scholarly journals Polarimetric survey of main-belt asteroids

2019 ◽  
Vol 626 ◽  
pp. A42 ◽  
Author(s):  
C. López-Sisterna ◽  
E. García-Migani ◽  
R. Gil-Hutton
Keyword(s):  
Separation Distance ◽  
Polarization Curves ◽  
Asteroid Belt ◽  
Sensitive Detector ◽  
Main Belt ◽  
Small Grains ◽  
The Mean ◽  
Taxonomic Groups ◽  
Second Period ◽  
Electrostatic Mechanism

Aims. We present the results of a polarimetric survey of main-belt asteroids at Complejo Astronómico El Leoncito (CASLEO), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry and to estimate the diversity in the polarimetric properties of asteroids. Methods. The survey began in 1995 and a second period began in 2013 using the CASPOL polarimeter with a more sensitive detector to study small asteroids, families, and special taxonomic groups. The data were obtained using this instrument at the 2.15 m telescope of CASLEO. Results. We present 128 observations for 82 asteroids of different taxonomic types. These results revealed phase-polarization curves and polarimetric parameters for 20 asteroids, amounting to a total of 135 objects with sufficient good data in the Catalogue of Asteroid Polarization Curves. Using the values obtained for the objects with a taxonomic classification, we obtained the mean polarimetric parameters for 19 taxonomic types and the Barbarians. The asteroids with large mean scatter separation distances have a minimum of the phase-polarization curve greater than − 1%, slopes at the inversion angle of less than 0.12−0.15% per degree, and perihelion distances 1.8 < q < 2.5 au; these measurements indicate the asteroids could have high or moderate albedos and that they are objects with perihelia in the inner asteroid belt. These large mean scatter separation distance values could be the result of an electrostatic mechanism acting on the small grains of the regolith, a manifestation of a coherent backscattering mechanism, or the result of a surface formed by a mixture of dark and bright particles.

scholarly journals Genetic gain in the breeding program of common beans at IAC from 1989 to 2007

2010 ◽  
Vol 10 (4) ◽  
pp. 329-336 ◽  
Author(s):  
Alisson Fernando Chiorato ◽  
Sérgio Augusto Morais Carbonell ◽  
Roland Vencovsky ◽  
Nelson da Silva Fonseca Júnior ◽  
José Baldin Pinheiro
Keyword(s):  
Grain Yield ◽  
Common Bean ◽  
Genetic Gain ◽  
Grain Quality ◽  
The State ◽  
Breeding Program ◽  
Common Beans ◽  
The Common ◽  
The Mean ◽  
Second Period

The goal of the present work was to evaluate the genetic gain obtained in grain yield for the common bean genotypes from 1989 until 2007, at the Instituto Agronômico de Campinas, in the state of São Paulo. Genetic gain has been separated into two research periods; the first, from 1989 to 1996, and the second, from 1997 to 2007. In the first period, a genetic gain of 1.07 % per year was obtained, whereas for the second period, the gain was zero. However, the mean yield of the evaluated lines was approximately 1000 kg ha-1 superior to the figures obtained in the first period. The main cause for the absence of genetic gain in the second period is that the focus of the breeding program was changed to grain quality. The individualized analysis of the genotypes with carioca grains in the second period indicated the lack of genetic gain during the investigated period.

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).

Hexazinone Gridballs™ applied with concurrent underplanting of white spruce in boreal mixedwoods: 7-year results

1986 ◽  
Vol 62 (4) ◽  
pp. 226-232 ◽  
Author(s):  
R. F. Sutton
Keyword(s):  
Picea Glauca ◽  
Ground Surface ◽  
White Spruce ◽  
Separation Distance ◽  
Stem Volume ◽  
Weed Growth ◽  
M 10 ◽  
The Mean ◽  
Boreal Mixedwoods ◽  
Maximum Separation

In mid-June 1978, hexazinone Gridball™ pellets were individually placed on the ground surface in two10-m × 10-m plots at each of two grid spacings in moderate-to-dense, woody weed growth in each of three boreal mixedwood stands in the Chapleau and Manitouwadge areas of Ontario. The rates of application were equivalent to 0.0, 1.4 and 4.2 kg a.i./ha. In these and a similar number of untreated plots, 16 white spruce (Picea glauca [Moench] Voss) were planted centrally in each plot at the same grid spacings used for the Gridballs™ but offset so as to give maximum separation between outplants and herbicide. The main study was supplemented by another to determine safe separation distance. GridballsTM at close spacing very significantly (P 0.01) increased growth of white spruce: at one location, the mean stem volume of spruce 7 years after planting was 438% that of spruce in the no-herbicide treatment; at a second location the comparable value was 503%. The evidence suggests that white spruce may be established in the boreal mixedwoods by underplanting and, concurrently, applying Gridballs™ at 1-m × 1-m spacing.

The long-term accumulation and depletion of copper in the liver of different breeds of sheep fed diets of differing copper content

1983 ◽  
Vol 100 (2) ◽  
pp. 441-449 ◽  
Author(s):  
J. A. Woolliams ◽  
N. F. Suttle ◽  
G. Wiener ◽  
A. C. Field ◽  
C. Woolliams
Keyword(s):  
Copper Content ◽  
Rate Of Increase ◽  
Breed Differences ◽  
The Mean ◽  
Second Period ◽  
Mean Concentration ◽  
Period Measurement

SUMMARYChanges in Cu concentration in the livers of adult Scottish Blackface (B), Welsh Mountain (W) and B × W ewes fed diets containing 4, 9, 17 and 29 mg Cu/kg D.M. were measured over a 28-week period. Measurement continued during two further periods of 18 weeks when first all sheep were fed the diet containing 4 mg Cu/kg D.M. and finally, when 4 mg Mo/kg D.M. was added to this diet.During the first period the increase on all diets was least in B ewes and, apart from the 4 mg Cu/kg D.M. diet, greatest in W ewes; this difference increased as the Cu in the diet increased. The rate of increase for all ewes diminished towards the end of the period. All breed types retained proportionately less Cu in their livers as the Cu in the diet increased; at one extreme B ewes fed 17 or 29 mg Cu/kg D.M. retained equal amounts.When during the second period all sheep were fed the 4 mg Cu/kg D.M. diet the Cu concentration in their livers decreased, the rate of decrease being greatest for ewes whose mean concentration in the liver was highest, but at similar concentrations the decrease was greater in B than W ewes. During the final period the decrease was faster and was again associated with the mean Cu concentration, but the decrease was not significantly affected by breed.Throughout the trial, W ewes had the highest concentration of Cu in their plasma, whilst B ewes and ewes fed the 4 mg Cu/kg D.M. diet throughout had the lowest concentrations both in plasma and in their kidneys at slaughter.The results show that breeds differ in their ability to retain Cu from the diet in their livers. The magnitude of these differences depends on the intake of Cu and Mo from the diet and is affected by the concentration of Cu in the liver. Breed differences in the absorption and endogenous loss of Cu are suggested.

scholarly journals New multi-part collisional model of the main belt: the contribution to near-Earth asteroids

2020 ◽  
Vol 639 ◽  
pp. A9
Author(s):  
P. S. Zain ◽  
G. C. de Elía ◽  
R. P. Di Sisto
Keyword(s):  
Significant Contribution ◽  
Asteroid Belt ◽  
Size Distributions ◽  
Main Belt ◽  
Yarkovsky Effect ◽  
Source Regions ◽  
Main Asteroid Belt ◽  
Near Earth Asteroids ◽  
Asteroid Families ◽  
Collisional Evolution

Aims. We developed a six-part collisional evolution model of the main asteroid belt (MB) and used it to study the contribution of the different regions of the MB to the near-Earth asteroids (NEAs). Methods. We built a statistical code called ACDC that simulates the collisional evolution of the MB split into six regions (namely Inner, Middle, Pristine, Outer, Cybele and High-Inclination belts) according to the positions of the major resonances present there (ν6, 3:1J, 5:2J, 7:3J and 2:1J). We consider the Yarkovsky effect and the mentioned resonances as the main mechanism that removes asteroids from the different regions of the MB and delivers them to the NEA region. We calculated the evolution of the NEAs coming from the different source regions by considering the bodies delivered by the resonances and mean dynamical timescales in the NEA population. Results. Our model is in agreement with the major observational constraints associated with the MB, such as the size distributions of the different regions of the MB and the number of large asteroid families. It is also able to reproduce the observed NEAs with H < 16 and agrees with recent estimations for H < 20, but deviates for smaller sizes. We find that most sources make a significant contribution to the NEAs; however the Inner and Middle belts stand out as the most important source of NEAs followed by the Outer belt. The contributions of the Pristine and Cybele regions are minor. The High-Inclination belt is the source of only a fraction of the actual observed NEAs with high inclination, as there are dynamical processes in that region that enable asteroids to increase and decrease their inclinations.

Evolution of bipolar disorder over 12 years in a psychiatric hospital

2016 ◽  
Vol 33 (S1) ◽  
pp. S125-S125
Author(s):  
E. Ribera ◽  
M. Grifell ◽  
M.T. Campillo ◽  
I. Ezquiaga ◽  
L. Martínez ◽  
...  
Keyword(s):  
Bipolar Disorder ◽  
Early Detection ◽  
Psychiatric Hospitals ◽  
Categorical Variables ◽  
Chi Square ◽  
Number Of Patients ◽  
Chi Square Test ◽  
The Mean ◽  
Second Period ◽  
Carlos Iii

IntroductionBipolar disorder is a leading cause of hospitalization in psychiatric hospitals. It is known that early detection of bipolar disorder is associated with a better prognosis.ObjectivesThe aim of this study is to conduct a demographic analysis of patients hospitalized for bipolar disorder in a single center between 2003 to 2014.MethodsRetrospective cohort study of 1230 patients admitted with bipolar disorder diagnosis from 2003 to 2014 at Centre Assistencial Emili Mira i López of Parc Salut Mar of Barcelona. We divided the study in two periods: 2003–2008 and 2009–2014. We analyzed the following variables: frequency of admissions, age, sex and days of hospital stay, comparing both periods. Chi-square test for categorical variables and Student t test for quantitative variables were applied.ResultsThe mean ages at the first and second period are 52 and 47, respectively (P < 0.001). There are no significant differences in sex and days of hospitalization. The frequency of admissions on the first and third trimesters is higher than in the second and fourth, although the differences are not statistically significant.ConclusionsDespite the large number of patients in the study, there are limitations, such as being a retrospective study and not being adjusted for confounding factors. The average age of patients in the second period is lower than in the first. This could suggest an improvement in early detection of bipolar disorder in the last years. Further research is needed to confirm this hypothesis.Disclosure of interestLG is funded by the Instituto de Salud Carlos III(CM14/00111).

The distribution of phytoplankton along trophic gradients and its mediation by available light in the pelagic zone of large eutrophic lakes

2012 ◽  
Vol 69 (12) ◽  
pp. 1935-1946 ◽  
Author(s):  
Min Zhang ◽  
Yang Yu ◽  
Zhen Yang ◽  
Xiaoli Shi ◽  
Fanxiang Kong
Keyword(s):  
Lake Management ◽  
Pelagic Zone ◽  
Light Limitation ◽  
Eutrophic Lakes ◽  
Large Lakes ◽  
Factors Affecting ◽  
Key Species ◽  
Principal Factors ◽  
The Mean ◽  
Taxonomic Groups

We describe the pattern and the principal factors affecting the phytoplankton biomass–nutrient relationship in the pelagic zone of large lakes. The results showed that the phytoplankton abundance and biomass of Cyanophyta, Cryptophyta, and Pyrrophyta were significantly correlated with trophic states. The total phosphorus (TP)–biomass relationship curves showed that the increment of biomass with TP is weak at high TP levels. The decrease in biomass at the high end of the curves might be a synthesis of the pattern of responses of the major taxonomic groups (except cyanobacteria) to environmental variables. Light limitation might be one of the important factors causing the decrease in the TP–biomass curve at high TP concentrations. If the mean underwater available light is lower than ∼250 µmol photons·m–2·s–1, clear-water species decline and cyanobacteria become dominant. The responses to available light of these key species play a central role in modulating the biomass–nutrient relationship. Our results contribute to the understanding of this relationship in the pelagic zone of large eutrophic lakes and have important practical implications for lake management.

Ion behaviour in plant cell walls. III. Measurement of the mean charge separation distance and the linear charge density parameter in delignified Sphagnum russowii cell walls

1990 ◽  
Vol 68 (4) ◽  
pp. 768-772 ◽  
Author(s):  
Conrad Richter ◽  
Jack Dainty
Keyword(s):  
Cell Wall ◽  
Charge Density ◽  
Charge Separation ◽  
Cell Walls ◽  
Separation Distance ◽  
Cation Binding ◽  
Density Parameter ◽  
Linear Charge Density ◽  
The Mean ◽  
Mean Charge

According to the Manning condensation theory, the structure of cation-binding uronates in the cell wall can influence ionic behaviour. Assuming the theory is valid, we measured, in cation-binding experiments, the dimensionless linear charge density parameter and the mean charge separation distance in the fully ionized delignified Sphagnum russowii cell wall. Our charge separation estimate, 1.00 ± 0.02 nm, indicates that approximately 1.3 neutral sugars are interpolated between the uronic acids in the polyuronate chains of the cation exchanger. This compares well with chemical data of isolated wall fractions from another Sphagnum species reported by other workers. The charge density parameter estimate, 0.71 ± 0.02, implies that univalent cations never condense, whereas cations with two or more positive charges condense when the degree of ionization of the fixed (wall) charges is high enough. Key words: ion exchange, cell wall, charge density.

Topological Stability of 2-D Vanishing Grains

1992 ◽  
Vol 278 ◽  
Author(s):  
V. E. Fradkov ◽  
M. E. Glicksman ◽  
J. Nordberg ◽  
M. Palmer ◽  
K. Rajan
Keyword(s):  
Computer Simulation ◽  
Grain Boundary ◽  
Grain Growth ◽  
Triple Junctions ◽  
Polycrystalline Films ◽  
Topological Stability ◽  
Von Neumann ◽  
Small Grains ◽  
The Mean ◽  
Boundary Model

AbstractGrain growth in polycrystals occurs by decreasing the total number of grains as a result of the disappearance of small ones. That is why the both the kinetic and topological details of shrinking of small grains are important.In 2-D, “uniform boundary model” assumptions imply the von Neumann-Mullins law, and all grains having less than 6 neighbors tend to shrink. The mean topological class ef vanishing grains was found experimentally to be about 4.3. This result suggests that most vanishing grains are either 4- or 5-sided, not transforming to 3-sided ones.Shrinking of 4- and 5-sided 2-D grains was studied experimentally on transparent, pure SCN, (succinonitrile) polycrystalline films and by direct computer simulation of grain boundary capillary motion together with triple junctions. It was found that the grains which are much smaller than their neighbors are topologically stable.

scholarly journals The Distribution of Main Belt Asteroids with Featureless Spectra from the Sloan Digital Sky Survey Photometry

2009 ◽  
Vol 5 (S263) ◽  
pp. 237-239
Author(s):  
Anderson O. Ribeiro ◽  
Fernando Roig
Keyword(s):  
Spectroscopic Data ◽  
Moving Objects ◽  
Photometric Data ◽  
Sloan Digital Sky Survey ◽  
Spectral Slope ◽  
Main Belt ◽  
Absorption Bands ◽  
Sky Survey ◽  
The Mean

AbstractIn this work, we propose to analyse the existence of possible correlations between the taxonomic classes of asteroids showing featureless spectra –i.e. a flat continuum with no absorption bands– and their orbital properties. We compute the mean spectral slope of 14 753 asteroids using the photometric data from the Sloan Digital Sky survey Moving Objects Catalog (SDSS-MOC4). Although the quality of these data is not comparable in resolution to the spectroscopic data, the amount of observations in the SDSS-MOC4 is more than 20 times larger that in the available spectral databases. This allows us to obtain a statistically significant result.

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