scholarly journals 12 years of stellar activity observations in Argentina

2011 ◽  
Vol 7 (S286) ◽  
pp. 317-323 ◽  
Author(s):  
P. J. D. Mauas ◽  
A. Buccino ◽  
R. Díaz ◽  
M. Vieytes ◽  
R. Petrucci ◽  
...  
Keyword(s):  
Spectral Range ◽  
Conversion Factor ◽  
Activity Levels ◽  
Late Type ◽  
Cyclic Activity ◽  
Chromospheric Activity ◽  
Activity Measurements ◽  
Radiative Losses ◽  
Hydrogen Lines ◽  
Observational Program

AbstractWe present an observational program we started in 1999, to systematically obtain mid-resolution spectra of late-type stars, to study in particular chromospheric activity. In particular, we found cyclic activity in four dM stars, including Prox-Cen. We directly derived the conversion factor that translates the known S index to flux in the Ca II cores, and extend its calibration to a wider spectral range. We investigated the relation between the activity measurements in the calcium and hydrogen lines, and found that the usual correlation observed is the product of the dependence of each flux on stellar color, and it is not always preserved when simultaneous observations of a particular star are considered. We also used our observations to model the chromospheres of stars of different spectral types and activity levels, and found that the integrated chromospheric radiative losses, normalized to the surface luminosity, show a unique trend for G and K dwarfs when plotted against the S index.

Chromospheric activity in several single late-type stars

2015 ◽  
Vol 15 (2) ◽  
pp. 252-274 ◽  
Author(s):  
Li-Yun Zhang ◽  
Qing-Feng Pi ◽  
Zhong-Zhong Zhu
Keyword(s):  
Late Type ◽  
Chromospheric Activity

scholarly journals Objective measurement of physical activity in Macaca fascicularis

1982 ◽  
Vol 16 (3) ◽  
pp. 240-243
Author(s):  
Wayne T. Corbett ◽  
Harry M. Schey ◽  
A. W. Green
Keyword(s):  
Physical Activity ◽  
Standard Deviation ◽  
Macaca Fascicularis ◽  
Living Environment ◽  
Activity Levels ◽  
Free Living ◽  
Activity Measurements ◽  
Active Intermediate ◽  
The Mean ◽  
The Relationship

The mean and standard deviation over 24 h for 3 groups of animals - active, intermediate and inactive - in physical activity units were 10948 ± 3360, 2611 ± 1973 and 484 ± 316 respectively. The differences were significant ( P = 0·004), demonstrating the ability of the method to distinguish between groups that can be visibly differentiated. The small within-animal physical activity standard deviation (18·85 PAU) obtained in another group, suggests that it also yields reliable physical activity measurements for non-human primates. The monitoring device used can discriminate between individual nonhuman primate physical activity levels in a free-living environment and does not alter daily behaviour. This makes possible the study of the relationship between physical activity and atherosclerosis in nonhuman primates.

scholarly journals The use of sexual activity measurements to assess ejaculatory performance of boars

2013 ◽  
Vol 56 (1) ◽  
pp. 1052-1059 ◽  
Author(s):  
S. Kondracki ◽  
M. Iwanina ◽  
A. Wysokińska ◽  
K. Górski
Keyword(s):  
Sexual Activity ◽  
Linear Correlation ◽  
Sexual Development ◽  
Sperm Count ◽  
Advanced Age ◽  
Phenotypic Correlation ◽  
Physical Parameters ◽  
Activity Levels ◽  
Activity Measurements

Abstract. The study involved 50 insemination boars at the age of 8–9 months at the beginning of the study. Each boar was assessed four times for its sexual activity: at the beginning of breeding service and after three, six and nine months into the insemination service. Ejaculates were collected for the purpose of the sexual activity parameters’ assessment. Physical parameters of the ejaculates were subsequently analysed. Pearson’s linear correlation was used to calculate the coefficients of a phenotypic correlation between sexual activity levels and physical parameters of the ejaculates. According to this an appropriate analysis was conducted concerning the changes in boars’ sexual activity throughout their dynamic, sexual development. It was proved, that ejaculate volume depends on the total time of copulation. The highest correlation between ejaculate volume and sexual urge levels was observed in the youngest boars at the beginning of insemination service. The correlation between the ejaculatory efficiency and a boar’s libido changes with age and sexual development. Changes in ejaculatory efficiency are the most dynamic at the age of approx. 1.5 years. At this age ejaculate volume and ejaculate sperm count dynamically increase. The insemination fitness forecasting in case of boars should include libido measurements taken at the beginning of an insemination service – within the first three months. Measurements taken at a more advanced age are of little use for the purpose of ejaculatory efficiency forecasting in case of boars.

scholarly journals A Radial velocity survey of spatially resolved young, low-mass binaries

2018 ◽  
Vol 618 ◽  
pp. A5 ◽  
Author(s):  
Stephen Durkan ◽  
Markus Janson ◽  
Simona Ciceri ◽  
Wolfgang Brandner ◽  
Joshua Schlieder ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Solar Neighborhood ◽  
Activity Level ◽  
Activity Levels ◽  
Old Field ◽  
Triple Systems ◽  
Chromospheric Activity ◽  
Low Mass ◽  
Orbital Periods ◽  
Moving Groups

The identification and characterisation of low-mass binaries is of importance for a range of astrophysical investigations. Low-mass binaries in young (∼10–100 Myr) moving groups (YMGs) in the solar neighborhood are of particular significance as they provide unique opportunities to calibrate stellar models and evaluate the ages and coevality of the groups themselves. Low-mass M-dwarfs have pre-main sequence life times on the order of ∼100 Myr and therefore are continually evolving along a mass-luminosity track throughout the YMG phase, providing ideal laboratories for precise isochronal dating, if a model-independent dynamical mass can be measured. AstraLux lucky imaging multiplicity surveys have recently identified hundreds of new YMG low-mass binaries, where a subsample of M-dwarf multiples have estimated orbital periods less than 50 yr. We have conducted a radial velocity survey of a sample of 29 such targets to complement the astrometric data. This will allow enhanced orbital determinations and precise dynamical masses to be derived in a shorter timeframe than possible with astrometric monitoring alone, and allow for a more reliable isochronal analysis. Here we present radial velocity measurements derived for our sample over several epochs. We report the detection of the three-component spectroscopic multiple 2MASS J05301858-5358483, for which the C component is a new discovery, and forms a tight pair with the B component. Originally identified as a YMG member, we find that this system is a likely old field interloper, whose high chromospheric activity level is caused by tidal spin-up of the tight BC pair. Two other triple systems with a tight pair exist in the sample, 2MASS J04244260-0647313 (previously known) and 2MASS J20163382-0711456, but for the rest of the targets we find that additional tidally synchronized companions are highly unlikely, providing further evidence that their high chromospheric activity levels are generally signatures of youth.

scholarly journals THE CHROMOSPHERIC ACTIVITY OF [HH97] FS Aur-79: A CLOSE BINARY WITH LATE-TYPE ACTIVE (dK7e+dM3e) COMPONENTS

2011 ◽  
Vol 141 (4) ◽  
pp. 124 ◽  
Author(s):  
S. J. Austin ◽  
J. W. Robertson ◽  
T. R. de Souza ◽  
C. Tycner ◽  
R. K. Honeycutt
Keyword(s):  
Close Binary ◽  
Late Type ◽  
Chromospheric Activity

Application of the CEN/ISO Standard for Phytase Activity Measurements to a New Phytase Product: Determination of a Robust Conversion Factor by an Interlaboratory Study for Screening Feed Samples

2019 ◽  
Vol 102 (6) ◽  
pp. 1808-1813
Author(s):  
María José González de la Huebra ◽  
Piotr Robouch ◽  
Håkan Emteborg ◽  
Stefano Bellorini ◽  
Aneta Cizek-Stroh ◽  
...  
Keyword(s):  
Conversion Factor ◽  
Feed Additives ◽  
Phytase Activity ◽  
Feed Additive ◽  
The European Union ◽  
Iso Standard ◽  
Official Control ◽  
Activity Measurements ◽  
Feed Samples

Abstract Background: Phytase-based preparations are important feed additives currently authorised in the European Union (EU). The European Standard (EN) and International Organization for Standardization (ISO) standard 30024 describes a harmonized method for the determination of phytase activity and is fit-for-purpose for official control of a group of phytase products. However, it is not suitable for the determination of the phytase activity of a new feed additive encoded as 4a16 in the EU Register of Feed Additives, to which a slightly different phytase activity definition has been attributed. Objective: To establish a robust conversion factor to support official control laboratories that apply the EN ISO method when monitoring feed products containing 4a16. Methods: The phytase activity of test materials was determined by the participants using the EN ISO and/or the “applicant” methods. Results: Robust relative SDs for repeatability and for reproducibility of the methods applied for the determination of the phytase activity in the materials containing the 4a16 feed additive ranged from 2.6 to 22% (EN ISO method) and from 2.4 to 39% (applicant method). Conclusions: The data obtained confirmed the performance characteristics published for other phytase-based feeds in the related standard methods. These results allowed us to estimate a factor of 2.68 to convert phytase activities measured with the EN ISO method into the enzyme activity measured with the applicant method. Highlights: The obtained conversion factor will allow EU official laboratories to screen feed samples supplemented with the 4a16 phytase by applying EN ISO Standard 30024.

scholarly journals Stars at γ-Ray Energies: the INTEGRAL Look at Stars

2004 ◽  
Vol 219 ◽  
pp. 55-62
Author(s):  
Thierry Montmerle
Keyword(s):  
Massive Stars ◽  
High Energy ◽  
Energy Sources ◽  
Late Type ◽  
X Ray ◽  
Γ Ray ◽  
October 17 ◽  
X Ray Binaries ◽  
Observational Program

The European γ-ray satellite INTEGRAL, launched on October 17, 2002, is the successor to the highly successful American satellite Compton-GRO. Even though its main observational program focuses on “classical” high-energy sources like compact X-ray binaries or AGNs, some time is being devoted to γ-ray studies of massive stars and magnetically active late-type stars. We briefly describe here the four instruments of INTEGRAL, and summarize the ongoing stellar programs.

scholarly journals Activity, Colour Anomalies and Temperature Determination in Solar-type Stars

1991 ◽  
Vol 130 ◽  
pp. 333-335
Author(s):  
J. Fabregat ◽  
V. Reglero ◽  
J. Suso ◽  
J.E. Armentia
Keyword(s):  
Broad Band ◽  
Activity Levels ◽  
Temperature Determination ◽  
Temperature Scales ◽  
Chromospheric Activity ◽  
Long Baseline ◽  
Solar Type ◽  
The Mean ◽  
Reliable Temperature

The presence of photometric anomalies in broad band colours produced by chromospheric activity was first suggested by Campbell (1984). He defined the colour anomaly δ(B–V)V–K as the deviation from the mean relation (B–V)–(V–K) for Hyades dwarfs, and found this anomaly correlated well with several activity indicators.Since the work of Campbell, several authors have discussed the relation between activity and colour anomalies, obtaining diverging results. This discussion is relevant because long baseline photometric colours are the most reliable temperature indicators, and the presence of such anomalies implies that no consistent temperature scales can be obtained for stars with different activity levels. These topics have been recently reviewed by Soderblom (1989).

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