Analysing Symbolic Regression Benchmarks under a Meta-Learning Approach

The definition of a concise and effective testbed for Genetic Programming (GP) is a recurrent matter in the research community. This paper takes a new step in this direction, proposing a different approach to measure the quality of the symbolic regression benchmarks quantitatively. The proposed approach is based on meta-learning and uses a set of dataset meta-features---such as the number of examples or output skewness---to describe the datasets. Our idea is to correlate these meta-features with the errors obtained by a GP method. These meta-features define a space of benchmarks that should, ideally, have datasets (points) covering different regions of the space. An initial analysis of 63 datasets showed that current benchmarks are concentrated in a small region of this benchmark space. We also found out that number of instances and output skewness are the most relevant meta-features to GP output error. Both conclusions can help define which datasets should compose an effective testbed for symbolic regression methods.Comment: 8 pages, 3 Figures, Proceedings of Genetic and Evolutionary Computation Conference Companion, Kyoto, Japa

An asynchronous, decentralised commitment protocol for semantic optimistic replication

We study large-scale distributed cooperative systems that use optimistic replication. We represent a system as a graph of actions (operations) connected by edges that reify semantic constraints between actions. Constraint types include conflict, execution order, dependence, and atomicity. The local state is some schedule that conforms to the constraints; because of conflicts, client state is only tentative. For consistency, site schedules should converge; we designed a decentralised, asynchronous commitment protocol. Each client makes a proposal, reflecting its tentative and{\slash}or preferred schedules. Our protocol distributes the proposals, which it decomposes into semantically-meaningful units called candidates, and runs an election between comparable candidates. A candidate wins when it receives a majority or a plurality. The protocol is fully asynchronous: each site executes its tentative schedule independently, and determines locally when a candidate has won an election. The committed schedule is as close as possible to the preferences expressed by clients

Distributed Subtyping

One of the most frequent operations in object-oriented programs is the "instanceof" test, also called the "subtyping" test or the "type inclusion" test. This test determines if a given object is an instance of some type. Surprisingly, despite a lot of research on distributed object-oriented languages and systems, almost no work has been devoted to the implementation of this test in a distributed environment. This paper presents the first algorithm to implement the "subtyping" test on an object received through the wire, without having to download the full code of the object type, nor to deserialize the object. We use a slicing technique that encodes a (multiple-subtyping) hierarchy using as little memory as the best known centralized implementation of the "subtyping" test. Our slicing technique is however different than centralized ones and allows for the dynamic addition of types without global reconfiguration. We convey the practicality of our algorithm through performance measures obtained from a fully distributed implementation of our algorithm which we experiment on standard Java hierarchies. In particular, we show that we can perform a subtyping test between 3 and 12 times faster than the code downloading approach without hampering the time taken for deserialization. Moreover, we require the same subtyping time as a string-based approach while reducing the encoding length by a factor of 50

Plane-Based Calibration of Central Catadioptric Cameras

International audienceWe present a novel calibration technique for all central catadioptric cameras using images of planar grids. We adopted the well-known sphere camera model to describe the catadioptric projection. We show that, using the so-called lifted coordinates, a linear relation mapping the grid points to the corresponding points on the image plane can be written as a 6 × 6 matrix Hcata , which acts like the classical 3 × 3 ho- mography for perspective cameras. We show how to compute the image of the absolute conic (IAC) from at least 3 homo- graphies and how to recover from it the intrinsic parameters of the catadioptric camera. In the case of paracatadioptric cameras one such homography is enough to estimate the IAC, thus allowing the calibration from a single image

Precipitation diurnal cycle assessment of satellite-based estimates over Brazil

The main objective of this study is to assess the ability of several high-resolution satellite-based precipitation estimates to represent the Precipitation Diurnal Cycle (PDC) over Brazil during the 2014–2018 period, after the launch of the Global Precipitation Measurement satellite (GPM). The selected algorithms are the Global Satellite Mapping of Precipitation (GSMaP), The Integrated Multi-satellitE Retrievals for GPM (IMERG) and Climate Prediction Center (CPC) MORPHing technique (CMORPH). Hourly rain gauge data from different national and regional networks were used as the reference dataset after going through rigid quality control tests. All datasets were interpolated to a common 0.1° × 0.1° grid every 3 h for comparison. After a hierarchical cluster analysis, seven regions with different PDC characteristics (amplitude and phase) were selected for this study. The main results of this research could be summarized as follow: (i) Those regions where thermal heating produce deep convective clouds, the PDC is better represented by all algorithms (in term of amplitude and phase) than those regions driven by shallow convection or low-level circulation; (ii) the GSMaP suite (GSMaP-Gauge (G) and GSMaP-Motion Vector Kalman (MVK)), in general terms, outperforms the rest of the algorithms with lower bias and less dispersion. In this case, the gauge-adjusted version improves the satellite-only retrievals of the same algorithm suggesting that daily gauge-analysis is useful to reduce the bias in a sub-daily scale; (iii) IMERG suite (IMERG-Late (L) and IMERG-Final (F)) overestimates rainfall for almost all times and all the regions, while the satellite-only version provide better results than the final version; (iv) CMORPH has the better performance for a transitional regime between a coastal land-sea breeze and a continental amazonian regime. Further research should be performed to understand how shallow clouds processes and convective/stratiform classification is performed in each algorithm to improve the representativity of diurnal cycle

Genetic subtyping, biofilm-forming ability and biocide susceptibility of Listeria monocytogenes strains isolated from a ready-to-eat food industry

Research Areas: Infectious Diseases ; Pharmacology & PharmacyListeria monocytogenes is a foodborne pathogen of special concern for ready-to-eat food producers. The control of its presence is a critical step in which food-grade sanitizers play an essential role. L. monocytogenes is believed to persist in food processing environments in biofilms, exhibiting less susceptibility to sanitizers than planktonic cells. This study aimed to test the susceptibility of L. monocytogenes in planktonic culture and biofilm to three commercial food-grade sanitizers and to benzalkonium chloride; together with the genetic subtyping of the isolates. L. monocytogenes isolates were collected from raw materials, final products and food-contact surfaces during a 6-year period from a ready-to-eat meat-producing food industry and genetically characterized. Serogrouping and pulsed-field gel electrophoresis (PFGE) revealed genetic variability and di erentiated L. monocytogenes isolates in three clusters. The biofilm-forming ability assay revealed that the isolates were weak biofilm producers. L. monocytogenes strains were susceptible both in the planktonic and biofilm form to oxidizing and ethanol-based compounds and to benzalkonium chloride, but not to quaternary ammonium compound. A positive association of biofilm-forming ability and LD90 values for quaternary ammonium compound and benzalkonium chloride was found. This study highlights the need for preventive measures improvement and for a conscious selection and use of sanitizers in food-related environments to control Listeria monocytogenes.info:eu-repo/semantics/publishedVersio

The Interpretation Of The Figure Of The Prophet Jonah By Michelangelo On The Ceiling Of The Sistine Chapel: Anatomical Urological Vision.

A detailed analysis in the iconography and pictorial appearance of the scene of the Prophet Jonah painted by the artist Michelangelo Buonarroti (1475-1564) on the ceiling of the Sistine Chapel between the years 1508 and 1512. Literature review on the Italian Renaissance period and the life of Michelangelo Buonarroti and analysis of historical aspects of the evolution of studies of human anatomy in this period and the works of the artist. A comparative analysis of the representation of the figure of the fish on the left thigh of Jonah with a cross section of penis shows a curious similarity. The pictorial and iconographic analysis reveals an intensity of light on the pubic area and the position of the prophet with the legs spread apart and left hand placed on this region. A tube-shaped cloth covers the region and the angel at the side seems to be looking at this anatomical region of Jonah. In fact, sets of iconographic and pictorial relate to the deciphered code. This description helps to confirm the relationship of the Renaissance art with the human anatomy; science has been much studied in this period. The design of a cross section of the penis is revealed with the two cavernous bodies with the septum between them and the spongy body. Considering the circumstances in which Michelangelo had painted, subjectivity was fundamental due to religious motivations added to the vigorous implications of a limited scientific knowledge typical of that era.38317-22; discussion 32

DLT-Like Calibration of Central Catadioptric Cameras

International audienceIn this study, we present a calibration technique that is valid for all single-viewpoint catadioptric cameras. We are able to represent the projection of 3D points on a catadioptric image linearly with a 6 × 10 projection matrix, which uses lifted coordinates for image and 3D points. This projection matrix can be computed with enough number of 3D-2D correspondences (minimum 20 points distributed in three different planes). We show how to decompose it to obtain intrinsic and extrinsic parameters. Moreover, we use this parameter estimation followed by a non-linear optimization to calibrate various types of cameras. Our results are based on the sphere camera model which considers that every central catadioptric system can be modeled using two projections, one from 3D points to a unitary sphere and then a perspective projection from the sphere to the image plane. We tested our method both with simulations and real images