Rabbit haemorrhagic disease: Cross-protection and comparative pathogenicity of GI.2/RHDV2/b and GI.1b/RHDV lagoviruses in a challenge trial

European rabbits (Oryctolagus cuniculus) are severely affected by rabbit haemorrhagic disease (RHD). Caused by a lagovirus, the disease leads to losses in the rabbit industry and has implications for wildlife conservation. Past RHD outbreaks have been caused by GI.1/RHDV genotype viruses. A new virus belonging to the GI.2/RHDV2/b genotype emerged in 2010, quickly spreading and replacing the former in several countries; however, limited data are available on its pathogenicity and epidemiological factors. The present work extends these issues and evaluates cross-protection between both genotypes. Ninety-four and 88 domestic rabbits were challenged with GI.2/RHDV2/b and GI.1b/RHDV variant isolates, respectively. Cross-protection was determined by a second challenge on survivors with the corresponding strain. Mortality by GI.2/RHDV2/b was highly variable due to unknown individual factors, whereas mortality by GI.1b/RHDV was associated with age. Mortality in rabbits < 4 weeks old was 84%, higher than previously reported. Cross-protection was not identical between the two viruses because the ratio of mortality rate ratios for the first and second challenges was 3.80 ± 2.68 times higher for GI.2/RHDV2/b than it was for GI.1b/RHDV. Rabbit susceptibility to GI.2/RHDV2/b varied greatly and appeared to be modulated by the innate functionality of the immune response and/or its prompt activation by other pathogens. GI.1b/RHDV pathogenicity appeared to be associated with undetermined age-related factors. These results suggest that GI.2/RHDV2/b may interact with other pathogens at the population level but does not satisfactorily explain the GI.1b/RHDV virus's quick replacement

Detection of Rabbit Hemorrhagic Disease Virus GI.2/RHDV2/b in the Mediterranean Pine Vole ( Microtus duodecimcostatus) and White-Toothed Shrew ( Crocidura russula)

The European wild rabbit ( Oryctolagus cuniculus) is a key prey species on the Iberian Peninsula, and several predator species that are at risk of extinction are dependent on them as prey. A new rabbit hemorrhagic disease (RHD) virus genotype (GI.2/RHDV2/b) emerged in 2010 and posed a threat to wild rabbit populations. During a survey aimed at investigating RHD epidemiology in wild rabbits, GI.2/RHDV2/b was detected by duplex real-time PCR in carcasses of one Mediterranean pine vole ( Microtus duodecimcostatus) and two white-toothed shrews ( Crocidura russula). Laboratory New Zealand white rabbits that were challenged with inocula obtained from the liver of the small mammals died showing RHD lesions, confirming the infectiousness of the isolates. Phylogenetic analysis of the VP60 gene nucleotide sequences showed complete homology between the isolates from the two small mammal species and a high degree of similarity, but not complete homology, to GI.2/RHDV2/b sequences from wild rabbits. The GI.2/RHDV2/b genotype has not been reported in species outside the order Lagomorpha

Numerical methods for non conservative perturbations of conservative problems

In this paper the numerical integration of non conservative perturbations of differential systems that possess a first integral, as for example slowly dissipative Hamiltonian systems, is considered. Numerical methods that are able to reproduce appropriately the evolution of the first integral are proposed. These algorithms are based on a combination of standard numerical integration methods and certain projection techniques. Some conditions under which known conservative methods reproduce that desirable evolution in the invariant are analysed. Finally, some numerical experiments in which we compare the behaviour of the new proposed methods, the averaged vector field method AVF proposed by Quispel and McLaren and standard RK methods of orders 3 and 5 are presented. The results confirm the theory and show a good qualitative and quantitative performance of the new projection methods

Experimental and computational analysis of microbial inactivation in a solid by ohmic heating using pulsed electric fields

Pulsed electric field technology (PEF) has traditionally been used as a technique to inactivate microorganisms in liquid foods at temperatures below those used in heat treatments; however, application of high-intensity PEF (E&gt;1 kV/cm) at high frequencies (&gt;10 Hz) can allow rapid and volumetric solid food electrical heating in order to replace traditional convection/conduction heating that progresses from the heating medium to the inside of the product. This investigation is the first one to evaluate the inactivation of Salmonella Typhimurium 878 in a solid product (cylinder of technical agar used as reference solid) by applying PEF treatments (2.5 and 3.75 kV/cm, and up to 9000 microseconds) at 50 Hz. The evolution of temperature in different locations of the agar cylinder was measured by observing the variability of heating rates depending on location and PEF intensity. Microbial inactivation was determined and compared with isothermal heat treatments that predicted similar inactivation values, but did not detect additional inactivation. Computational analysis enabled us to predict temperature and microbial inactivation for any spatial and temporal distribution of the cylinder agar by detecting the coldest point in the transition zone between the high-voltage electrode, the agar, and the plastic container of the treatment chamber. In order to evaluate the variability of the temperature, computational predictions were done each 0.5-mm. The difference between the coldest and the hottest point (e.g. at the center of the cylinder) resulted in around 10 °C and 10 second variation in temperature and processing time, respectively. In any case, it was possible to obtain 5-log10-reductions after 60 s of PEF treatments when using 2.5 kV/cm and 50% reduction for 3.75 kV/cm. These results suggested the potential of PEF technology as a rapid heating system based on ohmic heating for microbial inactivation in solid food products

Symmetrically Processed Splitting Integrators for Enhanced Hamiltonian Monte Carlo Sampling

[EN] We construct integrators to be used in Hamiltonian (or Hybrid) Monte Carlo sampling. The new integrators are easily implementable and, for a given computational budget, may deliver five times as many accepted proposals as standard leapfrog/Verlet without impairing in any way the quality of the samples. They are based on a suitable modification of the processing technique first introduced by Butcher. The idea of modified processing may also be useful for other purposes, like the construction of high-order splitting integrators with positive coefficients.The first, third, and fourth authors were supported by project PID2019-104927GB-C21 (AEI/FEDER, UE) . The second author was supported by projects PID2019-104927GB-C22 (GNI-QUAMC) , (AEI/FEDER, UE) VA105G18, and VA169P20 (Junta de Castilla y Leon, ES) co-financed by FEDER funds.Blanes Zamora, S.; Calvo, M.; Casas, F.; Sanz-Serna, JM. (2021). Symmetrically Processed Splitting Integrators for Enhanced Hamiltonian Monte Carlo Sampling. SIAM Journal on Scientific Computing. 43(5):A3357-A3371. https://doi.org/10.1137/20M137940X30SA3357A337143

Anatomical Retinal Changes after Photodynamic Therapy in Chronic Central Serous Chorioretinopathy

Purpose. To evaluate anatomical retinal changes measured by spectral-domain optical coherence tomography (SD-OCT), after applying photodynamic therapy (PDT) for treatment of chronic central serous chorioretinopathy (CSC). Methods. A retrospective analysis was conducted on 43 patients (48 eyes) with chronic CSC treated with PDT. Visual acuity (VA), central retinal thickness (CRT), outer nuclear layer (ONL) thickness, subretinal fluid (SRF), and photoreceptor ellipsoid zone (EZ) measured by SD-OCT were collected at baseline and at 3, 6, and 12 months after PDT. Differences between normally distributed variables were calculated by a paired-sample t-test; p < 0 05 was considered statistically significant. Results. Mean age was 50 +/- 9.8 years. Mean time from diagnosis to PDT was 12.5 months. Baseline VA was 0.51 +/- 0.24 and significantly improved (p < 0 001) to 0.74 +/- 0.26 one year after PDT. CRT and SRF significantly decreased (p < 0 001) at 3, 6, and 12 months after treatment. ONL thickness and EZ did not significantly change at any point during follow-up. Conclusions. Not significant changes were found in the ONL or EZ 12 months after PDT

The LEPR gene is associated with reproductive seasonality traits in Rasa Aragonesa sheep

The aim of this study was to characterize and identify causative polymorphisms in the leptin receptor (LEPR) gene responsible for the seasonal variation of reproductive traits in sheep. Three reproductive seasonality traits were studied: the total days of anoestrous (TDA), the progesterone cycling months (P4CM) and the oestrous cycling months (OCM). In total, 18 SNPs were detected in 33 ewes with extreme values for TDA and OCM. Six SNPs were non-synonymous substitutions and two of them were predicted in silico as deleterious: rs596133197 and rs403578195. These polymorphisms were then validated in 239 ewes. The SNP rs403578195, located in exon 8 and leading to a change of alanine to glycine (Ala284Gly) in the extracellular domain of the protein, was associated with the OCM trait, being the G allele associated with a decrease of 12 percent of the OCM trait. Haplotype analyses also suggested the involvement of other non-synonymous SNP located in exon 20 (rs405459906). This SNP also produces an amino acid change (Lys1069Glu) in the intracellular domain of the protein and segregates independently of rs403578195. These results confirm for the first time the role of the LEPR gene in sheep reproductive seasonality

Experimental study of the mechanical transmission of rabbit hemorrhagic disease virus (RHDV2/b) by Aedes Albopictus (Diptera: Clicidae) and Phlebotomus papatasi (diptera: psychodidae); 34447999

Rabbit hemorrhagic disease (RHD) is caused by a lagovirus mainly affecting European rabbits (Oryctolagus cuniculus), although other European and North American lagomorph species are also susceptible to fatal infection by the new viral variant RHDV2/b. In the present work, direct mechanical transmission of the rabbit hemorrhagic disease virus (RHDV2/b variant) by the hematophagous Diptera Aedes albopictus (Skuse) (Diptera: Culicidae) and the sand fly Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae) was tested. For each species, six and three laboratory rabbits were exposed to bites of dipterous females partially fed on RHDV2/b viral suspension 2 h and 24 h prior to exposure, respectively. The rabbits were then monitored for clinical changes and mortality for 35 d, and seroconversion was assessed by indirect ELISA. No rabbit died or showed clinical signs of disease, and seroconversion was recorded in two rabbits challenged with P. papatasi females fed the viral suspension 2 h prior to exposure. The number of RHDV2/b RNA copies/female was higher in Ae. albopictus than in P. papatasi but the decrease over time of RNA load in Ae. albopictus was greater than that in P. papatasi. The results of this study suggest the inability of Ae. albopictus to serve as a direct mechanical vector of RHDV2/b, but sand flies could play a role in the local transmission of RHD. © The Author(s) 2021. Published by Oxford University Press on behalf of Entomological Society of America

Portable lock-in amplifier for microcantilever based sensor array. Application to explosives detection using Co-BEA type zeolites as sensing materials

Recent advances in microcantilever-based sensors have led to a significant increase in sensitivity, making them a competitive solution in highly demanding applications as explosives detection. However, these sensors face severe challenges related to: reliability, sensitivity, reproducibility and throughput; that have yet to be solved for commercial applications. This paper describes our efforts in this direction, particularly on the reproducible detection of nitroaromatic type explosives by means of parallelization combined with: i) nanoporous solids as sensing materials; and, ii) a portable lowpower electronic readout interface capable of both excitation and measurement of the multisensing platform. The response of the sensor array, comprising 4 microcantilevers, due to presence of 2-nitrotoluene, a common explosive taggant, has been properly monitored. The obtained results with 4 identical Co-BEA coated Si microcantilevers underline the importance of a proper sensing material degassing on the sensor performance

Generation of femtosecond paraxial beams with arbitrary spatial distribution

We present an approach to generate paraxial laser beams with arbitrary spatial distribution in the femtosecond time regime. The proposed technique is based upon a pair of volume phase holographic gratings working in parallel arrangement. It exploits the spatial coherence properties of the incoming laser beam in a compact and robust setup that mitigates angular and spatial chirp. The gratings were recorded in a photopolymerizable glass with a high optical damage threshold and a large optical throughput. Setup performance is studied and experimentally demonstrated by generating Laguerre-Gaussian femtosecond pulses. © 2010 Optical Society of America.We thank Fransisco del Monte for valuable advice and CAI-UCM facilities. The financial support from the Spanish Ministry of Science and Innovation under projects TEC 2008-04105, CTQ2008-02578/BQU and Consolider SAUUL CSD2007-00013 is acknowledged. M. P. H.-G. and P. V. acknowledge the Spanish Ministry of Foreign Affairs and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) (Brazil) for financial support, respectively.Peer Reviewe