Light-in-flight recording. 5: Theory of slowing down the faster-than-light motion of the light shutter

Light-in-flight recording by holography uses a picosecond pulse for the reference beam, which like a sheet of light intersects the hologram plate and produces a sensitivity area that with a speed faster than light moves over the plate like a light shutter. If, however, the front of the reference pulse by diffraction in a grating is tilted relative to its direction of motion, the velocity of the light shutter can be slowed down resulting in increased recording time. The practical result using a reflection grating was a true recording that corresponded to a time compression of two to one. To minimize distortions of the recorded pulse shape we studied intersections that are identical for apparent (ellipsoidal) and true (spheroidal) wavefronts

Застосування визначеного інтегралу до розв’язування економічних задач

The aim of the present work was to study the influence of the stress on the electrode potential of the austenitic stainless steel301LN using Scanning Kelvin Probe (SKP). It was found that elastic deformation reversibly ennobles the potential whereas plasticdeformation decreases the potential in both tensile and compressive deformation mode and this decrease is retained even 24 h afterremoval of the load. To interpret the stress effects, different surface preparations were used and the composition and thickness ofthe passive film were determined by GDOES. Slip steps formed due to plastic deformation were observed using AFM. The effect ofplastic strain on the potential is explained by the formation of dislocations, which creates more a defective passive film.QC 20160516</p

A Case Study on Artefact-based RE Improvement in Practice

Most requirements engineering (RE) process improvement approaches are solution-driven and activity-based. They focus on the assessment of the RE of a company against an external norm of best practices. A consequence is that practitioners often have to rely on an improvement approach that skips a profound problem analysis and that results in an RE approach that might be alien to the organisational needs. In recent years, we have developed an RE improvement approach (called \emph{ArtREPI}) that guides a holistic RE improvement against individual goals of a company putting primary attention to the quality of the artefacts. In this paper, we aim at exploring ArtREPI's benefits and limitations. We contribute an industrial evaluation of ArtREPI by relying on a case study research. Our results suggest that ArtREPI is well-suited for the establishment of an RE that reflects a specific organisational culture but to some extent at the cost of efficiency resulting from intensive discussions on a terminology that suits all involved stakeholders. Our results reveal first benefits and limitations, but we can also conclude the need of longitudinal and independent investigations for which we herewith lay the foundation

Size-dependent long-term tissue response to biostable nanowires in the brain

AbstractNanostructured neural interfaces, comprising nanotubes or nanowires, have the potential to overcome the present hurdles of achieving stable communication with neuronal networks for long periods of time. This would have a strong impact on brain research. However, little information is available on the brain response to implanted high-aspect-ratio nanoparticles, which share morphological similarities with asbestos fibres. Here, we investigated the glial response and neuronal loss in the rat brain after implantation of biostable and structurally controlled nanowires of different lengths for a period up to one year post-surgery. Our results show that, as for lung and abdominal tissue, the brain is subject to a sustained, local inflammation when biostable and high-aspect-ratio nanoparticles of 5 μm or longer are present in the brain tissue. In addition, a significant loss of neurons was observed adjacent to the 10 μm nanowires after one year. Notably, the inflammatory response was restricted to a narrow zone around the nanowires and did not escalate between 12 weeks and one year. Furthermore, 2 μm nanowires did not cause significant inflammatory response nor significant loss of neurons nearby. The present results provide key information for the design of future neural implants based on nanomaterials

Grain refinement in additively manufactured ferritic stainless steel by in situ inoculation using pre-alloyed powder

For ferritic stainless steels, TiN has effectively been used as an inoculant to produce equiaxed grain structures in casting and welding. However, it is not established whether TiN would be an effective inoculant in additive manufacturing. In this study, the effectiveness of TiN as an inoculant in a ferritic stainless steel processed by laser powder-bed fusion is studied. An alloy without Ti is fabricated and compared to an alloy designed to form a high amount of TiN early during solidification. The work shows that the presence of TiN provides general grain refinement and that TiN-covered oxide particles are effective in enabling columnar-to-equiaxed transition in certain regions of the meltpool. The applied approach of pre-alloying powders with inoculant-forming elements offers a straightforward route to achieving fine, equiaxed grain structures in additively manufactured metallic materials. It also shows how oxygen present during the process can be utilized to nucleate effective inoculating phases

Early introduction of fish decreases the risk of eczema in infants

BACKGROUND: Atopic eczema in infants has increased in western societies. Environmental factors and the introduction of food may affect the risk of eczema. AIMS: To investigate the prevalence of eczema among infants in western Sweden, describe patterns of food introduction and assess risk factors for eczema at 1 year of age. METHODS: Data were obtained from a prospective, longitudinal cohort study of infants born in western Sweden in 2003; 8176 families were randomly selected and, 6 months after the infant\u27s birth, were invited to participate and received questionnaires. A second questionnaire was sent out when the infants were 12 months old. Both questionnaires were completed and medical birth register data were obtained for 4921 infants (60.2% of the selected population). RESULTS: At 1 year of age, 20.9% of the infants had previous or current eczema. Median age at onset was 4 months. In multivariable analysis, familial occurrence of eczema, especially in siblings (OR 1.87; 95% confidence interval (CI) 1.50 to 2.33) or the mother (OR 1.54; 95% CI 1.30 to 1.84), remained an independent risk factor. Introducing fish before 9 months of age (OR 0.76; 95% CI 0.62 to 0.94) and having a bird in the home (OR 0.35; 95% CI 0.17 to 0.75) were beneficial. CONCLUSIONS: One in five infants suffer from eczema during the first year of life. Familial eczema increased the risk, while early fish introduction and bird keeping decreased it. Breast feeding and time of milk and egg introduction did not affect the risk

Wong-Zakai approximation of solutions to reflecting stochastic differential equations on domains in Euclidean spaces II

The strong convergence of Wong-Zakai approximations of the solution to the reflecting stochastic differential equations was studied in [2]. We continue the study and prove the strong convergence under weaker assumptions on the domain.Comment: To appear in "Stochastic Analysis and Applications 2014-In Honour of Terry Lyons", Springer Proceedings in Mathematics and Statistic

Generation of Large-Scale Vorticity in a Homogeneous Turbulence with a Mean Velocity Shear

An effect of a mean velocity shear on a turbulence and on the effective force which is determined by the gradient of Reynolds stresses is studied. Generation of a mean vorticity in a homogeneous incompressible turbulent flow with an imposed mean velocity shear due to an excitation of a large-scale instability is found. The instability is caused by a combined effect of the large-scale shear motions (''skew-induced" deflection of equilibrium mean vorticity) and ''Reynolds stress-induced" generation of perturbations of mean vorticity. Spatial characteristics, such as the minimum size of the growing perturbations and the size of perturbations with the maximum growth rate, are determined. This instability and the dynamics of the mean vorticity are associated with the Prandtl's turbulent secondary flows. This instability is similar to the mean-field magnetic dynamo instability. Astrophysical applications of the obtained results are discussed.Comment: 8 pages, 3 figures, REVTEX4, submitted to Phys. Rev.

Evaluating range-expansion models for calculating nonnative species' expansion rate

Species range shifts associated with environmental change or biological invasions are increasingly important study areas. However, quantifying range expansion rates may be heavily influenced by methodology and/or sampling bias. We compared expansion rate estimates of Roesel's bush-cricket (Metrioptera roeselii, Hagenbach 1822), a nonnative species currently expanding its range in south-central Sweden, from range statistic models based on distance measures (mean, median, 95th gamma quantile, marginal mean, maximum, and conditional maximum) and an area-based method (grid occupancy). We used sampling simulations to determine the sensitivity of the different methods to incomplete sampling across the species' range. For periods when we had comprehensive survey data, range expansion estimates clustered into two groups: (1) those calculated from range margin statistics (gamma, marginal mean, maximum, and conditional maximum: similar to 3 km/year), and (2) those calculated from the central tendency (mean and median) and the area-based method of grid occupancy (similar to 1.5 km/year). Range statistic measures differed greatly in their sensitivity to sampling effort; the proportion of sampling required to achieve an estimate within 10% of the true value ranged from 0.17 to 0.9. Grid occupancy and median were most sensitive to sampling effort, and the maximum and gamma quantile the least. If periods with incomplete sampling were included in the range expansion calculations, this generally lowered the estimates (range 16-72%), with exception of the gamma quantile that was slightly higher (6%). Care should be taken when interpreting rate expansion estimates from data sampled from only a fraction of the full distribution. Methods based on the central tendency will give rates approximately half that of methods based on the range margin. The gamma quantile method appears to be the most robust to incomplete sampling bias and should be considered as the method of choice when sampling the entire distribution is not possible