scholarly journals The relationship between the `limiting' Yarkovsky drift speed and asteroid families' Yarkovsky V-shape

2020 ◽  
pp. 25-41
Author(s):  
I. Milic-Zitnik
Keyword(s):  
Interesting Property ◽  
Parent Body ◽  
Mean Motion Resonances ◽  
Mean Motion ◽  
Drift Speed ◽  
Yarkovsky Effect ◽  
The Mean ◽  
The Relationship ◽  
Asteroid Families

The Yarkovsky effect is an important force to consider in order to understand the long-term dynamics of asteroids. This non-gravitational force affects the orbital elements of objects revolving around a source of heat, especially their semi-major axes. Following the recently defined `limiting' value of the Yarkovsky drift speed at 7x10-5 au/Myr in Milic Zitnik (2019) (below this value of speed asteroids typically jump quickly across the mean motion resonances), we decided to investigate the relation between the asteroid family Yarkovsky V-shape and the `limiting' Yarkovsky drift speed of asteroid's semi-major axes. We have used the known scaling formula to calculate the Yarkovsky drift speed (Spoto et al. 2015) in order to determine the inner and outer `limiting' diameters (for the inner and outer V-shape borders) from the `limiting' Yarkovsky drift speed. The method was applied to 11 asteroid families of different taxonomic classes, origin type and age, located throughout the Main Belt. Here, we present the results of our calculation on relationship between asteroid families' V-shapes (crossed by strong and/or weak mean motion resonances) and the `limiting' diameters in the (a, 1=D) plane. Our main conclusion is that the `breakpoints' in changing V-shape of the very old asteroid families, crossed by relatively strong mean motion resonances on both sides very close to the parent body, are exactly the inverse of `limiting' diameters in the a versus 1=D plane. This result uncovers a novel interesting property of asteroid families' Yarkovsky V-shapes.

scholarly journals Higher Order and Iterative Theories to Compute Asteroid Mean Elements

1999 ◽  
Vol 172 ◽  
pp. 359-360 ◽  
Author(s):  
Z. Knežević ◽  
A. Milani
Keyword(s):  
Asteroid Belt ◽  
Dynamical Structure ◽  
Orbital Elements ◽  
Mean Motion Resonances ◽  
First Order ◽  
Mean Motion ◽  
Long Time ◽  
The Mean ◽  
Mean Elements ◽  
Asteroid Families

Mean orbital elements are obtained from their instantaneous, osculating counterparts by removal of the short periodic perturbations. They can be computed by means of different theories, analytical or numerical, depending on the problem and accuracy required. The most advanced contemporary analytical theory (Knežević 1988) accounts only for the perturbing effects due to Jupiter and Saturn, to the first order in their masses and to degree four in eccentricity and inclination. Nevertheless, the mean elements obtained by means of this theory are of satisfactory accuracy for majority of the asteroids in the main belt (Knežević et al. 1988), for the purpose of producing large catalogues of mean and proper elements, to identify asteroid families, to assess their age, to study the dynamical structure of the asteroid belt and chaotic phenomena of diffusion over very long time spans. In the vicinity of the main mean motion resonances, however, especially 2:1 mean motion resonance with Jupiter, these mean elements are of somewhat degraded accuracy.

Primordial Stability of the Earth–Mars Belt

2020 ◽  
Author(s):  
Yukun Huang ◽  
Brett Gladman
Keyword(s):  
Semimajor Axis ◽  
Orbital Stability ◽  
Terrestrial Planet ◽  
Mean Motion Resonances ◽  
Mean Motion ◽  
Yarkovsky Effect ◽  
The Earth ◽  
Steady State Model ◽  
Near Earth Objects

<p>Previous work has demonstrated orbital stability for 100 Myr of initially near-circular and coplanar small bodies in a region termed the 'Earth–Mars belt' from 1.08 au<a<1.28 au. Via numerical integration of 3000 particles, we studied orbits from 1.04–1.30 au for the age of the Solar system. We show that on this time scale, except for a few locations where mean-motion resonances with Earth affect stability, only a narrower 'Earth–Mars belt' covering a∼(1.09,1.17) au, e<0.04, and I<1◦ has over half of the initial orbits survive for 4.5 Gyr. In addition to mean-motion resonances, we are able to see how the ν3, ν4, and ν6 secular resonances contribute to long-term instability in the outer (1.17–1.30 au) region on Gyr time scales. We show that all of the (rather small) near-Earth objects (NEOs) in or close to the Earth–Mars belt appear to be consistent with recently arrived transient objects by comparing to a NEO steady-state model. Given the <200m scale of these NEOs, we estimated the Yarkovsky effect drift rates in semimajor axis, and use these to estimate that a diameter of ∼100km or larger would allow primordial asteroids in the Earth–Mars belt to likely survive. We conclude that only a few 100 km scale asteroids could have been present in the belt’s region at the end of the terrestrial planet formation.</p>

scholarly journals The functional relation between mean motion resonances and Yarkovsky force on small eccentricities

2020 ◽  
Vol 498 (3) ◽  
pp. 4465-4471
Author(s):  
I Milić Žitnik
Keyword(s):  
Time Delays ◽  
Semimajor Axis ◽  
Functional Relation ◽  
Orbital Eccentricity ◽  
Mean Motion Resonances ◽  
Mean Motion ◽  
Drift Speed ◽  
Yarkovsky Effect ◽  
Numerical Integrations ◽  
Time Lead

ABSTRACT This work examines asteroid’s motion with orbital eccentricity in the range (0.1, 0.2) across the two-body mean motion resonance (MMR) with Jupiter due to the Yarkovsky effect. We calculated time delays dtr caused by the resonance on the mobility of an asteroid with the Yarkovsky drift speed. Our final results considered only asteroids that successfully cross over the resonance without close encounters with planets. We found a functional relation that accurately describes dependence between the average time lead/lag 〈dtr〉, the strength of the resonance SR, and the semimajor axis drift speed da/dt with asteroids’ orbital eccentricities in the range (0.1, 0.2). We analysed average values of 〈dtr〉 using this functional relation comparing with obtained values of 〈dtr〉 from the numerical integrations, which were performed in an ORBIT9 integrator with a very large number of test asteroids. We checked the validity of our previous functional relation, derived for asteroids’ orbital eccentricities in the range (0, 0.1), on the present results for eccentricities in the range (0.1, 0.2). Also, we tried to find a unique functional relation for the whole interested interval of asteroids’ orbital eccentricities (0, 0.2) and discussed it.

Multi-Center Calibration of the Second Reference Material for Thromboplastin, Rabbit, Plain, Coded CRM 149R

1991 ◽  
Vol 65 (03) ◽  
pp. 263-267 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Reference Material ◽  
Standard Error ◽  
Standard Errors ◽  
Sensitivity Index ◽  
Long Term Stability ◽  
Significant Bias ◽  
The Mean ◽  
The Relationship ◽  
International Sensitivity Index

SummaryIn a collaborative trial of eleven laboratories which was performed mainly within the framework of the European Community Bureau of Reference (BCR), a second reference material for thromboplastin, rabbit, plain, was calibrated against its predecessor RBT/79. This second reference material (coded CRM 149R) has a mean International Sensitivity Index (ISI) of 1.343 with a standard error of the mean of 0.035. The standard error of the ISI was determined by combination of the standard errors of the ISI of RBT/79 and the slope of the calibration line in this trial.The BCR reference material for thromboplastin, human, plain (coded BCT/099) was also included in this trial for assessment of the long-term stability of the relationship with RBT/79. The results indicated that this relationship has not changed over a period of 8 years. The interlaboratory variation of the slope of the relationship between CRM 149R and RBT/79 was significantly lower than the variation of the slope of the relationship between BCT/099 and RBT/79. In addition to the manual technique, a semi-automatic coagulometer according to Schnitger & Gross was used to determine prothrombin times with CRM 149R. The mean ISI of CRM 149R was not affected by replacement of the manual technique by this particular coagulometer.Two lyophilized plasmas were included in this trial. The mean slope of relationship between RBT/79 and CRM 149R based on the two lyophilized plasmas was the same as the corresponding slope based on fresh plasmas. Tlowever, the mean slope of relationship between RBT/79 and BCT/099 based on the two lyophilized plasmas was 4.9% higher than the mean slope based on fresh plasmas. Thus, the use of these lyophilized plasmas induced a small but significant bias in the slope of relationship between these thromboplastins of different species.

scholarly journals Asteroid Proper Elements: The Big Picture

1994 ◽  
Vol 160 ◽  
pp. 143-158 ◽  
Author(s):  
Zoran Knežević ◽  
Andrea Milani
Keyword(s):  
Point Of View ◽  
Dynamical Structure ◽  
Main Belt ◽  
Secular Resonances ◽  
Mean Motion Resonances ◽  
Mean Motion ◽  
Proper Elements ◽  
Big Picture ◽  
Linear And Nonlinear ◽  
Asteroid Families

Four perturbation theories presently used to compute asteroid proper elements are reviewed, and their results are briefly discussed (Milani and Knežević, 1990, 1992, 1994, for low to moderate eccentricity/inclination main belt objects; Lemaitre and Morbidelli, 1994, for high e, I objects; Milani, 1993, for Trojans; Schubart, 1982, 1991 for Hildas). The most important recent improvements are described, in particular those pertaining to the upgrades of the previous analytic and semianalytic solutions. The dynamical structure of the asteroid main belt, as defined by the low order mean motion resonances and by linear and nonlinear secular resonances, is considered from the point of view of the effects of these resonances on the accuracy and/or reliability of the computation of proper elements and on the reliability of the identification of asteroid families.

Laying date of marsh tits Parus palustris in relation to climate change

Biologia ◽  
2006 ◽  
Vol 61 (5) ◽  
Author(s):  
Zdravko Dolenec
Keyword(s):  
Climate Change ◽  
Life History Traits ◽  
Laying Date ◽  
Bird Breeding ◽  
Spring Temperatures ◽  
The Mean ◽  
The Relationship ◽  
Marsh Tit ◽  
Term Data

AbstractIncreasing evidence suggests that climate change affects bird breeding phenology and other life-history traits of wildlife. This study is based on the mean spring temperatures (February, March, April) and laying dates of first eggs of the marsh tit Parus palustris. We collected data from 1984 to 2004 for the Mokrice area in NW Croatia. Correlation between laying date and mean spring temperatures was significant. The relationship between mean laying date (y) and air temperature (x) can be expressed as y = 44.69 − 2.08x. Results indicate that spring temperatures are a good predictor of timing of laying eggs. Such long-term data could than be used in order to assess the effects on biological systems if human activities influence climate.

scholarly journals Analyses of Monthly Discharges in Slovakia Using Hydrological Exploratory Methods

Proceedings ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 18
Author(s):  
Mária Ďurigová ◽  
Dominika Ballová ◽  
Kamila Hlavčová
Keyword(s):  
Change Points ◽  
Hydrological Data ◽  
Pettitt Test ◽  
The Mean ◽  
Monthly Discharge ◽  
Meteorological Elements ◽  
The Relationship ◽  
Annual Discharge ◽  
Hydrological Regimes

Detailed analyses of hydrological data are necessary in order to prove changes in their character. This article focuses on an analysis of the average monthly discharges of 14 stage-discharge gauging stations in Slovakia. The measured period is from 1931 to 2016. The approaches used are hydrological exploration methods, which were created by hydrologists to describe the behavior of hydrological time series. The methods are used to identify a change-point using an analysis of any residuals, the Pettitt test, and an analysis of the relationship between the mean annual discharge deviations from the long-term annual discharge and the deviations of the average monthly discharge from the long-term average monthly discharge. A considerable number of change-points were identified in the 1970s and 1980s. The results of the analyses show changes in the hydrological regimes, but to confirm the accuracy of the outcomes, it is also necessary to examine other hydrological and meteorological elements such as, e.g., precipitation and the air temperature.

scholarly journals Four-billion year stability of the Earth–Mars belt

2020 ◽  
Vol 500 (1) ◽  
pp. 1151-1157
Author(s):  
Yukun Huang (黄宇坤) ◽  
Brett Gladman
Keyword(s):  
Semimajor Axis ◽  
Orbital Stability ◽  
Terrestrial Planet ◽  
Small Bodies ◽  
Mean Motion Resonances ◽  
Mean Motion ◽  
The Earth ◽  
Steady State Model ◽  
Near Earth Objects

ABSTRACT Previous work has demonstrated orbital stability for 100 Myr of initially near-circular and coplanar small bodies in a region termed the ‘Earth–Mars belt’ from 1.08 < a < 1.28 au. Via numerical integration of 3000 particles, we studied orbits from 1.04–1.30 au for the age of the Solar system. We show that on this time-scale, except for a few locations where mean-motion resonances with Earth affect stability, only a narrower ‘Earth–Mars belt’ covering a ∼ (1.09, 1.17) au, e < 0.04, and I < 1° has over half of the initial orbits survive for 4.5 Gyr. In addition to mean-motion resonances, we are able to see how the ν3, ν4, and ν6 secular resonances contribute to long-term instability in the outer (1.17–1.30 au) region on Gyr time-scales. We show that all of the (rather small) near-Earth objects (NEOs) in or close to the Earth–Mars belt appear to be consistent with recently arrived transient objects by comparing to a NEO steady-state model. Given the <200 m scale of these NEOs, we estimated the Yarkovsky drift rates in semimajor axis and use these to estimate that a diameter of ∼100 km or larger would allow primordial asteroids in the Earth–Mars belt to likely survive. We conclude that only a few 100-km sized asteroids could have been present in the belt’s region at the end of the terrestrial planet formation.

Activity Behaviors of University Staff in the Workplace: A Pilot Study

2015 ◽  
Vol 12 (8) ◽  
pp. 1128-1132 ◽  
Author(s):  
Marie-Louise Bird ◽  
Cecilia Shing ◽  
Casey Mainsbridge ◽  
Dean Cooley ◽  
Scott Pedersen
Keyword(s):  
Pilot Study ◽  
Sedentary Time ◽  
Sitting Time ◽  
Moderate Activity ◽  
Activity Levels ◽  
University Staff ◽  
Light Activity ◽  
The Mean ◽  
The Relationship

Background:Sedentary behavior is related to metabolic syndrome and might have implications for the long-term health of workers in a low activity environment. The primary aim of this pilot study was to determine activity levels of adults working at a University during work hours. A secondary aim was to determine the relationship between actual and perceived activity levels.Methods:Activity levels of university staff (n = 15, male = 7, age = 53 ± 7 years, BMI = 26.5 ± 2.5kg·m2) were monitored over 5 consecutive workdays using SenseWear accelerometers, then participants completed a questionnaire of their perception of workplace sedentary time.Results:Each participant spent 71.5 ± 13.1% (358 ± 78 min) of their workday being sedentary (< 1.5 METs), 15.6 ± 9.0% involved in light activity (1.5–3 METs), 11.7 ± 10.0% in moderate activity (3–5 METs), and 1.1 ± 1.3% in vigorous activity (> 5 METs) (P < .0001). The mean difference between actual (SenseWear < 1.5 METs) and perceived sitting time was –2 ± 32%; however, perceived sedentary time was reported with a range of under-to-over estimation of –75% to 51%.Conclusion:This pilot study identifies long periods of low metabolic activity during the workday and poor perception of individual sedentary time. Interventions to reduce sedentary time in the workplace may be necessary to ensure that the work environment does not adversely affect long-term health.

scholarly journals Interaction between Yarkovsky force and mean-motion resonances: Some specific properties

2016 ◽  
pp. 19-26 ◽  
Author(s):  
I. Milic-Zitnik
Keyword(s):  
Time Delays ◽  
Functional Relationship ◽  
Major Axis ◽  
Asymmetric Distribution ◽  
Orbital Eccentricity ◽  
Semi Major Axis ◽  
Mean Motion Resonances ◽  
Mean Motion ◽  
Drift Speed

Recently, we analyzed the role of mean-motion resonances in semi-major axis mobility of asteroids, and established a functional relationship that describes the dependence of the average time spent inside the resonance on the strength of this resonance and the semi-major axis drift speed. Here we extend this analyzis in two directions. First, we study the distribution of time delays inside the resonance and found that it could be described by the modified Laplace asymmetric distribution. Second, we analyze how the time spent inside the resonance depends on orbital eccentricity, and propose a relation that allows to take into account this parameter as well.

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