A Kalman filter application to a spectral wave model

International audienceA sequential time dependent data assimilation scheme based on the Kalman filter is applied to a spectral wave model. Usually, the first guess covariance matrices used in optimal interpolation schemes are exponential spreading functions, which remain constant. In the present work the first guess correlation errors evolve in time according to the dynamic constraints of the wave model. A system error noise is deduced and used to balance numerical errors. The assimilation procedure is tested in a standard situation of swell propagation, where the Kalman filter is used to assimilate the significant wave height. The evolution of the wave field is described by a linear two-dimensional advection equation and the propagation of the error covariance matrix is derived according to Kalman's linear theory. Model simulations were performed in a 2-dimensional domain with deep-water conditions, a relatively small surface area and without wind forcing or dissipation. A true state simulation and a first guess simulation were used to illustrate the assimilation outcome, showing a reasonable performance of the Kalman filter

HEMATOLOGICAL STANDARDS, HORMONAL INDEXES AND GONADAL MORPHOLOGY OF ROADSIDE HAWKS (RUPORNIS MAGNIROSTRIS)

Efforts to conserve birds of prey have been increasing over the past three decades, highlighting breeding programs in captivity and zoos, scientific research, environmental education, rehabilitation and reintroduction. In order to generate subsidies for such actions, blood samples and gonads were collected from 24 roadside hawks to determine the hematological and hormonal indexes and gonadal morphology. Routine techniques for hematological, histological and chemiluminescence analyses were used to determine hematology, gonadal morphology and hormone levels, respectively. Hematological values of PCV, erythrocytes and lymphocytes differed between the birds recently-arrived in captivity and the birds with at least one year of captivity, a difference associated to the higher level of stress of the newly arrived animals due to the recent exposure to captivity conditions. T3 was significantly different between females and males, and T3 and T4 were higher in animals during feather moulting. The gonadal morphology was similar to that of other birds, however, persistence of the right ovary was observed in 66% of the cases, and other characteristics indicative of a seasonal reproductive cycle in the Brazilian Northeast. The data collected serve as subsidies for the clinical care of this species, besides providing a better understanding of the reproduction of birds of prey, and assisting in the preservation

In Vitro and In Vivo Biological Effects of Novel Arylimidamide Derivatives against Trypanosoma cruzi

ABSTRACT Chagas disease (CD), a neglected tropical disease caused by Trypanosoma cruzi , remains a serious public health problem in several Latin American countries. The available chemotherapies for CD have limited efficacy and exhibit undesirable side effects. Aromatic diamidines and arylimidamides (AIAs) have shown broad-spectrum activity against intracellular parasites, including T. cruzi . Therefore, our aim was to evaluate the biological activity of eight novel AIAs (16DAP002, 16SAB079, 18SAB075, 23SMB022, 23SMB026, 23SMB054, 26SMB070, and 27SMB009) against experimental models of T. cruzi infection in vitro and in vivo . Our data show that none of the compounds induced a loss of cellular viability up to 32 μM. Two AIAs, 18SAB075 and 16DAP002, exhibited good in vitro activity against different parasite strains (Y and Tulahuen) and against the two relevant forms of the parasite for mammalian hosts. Due to the excellent selective indexes of 18SAB075, this AIA was moved to in vivo tests for acute toxicity and parasite efficacy; nontoxic doses (no-observed-adverse-effect level [NOAEL], 50 mg/kg) were employed in the tests for parasite efficacy. In experimental models of acute T. cruzi infection, 18SAB075 reduced parasitemia levels only up to 50% and led to 40% protection against mortality (at 5 mg/kg of body weight), being less effective than the reference drug, benznidazole

Breast Cancer Epigenetics: From DNA Methylation to microRNAs

Both appropriate DNA methylation and histone modifications play a crucial role in the maintenance of normal cell function and cellular identity. In cancerous cells these “epigenetic belts” become massively perturbed, leading to significant changes in expression profiles which confer advantage to the development of a malignant phenotype. DNA (cytosine-5)-methyltransferase 1 (Dnmt1), Dnmt3a and Dnmt3b are the enzymes responsible for setting up and maintaining DNA methylation patterns in eukaryotic cells. Intriguingly, DNMTs were found to be overexpressed in cancerous cells, which is believed to partly explain the hypermethylation phenomenon commonly observed in tumors. However, several lines of evidence indicate that further layers of gene regulation are critical coordinators of DNMT expression, catalytic activity and target specificity. Splice variants of DNMT transcripts have been detected which seem to modulate methyltransferase activity. Also, the DNMT mRNA 3′UTR as well as the coding sequence harbors multiple binding sites for trans-acting factors guiding post-transcriptional regulation and transcript stabilization. Moreover, microRNAs targeting DNMT transcripts have recently been discovered in normal cells, yet expression of these microRNAs was found to be diminished in breast cancer tissues. In this review we summarize the current knowledge on mechanisms which potentially lead to the establishment of a DNA hypermethylome in cancer cells

The biological in vitro effect and selectivity of aromatic dicationic compounds on Trypanosoma cruzi

Trypanosoma cruzi is a parasite that causes Chagas disease, which affects millions of individuals in endemic areas of Latin America. One hundred years after the discovery of Chagas disease, it is still considered a neglected illness because the available drugs are unsatisfactory. Aromatic compounds represent an important class of DNA minor groove-binding ligands that exhibit potent antimicrobial activity. This study focused on the in vitro activity of 10 aromatic dicationic compounds against bloodstream trypomastigotes and intracellular forms of T. cruzi. Our data demonstrated that these compounds display trypanocidal effects against both forms of the parasite and that seven out of the 10 compounds presented higher anti-parasitic activity against intracellular parasites compared with the bloodstream forms. Additional assays to determine the potential toxicity to mammalian cells showed that the majority of the dicationic compounds did not considerably decrease cellular viability. Fluorescent microscopy analysis demonstrated that although all compounds were localised to a greater extent within the kinetoplast than the nucleus, no correlation could be found between compound activity and kDNA accumulation. The present results stimulate further investigations of this class of compounds for the rational design of new chemotherapeutic agents for Chagas disease

Simulation studies of the impact of the CMS radiation environment on RPC detectors

The High-Luminosity Large Hadron Collider (HL-LHC) upgrade aims to increase its luminosity by a factor of 5 beyond the LHC's design value, increasing the potential for discoveries after 2025. The increased collision rate of particles will be a challenge for the CMS systems as higher levels of radiation could degrade them and affect their performance. It is therefore important to understand the expected radiation environment and its impact on the different sub-detectors. In this study we use the FLUKA simulation package to reproduce the radiation environment during CMS Run-2 and the GEANT4 simulation package to estimate its impact on the RPC detectors. Results are compared with measurements collected by the RPC system during 2018 and reasonable agreement is observed. This study serves as a benchmark for future simulations with a Phase-2 (HL-LHC) configuration