THE ROLE OF RESONANCES IN PLANETARY SYSTEMS

2006 ◽  
Vol 16 (06) ◽  
pp. 1633-1644
Author(s):  
RUDOLF DVORAK
Keyword(s):  
Planetary Systems ◽  
The Other ◽  
Special Configuration ◽  
Small Bodies ◽  
Mean Motion Resonances ◽  
Extrasolar Systems ◽  
Eccentric Orbits ◽  
The Stability ◽  
Observational Techniques

This paper reviews the important role of resonances in the structure of planetary systems. After a short introduction to the basics of orbital dynamics of motion in resonances we describe the dynamics of our planetary systems and also of extrasolar planetary systems, where up to now more than 100 are known. In our planetary system the planets move in quite regular orbits with small eccentricities although it was found that the motion of the inner planets is "slightly" chaotic on time scales of tenths of millions of years. The quasi regularity (close to so-called quasi-periodic motion on a torus) is not true for the small bodies: the main belt of asteroids between Mars and Jupiter with gaps for special values of semimajor axes on one hand and with families of many small bodies on the other, is sculpted due to the presence of first mean motion resonances with Jupiter and second secular resonances with long-periodic motions of the nodes and perihelia of Jupiter and Saturn. In extrasolar systems the planets — rather surprisingly — are found to move sometimes in very high eccentric orbits when they are at distances comparable to the size of our planets. Because of our still limited observational techniques using indirect methods we have only discovered massive planets comparable to the size of Jupiter. When these planets orbit alone around their host star our research aims at the possibility of additional terrestrial planets moving in such a system. Because of mostly large eccentricities here the resonances are, in contrary to our planets, essential for the stability of orbits, and may protect or destroy an orbit. On the other hand, in multiple planetary systems we concentrate on the stability of their orbits as they are observed: a very interesting new result is that most of these multiple planetary systems with high eccentric orbits move in resonances with a special configuration which protects them from close encounters although these orbits are crossing.

scholarly journals Tetracycline Induces Stabilization of mRNA in Bacillus subtilis

2002 ◽  
Vol 184 (4) ◽  
pp. 889-894 ◽  
Author(s):  
Yi Wei ◽  
David H. Bechhofer
Keyword(s):  
Bacillus Subtilis ◽  
Mrna Stability ◽  
The Other ◽  
Leader Region ◽  
Subinhibitory Concentration ◽  
Coding Sequence ◽  
Mrna Stabilization ◽  
Threefold Increase ◽  
The Stability

ABSTRACT The tet(L) gene of Bacillus subtilis confers low-level tetracycline (Tc) resistance. Previous work examining the >20-fold-inducible expression of tet(L) by Tc demonstrated a 12-fold translational induction. Here we show that the other component of tet(L) induction is at the level of mRNA stabilization. Addition of a subinhibitory concentration of Tc results in a two- to threefold increase in tet(L) mRNA stability. Using a plasmid-borne derivative of tet(L) with a large in-frame deletion of the coding sequence, the mechanism of Tc-induced stability was explored by measuring the decay of tet(L) mRNAs carrying specific mutations in the leader region. The results of these experiments, as well as experiments with a B. subtilis strain that is resistant to Tc due to a mutation in the ribosomal S10 protein, suggest different mechanisms for the effects of Tc on translation and on mRNA stability. The key role of the 5" end in determining mRNA stability was confirmed in these experiments. Surprisingly, the stability of several other B. subtilis mRNAs was also induced by Tc, which indicates that addition of Tc may result in a general stabilization of mRNA.

scholarly journals Retrograde resonances in compact multi-planetary systems: a feasible stabilizing mechanism

2007 ◽  
Vol 3 (S249) ◽  
pp. 511-516 ◽  
Author(s):  
Julie Gayon ◽  
Eric Bois
Keyword(s):  
Body Problem ◽  
Extrasolar Planets ◽  
Planetary Systems ◽  
Central Star ◽  
Point Of View ◽  
Outer Planet ◽  
Mean Motion Resonances ◽  
Hot Jupiters ◽  
The Stability ◽  
Orbital Data

AbstractMulti-planet systems detected until now are in most cases characterized by hot-Jupiters close to their central star as well as high eccentricities. As a consequence, from a dynamical point of view, compact multi-planetary systems form a variety of the general N-body problem (with N ≥ 3), whose solutions are not necessarily known. Extrasolar planets are up to now found in prograde (i.e. direct) orbital motions about their host star and often in mean-motion resonances (MMR). In the present paper, we investigate a theoretical alternative suitable for the stability of compact multi-planetary systems. When the outer planet moves on a retrograde orbit in MMR with respect to the inner planet, we find that the so-called retrograde resonances present fine and characteristic structures particularly relevant for dynamical stability. We show that retrograde resonances and their resources open a family of stabilizing mechanisms involving specific behaviors of apsidal precessions. We also point up that for particular orbital data, retrograde MMRs may provide more robust stability compared to the corresponding prograde MMRs.

scholarly journals On the survival of resonant and non-resonant planetary systems in star clusters

2020 ◽  
Vol 497 (2) ◽  
pp. 1807-1825
Author(s):  
Katja Stock ◽  
Maxwell X Cai ◽  
Rainer Spurzem ◽  
M B N Kouwenhoven ◽  
Simon Portegies Zwart
Keyword(s):  
Solar System ◽  
Star Clusters ◽  
Planetary Systems ◽  
Dynamical Evolution ◽  
Giant Planets ◽  
Mean Motion Resonances ◽  
Orbital Parameters ◽  
Eccentric Orbits ◽  
The Individual ◽  
Exoplanet Systems

ABSTRACT Despite the discovery of thousands of exoplanets in recent years, the number of known exoplanets in star clusters remains tiny. This may be a consequence of close stellar encounters perturbing the dynamical evolution of planetary systems in these clusters. Here, we present the results from direct N-body simulations of multiplanetary systems embedded in star clusters containing N = 8k, 16k, 32k, and 64k stars. The planetary systems, which consist of the four Solar system giant planets Jupiter, Saturn, Uranus, and Neptune, are initialized in different orbital configurations, to study the effect of the system architecture on the dynamical evolution of the entire planetary system, and on the escape rate of the individual planets. We find that the current orbital parameters of the Solar system giants (with initially circular orbits, as well as with present-day eccentricities) and a slightly more compact configuration, have a high resilience against stellar perturbations. A configuration with initial mean-motion resonances of 3:2, 3:2, and 5:4 between the planets, which is inspired by the Nice model, and for which the two outermost planets are usually ejected within the first 105 yr, is in many cases stabilized due to the removal of the resonances by external stellar perturbation and by the rapid ejection of at least one planet. Assigning all planets the same mass of 1 MJup almost equalizes the survival fractions. Our simulations reproduce the broad diversity amongst observed exoplanet systems. We find not only many very wide and/or eccentric orbits, but also a significant number of (stable) retrograde orbits.

MODELING THE ROLE OF DISSOLVED OXYGEN-DEPENDENT BACTERIA ON BIODEGRADATION OF ORGANIC POLLUTANTS

2014 ◽  
Vol 07 (01) ◽  
pp. 1450008 ◽  
Author(s):  
J. B. SHUKLA ◽  
ASHISH GOYAL ◽  
P. K. TIWARI ◽  
A. K. MISRA
Keyword(s):  
Dissolved Oxygen ◽  
Water Body ◽  
Logistic Model ◽  
Simulation Analysis ◽  
Organic Pollutant ◽  
The Other ◽  
Nonlinear Mathematical Model ◽  
The Stability ◽  
The One

In this paper, a nonlinear mathematical model is proposed and analyzed to study the role of dissolved oxygen (DO)-dependent bacteria on biodegradation of one or two organic pollutant(s) in a water body. In the case of two organic pollutant(s), it is assumed that the one is fast degrading and the other is slow degrading and both are discharged into the water body from outside with constant rates. The density of bacteria is assumed to follow logistic model and its growth increases due to biodegradation of one or two organic pollutant(s) as well as with the increase in the concentration of DO. The model is analyzed using the stability theory of differential equations and by simulation. The model analysis shows that the concentration(s) of one or both organic pollutant(s) decrease(s) as the density of bacteria increases. It is noted that for very large density of bacteria, the organic pollutant(s) may be removed almost completely from the water body. It is found that simulation analysis confirms the analytical results. The results obtained in this paper are in line with the experimental observations published in literature.

Possible Perforin-Munc13-4 Gene-Gene Interaction in Familial Hemophagocytic Lymphohistiocytosis

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4643-4643
Author(s):  
Gunay Balta ◽  
Hamza Okur ◽  
Nurten Akarsu ◽  
Sule Unal ◽  
Cigdem Altay ◽  
...  
Keyword(s):  
Risk Factor ◽  
Genetic Risk ◽  
Genetic Risk Factor ◽  
The Other ◽  
Familial Hemophagocytic Lymphohistiocytosis ◽  
The Family ◽  
Syntaxin 11 ◽  
The Stability ◽  
Asymptomatic Sibling

Abstract Familial hemophagocytic lymphohistiocytosis (FHL) is an autosomal recessive immune dysregulation disorder associated with Perforin, Munc13-4 and Syntaxin 11 genes. The mutations in the Perforin gene are the most common cause of the disease. Among these mutations, the role of the Alanin91Valin (A91V) alteration in the pathogenesis of the disease has long been controversial. Even though this alteration can be considered as a polymorphism based on its high frequency in normal population (>3.7%) and homozygous existence in some healthy individuals, it is also considered as a genetic risk factor depending on its much higher frequency observed in FHL patients (22.7%) and compound heterozygous existence with other disease causing mutations in the Perforin gene in some FHL patients. Contrary to the previous publications concerning with the co-existence of heterozygous A91V with homozygous mutations in other described FHL genes, there has been no reports on homozygous co-existence of A91V up until this communication where we present the interesting results of a study which shed light not only on the role of A91V in development of FHL, but also on the etiopathogenesis of genetic diseases in general. The subject of the study was a 12 year old female patient who was a product of a first degree consanguineous marriage. Initial diagnosis was lymphomatoid granulomatosis due to the presence of symptoms associated solely with central nervous system. The correct diagnosis could be made 1 year later upon development of systemic findings of FHL. There was no history of similar disorder in the family. Linkage analysis in the family revealed homozygosity for both Perforin and Munc13-4 genes in the patient and for only Munc13-4 gene in one of the asymptomatic sibling who was heterozygous for Perforin gene. Syntaxin 11 gene was excluded in this analysis. Detected merely in the patient was a homozygous A91V substitution (272C>T) in the sequencing of the Perforin gene. Sequencing of the complete coding (32 exons) and the flanking sequences, on the other hand, led to the identification of a homozygous three nucleotide in-frame deletion (2135-2137delTCG) in exon 23 of Munc13-4 gene. This novel mutation resulted in the replacement of nonpolar two aminoacids (Ile-Gly) at positions 712-713 with a polar single aminoacid (Ser). It is plausible that the substitution of highly conserved two aminoacids, especially one (Ile) playing important role in the stability of proteins, with a hydrophilic one would alter the three dimensional structure and the stability of the protein, and would lead to FHL. Ironically, however, an asymptomatic sibling who is currently 22 year old was also homozygous for the mutation. This finding led to the assumption that the Munc13-4 mutation alone may not be sufficient for the development of the disease, but may be a genetic risk factor requiring co-existence of additional homozygous genetic risk factor situated in another FHL gene. If this is the case, it is reasonable to state that homozigosity for A91V in Perforin as well as homozygosity for the 2135-2137del mutation in Munc13-4 is a strong genetic susceptibility factor contributing significantly to the pathogenesis of the disease when they are co-existed. However, this notion could be valid as long as the sibling with homozygous Munc13-4 mutation stays asymptomatic. On the other hand, late onset and atypical presentation in the propositus may indicate that the homozygous co-existence of both alterations is not associated with serious clinical course of the disease as far as the presenting age of the disease is concerned.

Ti-Ni Phase Diagram with Applied Stress

1993 ◽  
Vol 311 ◽  
Author(s):  
A.Peter Jardine
Keyword(s):  
Thin Film ◽  
Phase Diagram ◽  
Single Phase ◽  
Phase Evolution ◽  
The Other ◽  
Β Phase ◽  
The Stability ◽  
Tini Phase ◽  
Rich Side

ABSTRACTThe role of stress on the phase evolution of thin-film TiNi has not been investigated and may play an important role in the phase evolution of thin film TiNi. In this paper, a preliminary set of phase diagrams for Ni-Ti at different pressures are presented relating the stability of the stoichiometric TiNi phase to the other well-documented intermetallics TiNi3 and NiTi2. It is found that for sufficient pressure of the order of a GPa, the region where NiTi (β) phase is single phase shifts towards the Ti-rich side of the diagram. The implications on the annealing of TiNi thin film is discussed.

scholarly journals The Role of Polarity on the Stability of Graphitic Compounds

1989 ◽  
Vol 162 ◽  
Author(s):  
Renata M. Wentzcovitch ◽  
Alessandra Continenza ◽  
A. J. Freeman
Keyword(s):  
The Other ◽  
Low Density ◽  
Hexagonal Diamond ◽  
The Family ◽  
The Stability

ABSTRACTThere is an old puzzle associated with the series of compounds formed by first row elements, C, BN, and BeO: similar to the other members of the family of octet semiconductors, these compounds exist in dense phases like diamond and zincblende, or hexagonal diamond (lonsdaleite) and wurtzite; however, whereas C and BN also exist in low density graphitic phases, BeO does not.

scholarly journals On secular resonances of small bodies in the planetary systems

2006 ◽  
Vol 2 (S236) ◽  
pp. 77-84
Author(s):  
Jianghui Ji ◽  
L. Liu ◽  
G. Y. Li
Keyword(s):  
Solar System ◽  
Planetary System ◽  
Planetary Systems ◽  
Giant Planets ◽  
Small Bodies ◽  
Secular Resonances ◽  
Mean Motion Resonances ◽  
The Earth ◽  
Habitable Zones ◽  
Earth Like Planets

AbstractWe investigate the secular resonances for massless small bodies and Earth-like planets in several planetary systems. We further compare the results with those of Solar System. For example, in the GJ 876 planetary system, we show that the secular resonances ν1 and ν2 (respectively, resulting from the inner and outer giant planets) can excite the eccentricities of the Earth-like planets with orbits 0.21≤ a <0.50 AU and eject them out of the system in a short timescale. However, in a dynamical sense, the potential zones for the existence of Earth-like planets are in the area 0.50≤ a ≤1.00 AU, and there exist all stable orbits last up to 105 yr with low eccentricities. For other systems, e.g., 47 UMa, we also show that the Habitable Zones for Earth-like planets are related to both secular resonances and mean motion resonances in the systems.

scholarly journals The 3D secular dynamics of radial-velocity-detected planetary systems

2019 ◽  
Vol 626 ◽  
pp. A74 ◽  
Author(s):  
Mara Volpi ◽  
Arnaud Roisin ◽  
Anne-Sophie Libert
Keyword(s):  
Radial Velocity ◽  
Spatial Configuration ◽  
Planetary Systems ◽  
Detection Methods ◽  
Secular Dynamics ◽  
Extrasolar Systems ◽  
Spatial Configurations ◽  
The Stability ◽  
Kozai Resonance

Aims. To date, more than 600 multi-planetary systems have been discovered. Due to the limitations of the detection methods, our knowledge of the systems is usually far from complete. In particular, for planetary systems discovered with the radial velocity (RV) technique, the inclinations of the orbital planes, and thus the mutual inclinations and planetary masses, are unknown. Our work aims to constrain the spatial configuration of several RV-detected extrasolar systems that are not in a mean-motion resonance. Methods. Through an analytical study based on a first-order secular Hamiltonian expansion and numerical explorations performed with a chaos detector, we identified ranges of values for the orbital inclinations and the mutual inclinations, which ensure the long-term stability of the system. Our results were validated by comparison with n-body simulations, showing the accuracy of our analytical approach up to high mutual inclinations (∼70 ° −80°). Results. We find that, given the current estimations for the parameters of the selected systems, long-term regular evolution of the spatial configurations is observed, for all the systems, (i) at low mutual inclinations (typically less than 35°) and (ii) at higher mutual inclinations, preferentially if the system is in a Lidov-Kozai resonance. Indeed, a rapid destabilisation of highly mutually inclined orbits is commonly observed, due to the significant chaos that develops around the stability islands of the Lidov-Kozai resonance. The extent of the Lidov-Kozai resonant region is discussed for ten planetary systems (HD 11506, HD 12661, HD 134987, HD 142, HD 154857, HD 164922, HD 169830, HD 207832, HD 4732, and HD 74156).

scholarly journals Long-term orbital stability of exosolar planetary systems with highly eccentric orbits

2015 ◽  
Vol 11 (A29A) ◽  
pp. 38-39
Author(s):  
Kyriaki I. Antoniadou ◽  
George Voyatzis
Keyword(s):  
Phase Space ◽  
Orbital Stability ◽  
Planetary Systems ◽  
Dynamical Analysis ◽  
Hill Stability ◽  
Mean Motion Resonances ◽  
Term Stability ◽  
Long Term Stability ◽  
Eccentric Orbits

AbstractNowadays, many extrasolar planetary systems possessing at least one planet on a highly eccentric orbit have been discovered. In this work, we study the possible long-term stability of such systems. We consider the general three body problem as our model. Highly eccentric orbits are out of the Hill stability regions. However, mean motion resonances can provide phase protection and orbits with long-term stability exist. We construct maps of dynamical stability based on the computation of chaotic indicators and we figure out regions in phase space, where the long-term stability is guaranteed. We focus on regions where at least one planet is highly eccentric and attempt to associate them with the existence of stable periodic orbits. The values of the orbital elements, which are derived from observational data, are often given with very large deviations. Generally, phase space regions of high eccentricities are narrow and thus, our dynamical analysis may restrict considerably the valid domain of the system's location.

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