Passive decoy-state quantum key distribution with imperfect source

Passive generation is a sophisticated way of state preparation in quantum key distribution (QKD) systems which is designed to exploit some internal physical process as a source of randomness. It can be profitable in a wide range of scenarios. However, the original analysis of the passive scheme implies an ideal interference which is almost impossible to assure in practice, therefore utilizing such method potentially compromises the security of the system. Here we develop a general technique to estimate decoy-state parameters for a passive protocol with an arbitrary experimental distribution of intensity. We compare this analysis with the original method and show that the proposed technique can provide higher key generation rates.

The Evolutions in Time of Probability Density Functions of Polydispersed Fuel Spray—The Continuous Mathematical Model

The dynamics of the particle size distribution (PSD) of polydispersed fuel spray is important in the evaluation of the combustion process. A better understanding of the dynamics can provide a tool for selecting a PSD that will more effectively meet the needs of the system. In this paper, we present an efficient and elegant method for evaluating the dynamics of the PSD. New insights into the behaviour of polydispersed fuel spray were obtained. A simplified theoretical model was applied to the experimental data and a known approximation of the polydispersed fuel spray. This model can be applied to any distribution, not necessarily an experimental distribution or approximation, and involves a time-dependent function of the PSD. Such simplified models are particularly helpful in qualitatively understanding the effects of various sub-processes. Our main results show that during the self-ignition process, the radii of the droplets decreased as expected, and the number of smaller droplets increased in inverse proportion to the radius. An important novel result (visualised by graphs) demonstrates that the mean radius of the droplets initially increases for a relatively short period of time, which is followed by the expected decrease. Our modified algorithm is superior to the well-known `parcel’ approach because it is much more compact; it permits analytical study because the right-hand sides of the mathematical model are smooth, and thus eliminates the need for a numerical algorithm to transition from one parcel to another. Moreover, the method can provide droplet radii resolution dynamics because it can use step functions that accurately describe the evolution of the radii of the droplets. The method explained herein can be applied to any approximation of the PSD, and involves a comparatively negligible computation time.

Origin of megacrysts by carbonate-bearing metasomatism – A case study for the Muskox kimberlite, Slave craton, Canada

Low-Cr and high-Cr clinopyroxene, garnet, olivine, and ilmenite megacrysts from the Muskox kimberlite (Canada) have been analyzed for major and trace elements, as well as Sr, Nd, and Pb isotopes. Samples display compositional overlap with respective phases in websterite, while clinopyroxene isotope systematics reveal similarities with both websteritic and metasomatic clinopyroxene in peridotites from the same kimberlite, in addition to Muskox and Jericho kimberlite. All lithologies may represent the products of mixing between EM1 mantle, relic Proterozoic enriched mantle and HIMU carbonatitic fluid. Equilibrium melts calculated from clinopyroxene trace element data using experimental distribution coefficients for feasible proto-kimberlitic melts yield a range of possible metasomatic agents. Conclusion on the carbonate-bearing nature of the metasomatism was based on the presence of a HIMU isotopic signature and results obtained from thermodynamic modeling using the Deep Earth Water model. The latter shows that mineral compositions analogous to megacrysts cannot be produced by metasomatism of mantle peridotite by H2O-rich kimberlitic fluids, or fluids in equilibrium with either asthenospheric or eclogitic mantle. Isotope systematics argue against a strictly cognate relationship between megacrysts and their host kimberlite, instead suggesting megacrysts and websterites may represent products of regional metasomatism by carbonatitic HIMU fluids shortly predating kimberlite magmatism.Supplementary material: Supplementary Table 1 contains the parameters used in isotopic mixing models https://doi.org/10.6084/m9.figshare.c.5255825

The walkoff effect: cargo distribution implies motor type in bidirectional microtubule bundles

Cells rely on molecular motors moving along an ever-shifting network of polymers (microtubules) for the targeted delivery of cell organelles to biologically-relevant locations. We present a stochastic model for a molecular motor stepping along a bidirectional bundle of microtubules, as well as a tractable analytical model. Using these models, we investigate how the preferred stepping direction of the motor (parallel or antiparallel to the microtubule growth, corresponding to kinesin and dynein motor families) quantitatively and qualitatively affects the cargo delivery. We predict which motor type is responsible for which cargo type, given the experimental distribution of cargo in the cell, and report experimental findings which support this guideline for motor classification.

On Causal Identification under Markov Equivalence

In this work, we investigate the problem of computing an experimental distribution from a combination of the observational distribution and a partial qualitative description of the causal structure of the domain under investigation. This description is given by a partial ancestral graph (PAG) that represents a Markov equivalence class of causal diagrams, i.e., diagrams that entail the same conditional independence model over observed variables, and is learnable from the observational data. Accordingly, we develop a complete algorithm to compute the causal effect of an arbitrary set of intervention variables on an arbitrary outcome set.

Genome-scale model of Rhodotorula toruloides metabolism

The basidiomycete red yeast Rhodotorula toruloides is a promising platform organism for production of biooils. We present rhto-GEM, the first genome-scale model of R. toruloides metabolism, that was largely reconstructed using RAVEN toolbox. The model includes 4869 genes, 897 reactions, and 3334 metabolites. Lipid metabolism was described using the SLIMEr formalism, which allows direct integration of lipid class and acyl chain experimental distribution data. The simulation results confirmed that the R. toruloides model provides valid growth predictions on glucose, xylose and glycerol, while prediction of genetic engineering targets to increase production of linolenic acid and triacylglycerols highlighted genes that have previously been successfully used to increase lipid production. This renders rtho-GEM useful for future studies to improve the production of other industrially important oleochemicals including both value-added fatty acids and carotenoids, while it will also be valuable tool for system-wide omics-data analysis in R. toruloides. Expanding the portfolio of GEMs for lipid accumulating fungi contributes to both understanding of metabolic mechanisms of the oleaginous phenotype but also uncover particularities of lipid production machinery in R. toruloides.

PRECISION, STABILITY ANALYSIS OF THE CRANKSHAFT GRINDING TECHNOLOGICAL PROCESS

Introduction. The article is devoted to the problem of the crankshafts quality of automotive tractor engines on the example of YaMZ - 238NB engines. Despite years of experience in the repair industry to implement the technological process of the crankshafts grinding during their restoration, the quality of its implementation is not sufficient. Therefore, for reducing errors in restoring crankshafts, as well as in any other parts, it is possible only if the reasons for their occurrence are promptly identified. The purpose of the research is to identify the reasons of the errors in the process of grinding crankshafts for repair dimensions according to the results of technical control and observation of the technological process.Materials and methods. The methodological basis for experimental and theoretical research is a system analysis. The structural and functional representation of the object is also used for research, and the model for the analysis of the grinding process serves as the basis for the decomposition.Results. While analyzing the measurements results of the rod necks connection and polishing for repair dimensions, the transformed experimental-statistical method is applied. The peculiarity of the method consists in the algebraic transformation of the calculation algorithm, which is reduced to simple formulas for semi-finished products and which makes it easy to program calculations on the computer. In addition, the order of processing the number of obtained numerical values and construction of distribution curves is stated for estimating the correspondence between the probability of the experimental distribution and the theoretical distribution.Discussion and conclusions. The implementation of the algorithm for calculating the accuracy and stability for the technological process of grinding the crankshafts during their restoration would reduce the error value. Moreover, the reduction of errors during the process of crankshafts restoration would improve the quality of repair, thus prolonging the crankshaft serviceability.