3 tera-basepairs as a fundamental limit for robust DNA replication

10 p.-2 tab.In order to maintain functional robustness and species integrity, organisms must ensure high fidelity of the genome duplication process. This is particularly true during early development, where cell division is often occurring both rapidly and coherently. By studying the extreme limits of suppressing DNA replication failure due to double fork stall errors, we uncover a fundamental constant that describes a trade-off between genome size and architectural complexity of the developing organism. This constant has the approximate value N_U ≈ 3×10^12 basepairs, and depends only on two highly conserved molecular properties of DNA biology. We show that our theory is successful in interpreting a diverse range of data across the Eukaryota.MAM, LA and TJN acknowledge prior support from the Scottish Universities Life Sciences Alliance. JJB acknowledges support from Cancer Research UK (grant C303/A14301) and the Wellcome Trust (grant WT096598MA). TJN acknowledges prior support from the National Institutes of Health (Physical Sciences in Oncology Centers, U54 CA143682).Peer reviewe

Evidence for a new path to the self-sustainment of the thermonuclear fusion in magnetically confined burning plasma experiments

In this work we provide the first explanation for observations made in 1997 on the Joint European Torus of unexpected ion heating with fusion-born alpha particles occurring over time scales much shorter than those theoretically foreseen. We demonstrate that non-thermal alpha particles above a critical concentration stabilize ion-drift-wave turbulence, therefore significantly reducing one of the main energy loss channels for thermal ions. As such ion heating occurs over times scales much shorter than those classically predicted, this mechanism opens new prospects on additional paths for the self-sustainment of thermonuclear fusion reactions in magnetically confined plasmas

A phenomenological explanation for the anomalous ion heating observed in the JET alpha-heating experiment of 1997

In the so-called alpha-heating experiment performed on the JET tokamak during the deuterium-tritium campaign of 1997, the ion temperature was found to be far exceeding (both in absolute value and in its rise time) the level that could have been expected from direct collisional heating by the fusion-born alpha particles themselves and energy equi-partition with the electrons. To date, no explanation has been put forward for this long standing puzzle, despite much work having been performed on this subject in the early 2000s. Two analysis methods that have recently become available have been employed to re-analyse these observations of an anomalous ion heating. First, an algorithm based on the Sparse Representation of Signals has been used to analyse magnetic, reflectometry and electron cyclotron emission measurements of the turbulence spectra in the drift-wave range of frequencies. This analysis has then been complemented with turbulence simulations performed with the GENE code. We find, both experimentally and in the simulations, that the presence of a minority, but sufficiently large, population of fusion-born alpha particles that have not yet fully thermalized stabilizes the turbulence in the ion-drift direction, but practically does not affect the turbulence in the electron-drift direction. We link such stabilization of the ion-drift-wave turbulence to the increase in the ion temperature above the level achieved in similar discharges that did not have (at all or enough) alpha particles. When the fusion-born alpha particles have fully thermalized, the turbulence spectrum in the ion-drift direction re-appears at somewhat larger amplitudes, which we link to the ensuing reduction in the ion temperature. This phenomenological dynamics fully corresponds to the actual experimental observations. By taking into account an effect of the alpha particles that had not been previously considered, our new analysis finally presents a phenomenological explanation for the so-far-unexplained anomalous ion heating observed in the JET alpha-heating experiment of 1997. Through the formulation of an empirical criterion for ion-drift-wave turbulence stabilization by fusion-born alpha particles, we also show why similar observations were not made in the other deuterium-tritium experiments run so far in JET and TFTR. This allows assessing the operational domain for this stabilization mechanism for ion-drift-wave turbulence in future burning plasma experiments such as ITER, which may open a new path towards the sustainment of a high energy gain in such forthcoming devices

Robust And Scalable Learning Of Complex Dataset Topologies Via Elpigraph

Large datasets represented by multidimensional data point clouds often possess non-trivial distributions with branching trajectories and excluded regions, with the recent single-cell transcriptomic studies of developing embryo being notable examples. Reducing the complexity and producing compact and interpretable representations of such data remains a challenging task. Most of the existing computational methods are based on exploring the local data point neighbourhood relations, a step that can perform poorly in the case of multidimensional and noisy data. Here we present ElPiGraph, a scalable and robust method for approximation of datasets with complex structures which does not require computing the complete data distance matrix or the data point neighbourhood graph. This method is able to withstand high levels of noise and is capable of approximating complex topologies via principal graph ensembles that can be combined into a consensus principal graph. ElPiGraph deals efficiently with large and complex datasets in various fields from biology, where it can be used to infer gene dynamics from single-cell RNA-Seq, to astronomy, where it can be used to explore complex structures in the distribution of galaxies.Comment: 32 pages, 14 figure

Numerical modelling of the electromagnetic turbulent transport of energetic ions in burning plasmas

We investigate the redistribution of the neutral beam driven current in the presence of small scale turbulence in the ITER steady-state scenario. Gyrokinetic simulations show that anomalous transport of beam ions can be larger than collisional estimates. The impact on the beam driven current in ITER is studied with a single particle following code. The results indicate that the current driven by the 1MeV neutral beam injection is not significantly redistributed by the microturbulent fields. The numerical investigation shows that a larger impact is expected for lower energy neutral beams

Influence of fine scale turbulence on the transport of high energy populations in burning plasmas

Tanzania Veterinary Journal, 2015; 30 (1): 1-10A study was conducted in Chunya District, Tanzania during December 2013 to assess the impact of tsetse fly and trypanosomosis control programme based on use of targets and traps. The trypanosome prevalence was determined by microscopic examination of thick and thin blood smears from 229 cattle selected randomly from 33 households. Additionally a semi-structured questionnaire was administered to heads or representatives of selected households to collect information on cattle- keepers’ knowledge on clinical features, transmission and control of trypanosomosis. Descriptive analysis of the data was done to establish proportions of different attributes and association between variables. Of 229 animals examined, six (2.6%) were positive for trypanosomes indicating significant decrease from baseline level of 13.8% found in 2010 at the beginning of the programme. Two trypanosome species, Trypanosoma vivax and T. congolense were identified in blood samples and vectors collected from the study area were identified as Glossina spp, Tabanus spp and Haematopota spp. Questionnaire results showed that burning of grasses (30.3%), theft of targets and traps (3.0%) and lack of follow up from the programme authority (6.1%) were major constraints that faced the programme. The study has shown a decline in prevalence of trypanosomosis which suggests that the application of traps and screens had a significantr impact on the disease and this warrants a recommendation of extending the trap and screen application technology to other similar tsetse infested areas of Tanzania