Nonlinear ion acoustic waves in a quantum degenerate warm plasma with dust grains

A study is made of the propagation of ion acoustic waves in a collisionless unmagnetized dusty plasma containing degenerate ion and electron gases at nonzero temperatures. In linear theory, a dispersion relation for isothermal ion acoustic waves is derived and an exact expression for the linear ion acoustic velocity is obtained. The dependence of the linear ion acoustic velocity on the dust density in a plasma is calculated. An analysis of the dispersion relation reveals parameter ranges in which the problem has soliton solutions. In nonlinear theory, an exact solution to the basic equations is found and examined. The analysis is carried out by Bernoulli’s pseudopotential method. The ranges of the phase velocities of periodic ion acoustic waves and the velocities of solitons are determined. It is shown that these ranges do not overlap and that the soliton velocity cannot be lower than the linear ion acoustic velocity. The profiles of the physical quantities in a periodic wave and in a soliton are evaluated, as well as the dependence of the critical velocity of solitons on the dust density in a plasma.     

Solitary fast magnetosonic waves propagating obliquely to the magnetic field in cold collisionless plasma

Solutions describing solitary fast magnetosonic (FMS) waves (FMS solitons) in cold magnetized plasma are obtained by numerically solving two-fluid hydrodynamic equations. The parameter domain within which steady-state solitary waves can propagate is determined. It is established that the Mach number for rarefaction FMS solitons is always less than unity. The restriction on the propagation velocity leads to the limitation on the amplitudes of the magnetic field components of rarefaction solitons. It is shown that, as the soliton propagates in plasma, the transverse component of its magnetic field rotates and makes a complete turn around the axis along which the soliton propagates.     

Large-amplitude ion acoustic solitons in a bi-ion plasma

A gas-dynamic model is used to study the conditions for the existence of large-amplitude ion acoustic solitons in a plasma with negative ions. It is shown that the limiting Mach number—the upper boundary of the region of existence of compression solitons—depends nonmonotonically on the temperature of the positive ions. The result is that, for certain fixed densities of the negative ions, there are one or two temperature boundaries between the regions where solitons can and cannot exist. It is found that, for rarefaction solitons, it is fundamentally important to take into account electron inertia and that the Mach number of such solitary waves is restricted not by the complete decompression of electrons within the wave (as thought previously), but by the fact that the electrons at the center of the wave reach the acoustic speed, above which the thermal-pressure-induced action cannot be transferred back to the electron flow and smooth continuous solutions are impossible.     

Slow electromagnetic solitons in electron-ion plasmas

A set of nonlinear differential equations that describe moving relativistic solitons is investigated analytically and solved numerically. The influence of the ion motion on the soliton structure is investigated. It is demonstrated that, depending on the propagation velocity, relativistic solitary waves can occur in the form of bright solitons, dark solitons, or collisionless electromagnetic shock waves. In the limit of a low propagation velocity, a dark soliton can trap the ions and accelerate them. In the case of a bright soliton, the effects of ion dynamics limit the soliton amplitude. The constraint on the maximum amplitude is related to either the breaking of ion motion or the intersection of electron trajectories. The soliton breaking provides a new mechanism for ion and electron acceleration in the interaction of high-intensity laser pulses with plasmas.     

Influence of electromagnetic radiation on molecular solitons

The soliton model of charge and energy transport in biological macromolecules is used to suggest one of the possible mechanisms for electromagnetic radiation influence on biological systems. The influence of the electromagnetic field (EMF) on molecular solitons is studied both analytically and numerically. Numerical simulations prove the stability of solitons for fields of large amplitude, and allow the study of emission of phonons. It is shown that in the spectra of biological effects of radiation there are two characteristic frequencies of EMFs, one of which is connected with the most intensive energy absorption and emission of sound waves by the soliton, and the other of which is connected with the soliton photodissociation into a delocalized state.     

The properties of bio-energy transport and influence of structure nonuniformity and temperature of systems on energy transport along polypeptide chains

A new theory of bio-energy transport along protein molecules in living systems, where the energy is released by hydrolysis of adenosine triphosphate (ATP), is proposed based on some physical and biological reasons. In the new theory, the Davydov's Hamiltonian and wave function of the systems are simultaneously modified and extended. A new interaction has been added into Davydov's Hamiltonian. The wave function of the excitation state of single particles for the excitons in the Davydov model is replaced by a new wave function of two-quanta quasicoherent state. In such a case, the bio-energy is transported by the new soliton, which differs from the Davydov's soliton. The soliton is formed through self- trapping of two excitons interacting amino acid residues. The exciton is generated by vibrations of amide-I (CO stretching) arising from the energy of hydrolysis of ATP. The properties of the new soliton are extensively studied by analytical method and its lifetime is calculated using the nonlinear quantum perturbation theory and a wide ranges of parameter values relevant to protein molecules. The lifetime of the new soliton at the biological temperature 300 K is enough large and belongs to the order of 10?1? s, or τ/τ?≥700, in which the soliton can transports over several hundreds amino acid residues. These studied results show clearly that the new soliton is thermally stable and has so larger lifetime that it can play an important role in biological processes. Thus the new model is a candidate of the bio-energy transport mechanism in protein molecules. In the meanwhile, the influences of structure nonuniformity in protein molecules and temperature of the systems on the states and properties of the soliton transport of bio-energy are numerically simulated and studied by the fourth-order Runge-Kutta method. The structure nonuniformity arises from the disorder distributions of masses of amino acid residues, side groups and impurities, which results also in the fluctuations of the spring constant of protein molecules, dipole-dipole interaction between the neighboring amides, exciton-phonon (vibration of amino acids)interaction, chain-chain interaction among the three channels and ground state energy of the systems. We investigated the behaviors and states of the new solitons in a single protein molecular chain and α-Helix protein molecules with three channels under influences of the structure nonuniformity. We prove first that the bio-energy is transported by a soliton, which can move without dispersion, retaining its shape, velocity and energy in a uniform and periodic protein molecule. When the structure nonuniformity exists, although the fluctuations of the spring constant, dipole-dipole interaction constant, exciton-phonon coupling constant and ground state energy and the nonuniformity distributions of masses of amino acid residues can change the states and properties of motion of new soliton, they are still quite stable and very robust against these structure nonuniformities, i.e., even there are a larger structure nonuniformity in the protein molecules, the new solitons cannot be still dispersed. If the effects of thermal perturbation of medium on the soliton in nonuniform proteins is considered again, the new soliton can transport also over a larger spacing of 400 amino acids and has a longer time period of 300 ps, it is still thermally stable up to 320 K under the influence of the above structure nonuniformities. However, the new soliton disperses in the case of a higher temperature of 325 K and in more large structure nonuniformity. Thus, we determine that the new soliton's lifetime and critical temperature are 300 ps and 320 K, respectively. These results are also consistent with analytical data obtained via quantum perturbed theory. For α-Helix protein molecules with three channels, the results obtained show that the structure nonuniformity and quantum fluctuation can change the states and features of the new solitons, for example, the amplitudes, energies and velocities of the new soliton are decreased, but the solitons have been not destroyed, they can still transport steadily along the molecular chains retaining energy and momentum. When the quantum fluctuations are larger, such as, structure disorders and quantum fluctuations of 0.67<α(K)<2, ΔW=±8%Wˉ, ΔJ=±1%Jˉ, Δ(χ?+χ?)=±3%(χˉ?+χˉ?) and ΔL=±1%Lˉ and Δ??=?|β(n)|, ?=0.1 meV, |β(n)|<0.5, the new soliton is still stable. Therefore, the new solitons are quite robust against these nonuniform effects. However, they will be dispersed or disrupted in cases of very large structure nonuniformity. When the influence of temperature on solitons is considered, we find that the new solitons can transport steadily over 333 amino acid residues in the case of a long time period of 120 ps, in which the soliton can retain its shape and energy to travel forward along protein molecules after their mutual collision at the biological temperature of 300 K. However, the soliton disperses in cases of higher temperatures 325 K under action of a larger structure disorder. Thus, its critical temperature is about 320 K. When the effects of structure nonuniformity and temperature are considered simultaneously, then the new soliton has still high thermal stability and can transport also along the protein molecular chains retaining its amplitude, energy and velocity, they will disperses in the larger fluctuations, for example, 0.67 Mˉ相似文献   

Electron dynamics in a parabolic magnetic field in the presence of an electrostatic wave

A study is made of the problem of electron dynamics in the presence of a plane electrostatic wave in a model in which the Earth’s magnetic field is parabolic. The problem is reduced to a Hamiltonian system with two degrees of freedom, which is investigated by the methods of perturbation theory. The structure of the phase space of the system is described, and the phenomena of capture into the resonance and scattering on the resonance are considered. It is shown that these phenomena lead to breaking of the second (longitudinal) adiabatic invariant and stochastization of the electron dynamics.     

A Theorem on Boussinesq Solitons or Why Soliton Formation Sharpens Resonant Absorption and Why This Has Nothing to Do With Real Polymers

Abstract

Soliton formation has been proposed as an explanation for anomalously sharp resonances observed in DNA microwave absorption. We give an elementary, physical explanation of why line narrowing occurs for Boussinesq solitons. We consider real atoms bound by realistic chemical bonds and show that even under the assumption of the most favorable possible conditions, the soliton narrowing mechanism is a maximum correction of only a few percent. At each step of the argument, the simple calculations we show are either exact-in the sense of following the Boussinesq equation-or err on the side of emphasizing the soliton lifetime enhancement. Thus our results serve as an upper bound to any enhancement effects.     

Electromagnetic Radiation Influence on Nonlinear Charge and Energy Transport in Biosystems

The influence of electromagnetic radiation (EMR) on charge and energy transport processes in biological systems is studied in the light of the soliton model. It is shown that in the spectrum of biological effects of EMR there are two frequency resonances corresponding to qualitatively different frequency dependent effects of EMR on solitons. One of them is connected with the quasiresonance dynamic response of solitons to the EMR. At EMR frequencies close to the dynamic resonance frequency the solitons absorb energy from the field and generate intensive vibrational modes in the macromolecule. The second EMR resonance is connected with soliton decay due to the quantum mechanical transition of the system from the bound soliton state into the excited unbound states.     

The effect of heterogeneously-distributed RyR channels on calcium dynamics in cardiac myocytes

Calcium plays an essential role in excitation-contraction coupling in muscle, and derangements in calcium handling can produce a variety of potentially harmful conditions, especially in cardiac muscle. In cardiac tissue specialized invaginations of the sarcolemma, called T-tubules, penetrate deep into each sarcomere, and depolarization of the SL leads to an influx of calcium through voltage-sensitive channels in the T-tubules that in turn triggers further calcium release from the sarcoplasmic reticulum via ryanodine-sensitive calcium channels. Under certain conditions, such as elevated external Ca²⁺, cardiac cells can release calcium from the sarcoplasmic reticulum spontaneously, producing a calcium ’spark’ and propagating traveling waves of elevated Ca²⁺ concentration, without depolarization of the SL (Wier and Blatter, 1991a, Cell Calcium 12, 241–254; Williams, 1993, Cell Calcium 14, 724–735; Cheng et al., 1993a, Science 262, 740–744). However, under normal resting conditions these potentially harmful waves seldom occur. In this paper we investigate the role of the periodic distribution of ryanodine-sensitive channels in determining whether a spark can trigger a wave, using a modification of the kinetic model proposed by Tang and Othmer, 1994b, Biophys. J. 67, 2223–2235, for calcium-induced calcium release. We show that the spatial localization of these channels near the T-tubules has a significant effect on both wave propagation and the onset of oscillations in this system. Spatial localization provides a possible explanation for the differing effects of various experimental protocols on the system’s ability to propagate a traveling wave. Supported in part by NIH Grant GM29123.     

Nonquasineutral current equilibria as elementary structures of plasma dynamics

A study is made of the fundamental features of current filaments with a nonzero electron vorticity Ω _e ≡ B − (c/e) ▿ × p _ee ≠ 0 and the corresponding Lagrangian invariant I _e . Such current structures can exist on spatial scales of up to ω _pi ⁻¹. It is shown that the dissipative stage of the plasma evolution and the violation of Thomson’s theorem on vorticity conservation in an electron fluid are of fundamental importance for the onset of electron current structures. A key role of the screening of electric and magnetic fields at distances on the order of the magnetic Debye radius r _B = B/(4πen _e )—the main property of such current structures in a Hall medium with σB/(en _e c) ≫ 1—is stressed. Since the minimum size of a vortex structure is the London length c/ω _pe , the structures under consideration correspond to the condition r _B > c/ω _pe or B ² > 4πn _e m _e c ², which leads to strong charge separation in the filament and relativistic electron drift. It is demonstrated that the specific energy content in current structures is high at a filament current of 10–15 kA: from 100 J/cm³ at a plasma density of 10¹⁴ cm⁻³ (the parameters of a lightning leader) to 10⁷ J/cm³ for a fully ionized atmospheric-pressure air. Estimates are presented showing that the Earth’s ionosphere, circumsolar space, and interstellar space are all Hall media in which current vortex structures can occur. A localized cylindrical equilibrium with a magnetic field reversal is constructed—an equilibrium that correlates with the magnetic structures observed in intergalactic space. It is shown that a magnetized plasma can be studied by using evolutionary equations for the electron and ion Lagrangian invariants I _e and I _i . An investigation is carried out of the evolution of a current-carrying plasma in a cylinder with a strong external magnetic field and with a longitudinal electron current turned on in the initial stage—an object that can serve as the simplest electrodynamic model of a tokamak. In this case, it is assumed that the plasma conductivity is low in the initial stage and then increases substantially with time. Based on the conservation of the integral momentum of the charged particles and electromagnetic field in a plasma cylinder within a perfectly conducting wall impenetrable by particles, arguments are presented in support of the generation of a radial electric field in a plasma cylinder and the production of drift ion fluxes along the cylinder axis. A hypothesis is proposed that the ionized intergalactic gas expands under the action of electromagnetic forces.     

Nonlinear mechanism for weak photon emission from biosystems

The nonlinear mechanism for the origin of the weak biophoton emission from biological systems is suggested. The mechanism is based on the properties of solitons that provide energy transfer and charge transport in metabolic processes. Such soliton states are formed in alpha-helical proteins. Account of the electron-phonon interaction in macromolecules results in the self-trapping of electrons in a localized soliton-like state, known as Davydov's solitons. The important role of the helical symmetry of macromolecules is elucidated for the formation, stability and dynamical properties of solitons. It is shown that the soliton with the lowest energy has an inner structure with the many-hump envelope. The total probability of the excitation in the helix is characterized by interspine oscillations with the frequency of oscillations, proportional to the soliton velocity. The radiative life-time of a soliton is calculated and shown to exceed the life-time of an excitation on an isolated peptide group by several orders of magnitude.     

Tilting after Dutch windmills: probably no long-lived Davydov solitons in proteins

We present a summary of picosecond pump-probe and photon echo experiments in the mid-IR at 6 μm on the protein myoglobin. The intriguing temperature dependence of the amide I band in Mb is rather similar to the temperature dependence of the amide I band of acetanilide, the molecule that launched Al Scott down the road of looking for Davydov solitons in biology. Alas, after much effort, we believe the data show that there is no long-lived Davydov soliton, at least in myoglobin. This work was supported by the Office of Naval Research and the Stichting voor Fundamenteel Onderzoek der Materie (FOM).     

Thermodynamic properties of bulk knitted structures

The mechanism of interaction of an external magnetic field with liquid was proposed. The statistical integral and configurational contributions for a free energy, entropy and specific heat for the soliton model of bulk knitted structures in a magnetic field were calculated. It was shown that the concentration of solitons depends on the effect of external fields. In the specific case of bulk knitted structures (liquid water without magnetic field), the theoretical data are consistent with experimental. The memory effects in systems with hydrogen bonds in magnetic field was explained in the framework of the continuum soliton concept.     

Calcium-induced exocytosis from actomyosin-driven, motile varicosities formed by dynamic clusters of organelles

Varicosities are ubiquitous neuronal structures that appear as local swellings along neurites of invertebrate and vertebrate neurons. Surprisingly little is known about their cell biology. We use here cultured Aplysia neurons and demonstrate that varicosities are motile compartments that contain large clusters of organelles. The content of varicosities propagate along neurites within the plasma membrane “sleeve”, split and merge, or wobble in place. Confocal imaging, retrospective immunolabeling, electron microscopy and pharmacological perturbations reveal that the motility of the varicosities’ organelle content occurs in concert with an actin scaffold and is generated by actomyosin motors. Despite the motility of these organelle clusters within the cytoplasm along the neurites, elevation of the free intracellular calcium concentration within varicosities by trains of action potentials induces exocytosis followed by membrane retrieval. Our observations demonstrate that varicosities formed in the absence of postsynaptic cells behave as “ready to go” prefabricated presynaptic terminals. We suggest that the varicosities’ motility serves to increase the probability of encountering a postsynaptic cell and to rapidly form a functional synapse. Electronic Supplementary Material Supplementary material is available in the online version of this article at These authors contributed equally to the paper.     

Evolution of early determinate tomato cultivars during the last three decades as a result of research conducted at Warsaw Agricultural University

Earliness is a crucial factor of tomato field production in Poland. A. Michalska and B. Kubicki (1978) conducted the first investigations on tomato earliness at the Department of Plant Genetics and Breeding. The main conclusions from these studies indicated that it was possible to obtain varieties earlier than ‘New Yorker’ as a result of transgression. The two new varieties (‘Alfa’ and ‘Akord F₁’) proved to be two weeks earlier than ‘New Yorker’. However, earliness was correlated with smaller fruit weight (30–40 g). At the next stage of experiment some improvement was achieved both in the size of fruit (45 g for ‘Beta’ up to 70 g for ‘Alka’) as well as colour intensity and good flavour. With the next few years fruit weight was still increased (up to 100 g for ‘Maskarena’) and a higher level of firmness was obtained (mid firm fruits for ‘Maskarena’ and ‘Delta’). At present, the Polish Research Centre for Cultivar Testing recommends our varieties ‘Betalux’, ‘Promyk’ and ‘Delta’ as standards.     

Effect of dust charge fluctuations on dust acoustic structures in magnetized dusty plasma containing nonextensive electrons and two-temperature isothermal ions

Effect of dust electrical charge fluctuations on the nature of dust acoustic solitary waves (DASWs) in a four-species magnetized dusty plasma containing nonextensive electrons and two-temperature isothermal ions has been investigated. In this model, the negative dust electric charge is considered to be proportional to the plasma space potential. The nonlinear Zakharov–Kuznetsov (ZK) and modified Zakharov–Kuznetsov (mZK) equations are derived for DASWs by using the standard reductive perturbation method. The combined effects of electron nonextensivity and dust charge fluctuations on the DASW profile are analyzed. The different ranges of the nonextensive q-parameter are considered. The results show that solitary waves the amplitude and width of which depend sensitively on the nonextensive q-parameter can exist. Due to the electron nonextensivity and dust charge fluctuation rate, our dusty plasma model can admit both positive and negative potential solitons. The results show that the amplitude of the soliton increases with increasing electron nonextensivity, but its width decreases. Increasing the electrical charge fluctuations leads to a decrease in both the amplitude and width of DASWs.     

Chemical evolution,recent syntheses of bioorganic molecules

This review covers important developments in abiological synthesis of biomonomers and biopolymers since about 1967. The significance of these experiments to the field of chemical evolution and the origin of life is also discussed. Lunar Science Institute Contribution. Continuation of: Oró, J.: ‘Extraterrestrial Organic Analysis’,Space Life Sci. 3 (1972), 507.     

T’ef (<Emphasis Type="Italic">Eragrostis tef</Emphasis>) in Ancient Agricultural Systems of Highland Ethiopia

T’ef ( Eragrostis tef ) in Ancient Agricultural Systems of Highland Ethiopia. T’ef (Eragrostis tef) has been cultivated in the Horn of Africa for at least 2,000 years. The earliest known agricultural systems in this region date to the Pre-Aksumite period (800–400 b.c.) and appear to have focused on Near Eastern crops, with indigenous African species increasing in importance during Aksumite times (400 b.c.–a.d. 700). While palaeoethnobotanical data are available from Pre-Aksumite and late Aksumite periods, macroscopic botanical remains from the site of Ona Nagast, northern Ethiopia, provide a first glimpse of agricultural systems dating to Proto-Aksumite (400–50 b.c.), Early to Classic (50 b.c.–a.d. 340), and Post-Aksumite (a.d. 700–900) times. Archaeological t’ef remains from Ona Nagast are examined in detail. Guidelines are developed for the identification of t’ef grains preserved on archaeological sites, with a focus on how to differentiate them from seeds of wild Eragrostis species. Charring experiments reveal that in some cases t’ef may not survive high temperatures tolerated by larger cereal grains, such as wheat and barley. The domestication history of t’ef appears to be different from some other cereals, a factor which may explain the preponderance of indeterminate Eragrostis seeds in archaeological samples. Selection of large seed size and intensified tillage were not key factors in t’ef domestication. Early cultivators were likely selecting for increased branching and higher percentage seed set under conditions of minimal tillage.