Narrow Cylinder Research Articles

Textures and NMR spectra of a superfluid 3He-A phase confined in rotating narrow cylinders

We confine a superfluid 3He-A phase in narrow cylinders, these radii are 0.05 and 0.1 mm. The system is rotated around the cylinder axis, and its rotation velocity ranges between −6.28 and 6.28 rad/s. The strong magnetic field (22 mT) is applied along cylinder axis. In these systems, we determined l - and d -textures by minimizing GL-free energies. In the case of the small cylinder ( R=0.05 mm) a dipole locked and a dipole unlocked Mermin–Ho textures are obtained as local minimum free energy states. In the case of the large cylinder ( R=0.1 mm), a single vortex and a three vortices states are obtained. The stability of each state depends on the rotating velocity. A vortex charge change of two quanta occurs by a pair of continuous vortices coming in and going out. For each case, the NMR spectrum of the transverse resonance mode is calculated by using a finite element method (FEM). Using the FEM the boundary condition of spin wave mode is strictly imposed and the higher resonance mode is also calculated. The calculated result agrees well with empirical data.

Polymer distribution in connected spherical domains

The distribution of neutral and charged polymers with different flexibilities between two spheres of varying volume connected by a short and narrow cylinder has been investigated by Monte Carlo simulations. The uncharged chain displayed mostly a single-sphere occupancy due to the high conformational entropy penalty of crossing the cylindrical domain, whereas for the charged polymer a double-sphere occupancy was obtained, except for very different spherical volumes. The origin of this different occupancy behavior stems from the counterion entropy. At increasing stiffness, a stronger preference for double-sphere occupancy was predicted.

Asymptotics of the reduced logarithmic capacity of a narrow cylinder

We consider the Dirichlet problem for the Laplace operator in the exterior of a narrow infinite cylinder with periodically varying directrix. The solution is sought in the class of functions logarithmically increasing as the distance from the cylinder is increased. The reduced logarithmic capacity is defined as a generalization of the logarithmic capacity (of the outer conformal radius).We construct and justify the asymptotics of the solution of the problem as the ratio of the diameter of the cross-section of the cylinder to its period tends to zero.

Vortex formation and annihilation in three textures of rotating superfluid 3He-A.

Textures, textural transformation, and formation and annihilation of a single vortex were investigated in narrow cylinders with 100 microm radius in A-phase under rotation up to 6.28 rad/sec. Three textures were found, depending on the cooling conditions of the sample through the superfluid transition temperature T(c). We found the gyromagnetic effect of textures; that is, two textures (A or B) could be selected either by applying a magnetic field in parallel or anti-parallel to the rotation axis. The critical angular speed of a single vortex formation Omega(f) and that of annihilation Omega(a) for each texture were measured. The textural transformation in type A texture was induced by rotation. Both type A and B textures held macroscopic angular momentum along the rotation axis. We identified the texture for type A, B, and C as Mermin-Ho, radial disgyration, and a soliton type of defect along the axis, respectively.

Energy spectrum of carriers in Kane-type hollow cylinder

The energy spectra of carriers confined to a narrow gap semiconductor hollow cylinder with hard walls are calculated both without and with an applied constant axial magnetic field, taking into account the real band structure of InSb-type materials: narrow energy gap and strong spin–orbit interaction. We calculated the size and magnetic field dependence of effective g -value in bare InSb-type hollow cylinder for electrons. It has been seen that the effective g -value of the electrons decreases with increasing radius. The magnetic field dependence of g -factor has a minimum only for subbands with the negative m .

Energy spectrum of carriers in Kane-type hollow cylinder

The energy spectra of carriers confined to a narrow gap semiconductor hollow cylinder with hard walls are calculated both without and with an applied constant axial magnetic field, taking into account the real band structure of InSb-type materials: narrow energy gap and strong spin–orbit interaction. We calculated the size and magnetic field dependence of effective g-value in bare InSb-type hollow cylinder for electrons. It has been seen that the effective g-value of the electrons decreases with increasing radius. The magnetic field dependence of g-factor has a minimum only for subbands with the negative m.

Radiation of an Electric Dipole from a Small Plasma Spheroid

We obtain and analyze an analytical solution of the boundary-value problem of the field of an electric dipole located in a small spheroid filled with a cold isotropic plasma. The conditions of resonant amplification of the field in vacuum are studied for various shapes and curvatures of the plasma spheroid. It is shown that for a certain spheroid shape, the resonant amplification increases several times compared with the case of spherical plasma environment. The obtained results are compared with the resonant radiation of a dipole from a narrow elliptical plasma cylinder.

Decomposition of the Superwind in M 82

We present new optical images ($B, V$, and $\mathrm{H}\alpha$) of the archetypical starburst/superwind galaxy M 82 obtained with the 8.2 m Subaru Telescope to reveal new detailed structures of the superwind-driven nebula and the high-latitude dark lanes. The emission-line nebula is decomposed into (1) a ridge-dominated component comprising numerous filament/loop sub-structures whose overall morphology appears as a pair of narrow cylinders, and (2) a diffuse component extended over much wider opening angle from the nucleus. We suggest that these two components have different origins. The ridge-dominated component appears as a pair of cylinders rather than a pair of cones. Since this morphological property is similar to that of hot plasma probed by soft X-ray, this component seems to surround the hot plasma. On the other hand, the diffuse component may arise from dust grains which scatter stellar light from the galaxy. Since inner region of this component is seen over the prominent “X”-shaped dark lanes streaming out from the nuclear region and they can be reproduced as a conical distribution of dust grains, there seems to be a dusty cold outflow as well as the hot one probed by soft X-ray and shock-excited optical emission lines. If this is the case, the presence of such high-latitude dust grains implies that neutral gaseous matter is also blown out during the course of the superwind activity.

Gnawing behavior of a mouse in a narrow cylinder: A simple system for the study of muscle activity, fatigue, and stress

When a mouse is put into a cylinder too narrow for it to turn (its front end being blocked with a thin plastic strip), the mouse gnaws away the plastic to escape. Hence, the weight reduction in the plastic can be used as an index of ‘gnawing activity (GA).’ GA was high at first, but decreased with time. Training augmented GA, but not the activity of the histamine-forming enzyme (histidine decarboxylase [HDC]: a proposed marker of muscle fatigue) in the masseter muscle. In trained mice, GA was higher at night than in the daytime, and was decreased by starvation. In mice prevented from reaching the strip, the elevation of serum cortisol was greater than that seen in mice able to gnaw at it. As such gnawing is a form of voluntary behavior, these results suggest that our experimental system may be useful for (i) the quantitative study of voluntary muscle activity associated with physical or mental fatigue or motivation, and (ii) the study of an animal's response to stress when it has, or alternatively does not have, an apparent way of escape.

Acoustically generated unsteady vorticity field in a long narrow cylinder with sidewall injection

Asymptotic and computational analyses of a well-posed initial-boundary-value problem are used to describe the time history of co-existing acoustic and rotational velocity disturbances in a long, narrow cylinder with uniform steady sidewall mass injection. Transient planar pressure disturbances prescribed on the open exit plane of the cylinder are the source of acoustic disturbances in the axisymmetric flow. Both the asymptotic and numerical solutions describe the nonlinear aspects of the flow interactions. The full computational results are compared favorably with those of the asymptotic study to show that; (1) transient vorticity is generated near the injection surface and is transported into the cylinder by the radial velocity component of the flow field, (2) at any sufficiently small value of time, a well defined front separates the fluid containing transient vorticity from a flow field in the interior of the cylinder containing a much smaller amplitude vorticity and, (3) at sufficiently large values of time, vorticity is present throughout the cylinder. In addition, the analytically derived acoustic solution obtained from the asymptotic analysis is used to show that the present numerical solution and all earlier studies of similar problems are missing travelling waves (eigenfunctions) which should be present in a complete mathematical solution of the defined initial-boundary-value problem.

In vitro rooting and anatomical study of leaves and roots of in vitro and ex vitro plants of Prunus x davidopersica 'Piroska'

The process of in vitro rooting and the anatomical characters of in vitro and ex vitro leaves and roots of Prunus x davidopersica 'Piroska' were studied. Best rooting percentage (50%) and highest root number (5.0) was achieved in spring on a medium containing 0.1 mg/I NAA + 30 g/1 glucose. At the end of rooting the parenchyma of the in vitro leaves was more loose and spongy, than during the proliferation period. In the first newly developed leaf of an acclimatised plant, the parenchyma was much more developed, contained less row of cells and less air space too, compared to the leaves developed in the field. The in vitro developed root had a broad cortex and narrow vascular cylinder with less developed xylem elements, but at the end of the acclimatisation the vascular system became dominant in the root.

A New Species of Nematodes Found in Rotting Seaweed on the Shore of the Black Sea

A new species of nematodes, Pellioditis obesasp. n., found in rotting seaweed in the supralittoral area of the Black Sea near Sevastopol (Ukraine) is described and illustrated. The new species is morphologically similar to P. ehrenbaumi(Bresslau and Sch. Stekhoven, 1935); but it differs in having a narrow protostoma cylinder, a shorter female tail, larger eggs, longer spicules and gubernaculum, and in the ratio of the anterior pharynx length to the posterior pharynx length.

Ultrastructure of the sperm of Catostylus mosaicus and Phyllorhiza punctata (Scyphozoa, Cnidaria): Implications for sperm terminology and the inference of reproductive mechanisms

Summary Sperm of marine organisms are usually classified as either “primitive” or “modified”. Primitive sperm, with heads comprised of a simple acrosome, spherical nuclei and mitochondria and a free flagellum, are thought to be associated with the occurrence of external fertilization. The implication is, of course, that external fertilization is a primitive condition wherever it occurs. Here the sperm of two Scyphozoa, Catostylus mosaicus (Quoy and Gaimard 1824) and Phyllorhiza punctata von Ledenfeld 1884, are described. Both of these taxa are known to brood planulae and are likely have some sort of internal fertilization. Catostylus mosaicus has a typical “primitive” sperm with a small head (2μm long) comprised of a short cylindrical nucleus, four spherical mitochondria and a some small spherical electron dense spheres that are may be acrosomal in function. The anchoring apparatus is comprised of two centrioles, a complex of satellite fibres and a striated “spur”. The flagellum contains a typical 9+2 axoneme. Phyllorhiza punctata has sperm with a head 6 μm long. The nucleus is a narrow cylinder, 4 μm long and curved in one plane. There are some anterior electron dense spheres, and five ellipsoidal mitochondria abut the nucleus posteriorly. Behind the mitochondria an anchoring apparatus comprised of the distal centriole and a satellite array is connected to the bases of the mitochondria. The flagellum contains a typical 9+2 axoneme. Sperm structure and the various reproductive modes occurring in Scyphozoa are reviewed and placed in a phylogenetic context based on the current classification of the group. It is concluded that external fertilization is likely to be the plesiomorphic condition in Scyphozoa, but there are various possible scenarios about the transformation to and from external fertilization within the group. Sperm structure is shown to be a poor predictor of reproductive mode. It is recommended that the terms “primitive sperm” and “modified sperm” be abandoned and replaced with terms that describe sperm in terms of function.

Minimal requirements on the smoothness of data preserving accuracy of a one-dimensional model of rods

We consider cylindrical rods whose elastic properties smoothly vary along the axis, i.e., the fast change of mechanic characteristics is admitted only in cross directions. In the general case, asymptotically exact estimates for the difference of a solution to the three-dimensional problem of elasticity theory in a narrow cylinder and an approximate solution constructed within the framework of a one-dimensional model of a rod age given. As was shown, under wakened smoothness requirements on the right-hand sides of the problem, the accuracy of approximation becomes lower. Bibliography: 21 titles.

Acoustically generated vorticity in an internal flow

A mathematical model is formulated to describe the initiation and evolution of intense unsteady vorticity in a low Mach number (M), weakly viscous internal flow sustained by mass addition through the sidewall of a long, narrow cylinder. An O(M) axial acoustic velocity disturbance, generated by a prescribed harmonic transient endwall velocity, interacts with the basically inviscid rotational steady injected flow to generate time-dependent vorticity at the sidewall. The steady radial velocity component convects the vorticity into the flow. The axial velocity associated with the vorticity field varies across the cylinder radius and in particular has an instantaneous oscillatory spatial distribution with a characteristic wavelength O(M) smaller than the radius. Weak viscous effects cause the vorticity to diffuse on the small radial length scale as it is convected from the wall toward the axis. The magnitude of the transient vorticity field is larger by O(M−1) than that in the steady flow.An initial-boundary-value formulation is employed to find nonlinear unsteady solutions when a pressure node exists at the downstream exit of the cylinder. The complete velocity consists of a superposition of the steady flow, an acoustic (irrotational) field and the rotational component, all of the same magnitude.

Density of states for a dielectric superlattice. II. TM polarization

We present an analysis of the band structure, the equifrequency surfaces, and the density of states (DOS) for the transverse magnetic (TM) polarization mode of the dielectric superlattice, modeled by means of Dirac-delta functions. This complements a recent article [Phys. Rev E 59, 3624 (1999)] that analyzes the case of transverse electric (TE) polarization. Unfortunately, for this simple model, there is no manifestation of the Brewster effect in the band structure for the TM modes. For large values of the frequency or the grating strength, the equifrequency surfaces essentially degenerate into a set of concentric, hollow, and narrow cylinders centered on the superlattice axis. The DOS is enhanced relative to free space for any frequency and it exhibits discontinuities in the slope at the band edges. These results are relevant to the spontaneous emission by an atom or to dipole radiation in one-dimensional periodic structures. The differences between TE and TM modes are discussed. We take the opportunity to correct an error in the DOS calculation for TE polarization in the article referred above.

Accurate three-dimensional modal solutions for optical resonators with periodic layered structure by using the finite element method

Accurate vector finite element solutions for three-dimensional (3-D) axisymmetric multilayered optical cavities are presented. Resonating wavelength and field profiles are shown for the fundamental and higher order modes for different types of optical cavities. The work has shown that for a narrow multilayered cylinder of diameter /spl les/0.5 /spl mu/m, for miniature vertical cavity surface emitting lasers (VCSEL), which is a popular class of laser showing favorable performance characteristics, the effect of waveguide dispersion is an important factor. This causes a blue shift of the output wavelength, requiring an adjustment to the layer thickness in the system design, to achieve the desired wavelength. The results of the simulation show close agreement with features obtained through experimental investigations.

Moderate and steep Faraday waves: instabilities, modulation and temporal asymmetries

Mild to steep standing waves of the fundamental mode are generated in a narrow rectangular cylinder undergoing vertical oscillation with forcing frequencies of 3.15 Hz to 3.34 Hz. A precise, non-intrusive optical wave profile measurement system is used along with a wave probe to accurately quantify the spatial and temporal surface elevations. These standing waves are also simulated by a two-dimensional spectral Cauchy integral code. Experiments show that contact-line effects increase the viscous natural frequency and alter the neutral stability curves. Hence, as expected, the addition of the wetting agent Photo Flo significantly changes the stability curve and the hysteresis in the response diagram. Experimentally, we find strong modulations in the wave amplitude for some forcing frequencies higher than 3.30 Hz. Reducing contact-line effects by Photo-Flo addition suppresses these modulations. Perturbation analysis predicts that some of this modulation is caused by noise in the forcing signal through ‘sideband resonance’, i.e. the introduction of small sideband forcing can generate large modulations of the Faraday waves. The analysis is verified by our numerical simulations and physical experiments. Finally, we observe experimentally a new form of steep standing wave with a large symmetric double-peaked crest, while simulation of the same forcing condition results in a sharper crest than seen previously. Both standing wave forms appear at a finite wave steepness far smaller than the maximum steepness for the classical standing wave and a surface tension far smaller than that for a Wilton ripple. In both physical and numerical experiments, a stronger second harmonic (in time) and temporal asymmetry in the wave forms suggest a 1:2 resonance due to a non-conventional quartet interaction. Increasing wave steepness leads to a new form of breaking standing waves in physical experiments.

Distribution and morphology of sinkholes triggered by flooding following Tropical Storm Alberto at Albany, Georgia, USA

Flooding of the Flint River in July 1994 triggered the collapse of at least 312 sinkholes in the karstic Dougherty Plain at Albany, Georgia. We examined the distribution and morphology of these new sinkholes to evaluate the mode of formation, to characterize early stages of the evolution of sinkhole form, and to estimate the lowering of the surface associated with the development of new sinkholes. Eighty-eight percent of sinkholes occur inside the limits of flooding, especially in areas of sandy overburden, and they often follow joint-controlled linear trends. Sinkhole dimensions are log-normally distributed with median values of circumference = 5.7 m, length = 1.8 m, width = 1.6 m, and depth = 0.7 m; asymmetry (L:W) = 1.2. Cross-sectional forms range from narrow cylinders to large bowls, with many sinkholes having undercut sides. Flooding triggered the formation of sinkholes by saturating and liquefying overburden, which caused soil arches to collapse and flow into cavities in bedrock. The prevalence of sinkholes near the periphery of flooding suggests that drainage and loss of buoyant support as flood waters subsided may also have contributed to failure. A volume ratio index is used to quantify the three dimensional geometric form of sinkholes. Initially, small cylindrical shafts open over a bedrock joint, followed by progressive slumping that leads to widening and increases in volume to a final bowl form. Estimates of the aggregate volume of overburden transported underground in flooded areas range from 7,990 to 11,130 m3. Averaged over flooded areas, this accounts for 0.26 to 0.37 mm/km 2 lowering of the surface. Based on a 500 year recurrence interval for the flood event, values for lowering of the surface range from 0.52 to 0.74 mm per 1,000 years. These values are an order of magnitude less than estimates of carbonate dissolution and suggest that transport of overburden underground is limited by triggering events.

Influence of natural leaf shapes on oviposition in three phytophagous flies: a comparative study

Entomologia Experimentalis et ApplicataVolume 80, Issue 1 p. 97-100 Influence of natural leaf shapes on oviposition in three phytophagous flies: a comparative study Thomas Degen, Thomas Degen Eidgenössische Forschungsanstalt, Schloss 334, CH-8820 Wädenswil, SwitzerlandSearch for more papers by this authorErich Städler, Erich Städler Eidgenössische Forschungsanstalt, Schloss 334, CH-8820 Wädenswil, SwitzerlandSearch for more papers by this author Thomas Degen, Thomas Degen Eidgenössische Forschungsanstalt, Schloss 334, CH-8820 Wädenswil, SwitzerlandSearch for more papers by this authorErich Städler, Erich Städler Eidgenössische Forschungsanstalt, Schloss 334, CH-8820 Wädenswil, SwitzerlandSearch for more papers by this author First published: July 1996 https://doi.org/10.1111/j.1570-7458.1996.tb00895.xCitations: 8AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume80, Issue1Special Issue: 9th International Symposium on Insect-Plant RelationshipsJuly 1996Pages 97-100 RelatedInformation