Supervised Learning in image enhance from electron microscopy inversion results

In Nondestructive testing there is a variety of applications in Material Science, where the specimen is imaged by an Electron Microscope and then by image inversion, informationis extracted for the material interior. This type of information might contain noise either by the imaging procedure or by the numerical part of the inversion. We present a method that can improve the interior density results of an inversed material from a series of Scanning Electron Microscope (SEM) images. For this method, the material density can contain some discontinuity, such as regions where it is dense and regions where there are voids.The proposed method directly stands on the Bayesian learning framework, adopting Gaussian Stochastic Processes (GSPs). Two test sample cases that contain some discontinuities in the density are tested. We also provide a comparison between two different GSP modelling approaches; one is a typical GSP and the other accounts for discontinuity, by introducing hyperparameters. The GSP method gives reconstructed data in reasonable agreement with the known original density distribution, giving confidence that the method can be applied to experimentally obtained SEM images.

An Experimental Study of Micro-Dimpled Texture in Friction Control under Dry and Lubricated Conditions

Friction control is a vital technology for reaching sustainable development goals, and surface texturing is one of the most effective and efficient techniques for friction reduction. This study investigated the performance of a micro-dimpled texture under varying texture densities and experimental conditions. Reciprocating sliding tests were performed to evaluate the effects of the micro-dimpled texture on friction reduction under different normal loads and lubrication conditions. The results suggested that a micro-dimpled texture could reduce the coefficient of friction (CoF) under dry and lubricated conditions, and high dimple density results in a lower CoF. The dominant mechanism of the micro-dimpled texture’s effect on friction reduction was discussed, and surface observation and simulation suggested that a micro-dimpled texture could reduce the contact area at the friction interface, thereby reducing CoF.

The Effect of Mirid Density on Volatile-Mediated Foraging Behaviour of Apolygus lucorum and Peristenus spretus

Plants would release herbivore-induced plant volatiles (HIPVs) to repel herbivores and attract natural enemies after being damaged by herbivores. In this study, after cotton plants were damaged by different densities of Apolygus lucorum, the behavioral responses of A. lucorum and Peristenus spretus to cotton plants volatiles were evaluated, and the quality and quantity of volatiles from cotton plants were analyzed. Only when cotton plants were damaged by four bugs did both A. lucorum and P. spretus show an obvious response to damaged cotton plants, which indicates that cotton defense is correlated with pest density. The collection and analysis of volatiles reveals that the increase in pest density results in the emission of new compounds and an increase in the total number of volatiles with an alteration in proportions among the compounds in the blend. These changes in volatile profiles might provide wasps and mirids with specific information on host habitat quality and thus could explain the behavioral responses of parasitoids and pests.

New Zero-Density Results for Automorphic L-Functions of GL(n)

Let L(s,π) be an automorphic L-function of GL(n), where π is an automorphic representation of group GL(n) over rational number field Q. In this paper, we study the zero-density estimates for L(s,π). Define Nπ(σ,T1,T2) = ♯ {ρ = β + iγ: L(ρ,π) = 0, σ<β<1, T1≤γ≤T2}, where 0≤σ<1 and T1<T2. We first establish an upper bound for Nπ(σ,T,2T) when σ is close to 1. Then we restrict the imaginary part γ into a narrow strip [T,T+Tα] with 0<α≤1 and prove some new zero-density results on Nπ(σ,T,T+Tα) under specific conditions, which improves previous results when σ near 34 and 1, respectively. The proofs rely on the zero detecting method and the Halász-Montgomery method.

Myelin densities in retinotopically defined dorsal visual areas of the macaque

The visuotopic organization of dorsal visual cortex rostral to area V2 in primates has been a longstanding source of controversy. Using sub-millimeter phase-encoded retinotopic fMRI mapping, we recently provided evidence for a surprisingly similar visuotopic organization in dorsal visual cortex of macaques compared to previously published maps in New world monkeys (Zhu and Vanduffel, Proc Natl Acad Sci USA 116:2306–2311, 2019). Although individual quadrant representations could be robustly delineated in that study, their grouping into hemifield representations remains a major challenge. Here, we combined in-vivo high-resolution myelin density mapping based on MR imaging (400 µm isotropic resolution) with fine-grained retinotopic fMRI to quantitatively compare myelin densities across retinotopically defined visual areas in macaques. Complementing previously documented differences in populational receptive-field (pRF) size and visual field signs, myelin densities of both quadrants of the dorsolateral posterior area (DLP) and area V3A are significantly different compared to dorsal and ventral area V3. Moreover, no differences in myelin density were observed between the two matching quadrants belonging to areas DLP, V3A, V1, V2 and V4, respectively. This was not the case, however, for the dorsal and ventral quadrants of area V3, which showed significant differences in MR-defined myelin densities, corroborating evidence of previous myelin staining studies. Interestingly, the pRF sizes and visual field signs of both quadrant representations in V3 are not different. Although myelin density correlates with curvature and anticorrelates with cortical thickness when measured across the entire cortex, exactly as in humans, the myelin density results in the visual areas cannot be explained by variability in cortical thickness and curvature between these areas. The present myelin density results largely support our previous model to group the two quadrants of DLP and V3A, rather than grouping DLP- with V3v into a single area VLP, or V3d with V3A+ into DM.

Analysis of Deformation and Erosion during CME Evolution

Magnetised coronal mass ejections (CMEs) are quite substantially deformed during their journey form the Sun to the Earth. Moreover, the interaction of their internal magnetic field with the magnetic field of the ambient solar wind can cause deflection and erosion of their mass and magnetic flux. We here analyse axisymmetric (2.5D) MHD simulations of normal and inverse CME, i.e., with the opposite or same polarity as the background solar wind, and attempt to quantify the erosion and the different forces that operate on the CMEs during their evolution. By analysing the forces, it was found that an increase of the background wind density results in a stronger plasma pressure gradient in the sheath that decelerates the magnetic cloud more. This in turn leads to an increase of the magnetic pressure gradient between the centre of the magnetic cloud and the separatrix, causing a further deceleration. Regardless of polarity, the current sheet that forms in our model between the rear of the CME and the closed field lines of the helmet streamer, results in magnetic field lines being stripped from the magnetic cloud. It is also found that slow normal CMEs experience the same amount of erosion, regardless of the background wind density. Moreover, as the initial velocity increases, so does the influence of the wind density on the erosion. We found that increasing the CME speed leads to a higher overall erosion due to stronger magnetic reconnection. For inverse CMEs, field lines are not stripped away but added to the magnetic cloud, leading to about twice as much magnetic flux at 1 AU than normal CMEs with the same initial flux.

Some Density Results on Sets of Primes for Hecke Eigenvalues

Let f and g be two distinct holomorphic cusp forms for S L 2 ℤ , and we write λ f n and λ g n for their corresponding Hecke eigenvalues. Firstly, we study the behavior of the signs of the sequences λ f p λ f p j for any even positive integer j . Moreover, we obtain the analytic density for the set of primes where the product λ f p i λ f p j is strictly less than λ g p i λ g p j . Finally, we investigate the distribution of linear combinations of λ f p j and λ g p j in a given interval. These results generalize previous ones.

Urban Boundary Layers Over Dense and Tall Canopies

Wind-tunnel experiments were carried out on four urban morphologies: two tall canopies with uniform height and two super-tall canopies with a large variation in element heights (where the maximum element height is more than double the average canopy height, $$h_{max}=2.5h_{avg}$$ h max = 2.5 h avg ). The average canopy height and packing density are fixed across the surfaces to $$h_{avg} = 80~\hbox {mm}$$ h avg = 80 mm , and $$\lambda _{p} = 0.44$$ λ p = 0.44 , respectively. A combination of laser Doppler anemometry and direct-drag measurements are used to calculate and scale the mean velocity profiles with the boundary-layer depth $$\delta $$ δ . In the uniform-height experiment, the high packing density results in a ‘skimming flow’ regime with very little flow penetration into the canopy. This leads to a surprisingly shallow roughness sublayer (depth $$\approx 1.15h_{avg}$$ ≈ 1.15 h avg ), and a well-defined inertial sublayer above it. In the heterogeneous-height canopies, despite the same packing density and average height, the flow features are significantly different. The height heterogeneity enhances mixing, thus encouraging deep flow penetration into the canopy. A deeper roughness sublayer is found to exist extending up to just above the tallest element height (corresponding to $$z/h_{avg} = 2.85$$ z / h avg = 2.85 ), which is found to be the dominant length scale controlling the flow behaviour. Results point toward the existence of a constant-stress layer for all surfaces considered herein despite the severity of the surface roughness ($$\delta /h_{avg} = 3 - 6.25$$ δ / h avg = 3 - 6.25 ). This contrasts with the previous literature.