272 research outputs found
Efficient Certified Resolution Proof Checking
We present a novel propositional proof tracing format that eliminates complex
processing, thus enabling efficient (formal) proof checking. The benefits of
this format are demonstrated by implementing a proof checker in C, which
outperforms a state-of-the-art checker by two orders of magnitude. We then
formalize the theory underlying propositional proof checking in Coq, and
extract a correct-by-construction proof checker for our format from the
formalization. An empirical evaluation using 280 unsatisfiable instances from
the 2015 and 2016 SAT competitions shows that this certified checker usually
performs comparably to a state-of-the-art non-certified proof checker. Using
this format, we formally verify the recent 200 TB proof of the Boolean
Pythagorean Triples conjecture
High-k GaAs metal insulator semiconductor capacitors passivated by ex-situ plasma-enhanced atomic layer deposited AlN for Fermi-level unpinning
This paper examines the utilization of plasma-enhanced atomic layer deposition grown AlN in the fabrication of a high-kinsulator layer on GaAs. It is shown that high-kGaAsMIS capacitors with an unpinned Fermi level can be fabricated utilizing a thin ex-situ deposited AlNpassivation layer. The illumination and temperature induced changes in the inversion side capacitance, and the maximum band bending of 1.2 eV indicates that the MIS capacitor reaches inversion. Removal of surface oxide is not required in contrast to many common ex-situ approaches.Peer reviewe
Optimization of single crystal mirrors for ITER diagnostics
Diagnostic mirrors are planned to be used in all optical diagnostics in ITER. Degradation of mirrors due to e.g. deposition of plasma impurities will hamper the entire performance of affected diagnostics. in situ mirror cleaning by plasma sputtering is presently envisaged for the recovery of contaminated mirrors. There are observations showing a signature of sputtering dependence on crystal orientation. Should such a dependence exist, the sputtering of single crystal mirrors could be minimized, thus prolonging a mirror lifetime. Four single crystal molybdenum mirrors with different orientations were produced to study the effect of crystal orientation on sputtering. Mirrors were exposed to argon plasma under identical plasma conditions relevant to those expected in the mirror cleaning systems of ITER. The energy of impinging ions was about 60 eV. The amount of sputtered material corresponded to about a hundred mirror cleaning cycles in argon. Plasma exposures did not affect the mirror reflectivity. The maximum decrease of specular reflectivity did not exceed 5% at 250 nm. The mirrors with orientations [110]/[101] demonstrated up to 42% less sputtering than the mirrors with other crystal orientations. These findings outline the advantage of a favorable crystal orientation for a cleaning of heavy contaminants from ITER mirrors.Peer reviewe
Network development in biological gels: role in lymphatic vessel development
In this paper, we present a model that explains the prepatterning of lymphatic vessel morphology in collagen gels. This model is derived using the theory of two phase rubber material due to Flory and coworkers and it consists of two coupled fourth order partial differential equations describing the evolution of the collagen volume fraction, and the evolution of the proton concentration in a collagen implant; as described in experiments of Boardman and Swartz (Circ. Res. 92, 801–808, 2003). Using linear stability analysis, we find that above a critical level of proton concentration, spatial patterns form due to small perturbations in the initially uniform steady state. Using a long wavelength reduction, we can reduce the two coupled partial differential equations to one fourth order equation that is very similar to the Cahn–Hilliard equation; however, it has more complex nonlinearities and degeneracies. We present the results of numerical simulations and discuss the biological implications of our model
Vertical profiles of volatile organic compounds and fine particles in atmospheric air by using an aerial drone with miniaturized samplers and portable devices
The increase in volatile organic compound (VOC) emissions
released into the atmosphere is one of the main threats to human health and
climate. VOCs can adversely affect human life through their contribution to
air pollution directly and indirectly by reacting via several mechanisms in
the air to form secondary organic aerosols. In this study, an aerial drone
equipped with miniaturized air-sampling systems including up to four
solid-phase microextraction (SPME) Arrows and four in-tube extraction (ITEX)
samplers for the collection of VOCs, along with portable devices for the
real-time measurement of black carbon (BC) and total particle numbers at
high altitudes was exploited. In total, 135 air samples were collected under
optimal sampling conditions from 4 to 14 October 2021 at the boreal
forest SMEAR II station, Finland. A total of 48 different VOCs, including
nitrogen-containing compounds, alcohols, aldehydes, ketones, organic acids,
and hydrocarbons, were detected at different altitudes from 50 to 400 m
above ground level with concentrations of up to 6898 ng m−3 in the gas
phase and 8613 ng m−3 in the particle phase. Clear differences in VOC
distributions were seen in samples collected from different altitudes,
depending on the VOC sources. It was also possible to collect aerosol
particles by the filter accessory attached on the ITEX sampling system, and
five dicarboxylic acids were quantified with concentrations of 0.43 to
10.9 µg m−3. BC and total particle number measurements
provided similar diurnal patterns, indicating their correlation. For spatial
distribution, BC concentrations were increased at higher altitudes, being
2278 ng m−3 at 100 m and 3909 ng m−3 at 400 m. The measurements
aboard the drone provided insights into horizontal and vertical variability
in BC and aerosol number concentrations above the boreal forest.</p
Genome-wide association study of primary tooth eruption identifies pleiotropic loci associated with height and craniofacial distances
Twin and family studies indicate that the timing of primary tooth eruption is highly heritable, with estimates typically exceeding 80%. To identify variants involved in primary tooth eruption we performed a population based genome-wide association study of ‘age at first tooth’ and ‘number of teeth’ using 5998 and 6609 individuals respectively from the Avon Longitudinal Study of Parents and Children (ALSPAC) and 5403 individuals from the 1966 Northern Finland Birth Cohort (NFBC1966). We tested 2,446,724 SNPs imputed in both studies. Analyses were controlled for the effect of gestational age, sex and age of measurement. Results from the two studies were combined using fixed effects inverse variance meta-analysis. We identified a total of fifteen independent loci, with ten loci reaching genome-wide significance (p<5x10−8) for ‘age at first tooth’ and eleven loci for ‘number of teeth’. Together these associations explain 6.06% of the variation in ‘age of first tooth’ and 4.76% of the variation in ‘number of teeth’. The identified loci included eight previously unidentified loci, some containing genes known to play a role in tooth and other developmental pathways, including a SNP in the protein-coding region of BMP4 (rs17563, P= 9.080x10−17). Three of these loci, containing the genes HMGA2, AJUBA and ADK, also showed evidence of association with craniofacial distances, particularly those indexing facial width. Our results suggest that the genome-wide association approach is a powerful strategy for detecting variants involved in tooth eruption, and potentially craniofacial growth and more generally organ development
Dental cell type atlas reveals stem and differentiated cell types in mouse and human teeth
Understanding cell types and mechanisms of dental growth is essential for reconstruction and engineering of teeth. Therefore, we investigated cellular composition of growing and non-growing mouse and human teeth. As a result, we report an unappreciated cellular complexity of the continuously-growing mouse incisor, which suggests a coherent model of cell dynamics enabling unarrested growth. This model relies on spatially-restricted stem, progenitor and differentiated populations in the epithelial and mesenchymal compartments underlying the coordinated expansion of two major branches of pulpal cells and diverse epithelial subtypes. Further comparisons of human and mouse teeth yield both parallelisms and differences in tissue heterogeneity and highlight the specifics behind growing and non-growing modes. Despite being similar at a coarse level, mouse and human teeth reveal molecular differences and species-specific cell subtypes suggesting possible evolutionary divergence. Overall, here we provide an atlas of human and mouse teeth with a focus on growth and differentiation. Unlike human teeth, mouse incisors grow throughout life, based on stem and progenitor cell activity. Here the authors generate single cell RNA-seq comparative maps of continuously-growing mouse incisor, non-growing mouse molar and human teeth, combined with lineage tracing to reveal dental cell complexity.Peer reviewe
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