Numerical treatment of the Filament Based Lamellipodium Model (FBLM)

We describe in this work the numerical treatment of the Filament Based Lamellipodium Model (FBLM). The model itself is a two-phase two-dimensional continuum model, describing the dynamics of two interacting families of locally parallel F-actin filaments. It includes, among others, the bending stiffness of the filaments, adhesion to the substrate, and the cross-links connecting the two families. The numerical method proposed is a Finite Element Method (FEM) developed specifically for the needs of these problem. It is comprised of composite Lagrange-Hermite two dimensional elements defined over two dimensional space. We present some elements of the FEM and emphasise in the numerical treatment of the more complex terms. We also present novel numerical simulations and compare to in-vitro experiments of moving cells

Precision segmented reflector, figure verification sensor

The Precision Segmented Reflector (PSR) program currently under way at the Jet Propulsion Laboratory is a test bed and technology demonstration program designed to develop and study the structural and material technologies required for lightweight, precision segmented reflectors. A Figure Verification Sensor (FVS) which is designed to monitor the active control system of the segments is described, a best fit surface is defined, and an image or wavefront quality of the assembled array of reflecting panels is assesse

Counter-propagating wave patterns in a swarm model with memory

Hyperbolic transport-reaction equations are abundant in the description of movement of motile organisms. Here, we focus on a system of four coupled transport-reaction equations that arises from an age-structuring of a species of turning individuals. By modeling how the behavior depends on the time since the last reversal, we introduce a memory effect. The highlight consists of the explicit construction and characterization of counter-propagating traveling waves, patterns which have been observed in bacterial colonies. Stability analysis reveals conditions for the wave formation as well as pulsating-in-time spatially constant solutions

Perceptual Ratings Regarding Individuals with High Functioning Autism

A perceptual rating scale evaluating appropriateness/inappropriateness of eight communicative behaviors was designed to determine if the general population perceives adult individuals with high functioning autism as different. In addition, the rating scale results were examined to determine which of the eight communicative characteristics were perceived as most different. The results were also evaluated to determine if a rating difference between genders existed. The subjects consisted of 453 college students who viewed videotaped interviews with five individuals, two considered normal and three diagnosed with high functioning autism who had received varying levels of remediation. After viewing each interview, subjects rated the interviewee based on the communicative behaviors indicated on the rating scale form. Results were analyzed by computer and statistical information yielded significance in all areas examined. The general population did perceive the individuals with high functioning autism as different. Female viewers rated the individuals with autism more favorably than male viewers. Characteristics perceived as most different were body posture, conversation effectiveness, and level of comfort, whereas word choice and eye contact were rated as least different for the individuals with high functioning autism. These findings indicate that the general population did perceive individuals with high functioning autism as significantly different than the normal population, as measured by the examiner\u27s rating scale. Degree of significance varied consistently with the degree of remediation for the autism disorder. Further research should expand this data base in determining specific characteristics which best respond to remediation and most significantly influence the perceptions of the general population

Perceptual Ratings Regarding Individuals with High Functioning Autism

A perceptual rating scale evaluating appropriateness/inappropriateness of eight communicative behaviors was designed to determine if the general population perceives adult individuals with high functioning autism as different. In addition, the rating scale results were examined to determine which of the eight communicative characteristics were perceived as most different. The results were also evaluated to determine if a rating difference between genders existed. The subjects consisted of 453 college students who viewed videotaped interviews with five individuals, two considered normal and three diagnosed with high functioning autism who had received varying levels of remediation. After viewing each interview, subjects rated the interviewee based on the communicative behaviors indicated on the rating scale form. Results were analyzed by computer and statistical information yielded significance in all areas examined. The general population did perceive the individuals with high functioning autism as different. Female viewers rated the individuals with autism more favorably than male viewers. Characteristics perceived as most different were body posture, conversation effectiveness, and level of comfort, whereas word choice and eye contact were rated as least different for the individuals with high functioning autism. These findings indicate that the general population did perceive individuals with high functioning autism as significantly different than the normal population, as measured by the examiner\u27s rating scale. Degree of significance varied consistently with the degree of remediation for the autism disorder. Further research should expand this data base in determining specific characteristics which best respond to remediation and most significantly influence the perceptions of the general population

Investigation of DC-8 nacelle modifications to reduce fan-compressor noise in airport communities. Part 3 - Static tests of noise suppressor configurations, May 1967 - October 1969

Static tests of noise suppressor configurations of DC-8 aircraft nacelle modifications to reduce fan-compressor noise levels - Part

An acoustical study of the KIWI B nuclear rocket

Kiwi B nuclear rocket acoustics - sound pressure distribution, energy conversion, and power distributio

Reverse engineering forces responsible for dynamic clustering and spreading of multiple nuclei in developing muscle cells

How cells position organelles is a fundamental biological question. During Drosophila embryonic muscle development, multiple nuclei transition from being clustered together, to splitting into two smaller clusters, to spreading along the myotube's length. Perturbations of microtubules and motor proteins disrupt this sequence of events. These perturbations do not allow intuiting which molecular forces govern the nuclear positioning; we therefore used computational screening to reverse engineer and identify these forces. The screen reveals three models: two suggest that the initial clustering is due to the nuclear repulsion from the cell poles, while the third, most robust, model poses that this clustering is due to a short-ranged internuclear attraction. All three models suggest that the nuclear spreading is due to the long-ranged internuclear repulsion. We test the robust model quantitatively by comparing it to data from perturbed muscle cells. We also test the model by using agent-based simulations with elastic dynamic microtubules and molecular motors. The model predicts that, in longer mammalian myotubes with a great number of nuclei, the spreading stage would be preceded with segregation of the nuclei into a large number of clusters, proportional to the myotube length, with a small average number of nuclei per cluster

Nuclear Scaling Is Coordinated among Individual Nuclei in Multinucleated Muscle Fibers

Optimal cell performance depends on cell size and the appropriate relative size, i.e., scaling, of the nucleus. How nuclear scaling is regulated and contributes to cell function is poorly understood, especially in skeletal muscle fibers, which are among the largest cells, containing hundreds of nuclei. Here, we present a Drosophila in vivo system to analyze nuclear scaling in whole multinucleated muscle fibers, genetically manipulate individual components, and assess muscle function. Despite precise global coordination, we find that individual nuclei within a myofiber establish different local scaling relationships by adjusting their size and synthetic activity in correlation with positional or spatial cues. While myonuclei exhibit compensatory potential, even minor changes in global nuclear size scaling correlate with reduced muscle function. Our study provides the first comprehensive approach to unraveling the intrinsic regulation of size in multinucleated muscle fibers. These insights to muscle cell biology will accelerate the development of interventions for muscle diseases

Kinetic modelling of colonies of myxobacteria

A new kinetic model for the dynamics of myxobacteria colonies on flat surfaces is derived formally, and first analytical and numerical results are presented. The model is based on the assumption of hard binary collisions of two different types: alignment and reversal. We investigate two different versions: a) realistic rod-shaped bacteria and b) artificial circular shaped bacteria called Maxwellian myxos in reference to the similar simplification of the gas dynamics Boltzmann equation for Maxwellian molecules. The sum of the corresponding collision operators produces relaxation towards nematically aligned equilibria, i.e. two groups of bacteria polarized in opposite directions. For the spatially homogeneous model a global existence and uniqueness result is proved as well as exponential decay to equilibrium for special initial conditions and for Maxwellian myxos. Only partial results are available for the rod-shaped case. These results are illustrated by numerical simulations, and a formal discussion of the macroscopic limit is presented