2013
It has been hypothesized that a high reproductive output contributes to the unique gigantism in large dinosaur taxa. In order to infer more information on dinosaur reproduction, we established allometries between body mass and different reproductive traits (egg mass, clutch mass, annual clutch mass) for extant phylogenetic brackets (birds, crocodiles and tortoises) of extinct non-avian dinosaurs. Allometries were applied to nine non-avian dinosaur taxa (theropods, hadrosaurs, and sauropodomorphs) for which fossil estimates on relevant traits are currently available. We found that the reproductive traits of most dinosaurs conformed to similar-sized or scaled-up extant reptiles or birds. The …
Statistical Multivariate Techniques for the Stock Location Assignment Problem
1998
In previous papers we proposed to apply multivariate statistical methodologies, like Multidimensional Scaling (MDS) and Seriation to the stock location assignment problem of a warehouse, often solved by considering the Cube per Order Index (COI). In this paper we compare the results by MDS, Seriation, a COI based method and the Maximum Path criterion, considering the data of a whole year of a Sicilian supermarket chain warehouse. The comparison is based on the simulated times to satisfy a sample of real orders.
Four new Candida cretensis strains isolated from Spanish fermented sausages (chorizo): Taxonomic and phylogenetic implications
2008
Four yeast strains were isolated from Spanish traditional fermented sausages (chorizo) spoiled by gas production. Using the classical identification procedures, they were identified as Debaryomyces hansenii. However, they fermented galactose and did not produce positive results in Debaryomyces differential medium (DDM), a growth medium highly specific for this species. Phylogenetic analysis showed identical sequences for the D1/D2 domain of the 26S rRNA gene and almost identical sequences for the 5.8S-ITS region with those of the recently described yeast species Candida cretensis. This result was confirmed by sequencing the gene encoding actin of the type and the new strains. Candida creten…
Lactobacillus uvarum sp. nov. - A new lactic acid bacterium isolated from Spanish Bobal grape must
2008
Five strains isolated from grape musts in Spain in 1997, have been characterized by several molecular techniques, and three of them have been identified as pertaining to a new species. All strains are Gram-positive rods, aerotolerant and homofermentative bacteria that do not exhibit catalase activity. Phylogenetic analysis based on 16S rRNA gene sequences placed these strains within the genus Lactobacillus, closely related to Lactobacillus mali. DNA-DNA hybridization experiments confirmed that strain 71 belongs to the lately described species L. satsumensis, strain 88 belongs to L. mali and the other three isolates have an independent status at species level. Restriction analysis of the amp…
A Grid Enabled Parallel Hybrid Genetic Algorithm for SPN
2004
This paper presents a combination of a parallel Genetic Algorithm (GA) and a local search methodology for the Steiner Problem in Networks (SPN). Several previous papers have proposed the adoption of GAs and others metaheuristics to solve the SPN demonstrating the validity of their approaches. This work differs from them for two main reasons: the dimension and the features of the networks adopted in the experiments and the aim from which it has been originated. The reason that aimed this work was namely to assess deterministic and computationally inexpensive algorithms which can be used in practical engineering applications, such as the multicast transmission in the Internet. The large dimen…
Adaptive trends of sequence compositional complexity over pandemic time in the SARS-CoV-2 coronavirus
2021
In the brief time since the outbreak of the COVID 19 pandemic, and despite its proofreading mechanism, the SARS-CoV-2 coronavirus has accumulated a significant amount of genetic variability through recombination and mutation events. To test evolutionary trends that could inform us on the adaptive process of the virus to its human host, we summarize all this variability in the Sequence Compositional Complexity (SCC), a measure of genome heterogeneity that captures the mutational and recombinational changes accumulated by a nucleotide sequence along time. Despite the brief time elapsed, we detected many differences in the number and length of compositional domains, as well as in their nucleot…