Summary
The fine morphology of the buccal capsule and intestine (midgut) of the marine free-living nematode Odontophora deconincki was investigated. The cheilostome is armed with six equal claw-like odontia that can evert radially by opening the mouth. Light-refracting accessory buccal structures within the cheilostomatal cuticle alternate with odontia and consist of two elements: anterior armilloids and posterior granular armilliths. The buccal cavity (pharyngostome) is surrounded by a complex of longitudinal and oblique muscles partially attached to the cheilostome cuticle at the sites of the accessory buccal structures and enabling a wide opening of the mouth. With the described stoma condition, the nematode probably scrapes food particles from the substrate surface. In cross-section, the midgut consists of 5-7 cells that appear uniform throughout its length. An extracellular matrix (glycocalyx) over the microvillar brush varies in thickness and stratification depending on presence or absence of food content in the lumen. Abundant spherocrystals (globular inclusions with concentric striations) were present in all gut cells. No indication of endocytosis or digestive vacuoles was observed in the gut cells and extracellular digestion predominates. Most specimens had a gut content formed from a long cylinder of compressed flocculent material with some barely identifiable components and few spherocrystals expelled from the enterocytes. We assume that the nematode diet comprises a wide range of objects, mainly eukariotic epigrowth organisms, which are shorn off and scraped from the surface of sand grains and then ingested.
We consider a 2D problem of a circular cylinder that is infinitely long and whose external surface is free from outside effects and acted upon by an asymmetrical temperature distribution that is harmonic in time. The problem is within the context of the theory of thermoelasticity without energy dissipation. The exact solution is obtained by a direct approach. The results are represented graphically and discussed.
A method is proposed for calculating the mechanical stresses of magnetic and current systems, calculated from the energy density of a uniformly magnetized cylinder. For the calculation, an average in volume demagnetizing factor of the cylinder is introduced, which is proportional to the ratio of the cylinder diameter to its length . It is shown that the demagnetization energy , negligible for a "long" cylinder , ( ), becomes decisive in the formation of stresses at . The radial and axial stresses are investigated in a wide range of ratios.
Many precision experiments have been done in the Casimir regime and in short range gravity when the separation between the interacting bodies is in the sub-micron range. Experimental complexity is minimized when one of the bodies is a sphere and the other one is a plate, making the alignment between the two bodies ubiquitous. Our group has produced the most precise Casimir measurements, and the best limits on predicted Yukawa-like potentials by measuring a force between a [Formula: see text] sphere attached to a [Formula: see text] micro-mechanical oscillator and a planar source mass. By replacing the spherical surface with a fraction of a [Formula: see text] long cylinder with [Formula: see text]m, the force sensitivity can be greatly enhanced. Here, it is paramount to know the angular deviation between the long axis of the cylinder and both the axis of rotation of the oscillator and the plate. Tests between a cylinder and a structure etched into a silicon wafer show that deviations of [Formula: see text]rad are readily accessible. Additionally, a scaled up experiment is used to investigate if capacitance measurements can determine the orientation of the cylinder with respect to a plane with the required precision.
Damped rotational vibrations of a long cylinder with a disk in the air flow
