Novelty Search in Competitive Coevolution

One of the main motivations for the use of competitive coevolution systems is their ability to capitalise on arms races between competing species to evolve increasingly sophisticated solutions. Such arms races can, however, be hard to sustain, and it has been shown that the competing species often converge prematurely to certain classes of behaviours. In this paper, we investigate if and how novelty search, an evolutionary technique driven by behavioural novelty, can overcome convergence in coevolution. We propose three methods for applying novelty search to coevolutionary systems with two species: (i) score both populations according to behavioural novelty; (ii) score one population according to novelty, and the other according to fitness; and (iii) score both populations with a combination of novelty and fitness. We evaluate the methods in a predator-prey pursuit task. Our results show that novelty-based approaches can evolve a significantly more diverse set of solutions, when compared to traditional fitness-based coevolution.Comment: To appear in 13th International Conference on Parallel Problem Solving from Nature (PPSN 2014

Development and validation of an in house multiplex real time PCR for quantification of all four serotypes of dengue virus

Objectives: In order to determine the infecting dengue virus (DENV) serotype and also to quantify the amount of virus in clinical samples and cell cultures, we proceeded to optimize and validate a quantitative real time RT-PCR assay.Methods: WHO reference strains of the four DENV serotypes were cultured on C6/36 cell lines for 7 days. The supernatants were used to determine plaque forming units (pfus) using BHK cell lines, which is indicative of infecting virus particles. cDNA was synthesized from RNA extracted from the virus culture supernatants. A tenfold dilution series (106 to 101 pfu/ml) of the known pfus of the viruses was prepared using the cDNA for standard curves. Data were analyzed using applied biosystems sequence detection systems. The threshold cycle value (Ct) for each reaction was determined by manually setting the threshold limit. Each standard curve was initially generated individually and later was used in a multiplex assay. All experiments were done in triplicate.Results: The optimized multiplex method detected all four DENV serotypes and generated standard curves with correlation coefficients (R2 values) above 0.95, which suggested that the standard curves and dilutions were of acceptable quality. The slope values of the standard curves were between -3.1 and -3.8 for all assays, implying that the PCR reactions were quite efficient.Conclusions: We have optimized and validated a multiplex quantitative real time RT-PCR assay, which can be effectively used to determine the infecting DENV in samples and also quantify the amount of virus

Determination of paralytic shellfish toxins using potentiometric electronic tongue

Paralytic shellfish toxins (PSTs) are monitored in commercial bivalves in several countries in the world due to their toxicity to human consumers. The present work examines the application of an electronic tongue based on potentiometric chemical sensors to the quantification of PSTs in mussel extracts. The electronic tongue comprised six miniaturized sensors with solid inner contact and plasticized polyvinylchloride membranes. Calibration models were calculated by PLS regression using measurements in sixteen model mixed solutions containing four PSTs commonly found in bivalves from the Portuguese coast. Transfer of the calibration models to sample matrix was done by joint-PLS regression using measurements in five mussel extracts spiked with PST standards. Quantification of PSTs in extracts of naturally contaminated mussels, using the electronic tongue and updated calibration model, was in agreement with values of the chromatographic reference method. Those sensors alone or combined in an electronic tongue are useful tools for rapid screening of PST in bivalves.publishe

Sphingosine 1-Phosphate in acute dengue infection

Objectives: Many mediators have been implicated in the vascular leak in dengue which is a hallmark of severe dengue. Sphingosine 1-Phosphate (S1P) has been shown to counteract the effects of other mediators that cause increase vascular permeability. Moreover, S1P has been shown to be important in barrier integrity. Therefore, we investigated the role of S1P in acute dengue. This has not been investigated previously.Methods: Serum samples from acute dengue patients were collected 12 hours apart throughout the course of their hospital stay. S1P levels in 32 patients with acute dengue and 12 healthy individuals were assessed using ELISA.Results: S1P levels were significantly lower in patients with acute dengue (p=0.002) and the levels in patients with DHF were significantly lower than those with dengue fever (p=0.005). S1P levels were low throughout the course of illness and S1P levels were < 0.5 μM in 12/23 patients with DHF when compared to 1/9 with dengue fever (DF). Majority of patients with DHF had lower S1P levels especially in the critical phase. Some patients with DF also had quite low levels at certain time points during the course of the illness. The serial S1P levels in patients with both DF and DHF significantly correlated with the serial platelet counts (Spearmans r =0.18, p=0.04).Conclusions: Low levels of S1P in acute dengue infection are likely to contribute to increased vascular permeability. Therefore S1P analogue may have a place in the treatment of acute dengue

Role of natural killer T cells in the pathogenesis of dengue infections

Objectives: The dengue virus exploits cellular lipid metabolism pathways and natural killer T cells (iNKT), which recognize glycolipids have been suggested to play a role in mouse models of acute dengue. Therefore, we set out to determine if iNKT cells play a role in acute dengue infectionMethods: The frequency of iNKT cells (CD3+, Vα24+) was determined in 49 acute dengue and 22 healthy individuals. The functionality and phenotype of iNKT cell subsets were defined only in 19 patients and 10 controls by flow cytometry. Clinical disease severity was determined by the WHO 2011 guidelinesResults: The proportion of iNKTs in patients with acute dengue were significantly higher (P=0.03) compared to healthy individuals. We found that the CD4+ iNKTs, which produce inflammatory cytokines and are less cytotoxic, were significantly expanded (p=0.01) in acute dengue. iNKTs of patients were also significantly (p=0.02) more activated (both CD38+ and HLA-DR+), that iNKT cell activation significantly and positively correlated with dengue-specific IgG antibody titres (Spearmans’ r=0.5018, P=0.03). iNKT of patients were also predominantly of the immature phenotype, as the expression of CD161 was significantly more than in healthy individuals (p=0.01).Conclusions: As the iNKT cell population, especially of the CD4+ T cell subset appears to be highly activated and expanded in acute dengue, iNKT cells could be contributing to the pathogenesis of dengue infection

Measurement of the Bs0→J/ψKS0B_s^0\to J/\psi K_S^0 branching fraction

The $B_s^0\to J/\psi K_S^0$ branching fraction is measured in a data sample corresponding to 0.41$fb^{-1}$ of integrated luminosity collected with the LHCb detector at the LHC. This channel is sensitive to the penguin contributions affecting the sin2$\beta$ measurement from $B^0\to J/\psi K_S^0$ The time-integrated branching fraction is measured to be $BF(B_s^0\to J/\psi K_S^0)=(1.83\pm0.28)\times10^{-5}$. This is the most precise measurement to date

Model-independent search for CP violation in D0→K−K+π−π+ and D0→π−π+π+π− decays

A search for CP violation in the phase-space structures of D0 and View the MathML source decays to the final states K−K+π−π+ and π−π+π+π− is presented. The search is carried out with a data set corresponding to an integrated luminosity of 1.0 fb−1 collected in 2011 by the LHCb experiment in pp collisions at a centre-of-mass energy of 7 TeV. For the K−K+π−π+ final state, the four-body phase space is divided into 32 bins, each bin with approximately 1800 decays. The p-value under the hypothesis of no CP violation is 9.1%, and in no bin is a CP asymmetry greater than 6.5% observed. The phase space of the π−π+π+π− final state is partitioned into 128 bins, each bin with approximately 2500 decays. The p-value under the hypothesis of no CP violation is 41%, and in no bin is a CP asymmetry greater than 5.5% observed. All results are consistent with the hypothesis of no CP violation at the current sensitivity

Search for the lepton-flavor-violating decays Bs0→e±μ∓ and B0→e±μ∓

A search for the lepton-flavor-violating decays Bs0→e±μ∓ and B0→e±μ∓ is performed with a data sample, corresponding to an integrated luminosity of 1.0  fb-1 of pp collisions at √s=7  TeV, collected by the LHCb experiment. The observed number of Bs0→e±μ∓ and B0→e±μ∓ candidates is consistent with background expectations. Upper limits on the branching fractions of both decays are determined to be B(Bs0→e±μ∓)101  TeV/c2 and MLQ(B0→e±μ∓)>126  TeV/c2 at 95% C.L., and are a factor of 2 higher than the previous bounds

Absolute luminosity measurements with the LHCb detector at the LHC

Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes and are valuable to quantify the performance of the accelerator. Using data taken in 2010, LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In addition to the classic "van der Meer scan" method a novel technique has been developed which makes use of direct imaging of the individual beams using beam-gas and beam-beam interactions. This beam imaging method is made possible by the high resolution of the LHCb vertex detector and the close proximity of the detector to the beams, and allows beam parameters such as positions, angles and widths to be determined. The results of the two methods have comparable precision and are in good agreement. Combining the two methods, an overall precision of 3.5% in the absolute luminosity determination is reached. The techniques used to transport the absolute luminosity calibration to the full 2010 data-taking period are presented.Comment: 48 pages, 19 figures. Results unchanged, improved clarity of Table 6, 9 and 10 and corresponding explanation in the tex

Absolute luminosity measurements with the LHCb detector at the LHC

Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes and are valuable to quantify the performance of the accelerator. Using data taken in 2010, LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In addition to the classic "van der Meer scan" method a novel technique has been developed which makes use of direct imaging of the individual beams using beam-gas and beam-beam interactions. This beam imaging method is made possible by the high resolution of the LHCb vertex detector and the close proximity of the detector to the beams, and allows beam parameters such as positions, angles and widths to be determined. The results of the two methods have comparable precision and are in good agreement. Combining the two methods, an overall precision of 3.5% in the absolute luminosity determination is reached. The techniques used to transport the absolute luminosity calibration to the full 2010 data-taking period are presented.Comment: 48 pages, 19 figures. Results unchanged, improved clarity of Table 6, 9 and 10 and corresponding explanation in the tex