The common origin of family and non-family asteroids: Implications for meteorites and NEAs

2018 ◽  
Vol 14 (S345) ◽  
pp. 281-282
Author(s):  
Stanley F. Dermott ◽  
Dan Li ◽  
Apostolos A. Christou
Keyword(s):  
Hierarchical Clustering ◽  
Common Origin ◽  
Clustering Method ◽  
Main Belt ◽  
Frequency Distributions ◽  
Size Frequency ◽  
The Family ◽  
The Common ◽  
The Mean ◽  
Asteroid Families

AbstractThe observed size-frequency distributions (SFDs) of the five major asteroid families in the Inner Main Belt (IMB), defined by Nesvorný (2015) using the Hierarchical Clustering Method (Zappala et al. 1990), are distinctly different and deviate significantly from the linear log-log relation described by Dohnanyi (1969). The existence of these differences in the SFDs, and the fact that the precursor bodies of the major families have distinctly different eccentricities and inclinations, provides an explanation for the observations that the mean sizes of both the family and the non-family asteroids are correlated with their mean proper eccentricities and anti-correlated with their mean proper inclinations. We deduce from this, and from the fact that the SFDs of the family and the non-family asteroids are almost identical, that the family and most of the non-family asteroids in the IMB have a common origin (Dermott et al. 2018).

The common origin of family and non-family asteroids: Implications

2018 ◽  
Vol 14 (A30) ◽  
pp. 23-23
Author(s):  
Stanley F. Dermott ◽  
Apostolos Christou ◽  
Dan Li
Keyword(s):  
Absolute Magnitude ◽  
Common Origin ◽  
Selection Effects ◽  
Simple Explanation ◽  
Orbital Elements ◽  
Frequency Distributions ◽  
The Family ◽  
The Common ◽  
The Mean ◽  
Asteroid Families

AbstractBecause the number of asteroids in the IMB with absolute magnitude H<16.5 is effectively complete, the distributions of the sizes and the orbital elements of these asteroids must be devoid of observational selection effects. This allows us to state that the observed size-frequency distributions (SFDs) of the five major asteroid families in the IMB, defined by Nesvorný (2015) using the Hierarchical Clustering Method (Zappala et al. 1990), are distinctly different and deviate significantly from the linear log-log relation described by Dohnanyi (1969). The existence of these differences in the SFDs, and the fact that the precursor bodies of the major families have distinctly different eccentricities and inclinations, provides a simple explanation for the observations that the mean sizes of the family asteroids, taken as a whole, are correlated with their mean proper eccentricities and anti-correlated with their mean proper inclinations. While the latter observations do have a simple explanation, we observe that the mean sizes of the non-family asteroids in the IMB are also correlated with their mean proper eccentricities and anti-correlated with their mean proper inclinations. We deduce from this, and from the fact that the SFDs of the non-family and the family asteroids (again taken as a whole) are almost identical, that the family and most of the non-family and asteroids have a common origin. We estimate that ~85% of all the asteroids in the IMB with H<16.5 originate from the Flora, Vesta, Nysa, Polana and Eulalia families with the remaining ~15% originating from either the same families or, more likely, a few ghost families (Dermott et al. 2018).

Determinacy of fecundity in sole (Solea solea) from the Bristol Channel

1990 ◽  
Vol 70 (4) ◽  
pp. 803-813 ◽  
Author(s):  
J. W. Horwood ◽  
M. Greer Walker
Keyword(s):  
Bay Of Biscay ◽  
English Channel ◽  
Potential Fecundity ◽  
Frequency Distributions ◽  
The North ◽  
Size Frequency ◽  
Solea Solea ◽  
The North Sea ◽  
The Common ◽  
Common Sole

Ovaries of the common sole (Solea solea (Linnaeus)) were collected prior to, or at the beginning of, spawning from the spawning grounds in the Bristol Channel. Size frequency distributions of oocytes over 100 μm are presented. They clearly show a break in the size frequency distributions, at about 170 μm, indicating that the production of new oocytes to be spawned that season had ceased. It indicates that the sole is a determinate spawner and that, at least for this population, an annual potential fecundity can be measured. Estimated annual fecundity at length of Bristol Channel sole is calculated, and values are compared with those found for sole from the North Sea, eastern English Channel and the Bay of Biscay.

scholarly journals An automatic approach to exclude interlopers from asteroid families

2017 ◽  
Vol 470 (1) ◽  
pp. 576-591 ◽  
Author(s):  
Viktor Radović ◽  
Bojan Novaković ◽  
Valerio Carruba ◽  
Dušan Marčeta
Keyword(s):  
Hierarchical Clustering ◽  
Family Members ◽  
Main Idea ◽  
Clustering Method ◽  
New Approach ◽  
Valuable Source ◽  
Additional Step ◽  
Chaining Effect ◽  
Source Of Information ◽  
Asteroid Families

Abstract Asteroid families are a valuable source of information to many asteroid-related researches, assuming a reliable list of their members could be obtained. However, as the number of known asteroids increases fast it becomes more and more difficult to obtain a robust list of members of an asteroid family. Here, we are proposing a new approach to deal with the problem, based on the well-known hierarchical clustering method. An additional step in the whole procedure is introduced in order to reduce a so-called chaining effect. The main idea is to prevent chaining through an already identified interloper. We show that in this way a number of potential interlopers among family members is significantly reduced. Moreover, we developed an automatic online-based portal to apply this procedure, i.e. to generate a list of family members as well as a list of potential interlopers. The Asteroid Families Portal is freely available to all interested researchers.

Life history, secondary production and population dynamics of Gammarus fossarum (Koch, 1836) in a constant temperature stream

Biologia ◽  
2012 ◽  
Vol 67 (1) ◽  
Author(s):  
Pavel Beracko ◽  
Anna Sýkorová ◽  
Andrej Štangler
Keyword(s):  
Life Cycle ◽  
Constant Temperature ◽  
Growth Function ◽  
Dry Mass ◽  
Frequency Method ◽  
Daily Growth ◽  
Gammarus Fossarum ◽  
Frequency Distributions ◽  
Size Frequency ◽  
The Mean

AbstractPopulation of the freshwater amphipod Gammarus fossarum was investigated in a calcareous stream with almost constant temperature (7–8°C) in the Chočské Vrchy Mts (West Carpathians, Slovakia). Quantitative samples of G. fossarum taken during 2005 showed population densities varying from 100 m−2 in August to 585 m−2 in late November. The population was split into juveniles, mature males, mature females without eggs and females with eggs. The percentage of juveniles (40–64%) was always the highest of any of the categories. Ovigerous females occurred throughout the year. The mean sex ratio was 1: 2.4 (male: female), although its values varied considerably with the time of year. Breeding was continuous, although juvenile recruitment peaked in early spring, summer and early winter. Three discrete cohorts were distinguished from the size frequency distributions. The life span was 6–7 months and the individuals matured approximately in the half of life cycle. The mean fecundity was 9.6 embryos per brood. Variation in fecundity was mostly explained by size of the incubating females. The absolute growth of this species was best described by the Gompertz growth function. Relative growth rates (% body DM day−1) fluctuated in a nonlinear manner with size and age. The highest values of daily growth (2–4% of dry mass per day) were noted approximately in the half of life cycle. Annual production, estimated by the size-frequency method, was 1618.9 g dry mass m−2 and P/B ratio was 5.15.

scholarly journals An integrated growth study for North Atlantic albacore (Thunnus alalunga Bonn. 1788)

2005 ◽  
Vol 62 (4) ◽  
pp. 740-749 ◽  
Author(s):  
J. Santiago ◽  
H. Arrizabalaga
Keyword(s):  
North Atlantic ◽  
Growth Parameters ◽  
Individual Variability ◽  
Growth Study ◽  
Combined Model ◽  
Frequency Distributions ◽  
Size Frequency ◽  
Age Dependent ◽  
Thunnus Alalunga ◽  
The Mean

Abstract The growth of North Atlantic albacore (Thunnus alalunga) was studied using three methods. Spines collected during a fishing season (n = 761) were read and used to estimate growth parameters. Additional growth estimates were obtained by applying MULTIFAN to quarterly size frequency distributions of total international catch for the period 1990–1999 as well as using tag-recapture data (n = 314). In the case of spines and tagging, models that allowed for individual variability in growth were evaluated. In the analysis with size frequency distributions, a model that allowed for seasonal growth and age-dependent standard deviation around the mean lengths-at-age was used. Growth estimates were consistent among the different methods, and a combined model based on ageing derived from spines and tagging data is proposed as the most comprehensive descriptor of growth of North Atlantic albacore.

Size–frequency distributions of fragments from SPH/N-body simulations of asteroid impacts: Comparison with observed asteroid families

Icarus ◽  
2007 ◽  
Vol 186 (2) ◽  
pp. 498-516 ◽  
Author(s):  
Daniel D. Durda ◽  
William F. Bottke ◽  
David Nesvorný ◽  
Brian L. Enke ◽  
William J. Merline ◽  
...  
Keyword(s):  
Frequency Distributions ◽  
Size Frequency ◽  
Asteroid Families

Use of Size–Frequency Data to Estimate the Age Composition of Crayfish Populations

1991 ◽  
Vol 48 (12) ◽  
pp. 2324-2332 ◽  
Author(s):  
Robert France ◽  
John Holmes ◽  
Alejandro Lynch
Keyword(s):  
Frequency Data ◽  
Age Classes ◽  
Age Composition ◽  
Frequency Distributions ◽  
Limited Success ◽  
Size Frequency ◽  
Independent Analysis ◽  
Mean Size ◽  
The Mean ◽  
Rates Of Growth

Age-classes in crayfish populations can be determined from size–frequency data provided four tenets are adhered to: (1) only crayfish collected from areas of rock substrate are used; (2) trapping data are excluded; (3) species do not have longevities exceeding about 4 yr; and most importantly, (4) sample sizes are greater than about 200. Studies that have failed to follow these guidelines have met with limited success in dissecting mixed frequency distributions. Further, three validation procedures must be undertaken: (1) temporal replication within molting events to measure the precision of both data collection and size–frequency analysis; (2) corroboration with known-age crayfish from either field recaptures or laboratory molt increments; and (3) concordance with independent analysis of the mean size at onset of sexual maturity. When these checks support the size–frequency results, population age composition and analyses of rates of growth or mortality can be considered reliable.

A comparative study of size frequency distributions of Jupiter Trojans, Hildas and main belt asteroids: A clue to planet migration history (corrigendum)

2020 ◽  
Vol 190 ◽  
pp. 104977
Author(s):  
Fumi Yoshida ◽  
Tsuyoshi Terai ◽  
Takashi Ito ◽  
Keiji Ohtsuki ◽  
Patryk Sofia Lykawka ◽  
...  
Keyword(s):  
Comparative Study ◽  
Main Belt ◽  
Frequency Distributions ◽  
Size Frequency ◽  
Migration History ◽  
Planet Migration

scholarly journals The Curious Case of the “Neurotoxic Skink”: Scientific Literature Points to the Absence of Venom in Scincidae

Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 114
Author(s):  
Kartik Sunagar ◽  
Siju V Abraham
Keyword(s):  
Clinical Case ◽  
Scientific Literature ◽  
Scientific Evidence ◽  
Common Origin ◽  
Southern India ◽  
Clinical Report ◽  
The Family ◽  
The Common

In contrast to the clearly documented evolution of venom in many animal lineages, the origin of reptilian venom is highly debated. Historically, venom has been theorised to have evolved independently in snakes and lizards. However, some of the recent works have argued for the common origin of venom in “Toxicofera” reptiles, which include the order Serpentes (all snakes), and Anguimorpha and Iguania lizards. Nevertheless, in both these contrasting hypotheses, the lizards of the family Scincidae are considered to be harmless and devoid of toxic venoms. Interestingly, an unusual clinical case claiming neurotoxic envenoming by a scincid lizard was recently reported in Southern India. Considering its potentially significant medicolegal, conservation and evolutionary implications, we have summarised the scientific evidence that questions the validity of this clinical report. We argue that the symptoms documented in the patient are likely to have resulted from krait envenomation, which is far too frequent in these regions.

Mapping of the asteroid families

2018 ◽  
Vol 14 (A30) ◽  
pp. 17-18
Author(s):  
Nataša Todorović
Keyword(s):  
Good Choice ◽  
Main Belt ◽  
The Family ◽  
Asteroid Families

AbstractIn this work we map one of the most populated regions in the main belt - the asteroid family Themis. Computed with a good choice of parameters, the map enables us to get a refined picture of the dynamics in the family, to reexamine the role of resonances therein, to understand better the distribution of asteroids inside the region and to identify dynamical pathways along which particles can drift away.

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