N-Body Simulation Program

Simulátor problému n těles předpovídá pohyb astronomických objektů pomocí numerické integrace pohybových zákonů. Gravitační interakce jsou počítány pomocí klasické Newtonovy mechaniky, tělesa jsou modelována jako hmotné body a neberou se v úvahu jiné síly než gravitační. Aplikace umožňuje nastavit počáteční polohy a rychlosti těles, animovat jejich pohyb, změnit numerickou metodu a bude dostupná pod licencí GPL. Může být použita při vyučování spojitých simulací na ukázání rozdílu mezi numerickými integrátory s různými časovými kroky. Dále může být použita studenty fyziky jako experimentační nástroj. Jsou dodány základní ukázky jako Sluneční soustava a problém tří těles se Zemí, Měsícem a Sluncem.The n -body problem simulator predicts the motion of celestial bodies by numerically integrating the laws of motion. Gravitational interactions are computed directly between the bodies using Newton's classical mechanics and the bodies are modelled as point masses. The application animates the problem and will be available under the GPL licence. It can be used while teaching continuous simulation to show accuracy differences between numerical integrators with various time steps. It can also serve as an experimentation tool for physics students. Some basic examples are included in the project, like the Solar System and the three body problem with the Earth, Moon and Sun.

The most common founder pathogenic variant c.868G > A (p.Val290Met) in the NPHS2 gene in a representative adult Czech cohort with focal segmental glomerulosclerosis is associated with a milder disease and its underdiagnosis in childhood

BackgroundGenetic focal segmental glomerulosclerosis (FSGS) is caused by pathogenic variants in a broad spectrum of genes that have a variable representation based on subjects' ethnicity and/or age. The most frequently mutated autosomal recessive gene in FSGS is NPHS2. In this study, we analyzed the spectrum of NPHS2 variants and their associated phenotype in Czech adult FSGS patients.MethodsA representative cohort of 234 adult patients with FSGS, derived from 225 families originating from all regions of Czechia, was analyzed by massively parallel sequencing. In this study, we focused on the comprehensive analysis of the NPHS2 gene. The histological classification of FSGS followed the Columbia classification.ResultsWe detected seven (3%) cases bearing homozygous or compound heterozygous pathogenic NPHS2 variants. A single pathogenic variant c.868G > A (p.Val290Met) was found in the majority of NPHS2-positive cases (86%; 6 out of 7) in histologically confirmed instances of FSGS. Its allele frequency among unrelated NPHS2-associated FSGS patients was 50% (6/12), and Haplotype analysis predicted its origin to be a result of a founder effect. There is an identical V290M-related haplotype on all V290M alleles spanning a 0,7 Mb region flanking NPHS2 in Central European FSGS populations. The phenotype of the p.Val290Met NPHS2-associated FSGS demonstrated a later onset and a much milder course of the disease compared to other NPHS2 pathogenic variants associated with FSGS. The mean age of the FSGS diagnosis based on kidney biopsy evaluation was 31.2 ± 7.46 years. In 50% of all cases, the initial disease manifestation of proteinuria occurred only in adulthood, with 83% of these cases not presenting with edemas. One-third (33%) of the studied subjects progressed to ESRD (2 out of 6) at the mean age of 35.0 ± 2.82 years.ConclusionsWe identified the most prevalent pathogenic variant, p.Val290Met, in the NPHS2 gene among Czech adult FSGS patients, which has arisen due to a founder effect in Central Europe. The documented milder course of the disease associated with this variant leads to the underdiagnosis in childhood. We established the histopathological features of the NPHS2-associated adult FSGS cases based on the Columbia classification. This might improve patient stratification and optimize their treatment