Random Spatial Distribution Research Articles

Habitat quality affects the social organization in mouse lemurs (Microcebus griseorufus)

Species can either maintain a certain social organization in different habitats or show different social organizations in similar habitats. The reasons underlying this variability are not always clear but might have consequences for population dynamics, especially under changing environmental conditions. Among mammals, the primate genus Microcebus lives in small groups of closely related females, derived from female philopatry and dispersed males, as illustrated by the well-studied Microcebus murinus. Here, we studied the genetic structure of a population of the congeneric Microcebus griseorufus, inhabiting three adjacent habitats with different resource availabilities. In order to learn more about the plasticity of the species’ social organization under these different conditions, we analyzed the spatial arrangement of mitochondrial haplotypes of 122 individuals. The study revealed high haplotype diversity and a pronounced difference in spatial distribution between the sexes. Females exhibited spatial aggregation of haplotypes, suggesting a system of female philopatry and matrilines, similar to M. murinus. Male haplotypes were dispersed, and males were more likely to carry rare haplotypes, indicating higher dispersal activity. These findings hint towards the unity of the social organization across the genus Microcebus, suggesting a phylogenetic origin of the social organization. Yet, with decreasing resources, the clustering of female haplotypes declined and approached a random distribution in the marginal habitat, with cluster sizes correlating with resource availability as predicted by the socioecological model. Our study supports the notion that social organization is shaped by both phylogenetic origin and ecological conditions, at least in these small primates.Significance statementImpacts of habitat degradation are mostly described in terms of changes in population densities in relation to the reduction of resources. This neglects the possible effects of altered social organizations due to declining resources or population densities. Using a genetic sampling of three subpopulations of mouse lemurs in Madagascar along a gradient of food availability up to the limit of the species’ ecological tolerance, we show that their social organization consisting of spatial clusters of closely related females and overdispersed males converges towards random spatial distributions of both sexes with declining food availability.

Void growth in ductile materials with realistic porous microstructures

In this paper, we have investigated void growth in von Mises materials which contain realistic porous microstructures. For that purpose, we have performed finite element calculations of cubic unit-cells which are subjected to periodic boundary conditions and include porosity distributions representative of three additively manufactured metals. The initial void volume fraction in the calculations varies between 0.00564% and 1.75%, the number of actual voids between 14 and 5715, and the pores size from 2.3μm to 110μm. Several tests with different void sizes and positions have been generated for each of the three porous microstructures considered, and for each test we have performed several realizations with different spatial arrangement of the voids. The simulations have been carried out with random spatial distributions of pores and with clusters of the same size and different void densities. The macroscopic stress state in the unit-cell is controlled by prescribing constant triaxiality and Lode parameter throughout the loading. Calculations performed exchanging the loading directions for a given distribution of void sizes and positions have shown that the porous microstructure makes the macroscopic strain softening of the unit-cell (slightly) anisotropic. Moreover, the results obtained with the realistic porous microstructures have been compared with unit-cell calculations having an equivalent single central pore, and with calculations in which the material behavior is modeled with Gurson plasticity. It has been shown that both initial void volume fraction and spatial and size distribution of voids affect the macroscopic response of the porous aggregate and the void volume fraction evolution. Moreover, the calculations with random spatial distribution of voids have brought out that different tests of the same microstructure carry significant variations to the effective behavior of the porous aggregate, and that the interaction between neighboring pores dictates the volume evolution of individual voids, especially at higher macroscopic triaxiality. The calculations with clusters have shown that pores clustering promotes localization/coalescence due to increased interaction between the voids, which results in an increased growth rate of voids in clusters with large number of pores. Moreover, the results for the evolution of the distribution of plastic strains in the unit-cell have provided quantitative indications of the role of porous microstructure on the development of heterogeneous plastic strain fields which promote macroscopic strain softening. Namely, the accelerated growth rate of the plastic strains near the voids which indicates the onset of localization/coalescence has been shown to occur earlier as the number of voids in the microstructure increases.

The influence of coarse particle abundance and spatial distribution on sediment transport and cluster evolution in steep channels under sediment-starved conditions

Large particles strongly influence flow resistance, energy dissipation, bed stability, and channel morphology in mountain streams. We conducted flume experiments to evaluate effects of the density and spatial distribution of coarse particles (i.e., keystones) on bed stability, surface texture and sediment transport in steep channels. Keystones were placed on the channel bed surface at the beginning of each experiment, both in clustered and in uniformly spaced (i.e., anti-clustered) configurations and in different numbers (i.e., for different values of keystone density). The flow rate was increased by 20 % every hour and each experiment continued until the bed was completely scoured. Sediment transport was measured with a sediment trap located at the flume outlet. Topographic data from high-resolution surface imagery and second-order structure functions (SSF) of bed elevations, were used to characterize bed surface structuring while the Ripley’s K function was used to assess the degree of clustering of keystones relative to random spatial distributions. Our results indicate that (1) the density and spatial distribution of keystones exert a minor control on the bed surface grain-size distribution (GSD), (2) for increasing flow rates, the spatial distribution of keystones naturally evolves towards a random distribution, regardless of the initial spatial arrangment, and (3) sediment transport has a higher correlation with the proportion of dislodged keystones than with flow discharge.

On the influence of the probabilistic microstructural characteristics of glass fiber‐reinforced composites on the wave propagation in GLARE

AbstractIn an attempt to reduce the crack propagation speed in structures made of fiber‐reinforced composites metal layers are added to the laminate forming a new group of materials, so‐called fiber metal laminates. GLARE, a combination of glass fiber‐reinforced polymer and aluminum, is well‐known and frequently used in the aeronautical industry. One major drawback of such materials is their susceptibility to impact damage, which is not detectable by visual inspections. Hence, an adequate structural health monitoring technique to detect interlaminar damage like delaminations is essential for components made from fiber metal laminates. One approach here is the use of guided ultrasonic waves because they travel long distances without substantial damping and cover the whole thickness of thin‐walled structures. However, the probabilistic microstructure causes a continuous mode conversion in wave guides made from fiber‐reinforced composites. This significantly influences the signal processing and as a consequence, the interpretation of captured time signals. This phenomenon is induced by the random spatial distribution of the fibers in the matrix material, leading to an ongoing excitation of new wave modes within the propagating S0 wave mode. In this research, the effect is studied for the wave propagation in GLARE 3/2‐0.4. Therefore, the spatial distribution of the transverse YOUNG's modulus for the glass fiber‐reinforced layers is represented by homogeneous second‐order GAUSSian random fields. Afterwards, the propagation of the guided ultrasonic wave is simulated numerically. The results reveal that the continuous mode conversion is not only observable within the glass fiber‐reinforced polymer layers but also at the top and bottom surface and hence, within the isotropic layers. This holds for the wave propagation both in and perpendicular to the fiber orientation of the glass fiber‐reinforced polymer layers.

Distribution and attribute analysis of soil selenium in Hebei Province, China

From 2004 to 2018, c. 73% of the land area in Hebei Province was surveyed by a 1:250 000 land quality geochemical survey of the National Geochemistry Survey of Land Quality. Based on the topsoil (0–20 cm) datasets (50 724 analysis samples) and attribute analysis of the key area with a semivariance function model, geographic detector model and random forest model, the content and spatial distribution of soil selenium (Se) in Hebei Province and the influencing factors of the distribution of Se in the Shijiazhuang–Xingtai–Handan area were obtained. The soil Se content in Hebei Province is low, ranging from 0.02 to 3.23 mg kg –1 , with an average of 0.20 mg kg –1 . The spatial distribution of soil Se was heterogeneous, and the marginal Se (0.125–0.175 mg kg –1 ) area and the sufficient Se (0.175–0.40 mg kg –1 ) area were widely distributed, but the acreage of the Se-rich (0.40–3.0 mg kg –1 ) area was very limited, accounting for only 2.43% of the total survey area. However, the Shijiazhuang–Xingtai–Handan area was a significant Se enrichment area. The spatial distribution of Se in this area was restricted by natural and socioeconomic factors. Soil organic matter was the most influential factor and showed good coordination with Se. Coal burning superimposed on natural factors promotes the spatial differentiation of soil Se to a certain extent.

Resonance behaviors of encapsulated microbubbles oscillating nonlinearly with ultrasonic excitation

The resonance behaviors of a few lipid-coated microbubbles acoustically activated in viscoelastic media were comprehensively examined via radius response analysis. The size polydispersity and random spatial distribution of the interacting microbubbles, the rheological properties of the lipid shell and the viscoelasticity of the surrounding medium were considered simultaneously. The obtained radius response curves present a successive occurrence of linear resonances, nonlinear harmonic and sub-harmonic resonances with the acoustic pressure increasing. The microbubble resonance is radius-, pressure- and frequency-dependent. Specifically, the maximum bubble expansion ratio at the main resonance peak increases but the resonant radius decreases as the ultrasound pressure increases, while both of them decrease with the ultrasound frequency increasing. Moreover, compared to an isolated microbubble case, it is found that large microbubbles in close proximity prominently suppress the resonant oscillations while slightly increase the resonant radii for both harmonic and subharmonic resonances, even leading to the disappearance of the subharmonic resonance with the influences increasing to a certain degree. In addition, the results also suggest that both the encapsulating shell and surrounding medium can substantially dampen the harmonic and subharmonic resonances while increase the resonant radii, which seem to be affected by the medium viscoelasticity to a greater degree rather than the shell properties. This work offers valuable insights into the resonance behaviors of microbubbles oscillating in viscoelastic biological media, greatly contributing to further optimizing their biomedical applications.

A TRUNCATED GAUSSIAN RANDOM FIELD METHOD FOR MODELING THE POROSITY DEFECT IN COMPOSITE STRUCTURES

Reducing the cost of manufacturing of primary structures can be achieved by better control of the manufacturing tolerances and acceptable levels of variability. Predicting the effect of defects can also help clear quality concerns that affect the amount of parts that require repairs or need to be scrapped. In this paper, a numerical method is presented for the assessment of the effect of a variable distribution of porosity defects in composite structures at the macroscale. A numerical method is first implemented to simulate random porous zones over the 3-D surface of the composite part. Two or more material configurations can be considered: the sane one and the porous ones. In the numerical model, each element of the part mesh is assigned one of the materials. The random choice between the materials for each element is based on the simulation of a truncated Gaussian random field over the 3-D surface. A Monte Carlo simulation method is used to study the effect of the random spatial distribution of porosity on the mechanical performance of the structure. To illustrate this approach, the case of a curved stiffened panel with a compression load case is considered, and the mechanical performance is evaluated. By taking all the samples of random porosity distributions that have high values for displacement and stress, the critical zones of the structure are identified. Based on these predictive methods, a methodology could further be defined to select more critical areas for inspection and potentially reduce time required for quality controls.

Colossal negative magnetoresistance from hopping in insulating ferromagnetic semiconductors

Ferromagnetic semiconductor Ga1–x Mn x As1–y P y thin films go through a metal–insulator transition at low temperature where electrical conduction becomes driven by hopping of charge carriers. In this regime, we report a colossal negative magnetoresistance (CNMR) coexisting with a saturated magnetic moment, unlike in the traditional magnetic semiconductor Ga1– x Mn x As. By analyzing the temperature dependence of the resistivity at fixed magnetic field, we demonstrate that the CNMR can be consistently described by the field dependence of the localization length, which relates to a field dependent mobility edge. This dependence is likely due to the random environment of Mn atoms in Ga1–x Mn x As1–y P y which causes a random spatial distribution of the mobility that is suppressed by an increasing magnetic field.

Numerical simulation of oil-water displacements in naturally fractured reservoirs using a hybrid grid MPFA-streamline (SLS-HyG) formulation

The numerical simulation of fluid displacements in naturally fractured reservoirs is rather expensive in terms of CPU requirements and challenging, due to the random spatial distribution of fractures of different sizes and shapes. In this paper, we present a numerical formulation to simulate the 2-D two-phase flow of oil and water in naturally fractured oil reservoirs using unstructured quadrilateral meshes. In our Hybrid-Grid MPFA-Streamline (SLS-HyG) formulation, the elliptic pressure equation is discretised by a finite volume method with a Multipoint Flux Approximation using a Diamond stencil. This formulation is able to handle a full permeability tensor representation in an arbitrary polygonal grid. For the advective saturation problem, we used the streamline-based method, which decouples the transport equations into several 1-D problems solved along each streamline. These formulations were implemented in the framework of the Hybrid-Grid (HyG) representation of fractures, where the fractures in the physical domain are represented by 1-D objects in 2-D domains and extended to the same dimension of the matrix problem. The coupling between the flow and the transport problem is done by a modified implicit pressure explicit saturation procedure. We have solved some reference problems from the literature, obtaining promising results when compared to other classical formulations.

Detection of defect in ballastless track based on impact echo method combined with improved SAFT algorithm

Impact echo method is a superior method for structural health monitoring in concrete, but it has the disadvantages of low accuracy in detecting multi-layer structures. To overcome this limitation, an improved synthetic aperture focusing technique (SAFT) algorithm was proposed and combined with impact echo method for the detection of ballastless track. The improved SAFT algorithm makes full use of time domain echo signals containing multiple conversion elastic waves to image ballastless track defect. Simulation analysis based on finite difference time-domain (FDTD) method and a laboratory experiment were conducted to verify the effectiveness of improved SAFT algorithm combined with impact echo method for the identification of ballastless track defect. The results show that the decrease of sensor spacing and contact time in impact echo method contributes to the visual identification of defects by the improved SAFT algorithm, the visualization effect of defects can be improved by adjusting the minimum threshold level of the color scale of reconstructed image. Except for defect near the boundary, impact echo method combined with the improved SAFT algorithm has good applicability for the detection of ballastless track defects with random spatial location and number distribution.

An XFEM‐strain gradient damage model for efficient modeling of materials with reinforcement particles

A coupling of extended finite element method (XFEM) and strain gradient enhanced damage method is proposed to model damage initiation and growth in the materials with reinforcement particles. The proposed model inherits the advantages of both methods i.e., simple definition of reinforcement particles from XFEM and numerical stability during damage evolution from the strain gradient damage model. The capability of the proposed XFEM-strain gradient damage model has been demonstrated by simulating mode-I, mode-II, and the mix-mode failure mechanism in the SENB, SEN, and L-shaped specimen with reinforcement particles respectively. The numerical simulations are performed by considering hard and soft reinforcement particles in a matrix. Mesh-sensitivity and particle-sensitivity analysis are performed to quantify effect of various parameters like mesh size, particle size and volume fraction on behavior of SENB specimen. The proposed XFEM model is at least 10% efficient (at higher mesh densities) than the standard FEM model for solving the SENB specimen with reinforcement particles. In the particle sensitivity analysis, proposed XFEM model used only one mesh density (unlike FEM model that needs different conformal meshes) to simulate set of 400 realizations with random spatial distribution of reinforcement particles. The analysis shows that the computational demand for the creation of conformal mesh is alleviated with the use of XFEM for defining reinforcement particles. The mesh-sensitivity analysis shows that difference in the solution obtained using proposed XFEM model and standard FEM model is negligible (less than 1% at higher mesh densities). Therefore, the proposed XFEM-strain gradient damage model can substitute FEM-strain gradient damage model with above mentioned efficiencies.

Collision Fluctuations of Lucky Droplets with Superdroplets

Abstract It was previously shown that the superdroplet algorithm for modeling the collision–coalescence process can faithfully represent mean droplet growth in turbulent clouds. An open question is how accurately the superdroplet algorithm accounts for fluctuations in the collisional aggregation process. Such fluctuations are particularly important in dilute suspensions. Even in the absence of turbulence, Poisson fluctuations of collision times in dilute suspensions may result in substantial variations in the growth process, resulting in a broad distribution of growth times to reach a certain droplet size. We quantify the accuracy of the superdroplet algorithm in describing the fluctuating growth history of a larger droplet that settles under the effect of gravity in a quiescent fluid and collides with a dilute suspension of smaller droplets that were initially randomly distributed in space (“lucky droplet model”). We assess the effect of fluctuations upon the growth history of the lucky droplet and compute the distribution of cumulative collision times. The latter is shown to be sensitive enough to detect the subtle increase of fluctuations associated with collisions between multiple lucky droplets. The superdroplet algorithm incorporates fluctuations in two distinct ways: through the random spatial distribution of superdroplets and through the Monte Carlo collision algorithm involved. Using specifically designed numerical experiments, we show that both on their own give an accurate representation of fluctuations. We conclude that the superdroplet algorithm can faithfully represent fluctuations in the coagulation of droplets driven by gravity.

Multi-moded high-index contrast optical waveguide for super-contrast high-resolution label-free microscopy.

The article elucidates the physical mechanism behind the generation of superior-contrast and high-resolution label-free images using an optical waveguide. Imaging is realized by employing a high index contrast multi-moded waveguide as a partially coherent light source. The modes provide near-field illumination of unlabeled samples, thereby repositioning the higher spatial frequencies of the sample into the far-field. These modes coherently scatter off the sample with different phases and are engineered to have random spatial distributions within the integration time of the camera. This mitigates the coherent speckle noise and enhances the contrast (2-10) × as opposed to other imaging techniques. Besides, the coherent scattering of the different modes gives rise to fluctuations in intensity. The technique demonstrated here is named chip-based Evanescent Light Scattering (cELS). The concepts introduced through this work are described mathematically and the high-contrast image generation process using a multi-moded waveguide as the light source is explained. The article then explores the feasibility of utilizing fluctuations in the captured images along with fluorescence-based techniques, like intensity-fluctuation algorithms, to mitigate poor-contrast and diffraction-limited resolution in the coherent imaging regime. Furthermore, a straight waveguide is demonstrated to have limited angular diversity between its multiple modes and therefore, for isotropic sample illumination, a multiple-arms waveguide geometry is used. The concepts introduced are validated experimentally via high-contrast label-free imaging of weakly scattering nanosized specimens such as extra-cellular vesicles (EVs), liposomes, nanobeads and biological cells such as fixed and live HeLa cells.

Thermal conductivity of crack-containing media: A numerical study

The present study aims to evaluate the effective thermal conduction behavior of crack-containing media through micromechanical modeling. Numerical analyses were performed using the finite element method, first using periodic arrays of elliptical pores and then reducing the elliptical minor axis to reach the crack limit. This parametric approach was seen to be able to capture the effect of discontinuity across the crack face in a straightforward manner. The overall thermal conductivity of the model structures, encompassing a range of crack densities and spatial distributions, was investigated. It was found that, for cracks with mixed orientations, the effective thermal conductivity is insensitive to the actual crack alignment and can be uniquely represented by the crack density. The mixed-orientation periodic crack configurations are also representative of random sizes, orientations, and spatial distributions of cracks, thus exhibiting a high degree of generality. The modeling analyses can also be used to determine simple empirical expressions for two- and three-dimensional media containing random cracks.

Myoendothelial junction heterogeneity enables phosphatidylserine regulation of Kir2.1‐mediated vasodilation

In resistance arteries, matrix‐devoid holes in the internal elastic lamina (HIEL) are presumably always the site of endothelial and smooth muscle contact (myoendothelial junction; MEJs). MEJs are signaling microdomains and we have previously demonstrated that specific protein localization regulates heterocellular communication. However, it is time consuming to localize proteins at the MEJ as it requires electron microscopy (EM) verification—it also lacks quantitative analysis for spatial localization both within endothelial cells and within the tissue. Thus, we wanted to determine if every HIEL was an MEJ without relying on any single protein marker. We first developed an in‐house MATLAB analysis program to obtain quantitative data from en face images of third order mesenteric arteries, including an evaluation of spatial distribution using Monte Carlo simulations, which revealed HIEL exhibit a random spatial distribution. We then converted these metrics from en face XY views to XZ views of TEM sections, where the presence of MEJs can unequivocally be detected. We predicted an incidence of 5 ‐ 17.5 HIEL per 1000um IEL length in TEM cross‐sections (corresponding to a 190.75 HIEL/um2 density in en face images), and the measured incidence was 11.97, where every detected HIEL contained cellular contents. We concluded every HIEL was an MEJ. Next, we wanted to investigate the spatial distribution and function of a novel lipid marker of the MEJ, phosphatidylserine, which we previously demonstrated was enriched within in vitro MEJs by mass spectrometry, but had not been demonstrated on intact tissue. It is well described that lipid species, like PIP2, have key roles in regulating the function of channels, and thus we hypothesized that PS may function in a regulatory capacity within these signaling microdomains. We first determined PS‐MEJ incidence and spatial distribution. Immunohistochemistry on en face third order mesenteric arteries revealed that PS comprised on average a 13.8% subset of total MEJs, indicating a heterogeneous nature to these microdomains. Within individual endothelial cells, an average of 9.89 MEJs were identified, and an average of 1.13 of these MEJs were PS positive. Monte Carlo analysis did not find unique PS‐MEJs spatial segregation to endoplasmic reticulum, nucleus, or interendothelial junctions. It wasn’t clear the biological rationale for the PS segregation in MEJs. However, recent in silico studies predicted that PS, in addition to PIP2, interacts with the inward rectifying potassium channel 2.1 (Kir2.1). Staining for Kir2.1, we found that it only localized to 1.5% of total MEJs, and yet remarkably, 83.3% of Kir2.1‐MEJs localized to PS‐MEJs. This contrasted with Cx40‐MEJs, where only 14.6% localized to PS‐MEJs. This observation led us to test the hypothesis that PS may regulate Kir2.1. Using pressurized third order mesenteric arteries, we performed dose response curves with NS309, a drug that can activate Kir2.1 channels. Application of either 1 uM or 10 uM exogenous PS demonstrated a significant reduction in dilation to the early range of NS309 doses comparable to arteries treated with the 3.6 uM ML‐133 and 30 uM Ba2+. In addition, direct application of 10 uM PS induced a significant constriction. Thus, we hypothesize PS may provide a mechanism for counteracting the dilatory effect of PIP2. Based on this data, we conclude MEJ heterogeneity may regulate vascular function.

Data Analysis Methods of Natural Fragment Spatial Distribution

Abstract This paper aims to explore the simulation method of random spatial distribution of natural fragments. The transformation between three-dimensional spatial coordinates and two-dimensional planar coordinates of fragments is realized by coordinate mapping and inverse mapping, and the random uniform distribution of fragments in the two-dimensional plane is realized by the Monte Carlo stochastic points method, so as to obtain the spatial position distribution of fragments.

A mechanical model of three-dimensional electrospun fiber scaffolds

Fiber scaffolds prepared by electrospinning method can be used for the repairing of soft tissues such as skin, and have been widely used in biomedical field. The mechanical properties of scaffolds needed to be considered in the process of preparing scaffolds. Based on the principle of statistics and the method of micromechanics, a mechanical model for calculating the elastic characteristics of fiber scaffolds with spatial random distribution characteristics was established. The model comprehensively considered the parameters such as mechanical properties of constituent units of fiber scaffolds, fiber diameter and fiber density. The quantitative relationship between the elastic mechanical properties of fiber scaffolds and their tissue unit parameters can be calculated, which provided a research basis for further research and improvement of the mechanical properties of three-dimensional fiber scaffolds.

Global land use extent and dispersion within natural land cover using Landsat data

The conversion of natural land cover into human-dominated land use systems has significant impacts on the environment. Global mapping and monitoring of human-dominated land use extent via satellites provides an empirical basis for assessing land use pressures. Here, we present a novel 2019 global land cover, land use, and ecozone map derived from Landsat satellite imagery and topographical data using derived image feature spaces and algorithms suited per theme. From the map, we estimate the spatial extent and dispersion of land use disaggregated by climate domain and ecozone, where dispersion is the mean distance of land use to all land within a subregion. We find that percent of area under land use and distance to land use follow a power law that depicts an increasingly random spatial distribution of land use as it extends across lands of comparable development potential. For highly developed climate/ecozones, such as temperate and sub-tropical terra firma vegetation on low slopes, area under land use is contiguous and remnant natural land cover have low areal extent and high fragmentation. The tropics generally have the greatest potential for land use expansion, particularly in South America. An exception is Asian humid tropical terra firma vegetated lowland, which has land use intensities comparable to that of temperate breadbaskets such as the United States’ corn belt. Wetland extent is inversely proportional to land use extent within climate domains, indicating historical wetland loss for temperate, sub-tropical, and dry tropical biomes. Results highlight the need for planning efforts to preserve natural systems and associated ecosystem services. The demonstrated methods will be implemented operationally in quantifying global land change, enabling a monitoring framework for systematic assessments of the appropriation and restoration of natural land cover.

A first comprehensive ecological approach on the highly endemic mygalomorph spider Mecicobothrium thorelli (Araneae: Mecicobothriidae): understanding life history traits to address future conservation issues

ABSTRACT Mecicobothrium thorelli is a very small mygalomorph spider that exclusively inhabits native mountainous grasslands of southern South America (Argentina and Uruguay). Several aspects of the biology of M. thorelli are still unknown. The goal of this study is to provide knowledge about the ecology of this species in a threatened habitat for the first time, based on extensive field work carried out during one year. A total of 119 individuals were registered. The species was found to select large refuges (rocks) and avoid small refuges, while the temperature of these did not seem to influence refuge selection. Juveniles and adults represented 69.9% and 30.1% of the total, respectively. Juveniles were found throughout the whole sampling period, while females were found mostly in June and males were recorded in May (winter in the southern hemisphere). The spatial distribution was random on most dates, with the exception of June, July and May. Also, a regular spatial pattern was observed in June. Mecicobothrium thorelli has a wintery life cycle, increasing its abundance during the coldest months of the year, and chooses particular characteristics of the microenvironment, such as refuge size. It usually presents a random spatial distribution, except at smaller scales during the reproductive period.

Investigation on Variability of Ferroelectric-Gate Field-Effect Transistor Memory by Random Spatial Distribution of Interface Trap

We investigated the variability of memory window (MW) in ferroelectric-gate field-effect transistor (FeFET) by considering the spatial distribution of the trap density at the ferroelectric layer/interfacial layer (FE/IL) interface. Through technology computer-aided design (TCAD) simulations including calibrated ferroelectric parameters, the variability of ultrathin body (UTB) structured FeFETs by the scaling of IL and channel area was confirmed. It was revealed that the reduction of IL thickness (T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IL</sub> ) not only increases mean of MW (μMW) but also decreases standard deviation of MW (σMW). Additionally, by identifying the σMW/μMW sensitivity for the reduction of gate length (L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> ) and channel width (W), it was indicated that W causes the more serious σMW degradation because short channel effects by L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> scaling mitigate the σMW degradation.