Modeling Heterogeneous Materials via Two-Point Correlation Functions: I. Basic Principles

Heterogeneous materials abound in nature and man-made situations. Examples include porous media, biological materials, and composite materials. Diverse and interesting properties exhibited by these materials result from their complex microstructures, which also make it difficult to model the materials. In this first part of a series of two papers, we collect the known necessary conditions on the standard two-point correlation function S2(r) and formulate a new conjecture. In particular, we argue that given a complete two-point correlation function space, S2(r) of any statistically homogeneous material can be expressed through a map on a selected set of bases of the function space. We provide new examples of realizable two-point correlation functions and suggest a set of analytical basis functions. Moreover, we devise an efficient and isotropy- preserving construction algorithm, namely, the Lattice-Point algorithm to generate realizations of materials from their two- point correlation functions based on the Yeong-Torquato technique. Subsequent analysis can be performed on the generated images to obtain desired macroscopic properties. These developments are integrated here into a general scheme that enables one to model and categorize heterogeneous materials via two-point correlation functions.Comment: 37 pages, 26 figure

Probabilistic models of information retrieval based on measuring the divergence from randomness

We introduce and create a framework for deriving probabilistic models of Information Retrieval. The models are nonparametric models of IR obtained in the language model approach. We derive term-weighting models by measuring the divergence of the actual term distribution from that obtained under a random process. Among the random processes we study the binomial distribution and Bose--Einstein statistics. We define two types of term frequency normalization for tuning term weights in the document--query matching process. The first normalization assumes that documents have the same length and measures the information gain with the observed term once it has been accepted as a good descriptor of the observed document. The second normalization is related to the document length and to other statistics. These two normalization methods are applied to the basic models in succession to obtain weighting formulae. Results show that our framework produces different nonparametric models forming baseline alternatives to the standard tf-idf model

A survey of bullbar prevalence at pedestrian crash sites in Adelaide, South Australia

This survey was designed to examine the proportion of vehicles fitted with bull bars in Adelaide, South Australia, at the sites where pedestrian crashes have occurred in the past. The sample was stratified to examine the prevalence in separate geographical regions of the metropolitan area of Adelaide. Survey results were combined using weights determined from the relative incidence of pedestrian crashes in the three survey strata. Overall, 8.6% of traffic was equipped with bull bars. Bull bar prevalence was much greater amongst heavy vehicles (28%), but heavy vehicles formed only a minor component of the traffic volume. The average site prevalence amongst light vehicle traffic was 7.5%. Site prevalence was lowest in the CBD (average 5.5%) and highest in the Outer Metropolitan Region (average 9.1%). Differences between the site prevalence in each region were statistically significant, and there was additional variation between sites within each region. 4WD vehicles are the most common vehicle type to have a bull bar fitted and 4WD vehicles with bull bars are twice as prevalent at the sites of crashes as the next most common type of bull bar equipped vehicle, work utilities.R. W. G. Anderson, G. Ponte, S. Doeck

Electromagnetically induced transparency and dynamic Stark effect in coupled quantum resonators

In this work we reproduce the phenomenology of the electromagnetically induced transparency and dynamic Stark effect in a dissipative system composed by two coupled bosonic fields under linear and nonlinear amplification process. Such a system can be used as a quantum switch in networks of oscillators

The potential of autonomous emergency braking systems to mitigate passenger vehicle crashes

This paper details part of a research program conducted to examine the potential effect of autonomous emergency braking (AEB) systems on common crash types that involve a frontal collision. To accomplish this, simulations were conducted of 103 real world crashes. AEB system models with differing specifications were applied to these simulations to determine the change in impact speed that various AEB interventions could produce. It was found that AEB systems have the potential to reduce the impact speed, and hence the severity, in pedestrian crashes, right turn crashes, head on crashes, rear end crashes and hit fixed object crashes. The greatest potential reductions were for pedestrian crashes, head on crashes and rear end crashes. The variations in system specification demonstrate the advantages of a longer time-to-collision and higher autonomous deceleration. A system that has less potential to generate false alarms than the other systems was considered and demonstrated potential for reducing the impact speed in pedestrian, head on, rear end and hit fixed object crashes.S.D. Doecke, R.W.G. Anderson, J.R.R. Mackenzie and G. Pont

Development of Glomerella leaf spot is enhanced in virus-infected Maxi Gala apples.

Apples are commercially grown in Brazil in a subtropical environment that favors the development of fungal diseases such as Glomerella leaf spot (GLS) caused mainly by Glomerella cingulata (anamorph Colletotrichum gloeosporioides). The main objective of this work was to evaluate the effect of mixed infections by Apple stem grooving virus (ASGV) and Apple stem pitting virus (ASPV) on the infection and the colonization processes of C. gloeosporiodes in cv. Maxi Gala plants. Leaves of 16-month-old potted plants were spray-inoculated and both the disease incidence and lesion count were monitored over time and leaf severity was assessed in the final evaluation using an image analysis tool. Results showed that initial infection estimated from a monomolecular model fitted to progress of lesion count was higher and the incubation period (time to reach 50% incidence) was on average 10 h shorter in virus-infected plants compared to non-infected plants. It is hypothesized that initial events such as conidial germination and fungal penetration into plant cells were facilitated by the presence of viral infection. Also, final GLS severity was significantly higher in the virus-infected plants. Mixed infections by ASGV/ASPV seemed to make apple leaves more susceptible to the initial infection and colonization by C. gloeosporioides

Efeito da radiação ultravioleta C no desenvolvimento vegetativo e na germinação de esporos de Aspergillus flavus link da castanha-do-Brasil.

Resumo: A castanha-do-Brasil, proveniente da região Norte do Brasil, tem apresentado elevado nível de contaminação por fungos toxigênicos, devido ao modelo de exploração extrativista do produto em que os frutos permanecem muito tempo amontoados aos pés da castanheira, em condições ideais para desenvolvimento de Aspergillus flavus. Este fungo tem elevada capacidade de produzir a aflatoxina AFB1, potente agente hepatocarcinogênico. O objetivo deste trabalho foi avaliar o efeito da radiação UV-C na germinação de esporos e no desenvolvimento vegetativo de A. flavus da castanha-do-Brasil, e sua eficiência no controle do fungo na castanha. Avaliaram-se, no controle de esporos: 0,12; 0,25; 0,5; 1,0 e 2,0 kJ m-2; no crescimento micelial: 1,0; 2,0; 4,0; 8,0 e 10 kJ m-2 e na irradiação de castanhas: 1,0; 2,0; 3,0; 4,0 e 5,0 kJ m-2. O delineamento utilizado foi inteiramente casualizado com quatro repetições. Os resultados demonstraram que o esporo de A. flavus apresenta elevada sensibilidade à luz UV-C, sendo que a dose de 0,5 kJ m-2 possibilitou um controle superior a 98% de unidades formadoras de colônia (UFC), não diferindo estatisticamente de 2,0 kJ m-2, que controlou completamente. Por outro lado, a radiação UV-C apresentou baixa eficiência de controle do desenvolvimento vegetativo, sendo que mesmo a dose de 10 kJ m-2 não conseguiu inibir o crescimento micelial de A. flavus. Provavelmente, devido ao longo período de armazenamento prévio das amostras de castanha, o fungo já havia germinado, estando presente na forma micelial, de maneira que mesmo a dose de 5,0 kJ m-2 não foi suficiente para controlá-lo. Abstract: The Brazil nut, from Northern region of Brazil, has presented high level of contamination by toxigenic fungi due to extractive exploitation model of the product, in which the fruit remains piled up on forest ground for long periods, in ideal conditions for the development of Aspergillus flavus. This fungus is highly efficient in producing aflatoxin AFB1, described as a powerful hepatocarcinogenic agent. The objective of this study was to evaluate the effect of UV-C radiation on the germination of spores and vegetative growth of A. flavus and its efficiency to control this fungus on Brazil nut. The following doses of UV-C light were evaluated, for spore inhibition: 0.12, 0.25, 0.5, 1.0, 2.0 kJ m-2; for mycelial growth: 1.0, 2.0, 4.0, 8.0, 10 kJ m-2 and for irradiation of nuts: 1.0, 2.0, 3.0, 4.0 and 5.0 kJ m-2. The experiment was laid out in a completely randomized design with four replications. The results showed that the dose of 0.5 kJ m-2 enabled more than 98% of control of colony-forming unit (CFU) which were not statistically different from the dose of 2.0 kJ m-2, which completely inhibited the spore germination, demonstrating the high sensibility of the spores of A. flavus to UV-C light. By the other hand UV-C radiation showed a low efficiency to control vegetative development. The irradiation of 10 kJ m-2 was not enough to inhibit the mycelial growth. Probably due to the long period of prior storage of the nut samples, the fungus colonization had already begun on the nut surface, so even the dose of 5.0 kJ m-2 of UV-C radiation was not efficient to the control the contamination, not differing from the Control

The survey and reference assisted assembly of the Octopus vulgaris genome

The common octopus, Octopus vulgaris, is an active marine predator known for the richness and plasticity of its behavioral repertoire, and remarkable learning and memory capabilities. Octopus and other coleoid cephalopods, cuttlefish and squid, possess the largest nervous system among invertebrates, both for cell counts and body to brain size. O. vulgaris has been at the center of a long-tradition of research into diverse aspects of its biology. To leverage research in this iconic species, we generated 270\u2009Gb of genomic sequencing data, complementing those available for the only other sequenced congeneric octopus, Octopus bimaculoides. We show that both genomes are similar in size, but display different levels of heterozygosity and repeats. Our data give a first quantitative glimpse into the rate of coding and non-coding regions and support the view that hundreds of novel genes may have arisen independently despite the close phylogenetic distance. We furthermore describe a reference-guided assembly and an open genomic resource (CephRes-gdatabase), opening new avenues in the study of genomic novelties in cephalopods and their biology

Brown dwarf census with the Dark Energy Survey year 3 data and the thin disc scale height of early L types

27 pages, 18 figuresIn this paper we present a catalogue of 11 745 brown dwarfs with spectral types ranging from L0 to T9, photometrically classified using data from the Dark Energy Survey (DES) year 3 release matched to the Vista Hemisphere Survey (VHS) DR3 and Wide-field Infrared Survey Explorer (WISE) data, covering ≈2400 deg2 up to iAB = 22. The classification method follows the same phototype method previously applied to SDSS-UKIDSS-WISE data. The most significant difference comes from the use of DES data instead of SDSS, which allow us to classify almost an order of magnitude more brown dwarfs than any previous search and reaching distances beyond 400 pc for the earliest types. Next, we also present and validate the GalmodBD simulation, which produces brown dwarf number counts as a function of structural parameters with realistic photometric properties of a given survey. We use this simulation to estimate the completeness and purity of our photometric LT catalogue down to iAB = 22, as well as to compare to the observed number of LT types. We put constraints on the thin disc scale height for the early L (L0–L3) population to be around 450 pc, in agreement with previous findings. For completeness, we also publish in a separate table a catalogue of 20 863 M dwarfs that passed our colour cut with spectral types greater than M6. Both the LT and the late M catalogues are found at DES release page https://des.ncsa.illinois.edu/releases/other/y3-mlt.Peer reviewedFinal Published versio