537 research outputs found
On the Influence of Corpuscular Fluxes and of Electron Photoloosening Reaction on the Formation of the D-Layer of the Ionosphere
Effect of corpuscular fluxes and electron photoloosening reaction on formation of ionospheric D laye
Toward Robust Manufacturing Scheduling: Stochastic Job-Shop Scheduling
Manufacturing plays a significant role in promoting economic development,
production, exports, and job creation, which ultimately contribute to improving
the quality of life. The presence of manufacturing defects is, however,
inevitable leading to products being discarded, i.e. scrapped. In some cases,
defective products can be repaired through rework. Scrap and rework cause a
longer completion time, which can contribute to the order being shipped late.
In addition, complex manufacturing scheduling becomes much more challenging
when the above uncertainties are present. Motivated by the presence of
uncertainties as well as combinatorial complexity, this paper addresses the
challenge illustrated through a case study of stochastic job-shop scheduling
problems arising within low-volume high-variety manufacturing. To ensure
on-time delivery, high-quality solutions are required, and near-optimal
solutions must be obtained within strict time constraints to ensure smooth
operations on the job-shop floor. To efficiently solve the stochastic job-shop
scheduling (JSS) problem, a recently-developed Surrogate "Level-Based"
Lagrangian Relaxation is used to reduce computational effort while efficiently
exploiting the geometric convergence potential inherent to Polyak's step-sizing
formula thereby leading to fast convergence. Numerical testing demonstrates
that the new method is more than two orders of magnitude faster as compared to
commercial solvers
Geological-hydrogeochemical characteristics of a "silver spring" water source (the Lozovy ridge)
Geological and hydrogeological characteristics of the Lozovy ridge (Southern Primorye) are studied, as far as karst phenomena are widely distributed within its boundaries. Water-bearing rocks of the karst water source "Silver Spring" ("Serebryany Klyuch"), which is located near the bottom of the "Bear's fang" ("Medvezhiy klyk") cave, are investigated. It is found that karst rocks are presented by calcite (CaCO[3]), and an accessory mineral is barite (BaSO[4]). It is determined that among the trace elements forming the composition of carbonate water-bearing rocks the maximum concentrations are typical for Sr, Ba, Fe, Al, Za, Mn, Cu, and Ni. Also, the chemical composition of the waters taken from the "Silver Spring" water source is studied. These waters are fresh, hydrocarbonate, calcium, and weakly alkaline. Among the elements of the spring, such elements as Sr, Ba, Fe, Al, Zn, Mn, Cu, and Ni have the maximum concentration. The other elements have concentrations less than 1 [mu]g/l
Temporal decorrelation of collective oscillations in neural networks with local inhibition and long-range excitation
We consider two neuronal networks coupled by long-range excitatory
interactions. Oscillations in the gamma frequency band are generated within
each network by local inhibition. When long-range excitation is weak, these
oscillations phase-lock with a phase-shift dependent on the strength of local
inhibition. Increasing the strength of long-range excitation induces a
transition to chaos via period-doubling or quasi-periodic scenarios. In the
chaotic regime oscillatory activity undergoes fast temporal decorrelation. The
generality of these dynamical properties is assessed in firing-rate models as
well as in large networks of conductance-based neurons.Comment: 4 pages, 5 figures. accepted for publication in Physical Review
Letter
Defining metrics for whole-genome sequence analysis of MRSA in clinical practice.
Bacterial sequencing will become increasingly adopted in routine microbiology laboratories. Here, we report the findings of a technical evaluation of almost 800 clinical methicillin-resistant Staphylococcus aureus (MRSA) isolates, in which we sought to define key quality metrics to support MRSA sequencing in clinical practice. We evaluated the accuracy of mapping to a generic reference versus clonal complex (CC)-specific mapping, which is more computationally challenging. Focusing on isolates that were genetically related (50 bp apart to identify same-species contamination for MRSA. These metrics were combined into a quality-control (QC) flowchart to determine whether sequence runs and individual clinical isolates passed QC, which could be adapted by future automated analysis systems to enable rapid hands-off sequence analysis by clinical laboratories
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Evaluation of a fully automated bioinformatics tool to predict antibiotic resistance from MRSA genomes.
OBJECTIVES: The genetic prediction of phenotypic antibiotic resistance based on analysis of WGS data is becoming increasingly feasible, but a major barrier to its introduction into routine use is the lack of fully automated interpretation tools. Here, we report the findings of a large evaluation of the Next Gen Diagnostics (NGD) automated bioinformatics analysis tool to predict the phenotypic resistance of MRSA. METHODS: MRSA-positive patients were identified in a clinical microbiology laboratory in England between January and November 2018. One MRSA isolate per patient together with all blood culture isolates (total n = 778) were sequenced on the Illumina MiniSeq instrument in batches of 21 clinical MRSA isolates and three controls. RESULTS: The NGD system activated post-sequencing and processed the sequences to determine susceptible/resistant predictions for 11 antibiotics, taking around 11 minutes to analyse 24 isolates sequenced on a single sequencing run. NGD results were compared with phenotypic susceptibility testing performed by the clinical laboratory using the disc diffusion method and EUCAST breakpoints. Following retesting of discrepant results, concordance between phenotypic results and NGD genetic predictions was 99.69%. Further investigation of 22 isolate genomes associated with persistent discrepancies revealed a range of reasons in 12 cases, but no cause could be found for the remainder. Genetic predictions generated by the NGD tool were compared with predictions generated by an independent research-based informatics approach, which demonstrated an overall concordance between the two methods of 99.97%. CONCLUSIONS: We conclude that the NGD system provides rapid and accurate prediction of the antibiotic susceptibility of MRSA
Collective Modes of Tri-Nuclear Molecules
A geometrical model for tri-nuclear molecules is presented. An analytical
solution is obtained provided the nuclei, which are taken to be prolately
deformed, are connected in line to each other. Furthermore, the tri-nuclear
molecule is composed of two heavy and one light cluster, the later sandwiched
between the two heavy clusters. A basis is constructed in which Hamiltonians of
more general configurations can be diagonalized. In the calculation of the
interaction between the clusters higher multipole deformations are taken into
account, including the hexadecupole one. A repulsive nuclear core is introduced
in the potential in order to insure a quasi-stable configuration of the system.
The model is applied to three nuclear molecules, namely Sr + Be +
Ba, Mo + Be + Te and Ru + Be +
Sn.Comment: 24 pages, 9 figure
Spatial characterization of interictal high frequency oscillations in epileptic neocortex
Interictal high frequency oscillations (HFOs), in particular those with frequency components in excess of 200 Hz, have been proposed as important biomarkers of epileptic cortex as well as the genesis of seizures. We investigated the spatial extent, classification and distribution of HFOs using a dense 4 × 4 mm2 two dimensional microelectrode array implanted in the neocortex of four patients undergoing epilepsy surgery. The majority (97%) of oscillations detected included fast ripples and were concentrated in relatively few recording sites. While most HFOs were limited to single channels, ∼10% occurred on a larger spatial scale with simultaneous but morphologically distinct detections in multiple channels. Eighty per cent of these large-scale events were associated with interictal epileptiform discharges. We propose that large-scale HFOs, rather than the more frequent highly focal events, are the substrates of the HFOs detected by clinical depth electrodes. This feature was prominent in three patients but rarely seen in only one patient recorded outside epileptogenic cortex. Additionally, we found that HFOs were commonly associated with widespread interictal epileptiform discharges but not with locally generated ‘microdischarges’. Our observations raise the possibility that, rather than being initiators of epileptiform activity, fast ripples may be markers of a secondary local response
Polymorphism of lipid exchange genes in some populations of South and East Siberia
Lipid metabolism disorders underlie the pathogenesis of a number of diseases. Indigenous peoples of Siberia have a specific genetically determined type of metabolism supporting such lipid blood parameters that favor increased consumption (in comparison with Caucasians) of animal products. At the same time, indigenous Siberian ethnic groups are less susceptible to metabolic diseases. The objective of the presented study was to investigate the allele frequencies of lipid metabolism genes in indigenous populations of Siberia to identify the ethnic features of allele frequency distribution for polymorphic variants in genes CETP (G1264A, rs5882), LPL (C1791G, rs328) and FTO (C83401A, rs8050136) in the samples taken from Buryats, Teleuts and Russians of Eastern Siberia, and to compare them with data on world populations. Samples of the Eastern (N = 132) and Western (N = 278) Buryats, Teleuts (N = 120), Russians (N = 122) and persons of mixed Buryat-Russian origin (N = 56) were genotyped by real-time PCR using competitive TaqMan-probes. The obtained results have for the first time demonstrated that the CETP and FTO allele frequencies in the Buryat samples are intermediate between European and East Asian populations. Significantly lower incidence of the obesity-assossiated 83401A allele of the FTO gene has been shown in Buryats, compared with Russians, which is consistent with lower susceptibility of the indigenous ethnic groups to metabolic disorders. There have been no population differences in the distribution of LPL gene polymorphic variants associated with dyslipidemia, which means they probably do not contribute to the ethnic characteristics of the lipid profile. The intermediate frequencies of the CETP 1264G and FTO 83401A alleles found in the metis group demonstrate that the metabolic disorders associated with these variants can be rather expected in the descendants of mixed marriages than among Buryats. It has also been demonstrated that Teleuts differ by FTO 83401A allele frequency from some of the European groups and have the lowest detected frequency of the allele CETP 1264G associated with the favorable lipid blood parameters
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