Bibliographies thématiques / Open cluster and associations

Littérature scientifique sur le sujet « Open cluster and associations »

Auteur : Grafiati
Publié le 11 mars 2023

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Articles de revues sur le sujet "Open cluster and associations"

1

Torres, C. A. O., G. R. Quast, C. H. F. Melo, M. Sterzik, R. de la Reza et Licio da Silva. « sacy : open clusters connected to young nearby associations ». Proceedings of the International Astronomical Union 5, S266 (août 2009) : 544. http://dx.doi.org/10.1017/s1743921309992018.

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AbstractIn recent years. we have spectroscopically observed thousands of counterparts of selected ROSAT bright sources in the sacy project (Search for Associations Containing Young stars). We demonstrated that hundreds of the young stars found this way belong to nearby young, loose associations, some detected only in sacy, with ages in the range from 5 to 100 Myr. For their ages, these associations show no trace of their primitive nurseries, which poses some difficulties as to their origins. Nevertheless, there are some associations clearly associated with young open clusters, such as the ϵ Cha association (6 Myr) with the η Cha cluster, and the Argus association with IC 2391 (40 Myr). There seem to exist also more subtle connections, such as the AB Dor association (75 Myr) with the Pleiades. Here, we present evidence of the connections of young associations to open clusters, to understand their origin and their possible insertion in the cluster infant-mortality and Gould Belt scenarios.
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Freeman, K. C., D. C. Heggie, G. L. H. Harris, G. Lynga, P. E. Nissen, C. Pilachowski et G. N. Salufcvadze. « Commission 37 : Star Clusters and Associations ». Transactions of the International Astronomical Union 19, no 1 (1985) : 521–45. http://dx.doi.org/10.1017/s0251107x0000660x.

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The last three years have been very productive for cluster research. This report, on activities in the field, has been compiled by the members of Commission 37. It begins with sections on recent meetings, and on data catalogs (G. Lynga). Detailed tables of work on associations (P.E. Nissen), open clusters (G.L.H. Harris) and globular clusters (R.E. White) are then given. A section on cluster dynamics (D.C. Heggie) follows, and the final section concerns present trends in cluster research (C. Pilachowski).
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Medina, Gustavo E., Bertrand Lemasle et Eva K. Grebel. « A revisited study of Cepheids in open clusters in the Gaia era ». Monthly Notices of the Royal Astronomical Society 505, no 1 (4 mai 2021) : 1342–66. http://dx.doi.org/10.1093/mnras/stab1267.

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ABSTRACT In this paper, we revisit the problem of identifying bona fide cluster Cepheids by performing an all-sky search for Cepheids associated with open clusters and making use of state-of-the-art catalogued information for both Cepheids and clusters, based on the unparalleled astrometric precision of the second and early third data releases of the Gaia satellite. We determine membership probabilities by following a Bayesian approach using spatial and kinematic information of the potential cluster-Cepheid pairs. We confirm 19 Cepheid-cluster associations considered in previous studies as bona fide, and question the established cluster membership of six other associations. In addition, we identify 138 cluster Cepheid candidates of potential interest, mostly in recently discovered open clusters. We report on at least two new clusters possibly hosting more than one Cepheid. Furthermore, we explore the feasibility of using open clusters hosting Cepheids to empirically determine the Cepheid period–age relation through the use of Gaia and 2MASS photometry and a semiautomated method to derive cluster ages. We conclude that the usage of cluster Cepheids as tentative probes of the period–age relations still faces difficulties due to the sparsely populated red giant branch and the stochastically sampled main-sequence turn-off of the open clusters, making age determinations a challenging task. This biases the age-datable cluster selection for Cepheid period-age studies towards older and high-mass clusters.
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Deacon, N. R., et A. L. Kraus. « Wide binaries are rare in open clusters ». Monthly Notices of the Royal Astronomical Society 496, no 4 (30 juin 2020) : 5176–200. http://dx.doi.org/10.1093/mnras/staa1877.

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ABSTRACT The population statistics of binary stars are an important output of star formation models. However, populations of wide binaries evolve over time due to interactions within a system’s birth environment and the unfolding of wide, hierarchical triple systems. Hence, the wide binary populations observed in star-forming regions or OB associations may not accurately reflect the wide binary populations that will eventually reach the field. We use Gaia DR2 data to select members of three open clusters, Alpha Per, the Pleiades, and Praesepe and to flag cluster members that are likely unresolved binaries due to overluminosity or elevated astrometric noise. We then identify the resolved wide binary population in each cluster, separating it from coincident pairings of unrelated cluster members. We find that these clusters have an average wide binary fraction in the 300–3000 au projected separation range of 2.1$\pm ^{0.4}_{0.2}$ per cent increasing to 3.0$\pm ^{0.8}_{0.7}$ per cent for primaries with masses in the 0.5–1.5 M⊙ range. This is significantly below the observed field wide binary fraction, but shows some wide binaries survive in these dynamically highly processed environments. We compare our results with another open cluster (the Hyades) and two populations of young stars that likely originated in looser associations (young moving groups and the Pisces-Eridanus stream). We find that the Hyades also has a deficit of wide binaries while the products of looser associations have wide binary fractions at or above field level.
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Zinnecker, Hans. « Embedded and open star clusters : basic questions ». Proceedings of the International Astronomical Union 5, S266 (août 2009) : 17–23. http://dx.doi.org/10.1017/s1743921309990810.

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AbstractThis paper provides an introduction to IAU Symposium 266 on star clusters as basic building blocks in space and time. We define clusters as bound systems and discriminate them from general stellar clusterings or groups and unbound associations. We give a few examples of young, embedded, compact clusters which may evolve into looser, open clusters after dynamical relaxation due to mass loss and secular relaxation processes. We ask how and where star clusters form (in normal and interacting galaxies) and provide statistics of open clusters in terms of cluster masses and ages in the solar neighborhood (where observational data are most complete). Finally, we list a number of basic questions for current and future star cluster research and discuss the prospects for cluster studies with the next generation infrared and submillimeter telescopes (Herschel; JWST, E–ELT; ALMA, NOEMA).
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Heggie, D. C., G. L. H. Harris, K. C. Freeman, J. E. Hesser, P. E. Nissen, C. Pilachowski et G. N. Salukvadze. « Commission 37 : Star Clusters and Associations (Amas Stellaires Et Associations) ». Transactions of the International Astronomical Union 20, no 01 (1988) : 509–35. http://dx.doi.org/10.1017/s0251107x00007355.

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The last three years have been very productive for cluster research, especially now that observations with CCDs have become so routine. After a section on recent meetings, and one on data catalogues (by J.-C. Mermilliod), subsequent sections of this report go into details on individual topics: associations (P.E. Nissen), open clusters (G.L.H. Harris), globular clusters and cluster systems (R.E. White) and dynamical theory (D.C. Heggie).The rapid growth in the volume of observational data has meant regrettably that the information has had to be tabulated in an even more compressed form than in earlier Reports. As in previous Reports, three-figure references are to Astronomy and Astrophysics Abstracts, and two-figure references to Physics Abstracts. Most entries cover publications from 1 July 1984 to 30 June 1987, but some exceptions are noted under the individual sections. For abbreviations see §6.
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Fragkou, Vasiliki, Quentin A. Parker, Albert A. Zijlstra, Roberto Vázquez, Laurence Sabin et Jackeline Suzett Rechy-Garcia. « The Planetary Nebula in the 500 Myr Old Open Cluster M37 ». Astrophysical Journal Letters 935, no 2 (1 août 2022) : L35. http://dx.doi.org/10.3847/2041-8213/ac88c1.

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Abstract We report confirmation of a large, evolved, bipolar planetary nebula and its blue, white dwarf central star as a member of the ∼500 Myr old Galactic open star cluster M37 (NGC 2099). This is only the third known example of a planetary nebula in a Galactic open cluster and was found via our ongoing program of identifying and studying planetary nebulae—open cluster associations. High confidence in the association comes from the consistent radial velocities and proper motions for the confirmed central star and cluster stars from Gaia, reddening agreement, and location of the planetary nebula well within the tidal cluster boundary. Interestingly, all three Galactic examples have bipolar morphology and likely Type-I chemistry, both characteristics of higher mass progenitors. In this case the progenitor star mass is in the midrange of ∼2.8 M ☉. It provides a valuable, additional point on the key stellar initial-to-final mass relation independent of cluster white dwarf estimates and also falls in a gap in the poorly sampled mass region. This planetary nebula also appears to have the largest kinematical age ever determined and implies increased visibility lifetimes when they are located in clusters.
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Schneider, H. « CP3 Stars in Open Clusters ». International Astronomical Union Colloquium 138 (1993) : 639–43. http://dx.doi.org/10.1017/s0252921100021138.

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AbstractAbt published in 1979 frequencies of peculiar stars in open clusters based on published classifications for 661 stars in 14 open clusters and associations. Among others he discussed an age dependence of the frequencies of CP3 stars and found them increasing with age. Furthermore, he suggested a possible age dependence of the rotational velocity of these stars.But the sample he used was rather small: he found eight CP3 stars in 5 open clusters. In the mean time the number of cluster CP3 stars was more than double. Therefore, the findings of Abt shall be examined on the basis of the larger sample.
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Prišegen, M., M. Piecka, N. Faltová, M. Kajan et E. Paunzen. « White dwarf-open cluster associations based on Gaia DR2 ». Astronomy & ; Astrophysics 645 (21 décembre 2020) : A13. http://dx.doi.org/10.1051/0004-6361/202039276.

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Context. Fundamental parameters and physical processes leading to the formation of white dwarfs (WDs) may be constrained and refined by discovering WDs in open clusters (OCs). Cluster membership can be utilized to establish the precise distances, luminosities, ages, and progenitor masses of such WDs. Aims. We compile a list of probable WDs that are OC members in order to facilitate WD studies that are impractical or difficult to conduct for Galactic field WDs. Methods. We use recent catalogs of WDs and OCs that are based on the second data release of the Gaia satellite mission (GDR2) to identify WDs that are OC members. This crossmatch is facilitated by the astrometric and photometric data contained in GDR2 and the derived catalogs. Assuming that most of the WD members are of the DA type, we estimate the WD masses, cooling ages, and progenitor masses. Results. We have detected several new likely WD members and reassessed the membership of the literature WDs that had been previously associated with the studied OCs. Several of the recovered WDs fall into the recently reported discontinuity in the initial-final mass relation (IFMR) around Mi ∼ 2.0 M⊙, which allows for tighter constrains on the IFMR in this regime.
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Dinnbier, František, Pavel Kroupa, Ladislav Šubr et Tereza Jeřábková. « Estimating the Ages of Open Star Clusters from Properties of Their Extended Tidal Tails ». Astrophysical Journal 925, no 2 (1 février 2022) : 214. http://dx.doi.org/10.3847/1538-4357/ac400e.

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Abstract The most accurate current methods for determining the ages of open star clusters, stellar associations, and stellar streams are based on isochrone fitting or the lithium depletion boundary. We propose another method for dating these objects based on the morphology of their extended tidal tails, which have been recently discovered around several open star clusters. Assuming that the tidal tails originate from the stars released from the cluster during early gas expulsion, or that they form in the same star-forming region as the cluster (i.e., being coeval with the cluster), we derive the analytical formula for the tilt angle β between the long axis of the tidal tail and the orbital direction for clusters or streams on circular trajectories. Since at a given Galactocentric radius β is only a function of age t regardless of the initial properties of the cluster, we estimate the cluster age by inverting the analytical formula β = β(t). We illustrate the method on a sample of 12 objects, which we compiled from the literature, and we find a reasonable agreement with previous dating methods in ≈70% of the cases. This can probably be improved by taking into account the eccentricity of the orbits and by revisiting the dating methods based on stellar evolution. The proposed morphological method is suitable for relatively young clusters (age ≲300 Myr), where it provides a relative age error of the order of 10%−20% for an error in the observed tilt angle of 5°.
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Thèses sur le sujet "Open cluster and associations"

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Balog, Zoltan, Nick Siegler, G. H. Rieke, L. L. Kiss, James Muzerolle, R. A. Gutermuth, Cameron P. M. Bell et al. « PROTOPLANETARY AND TRANSITIONAL DISKS IN THE OPEN STELLAR CLUSTER IC 2395 ». IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/622451.

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We present new deep UBVRI images and high-resolution multi-object optical spectroscopy of the young (similar to 6-10 Myr old), relatively nearby (800 pc) open cluster IC 2395. We identify nearly 300 cluster members and use the photometry to estimate their spectral types, which extend from early B to middle M. We also present an infrared imaging survey of the central region using the IRAC and MIPS instruments on board the Spitzer Space Telescope, covering the wavelength range from 3.6 to 24 mu m. Our infrared observations allow us to detect dust in circumstellar disks originating over a typical range of radii from similar to 0.1 to similar to 10 au from the central star. We identify 18 Class II, 8 transitional disk, and 23 debris disk candidates, respectively, 6.5%, 2.9%, and 8.3% of the cluster members with appropriate data. We apply the same criteria for transitional disk identification to 19 other stellar clusters and associations spanning ages from similar to 1 to similar to 18 Myr. We find that the number of disks in the transitional phase as a fraction of the total with strong 24 mu m excesses ([8] - [24]. 1.5) increases from (8.4. +/- 1.3)% at similar to 3 Myr to (46. +/- 5)% at similar to 10 Myr. Alternative definitions of transitional disks will yield different percentages but should show the same trend.
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Lim, Beomdu, Hwankyung Sung, Jinyoung S. Kim, Michael S. Bessell, Narae Hwang et Byeong-Gon Park. « A CONSTRAINT ON THE FORMATION TIMESCALE OF THE YOUNG OPEN CLUSTER NGC 2264 : LITHIUM ABUNDANCE OF PRE-MAIN SEQUENCE STARS ». IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/622162.

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The timescale of cluster formation is an essential parameter in order to understand the formation process of star clusters. Pre-main sequence (PMS) stars in nearby young open clusters reveal a large spread in brightness. If the spread were considered to be a result of a real spread in age, the corresponding cluster formation timescale would be about 5-20 Myr. Hence it could be interpreted that star formation in an open cluster is prolonged for up to a few tens of Myr. However, difficulties in reddening correction, observational errors, and systematic uncertainties introduced by imperfect evolutionary models for PMS stars can result in an artificial age spread. Alternatively, we can utilize Li abundance as a relative age indicator of PMS star to determine the cluster formation timescale. The optical spectra of 134 PMS stars in NGC 2264 have been obtained with MMT/Hectochelle. The equivalent widths have been measured for 86 PMS stars with a detectable Li line (3500 < T-eff [K] <= 6500). Li abundance under the condition of local thermodynamic equilibrium (LTE) was derived using the conventional curve of growth method. After correction for non-LTE effects, we find that the initial Li abundance of NGC 2264 is A(Li)= 3.2 +/- 0.2. From the distribution of the Li abundances, the underlying age spread of the visible PMS stars is estimated to be about 3-4 Myr and this, together with the presence of embedded populations in NGC 2264, suggests that the cluster formed on a timescale shorter than 5 Myr.
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Messina, Angela Elisa. « Chromospheric activity and lithium abundance in the NGC2516 and NGC3766 open clusters ». Thesis, Università degli Studi di Catania, 2011. http://hdl.handle.net/10761/212.

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The aim of this thesis is the analysis of chromospheric activity and lithium abundance of late type stars in open clusters of different ages. The study of open cluster is very important for our understanding of stellar evolution and atmospheres, since all cluster members have almost the same age and chemical composition and this allows to infer their properties more easily than individual stars. In this work two open clusters have been considered, NGC2516 and NGC3766, using spectra acquired by the ESO spectrograph FLAMES at VLT, in the LiI and CaII H and K region. Most of our knowledge of young stars comes from the observations of general properties of open clusters, since they represents a good tool for testing the stellar evolution models, and the age measurement' methods. In fact, stellar ages can be determined only by comparison with theoretical models, and open clusters are widely used to calibrate methods of age determination, since their observation allows to determine average properties of a group of stars approximatly coeval. One of the methods used to determine the age of young stars is the lithium depletion, based on the determination of the lithium abundance of a cluster's star. This method has been used in this work to determine the age of both observed clusters. Their lithium depletion has been derived, confirming that, for the cluster NGC2516, the age is approximatly around 150Myr, as observed previously by other authors. Assuming solar metallicity for NGC3766, direct comparison of Li equivalent with other clusters indicates an age close to that of the Pleiades or even older, in disagreement with previous age determination. A metallicity higher than solar may explain at least partially this disagreement. Chromospheric activity in NGC2516 has also been studied using Ca II H & K lines VLT/FLAMES-GIRAFFE observations. Since no VLT/FLAMES-GIRAFFE observations of Mt. Wilson standards are available, I applied the method of Linsky et al.,1979, ApJs,41,47, and Strassmeier et al., 2000,A&AS, 142, 275. A comparison with the standard Mt. Wilson method has been done using FEROS spectra. A study of astrophysical parameter determination using the spectral region between 3990 and 4040 A has also been performed. This work is organised as follows: the problem of age determination in open clusters is briefly discussed in Chapter 1; Chapter 2 contains a review of chromospheric activity indicators; Chapter 3 contains a description of the cluster studied; Chapter 4 describes the reduction of VLT/FLAMES-GIRAFFE data; Chapter 5 describes the method used to derive stellar physical parameters. Finally, in Chapter 6 the chromospheric activity analysis for NGC2516 and the lithium abundance analysis in both NGC2516 and NGC3766 are presented.
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Da, Rio Nicola, Jonathan C. Tan, Kevin R. Covey, Michiel Cottaar, Jonathan B. Foster, Nicholas C. Cullen, John Tobin et al. « IN-SYNC. V. Stellar Kinematics and Dynamics in the Orion A Molecular Cloud ». IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/625776.

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The kinematics and dynamics of young stellar populations enable us to test theories of star formation. With this aim, we continue our analysis of the SDSS-III/APOGEE IN-SYNC survey, a high-resolution near-infrared spectroscopic survey of young clusters. We focus on the Orion A star-forming region, for which IN-SYNC obtained spectra of similar to 2700 stars. In Paper IV we used these data to study the young stellar population. Here we study the kinematic properties through radial velocities (vr). The young stellar population remains kinematically associated with the molecular gas, following a similar to 10 km s(-1) gradient along the filament. However, near the center of the region, the vr distribution is slightly blueshifted and asymmetric; we suggest that this population, which is older, is slightly in the foreground. We find evidence for kinematic subclustering, detecting statistically significant groupings of colocated stars with coherent motions. These are mostly in the lower-density regions of the cloud, while the ONC radial velocities are smoothly distributed, consistent with it being an older, more dynamically evolved cluster. The velocity dispersion sigma(v) varies along the filament. The ONC appears virialized, or just slightly supervirial, consistent with an old dynamical age. Here there is also some evidence for ongoing expansion, from a v(r)-extinction correlation. In the southern filament, sigma(v) is similar to 2-3 times larger than virial in the L1641N region, where we infer a superposition along the line of sight of stellar subpopulations, detached from the gas. In contrast, sv decreases toward L1641S, where the population is again in agreement with a virial state.
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Joner, Michael Deloss. « High-Quality Broadband BVRI Photometry of Benchmark Open Clusters ». BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2495.

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Photometric techniques are often used to observe stars and it can be demonstrated that fundamental stellar properties can be observationally determined using calibrated sets of photometric data. Many of the most powerful techniques utilized to calibrate stellar photometry employ the use of stars in clusters since the individual stars are believed to have many common properties such as age, composition, and approximate distance. Broadband photometric Johnson/Cousins BVRI observations are presented for several nearby open clusters. The new photometry has been tested for consistency relative to archival work and shown to be both accurate and precise. The careful use of a regular routine when making photometric observations, along with the monitoring of instrumental systems and the use of various quality control techniques when making observations or performing data reductions, will enhance an observer's ability to produce high-quality photometric measurements. This work contains a condensed review of the history of photometry, along with a brief description of several popular photometric systems that are often utilized in the field of stellar astrophysics. Publications written by Taylor or produced during the early Taylor and Joner collaboration are deemed especially relevant to the current work. A synopsis of seven archival publications is offered, along with a review of notable reports of VRI photometric observations for the nearby Hyades open star cluster. The body of this present work consists of four publications that appeared between the years 2005 and 2008, along with a soon to be submitted manuscript for a fifth publication. Each of these papers deals specifically with high-quality broadband photometry of open clusters with new data being presented for the Hyades, Coma, NGC 752, Praesepe, and M67. It is concluded that the VRI photometry produced during the Taylor and Joner collaborative investigations forms a high-quality data set that has been: 1) stable for a period of more than 25 years; 2) monitored and tested several times for consistency relative to the broadband Cousins system, and 3) shown to have well-understood transformations to other versions of broadband photometric systems. Further work is suggested for: 1) the transformation relationships for the reddest stars available for use as standards; 2) the standardization of more fields for use with CCD detectors; 3) a further investigation of transformations of blue color indices for observations done using CCD detectors with enhanced UV sensitivity, and 4) a continuation of work on methods to produce high-quality observations of assorted star clusters (both open and globular) with CCD-based instrumentation and intermediate-band photometric systems.
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An, Deokkeun. « Improving the Local Distance Scale from Empirically Calibrated Stellar Isochrones ». The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1218593380.

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Eisner, J. A., J. M. Bally, A. Ginsburg et P. D. Sheehan. « PROTOPLANETARY DISKS IN THE ORION OMC1 REGION IMAGED WITH ALMA ». IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621374.

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We present ALMA observations of the Orion Nebula that cover the OMC1 outflow region. Our focus in this paper is on compact emission from protoplanetary disks. We mosaicked a field containing similar to 600 near-IR-identified young stars, around which we can search for sub-millimeter emission tracing dusty disks. Approximately 100 sources are known proplyds identified with the Hubble Space Telescope. We detect continuum emission at 1 mm wavelengths toward similar to 20% of the proplyd sample, and similar to 8% of the larger sample of near-IR objects. The noise in our maps allows 4 sigma detection of objects brighter than similar to 1.5 mJy, corresponding to protoplanetary disk masses larger than 1.5 M-J (using standard assumptions about dust opacities and gas-to-dust ratios). None of these disks are detected in contemporaneous CO(2-1) or (CO)-O-18(2-1) observations, suggesting that the gas-to-dust ratios may be substantially smaller than the canonical value of 100. Furthermore, since dust grains may already be sequestered in large bodies in Orion Nebula cluster (ONC) disks, the inferred masses of disk solids may be underestimated. Our results suggest that the distribution of disk masses in this region is compatible with the detection rate of massive planets around M dwarfs, which are the dominant stellar constituent in the ONC.
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Spitoni, Emanuele. « The effects of galactic fountains on the chemical evolution of galaxies ». Doctoral thesis, Università degli studi di Trieste, 2010. http://hdl.handle.net/10077/3435.

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2008/2009
In this thesis we study the effect of galactic fountains, namely gas and flows from the disk of galaxies produced by multiple supernova explosions, on the chemical evolution of galaxies. Sequential supernova explosions create a superbubble, whereas the swept up interstellar medium is concentrated in a supershell which can break out a stratified medium, producing bipolar outflows. The gas of the supershells can fragment into clouds which eventually fall toward the disk producing so-called galactic fountains. Many works in literature have dealt with superbubble expansion in stratified media. However, very few papers in the past have taken into account the chemical evolution of the superbubble and how the supershell get polluted from the metals produced by supernova explosions. With this thesis for the first time the effect of galactic fountains we consider in a detailed chemical evolution model for the Milky Way. In the first part of our work we study the expansion law and chemical enrichment of a supershell powered by the energetic feedback of a typical Galactic OB association at various galactocentric radii. We follow the orbits of the fragments created when the supershell breaks out and we compare their kinetic and chemical properties with the available observations of high - and intermediate - velocity clouds. We use the Kompaneets (1960) approximation for the evolution of the superbubble driven by sequential supernova explosions and we compute the abundances of oxygen and iron residing in the thin cold supershell. Due to Rayleigh-Taylor instabilities we assume that supershells are fragmented and we follow the orbit of the clouds either ballistically or by means of a hybrid model considering viscous interaction between the clouds and the extra-planar gas. We find that if the initial metallicity is solar, the pollution from the dying stars of the OB association has a negligible effect on the chemical composition of the clouds. The maximum height reached by the clouds above the plane seldom exceeds 2 kpc and when averaging over different throwing angles, the landing coordinate differs from the throwing coordinate by only 1 kpc. Therefore, it is unlikely that galactic fountains can affect abundance gradients on large scales. The range of heights and [O/Fe] ratios spanned by our clouds suggest that the high velocity clouds cannot have a Galactic origin, whereas intermediate velocity clouds have kinematic properties similar to our predicted clouds but have observed overabundances of the [O/Fe] ratios that can be reproduced only with initial metallicities which are too low compared to those of the Galaxy disk. Even if it is unlikely that galactic fountains can affect abundance gradients on large scales, they can still affect the chemical enrichment of the interstellar medium (ISM) because of the time-delay due to the non-negligible time taken by fountains to orbit around and fall back into the Galaxy. This implies a delay in the mixing of metals in ISM which conflicts with the instantaneous mixing approximation usually assumed in all models in literature. We test whether relaxing this approximation in a detailed chemical evolution model can improve or worsen the agreement with observations. To do that, we investigate two possible causes for relaxing of the instantaneous mixing: i) the ``galactic fountain time delay effect'' and ii) the ``metal cooling time delay effect''. We find that the effect of galactic fountains is negligible if an average time delay of 0.1 Gyr, as suggested by our model, is assumed. Longer time delays produce differences in the results but they are not realistic. The metal cooling time delays produce strong effects on the evolution of the chemical abundances only if we adopt stellar yields depending on metallicity. If, instead, the yields computed for the solar chemical composition are adopted, negligible effects are produced, as in the case of the galactic fountain delay. The relaxation of the IMA by means of the galactic fountain model, where the delay is considered only for massive stars and only in the disk, does not affect the chemical evolution results. The combination of metal dependent yields and time delay in the chemical enrichment from all stars starting from the halo phase, instead, produces results at variance with observations.
XXII Ciclo
1979
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Kiminki, Megan M., Nathan Smith, Megan Reiter et John Bally. « Proper motions of five OB stars with candidate dusty bow shocks in the Carina Nebula ». OXFORD UNIV PRESS, 2017. http://hdl.handle.net/10150/624060.

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We constrain the proper motions of five OB stars associated with candidate stellar wind bow shocks in the Carina Nebula using Hubble Space Telescope ACS imaging over 9-10 yr baselines. These proper motions allow us to directly compare each star's motion to the orientation of its candidate bow shock. Although these stars are saturated in our imaging, we assess their motion by the shifts required to minimize residuals in their airy rings. The results limit the direction of each star's motion to sectors less than 90 degrees wide. None of the five stars are moving away from the Carina Nebula's central clusters as runaway stars would be, confirming that a candidate bow shock is not necessarily indicative of a runaway star. Two of the five stars are moving tangentially relative to the orientation of their candidate bow shocks, both of which point at the OB cluster Trumpler 14. In these cases, the large-scale flow of the interstellar medium, powered by feedback from the cluster, appears to dominate over the motion of the star in producing the observed candidate bow shock. The remaining three stars all have some component of motion towards the central clusters, meaning that we cannot distinguish whether their candidate bow shocks are indicators of stellar motion, of the flow of ambient gas or of density gradients in their surroundings. In addition, these stars' lack of outward motion hints that the distributed massive-star population in Carina's South Pillars region formed in place, rather than migrating out from the association's central clusters.
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Bell, Cameron Pearce MacDonald. « A critical assessment of ages derived using pre-main-sequence isochrones in colour-magnitude diagrams ». Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/4017.

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In this thesis a critical assessment of the ages derived using theoretical pre-main-sequence (pre-MS) stellar evolutionary models is presented by comparing the predictions to the low-mass pre-MS population of 14 young star-forming regions (SFRs) in colour-magnitude diagrams (CMDs). Deriving pre-MS ages requires precise distances and estimates of the reddening. Therefore, the main-sequence (MS) members of the SFRs have been used to derive a self-consistent set of statistically robust ages, distances and reddenings with associated uncertainties using a maximum-likelihood fitting statistic and MS evolutionary models. A photometric method (known as the Q-method) for de-reddening individual stars in regions where the extinction is spatially variable has been updated and is presented. The effects of both the model dependency and the SFR composition on these derived parameters are also discussed. The problem of calibrating photometric observations of red pre-MS stars is examined and it is shown that using observations of MS stars to transform the data into a standard photometric system can introduce significant errors in the position of the pre-MS locus in CMD space. Hence, it is crucial that precise photometric studies (especially of pre- MS objects) be carried out in the natural photometric system of the observations. This therefore requires a robust model of the system responses for the instrument used, and thus the calculated responses for the Wide-Field Camera on the Isaac Newton Telescope are presented. These system responses have been tested using standard star observations and have been shown to be a good representation of the photometric system. A benchmark test for the pre-MS evolutionary models is performed by comparing them to a set of well-calibrated CMDs of the Pleiades in the wavelength regime 0.4−2.5 μm. The masses predicted by these models are also tested against dynamical masses using a sample of MS binaries by calculating the system magnitude in a given photometric band- pass. This analysis shows that for Teff ≤ 4000 K the models systematically overestimate the flux by a factor of 2 at 0.5 μm, though this decreases with wavelength, becoming negligible at 2.2 μm. Thus before the pre-MS models are used to derive ages, a recalibration of the models is performed by incorporating an empirical colour-Teff relation and bolometric corrections based on the Ks-band luminosity of Pleiades members, with theoretical corrections for the dependence on the surface gravity (log g). The recalibrated pre-MS model isochrones are used to derive ages from the pre-MS populations of the SFRs. These ages are then compared with the MS derivations, thus providing a powerful diagnostic tool with which to discriminate between the different pre- MS age scales that arise from a much stronger model dependency in the pre-MS regime. The revised ages assigned to each of the 14 SFRs are up to a factor two older than previous derivations, a result with wide-ranging implications, including that circumstellar discs survive longer and that the average Class II lifetime is greater than currently believed.
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Livres sur le sujet "Open cluster and associations"

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Efremov, Yu N. Open clusters, associations and stellar complexes. Chur : Harwood Academic Publishers, 1989.

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Nestle, Volker. Open Innovation im Cluster. Wiesbaden : Gabler, 2011. http://dx.doi.org/10.1007/978-3-8349-6753-4.

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Dunbar, Peter M. The law of Florida homeowners associations : Single family subdivisions, townhouse & cluster developments, master community associations. 9e éd. Sarasota, Fla : Pineapple Press, 2012.

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F, Dudley Charles, dir. The law of Florida homeowners associations : Single family subdivisions, townhouse & cluster developments, master community associations. 8e éd. Sarasota, Fla : Pineapple Press, 2010.

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F, Dudley Charles, dir. The law of Florida homeowners' associations : Single family subdivisions, townhouse & cluster developments, master community associations. 3e éd. Tallahassee, Fla : Suncoast Professional Pub. Corp., 1997.

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F, Dudley Charles, dir. The law of Florida homeowners associations : Single family subdivisions, townhouse & cluster developments, master community associations. 7e éd. Sarasota, Fla : Pineapple Press, 2007.

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W, Dunbar Marc, dir. The homeowners association manual : Family subdivisions, townhouse & cluster developments, mobile homeowners associations, master community associations. 4e éd. Tallahassee, Fla : ARAS Pub., 1999.

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F, Dudley Charles, dir. The law of Florida homeowners' associations : Single family subdivisions, townhouse & cluster developments, master community associations. 2e éd. Tallahassee, Fla : Suncoast Professional Pub. Corp., 1996.

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The homeowners association manual : Family subdivisions, townhouse & cluster developments, mobile homeowners associations, master community associations. 3e éd. Tallahassee, Fla : Suncoast Professional Pub. Corp., 1997.

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10

Giampapa, M. S. X-ray activity in the open cluster IC 4665. [Tucson, Ariz.] : National Optical Astronomy Observatories, 1997.

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Chapitres de livres sur le sujet "Open cluster and associations"

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Mathieu, Robert D. « Introduction to Open Clusters ». Dans Dynamics of Young Star Clusters and Associations, 105–22. Berlin, Heidelberg : Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-47290-3_8.

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Pigatto, L. « Flare Stars as Age Indicators in Open Clusters ». Dans Flare Stars in Star Clusters, Associations and the Solar Vicinity, 117–20. Dordrecht : Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0607-5_28.

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Makarov, V. « Encounters and Close Fly-Bys of Galactic Clusters and Associations in the Past 50 Myr ». Dans Open Issues in Local Star Formation, 33–38. Dordrecht : Springer Netherlands, 2003. http://dx.doi.org/10.1007/1-4020-2600-5_3.

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Prantzos, Nikos. « Open Cluster ». Dans Encyclopedia of Astrobiology, 1177. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-11274-4_1113.

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Prantzos, Nikos. « Open Cluster ». Dans Encyclopedia of Astrobiology, 1778. Berlin, Heidelberg : Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-44185-5_1113.

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Prantzos, Nikos. « Open Cluster ». Dans Encyclopedia of Astrobiology, 1. Berlin, Heidelberg : Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-27833-4_1113-2.

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Nestle, Volker. « Einleitung ». Dans Open Innovation im Cluster, 1–8. Wiesbaden : Gabler, 2011. http://dx.doi.org/10.1007/978-3-8349-6753-4_1.

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Nestle, Volker. « Theoretischer Hintergrund und Hypothesenentwicklung ». Dans Open Innovation im Cluster, 9–111. Wiesbaden : Gabler, 2011. http://dx.doi.org/10.1007/978-3-8349-6753-4_2.

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Nestle, Volker. « Forschungsintensive Technologien am Beispiel der Mikrosystemtechnik ». Dans Open Innovation im Cluster, 112–18. Wiesbaden : Gabler, 2011. http://dx.doi.org/10.1007/978-3-8349-6753-4_3.

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Nestle, Volker. « Methodik und Datenerhebung ». Dans Open Innovation im Cluster, 119–60. Wiesbaden : Gabler, 2011. http://dx.doi.org/10.1007/978-3-8349-6753-4_4.

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Actes de conférences sur le sujet "Open cluster and associations"

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Wang, Liya, Doreen Ware, Nirav Merchant et Carol Lushbough. « Building an open Genome Wide Association Study (GWAS) platform ». Dans 2013 IEEE International Conference on Cluster Computing (CLUSTER). IEEE, 2013. http://dx.doi.org/10.1109/cluster.2013.6702696.

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Knödlseder, Jürgen. « Gamma-ray line emission from OB associations and young open clusters ». Dans Fifth compton symposium. AIP, 2000. http://dx.doi.org/10.1063/1.1303170.

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Rumyantsev, Alexander, Taisia Morozova et Robert Basmadjian. « Discrete-Event Modeling of a High-Performance Computing Cluster with Service Rate Control ». Dans 2018 22nd Conference of Open Innovations Association (FRUCT). IEEE, 2018. http://dx.doi.org/10.23919/fruct.2018.8468284.

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Khaydarova, Rezeda, Vladislav Fishchenko, Dmitriy Mouromtsev, Vladislav Shmatkov et Maksim Lapaev. « ROCK-CNN : a Distributed RockPro64-based Convolutional Neural Network Cluster for IoT. Verification and Performance Analysis ». Dans 2020 26th Conference of Open Innovations Association (FRUCT). IEEE, 2020. http://dx.doi.org/10.23919/fruct48808.2020.9087457.

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Prakash, S. P. Shiva, T. N. Nagabhushan et Kirill Krinkin. « Cluster based approach to minimize delay in energy aware routing for ieee 802.11s Wireless Mesh Networks under mobility conditions ». Dans 2016 19th Conference of Open Innovations Association (FRUCT). IEEE, 2016. http://dx.doi.org/10.23919/fruct.2016.7892200.

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Usenko, Igor A., Valery V. Kovtyukh, Sergej M. Andrievsky, Valentina G. Klochkova et Vladimir E. Panchuk. « High-resolution spectroscopy investigation of classical Cepheids and main-sequence B-stars in galactic open clusters and associations ». Dans Astronomical Telescopes and Instrumentation, sous la direction de Jacqueline Bergeron. SPIE, 2000. http://dx.doi.org/10.1117/12.390139.

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Darmawan, B. « The Implementation of Hybrid Parallel Computation for Complex and Fine Reservoir Model Using Cluster Technology ». Dans Indonesian Petroleum Association 44th Annual Convention and Exhibition. Indonesian Petroleum Association, 2021. http://dx.doi.org/10.29118/ipa21-e-53.

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Pertamina EP plays an important role in maintaining the oil production supply for national energy stability. Thus, they bear a great responsibility to accelerate all the development plans and execute them in timely manner. However, there is big challenge in the realization of those plans since they are not fully equipped with the advance computing technology to boost the reservoir modeling and simulation phase. Therefore, the effort on finalizing and executing of 33 Plan of development (POD) projects within 5 years was looked like a never-ending project. To face the challenge, Pertamina EP evaluated the possibility to create a cluster technology that can accommodate high intensity of simulation numbers and high load of simulation process. The evaluation process covers: compiling, sorting and selecting the analog reservoir model (highest grid number and longest simulation time), benchmarking and performance test to get the most optimum cluster configuration. Supercomputer was then procured and set based on the optimized model, then completed by implementing the test on three most extreme POD models. This paper described the success story and innovation of a complex simulation and finer scale reservoir model using the hybrid parallel-computing technology with a set of 8 nodes high performing computer. Three models were tested with satisfying results. This paper discusses the parallel scalability of complex computing systems of multi-CPU clusters. Multi-CPU distributed memory computing system is proven to be able to improve and accelerate the reservoir modeling and simulation time, when it is used in combination with a new so called “hybrid” approach. In this approach, the common Message Passing Interface (MPI) synchronization between the cluster nodes is being interleaved with a shared memory system thread-based synchronization at the node level. The model with the longest simulation time has been accelerated by magnitude of 60%. The most exhausted model with highest number of simulation steps has been accelerated by magnitude of 80%. The model with the greatest number of grid (21.7 million active grids) has finally finished its simulation just in 27 minutes where previously was impossible to have it open and run. The successful study case is then followed by the implementation of the cluster computing technology for two pilot POD projects which led to the very good result. With this improvement, Pertamina EP can finally perform the probabilistic simulation as recommended by SKKMIGAS in PTK Rev-2/2018. It is now possible to run all 33 structures of multiple reservoir realizations for each POD.
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Eck, Nees Jan van, Flavius Frasincar et Dwain Chang. « Cluster-Based Visualization of Concept Associations ». Dans 2008 12th International Conference Information Visualisation (IV). IEEE, 2008. http://dx.doi.org/10.1109/iv.2008.54.

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Zhiryaeva, Elena, Vladimir Naumov et Pavel Naumov. « Formation of Export Clusters in Food Trade of the Russian Federation in the Conditions of Digital Transformation of the Economy ». Dans 2019 24th Conference of Open Innovations Association (FRUCT). IEEE, 2019. http://dx.doi.org/10.23919/fruct.2019.8711922.

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Fitnawan, Eko Awan Yudha, Wibi Aulia Harsum, Agus Hasan, Muhammad Iffan Hannanu, Steven Leonardus Paulus, Surya Dharma, Boya Subhono et al. « Towards Achieving Indonesia's Oil Production Target of 1 MMBOPD by 2030 : An Outlook from IATMI Norway ». Dans SPE/IATMI Asia Pacific Oil & Gas Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205753-ms.

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Abstract Indonesia has become a net-oil importer since 2004 as the growing internal demand exceeds Indonesia's oil production. As many fields go into mature phase and combined with other challenges, the national oil production in the last decade has been decreasing from 945 MBOPD to 745 MBOPD with a decline rate of 3-5% per year. Thus, the contribution of the oil and gas sector to the state revenues has also shown a downward trend from 21% in 2010 to only 9.2% in 2019. However, oil production is still strategically important for the national economy. It is important for economic value creation, power generation, transportation, and industries as most of the archipelago's infrastructures are still based on fossil energy. If no effort is made to increase production, the country will be fully dependent on crude oil imports, which poses a threat to national energy security. It is therefore in the nation's great interest to enhance oil production, minimizing the deficit gap between export and import. Several key strategies may be considered to achieve this ambitious target. These strategies can be categorized into the following: 1) People and high performing organization; 2) Exploration, as critical factor for future production; 3) Improved oil recovery (including enhanced oil recovery) technologies, to grow production from the maturing fields; 4) Fast track and simplified project to develop small field discoveries; 5) Strong collaboration between government, industry, academia, and professional associations; and 6)Cost conscious culture. The derivatives of the above-mentioned strategies are among others: standardized resource data management, open source & digitalized geoscience data library, reimbursement system for exploration costs, near field/infrastructure exploration, new play concept, cluster license collaboration, infill wells campaign, multilateral wells, waterflooding, gas injection, stimulation and hydraulic fracturing campaign, well interventions, EOR screening, perfect-well optimization, standardize subsea and/or topside production system, digitalization, and attractive fiscal and regulation that encourages not only the ‘big operator’ to participate in the petroleum sector. The foundation of these strategies should be the legal certainty and effective & proactive bureaucracy. Above all, it is also important to emphasize the common ground of having early HSE involvement as part of the solution. In this paper, the authors would like to contribute in sharing the knowledge, technology and perspectives to all petroleum industry professionals in Indonesia based on the authors exposure in the Norwegian petroleum activities. The paper will also review the strategies, short term and long-term opportunities that may inspire Indonesian petroleum authorities and industry in transforming the ambition into action to achieve the national production target of 1 MMBOPD and 12 BCFD gas by 2030.
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Rapports d'organisations sur le sujet "Open cluster and associations"

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Dubinina, S. V. Upper Cambrian and Lower Ordovician Conodont Associations From Open Ocean Paleoenvironments, Illustrated By Batyrbay and Sarykum Sections in Kazakhstan. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1991. http://dx.doi.org/10.4095/132181.

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Ramm-Granberg, Tynan, F. Rocchio, Catharine Copass, Rachel Brunner et Eric Nelsen. Revised vegetation classification for Mount Rainier, North Cascades, and Olympic national parks : Project summary report. National Park Service, février 2021. http://dx.doi.org/10.36967/nrr-2284511.

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Field crews recently collected more than 10 years of classification and mapping data in support of the North Coast and Cascades Inventory and Monitoring Network (NCCN) vegetation maps of Mount Rainier (MORA), Olympic (OLYM), and North Cascades (NOCA) National Parks. Synthesis and analysis of these 6000+ plots by Washington Natural Heritage Program (WNHP) and Institute for Natural Resources (INR) staff built on the foundation provided by the earlier classification work of Crawford et al. (2009). These analyses provided support for most of the provisional plant associations in Crawford et al. (2009), while also revealing previously undescribed vegetation types that were not represented in the United States National Vegetation Classification (USNVC). Both provisional and undescribed types have since been submitted to the USNVC by WNHP staff through a peer-reviewed process. NCCN plots were combined with statewide forest and wetland plot data from the US Forest Service (USFS) and other sources to create a comprehensive data set for Washington. Analyses incorporated Cluster Analysis, Nonmetric Multidimensional Scaling (NMS), Multi-Response Permutation Procedure (MRPP), and Indicator Species Analysis (ISA) to identify, vet, and describe USNVC group, alliance, and association distinctions. The resulting revised classification contains 321 plant associations in 99 alliances. A total of 54 upland associations were moved through the peer review process and are now part of the USNVC. Of those, 45 were provisional or preliminary types from Crawford et al. (2009), with 9 additional new associations that were originally identified by INR. WNHP also revised the concepts of 34 associations, wrote descriptions for 2 existing associations, eliminated/archived 2 associations, and created 4 new upland alliances. Finally, WNHP created 27 new wetland alliances and revised or clarified an additional 21 as part of this project (not all of those occur in the parks). This report and accompanying vegetation descriptions, keys and synoptic and environmental tables (all products available from the NPS Data Store project reference: https://irma.nps.gov/DataStore/Reference/Profile/2279907) present the fruit of these combined efforts: a comprehensive, up-to-date vegetation classification for the three major national parks of Washington State.
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Gao, Jiang-Ping, Wei Guo et Hong-Peng Zhang. Prevalence and Prognostic Associations of Early Postoperative Stroke and Death among Patients Undergoing Inner Branched Thoracic Endovascular Repair of Aortic Arch Pathologies : A systematic Review and Meta-analysis. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, août 2022. http://dx.doi.org/10.37766/inplasy2022.8.0010.

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Review question / Objective: To assess the prevalence and associations of early postoperative stroke and death among patients undergoing inner branched thoracic endovascular aortic repair (TEVAR) of arch pathologies. Eligibility criteria: Our including criteria are as follows: 1) Patients with aortic arch pathologies, who were judged unfit for open surgery in a multidisciplinary path; 2) using inner branched TEVAR for the endovascular repair. 3) report the prevalence of 30-day postoperative stroke or death as result. Excluding criteria: 1) combined with fenestration or chimney in TEVAR; 2) full-text unavailable; 2) case reports with fewer than three cases; 3) studies with an only reconstruction of the left subclavian artery (LSA) rather than innominate artery or left common carotid artery (LCCA).
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O'Neill, H. B., S. A. Wolfe et C. Duchesne. Ground ice map of Canada. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330294.

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This Open File presents national-scale mapping of ground ice conditions in Canada. The mapping depicts a first-order estimate of the combined volumetric percentage of excess ice in the top 5 m of permafrost from segregated, wedge, and relict ice. The estimates for the three ice types are based on modelling by O'Neill et al. (2019) (https://doi.org/10.5194/tc-13-753-2019), and informed by available published values of ground ice content and expert knowledge. The mapping offers an improved depiction of ground ice in Canada at a broad scale, incorporating current knowledge on the associations between geological and environmental conditions and ground ice type and abundance. It provides a foundation for hypothesis testing related to broad-scale controls on ground ice formation, preservation, and melt. Additional compilation of quantitative field data on ground ice and improvements to national-scale surficial geology mapping will allow further assessment and refinement of the representation of ground ice in Canada. Continued research will focus on improving the lateral and vertical representation of ground ice required for incorporation into Earth system models and decision-making. Spatial data files of the mapping are available as downloads with this Open File.
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Nobile, F., Q. Ayoul-Guilmard, S. Ganesh, M. Nuñez, A. Kodakkal, C. Soriano et R. Rossi. D6.5 Report on stochastic optimisation for wind engineering. Scipedia, 2022. http://dx.doi.org/10.23967/exaqute.2022.3.04.

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This report presents the latest methods of optimisation under uncertainties investigated in the ExaQUte project, and their applications to problems related to civil and wind engineering. The measure of risk throughout the report is the conditional value at risk. First, the reference method is presented: the derivation of sensitivities of the risk measure; their accurate computation; and lastly, a practical optimisation algorithm with adaptive statistical estimation. Second, this method is directly applied to a nonlinear relaxation oscillator (FitzHugh–Nagumo model) with numerical experiments to demonstrate its performance. Third, the optimisation method is adapted to the shape optimisation of an airfoil and illustrated by a large-scale experiment on a computing cluster. Finally, the benchmark of the shape optimisation of a tall building under a turbulent flow is presented, followed by an adaptation of the optimisation method. All numerical experiments showcase the open-source software stack of the ExaQUte project for large-scale computing in a distributed environment.
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Iatsyshyn, Anna V., Iryna H. Hubeladze, Valeriia O. Kovach, Valentyna V. Kovalenko, Volodymyr O. Artemchuk, Maryna S. Dvornyk, Oleksandr O. Popov, Andrii V. Iatsyshyn et Arnold E. Kiv. Applying digital technologies for work management of young scientists' councils. [б. в.], juin 2021. http://dx.doi.org/10.31812/123456789/4434.

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The publication explores the features of the digital technologies’ usage to organize the work of the Young Scientists’ Councils and describes the best practices. The digital transformation of society and the quarantine restrictions caused by the COVID-19 pandemic have forced the use of various digital technologies for scientific communication, the organization of work for youth associations, and the training of students and Ph.D. students. An important role in increasing the prestige of scientific activity and encouraging talented young people to participate in scientific projects belongs to the Young Scientists’ Councils, which are created at scientific institutions and higher education institutions. It is determined that the peculiarities of the work of Young Scientists’ Councils are in providing conditions for further staff development of the institution in which they operate; contribution to the social, psychological and material support of young scientists and Ph.D. students; creating an environment for teamwork and collaborative partnership; development of leadership and organizational qualities; contribution to the development of digital competence. The advantages of using electronic social networks in higher education and research institutions are analyzed, namely: general popularity and free of charge; prompt exchange of messages and multimedia data; user-friendly interface; availability of event planning functions, sending invitations, setting reminders; support of synchronous and asynchronous communication between network participants; possibility of access from various devices; a powerful tool for organizing the learning process; possibility of organization and work of closed and open groups; advertising of various events, etc. Peculiarities of managing the activity of the Young Scientists’ Council with the use of digital technologies are determined. The Young Scientists’ Council is a social system, and therefore the management of this system refers to social management. The effectiveness of the digital technologies’ usage to manage the activities of the Young Scientists’ Council depends on the intensity and need for their use to implement organizational, presentation functions and to ensure constant communication. The areas to apply digital technologies for the work managing of Young Scientists’ Councils are sorted as the presentation of activity; distribution of various information for young scientists; conducting questionnaires, surveys; organization and holding of scientific mass events; managing of thematic workgroups, holding of work meetings. It is generalized and described the experience of electronic social networks usage for organizing and conducting of scientific mass events.
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Mizrahi, Itzhak, et Bryan A. White. Uncovering rumen microbiome components shaping feed efficiency in dairy cows. United States Department of Agriculture, janvier 2015. http://dx.doi.org/10.32747/2015.7600020.bard.

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Ruminants provide human society with high quality food from non-human-edible resources, but their emissions negatively impact the environment via greenhouse gas production. The rumen and its resident microorganisms dictate both processes. The overall goal of this project was to determine whether a causal relationship exists between the rumen microbiome and the host animal's physiology, and if so, to isolate and examine the specific determinants that enable this causality. To this end, we divided the project into three specific parts: (1) determining the feed efficiency of 200 milking cows, (2) determining whether the feed- efficiency phenotype can be transferred by transplantation and (3) isolating and examining microbial consortia that can affect the feed-efficiency phenotype by their transplantation into germ-free ruminants. We finally included 1000 dairy cow metadata in our study that revealed a global core microbiome present in the rumen whose composition and abundance predicted many of the cows’ production phenotypes, including methane emission. Certain members of the core microbiome are heritable and have strong associations to cardinal rumen metabolites and fermentation products that govern the efficiency of milk production. These heritable core microbes therefore present primary targets for rumen manipulation towards sustainable and environmentally friendly agriculture. We then went beyond examining the metagenomic content, and asked whether microbes behave differently with relation to the host efficiency state. We sampled twelve animals with two extreme efficiency phenotypes, high efficiency and low efficiency where the first represents animals that maximize energy utilization from their feed whilst the later represents animals with very low utilization of the energy from their feed. Our analysis revealed differences in two host efficiency states in terms of the microbial expression profiles both with regards to protein identities and quantities. Another aim of the proposal was the cultivation of undescribed rumen microorganisms is one of the most important tasks in rumen microbiology. Our findings from phylogenetic analysis of cultured OTUs on the lower branches of the phylogenetic tree suggest that multifactorial traits govern cultivability. Interestingly, most of the cultured OTUs belonged to the rare rumen biosphere. These cultured OTUs could not be detected in the rumen microbiome, even when we surveyed it across 38 rumen microbiome samples. These findings add another unique dimension to the complexity of the rumen microbiome and suggest that a large number of different organisms can be cultured in a single cultivation effort. In the context of the grant, the establishment of ruminant germ-free facility was possible and preliminary experiments were successful, which open up the way for direct applications of the new concepts discovered here, prior to the larger scale implementation at the agricultural level.
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Cox, Jeremy. The unheard voice and the unseen shadow. Norges Musikkhøgskole, août 2018. http://dx.doi.org/10.22501/nmh-ar.621671.

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The French composer Francis Poulenc had a profound admiration and empathy for the writings of the Spanish poet Federico García Lorca. That empathy was rooted in shared aspects of the artistic temperament of the two figures but was also undoubtedly reinforced by Poulenc’s fellow-feeling on a human level. As someone who wrestled with his own homosexuality and who kept his orientation and his relationships apart from his public persona, Poulenc would have felt an instinctive affinity for a figure who endured similar internal conflicts but who, especially in his later life and poetry, was more open about his sexuality. Lorca paid a heavy price for this refusal to dissimulate; his arrest in August 1936 and his assassination the following day, probably by Nationalist militia, was accompanied by taunts from his killers about his sexuality. Everything about the Spanish poet’s life, his artistic affinities, his personal predilections and even the relationship between these and his death made him someone to whom Poulenc would be naturally drawn and whose untimely demise he would feel keenly and might wish to commemorate musically. Starting with the death of both his parents while he was still in his teens, reinforced by the sudden loss in 1930 of an especially close friend, confidante and kindred spirit, and continuing throughout the remainder of his life with the periodic loss of close friends, companions and fellow-artists, Poulenc’s life was marked by a succession of bereavements. Significantly, many of the dedications that head up his compositions are ‘to the memory of’ the individual named. As Poulenc grew older, and the list of those whom he had outlived lengthened inexorably, his natural tendency towards the nostalgic and the elegiac fused with a growing sense of what might be termed a ‘survivor’s anguish’, part of which he sublimated into his musical works. It should therefore come as no surprise that, during the 1940s, and in fulfilment of a desire that he had felt since the poet’s death, he should turn to Lorca for inspiration and, in the process, attempt his own act of homage in two separate works: the Violin Sonata and the ‘Trois Chansons de Federico García Lorca’. This exposition attempts to unfold aspects of the two men’s aesthetic pre-occupations and to show how the parallels uncovered cast reciprocal light upon their respective approaches to the creative process. It also examines the network of enfolded associations, musical and autobiographical, which link Poulenc’s two compositions commemorating Lorca, not only to one another but also to a wider circle of the composer’s works, especially his cycle setting poems of Guillaume Apollinaire: ‘Calligrammes’. Composed a year after the ‘Trois Chansons de Federico García Lorca’, this intricately wrought collection of seven mélodies, which Poulenc saw as the culmination of an intensive phase in his activity in this genre, revisits some of ‘unheard voices’ and ‘unseen shadows’ enfolded in its predecessor. It may be viewed, in part, as an attempt to bring to fuller resolution the veiled but keenly-felt anguish invoked by these paradoxical properties.
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European experience of sports cluster associations creation and development. Liliya Sh. Shitova, Victor B. Myakonkov, mars 2020. http://dx.doi.org/10.14526/2070-4798-2020-15-1-120-126.

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