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Academic literature on the topic 'Young cluster'

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Published: 10 March 2023

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Journal articles on the topic "Young cluster"

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Randriamanakoto, Zara, and Petri Väisänen. "Young massive clusters in Arp 299." Proceedings of the International Astronomical Union 14, S351 (May 2019): 143–46. http://dx.doi.org/10.1017/s1743921319007701.

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AbstractBecause of their young ages and compact densities, young massive star clusters (YMCs) are widely considered as potential proto-globular clusters. They are ubiquitous in environments with ongoing star formation activity such as interacting luminous infrared galaxies. To determine the galactic environmental effects on the star cluster formation and evolution, we study the YMC population of Arp 299 (NGC 3690E/NGC 3690W) using data taken with the HST WFC3/UVIS camera. By fitting the multiband photometry with the Yggdrasil models, we derive the star cluster masses, ages and extinction. While the cluster mass-galactocentric radius relation of NGC 3690E indicates that there could be an influence of the gas density distribution on the cluster formation, the age distribution of the western component suggests that YMCs in that galaxy endure stronger disruption mechanisms. With a cluster formation efficiency of 19 percent, star formation happening in bound clusters in Arp 299 is 3–5 times higher than that of a typical normal spiral.
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Brown, Gillen, and Oleg Y. Gnedin. "Radii of young star clusters in nearby galaxies." Monthly Notices of the Royal Astronomical Society 508, no. 4 (October 8, 2021): 5935–53. http://dx.doi.org/10.1093/mnras/stab2907.

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ABSTRACT We measure the projected half-light radii of young star clusters in 31 galaxies from the Legacy Extragalactic UV Survey (LEGUS). We implement a custom pipeline specifically designed to be robust against contamination, which allows us to measure radii for 6097 clusters. This is the largest sample of young star cluster radii currently available. We find that most (but not all) galaxies share a common cluster radius distribution, with the peak at around 3 pc. We find a clear mass–radius relation of the form Reff ∝ M0.24. This relation is present at all cluster ages younger than 1 Gyr, but with a shallower slope for clusters younger than 10 Myr. We present simple toy models to interpret these age trends, finding that high-mass clusters are more likely to be not tidally limited and expand. We also find that most clusters in LEGUS are gravitationally bound, especially at older ages or higher masses. Lastly, we present the cluster density and surface density distributions, finding a large scatter that appears to decrease with cluster age. The youngest clusters have a typical surface density of 100$\, \mathrm{ M}_\odot \, \mathrm{pc}^{-2}$.
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Rosenberg, A., I. Saviane, G. Piotto, S. Zaggia, and A. Aparicio. "Pal 1: Another Young Globular Cluster?" Symposium - International Astronomical Union 174 (1996): 341–42. http://dx.doi.org/10.1017/s0074180900001728.

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We present a color magnitude diagram (CMD) in the V and I bands reaching ∼ 4 magnitudes below the turn off (TO) for the galactic globular (?) cluster Pal 1. A comparison with other well-observed clusters and theoretical models suggests that Pal 1 has an age of 8±2 Gyrs, which would make it the youngest globular cluster of our Galaxy.
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Cox, Georgina R., Jo Robinson, Michelle Williamson, Anne Lockley, Yee Tak Derek Cheung, and Jane Pirkis. "Suicide Clusters in Young People." Crisis 33, no. 4 (July 1, 2012): 208–14. http://dx.doi.org/10.1027/0227-5910/a000144.

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Background: Suicide clusters have commonly been documented in adolescents and young people. Aims: The current review conducts a literature search in order to identify and evaluate postvention strategies that have been employed in response to suicide clusters in young people. Methods: Online databases, gray literature, and Google were searched for relevant articles relating to postvention interventions following a suicide cluster in young people. Results: Few studies have formally documented response strategies to a suicide cluster in young people, and at present only one has been longitudinally evaluated. However, a number of strategies show promise, including: developing a community response plan; educational/psychological debriefings; providing both individual and group counseling to affected peers; screening high risk individuals; responsible media reporting of suicide clusters; and promotion of health recovery within the community to prevent further suicides. Conclusions: There is a gap in formal evidence-based guidelines detailing appropriate postvention response strategies to suicide clusters in young people. The low-frequency nature of suicide clusters means that long-term systematic evaluation of response strategies is problematic. However, some broader suicide prevention strategies could help to inform future suicide cluster postvention responses.
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Anders, Peter, Uta Fritze –. v. Alvensleben, and Richard de Grijs. "Young Star Clusters: Progenitors of Globular Clusters!?" Highlights of Astronomy 13 (2005): 366–68. http://dx.doi.org/10.1017/s1539299600015987.

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AbstractStar cluster formation is a major mode of star formation in the extreme conditions of interacting galaxies and violent starbursts. Young clusters are observed to form in a variety of such galaxies, a substantial number resembling the progenitors of globular clusters in mass and size, but with significantly enhanced metallicity. From studies of the metal-poor and metal-rich star cluster populations of galaxies, we can therefore learn about the violent star formation history of these galaxies, and eventually about galaxy formation and evolution. We present a new set of evolutionary synthesis models of our GALEV code, with special emphasis on the gaseous emission of presently forming star clusters, and a new tool to compare extensive model grids with multi-color broad-band observations to determine individual cluster masses, metallicities, ages and extinction values independently. First results for young star clusters in the dwarf starburst galaxy NGC 1569 are presented. The mass distributions determined for the young clusters give valuable input to dynamical star cluster system evolution models, regarding survival and destruction of clusters. We plan to investigate an age sequence of galaxy mergers to see dynamical destruction effects in process.
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Webb, Jeremy J., and Alison Sills. "The initial properties of young star clusters in M83." Monthly Notices of the Royal Astronomical Society 501, no. 2 (December 12, 2020): 1933–39. http://dx.doi.org/10.1093/mnras/staa3832.

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ABSTRACT The initial sizes and masses of massive star clusters provide information about the cluster formation process and also determine how cluster populations are modified and destroyed, which have implications for using clusters as tracers of galaxy assembly. Young massive cluster populations are often assumed to be unchanged since cluster formation; therefore, their distributions of masses and radii are used as the initial values. However, the first few hundred million years of cluster evolution does change both cluster mass and cluster radius, through both internal and external processes. In this paper, we use a large suite of N-body cluster simulations in an appropriate tidal field to determine the best initial mass and initial size distributions of young clusters in the nearby galaxy M83. We find that the initial masses follow a power-law distribution with a slope of −2.7 ± 0.4 , and the half-mass radii follow a lognormal distribution with a mean of 2.57 ± 0.04 pc and a dispersion of 1.59 ± 0.01 pc. The corresponding initial projected half-light radius function has a mean of 2.7 ± 0.3 pc and a dispersion of 1.7 ± 0.2 pc. The evolution of the initial mass and size distribution functions is consistent with mass-loss and expansion due to stellar evolution, independent of the external tidal field and the cluster’s initial density profile. Observed cluster sizes and masses should not be used as the initial values, even when clusters are only a few hundred million years old.
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Grosbøl, P., and H. Dottori. "Expulsion of Dust from Young Stellar Clusters." Proceedings of the International Astronomical Union 8, S292 (August 2012): 287. http://dx.doi.org/10.1017/s1743921313001415.

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AbstractYoung stellar clusters were identified on deep near-infrared images of 6 nearby, grand-design spirals observed with HAWK-I/VLT. A 90% completeness was reached for cluster complexes with MK = −11.5m (corresponding to masses around 104 M⊙) while the linear resolution was around 40 pc. The distribution of clusters in the (H-K)–(J-H) diagrams revealed two groups of clusters. Comparing with Starburst99 model tracks, the groups could be interpreted as one old population of clusters with low extinction and one consisting of young clusters with visual extinction as high as AV = 7m. The clear separation between the two groups suggests a rapid expulsion of dust from the young clusters.Monte-Carlo models were made assuming a cluster distribution function g(Mc, τ) = Mc−a τ−γ where Mc and τ are cluster mass and age, respectively. Fitting such models to the observed NIR color distributions, it was concluded that the cluster mortality had to be significant with γ = 0.8-1.0. Further, the star formation phase of clusters has to extend over several Myr. Young clusters have high extinctions at least the first 3 Myr but then lose their reddening over a period of around 5 Myr, depending on the exact evolutionary tracks used.
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Rochau, Boyke, Wolfgang Brandner, Andrea Stolte, Mario Gennaro, and Thomas Henning. "Internal dynamics of the NGC 3603 young cluster." Proceedings of the International Astronomical Union 5, S266 (August 2009): 517. http://dx.doi.org/10.1017/s174392130999189x.

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AbstractStarburst clusters are spectacular young and dense stellar systems containing copious numbers of massive O-type and Wolf–Rayet stars. These objects depict a stellar population comprising stars over the entire mass range, making them ideal objects to study cluster formation and evolution as well as to test and calibrate stellar evolutionary models. Among the Galactic spiral-arm starburst clusters, NGC 3603 Young Cluster (YC), which is located in the Carina spiral arm, is the youngest and most compact one. Galactic starburst clusters also serve as templates for extragalactic super star clusters as observed, e.g., in the Antennae galaxies. Based on two epochs (obtained 10 yr apart) of high-quality astrometric HST/WFPC2 observations, we derive individual proper motions for several hundred stars. The proper motions enable us to distinguish cluster members from field stars, and to derive a first estimate of the internal cluster dynamics. Photometry of the clean sample of cluster stars allows us to create color–magnitude diagrams (CMDs) that are not contaminated by field stars, and to compare the sequence of cluster members with different sets of theoretical isochrones and evolutionary tracks. We clearly identify a lower-mass pre-main-sequence and a higher-mass main-sequence stellar population in NGC 3603. A particular focus of our comparison with theoretical isochrones is the exact shape and extent of the pre-main-sequence/main-sequence transition region in NGC 3603 YC. The proper motions also contain dynamical information. From this, we derive a velocity dispersion, which leads to the first dynamical mass estimate of the NGC 3603 cluster. We also investigate whether or not NGC 3603 YC is virialized, and study evidence for primordial versus dynamical mass segregation. Past and future evolution of NGC 3603 YC can be studied and will tell us about the clusters ‘fate’ and its long-term survival chances.
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Larsen, Søren S. "Open, Massive and Globular Clusters — Part of the Same Family?" Symposium - International Astronomical Union 207 (2002): 421–27. http://dx.doi.org/10.1017/s0074180900224133.

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Populations of young star clusters show significant differences even among “normal” disk galaxies. In this contribution I discuss how properties of young cluster systems are related to those of their host galaxies, based on a recent study of clusters in a sample of 22 nearby spiral galaxies. Luminous young clusters similar to the “super” star clusters observed in starbursts and mergers exist in several of these galaxies, and it is found that the luminosity of the brightest star cluster as well as the specific luminosity of the cluster systems both correlate well with the host galaxy star formation rate. When considering star clusters in different environments the traditional distinction between “open”, “massive” and “globular” clusters breaks down, underscoring the need for a universal physical description of cluster formation.
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Hashimoto, Tetsuya, Tomotsugu Goto, Rieko Momose, Chien-Chang Ho, Ryu Makiya, Chia-Ying Chiang, and Seong Jin Kim. "A young galaxy cluster in the old Universe." Monthly Notices of the Royal Astronomical Society 489, no. 2 (August 12, 2019): 2014–29. http://dx.doi.org/10.1093/mnras/stz2182.

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ABSTRACT Galaxies evolve from a blue star-forming phase into a red quiescent one by quenching their star formation activity. In high-density environments, this galaxy evolution proceeds earlier and more efficiently. Therefore, local galaxy clusters are dominated by well-evolved red elliptical galaxies. The fraction of blue galaxies in clusters monotonically declines with decreasing redshift, i.e. the Butcher–Oemler effect. In the local Universe, observed blue fractions of massive clusters are as small as ≲0.2. Here we report a discovery of a ‘blue cluster’ that is a local galaxy cluster with an unprecedentedly high fraction of blue star-forming galaxies yet hosted by a massive dark matter halo. The blue fraction is 0.57, which is 4.0σ higher than those of the other comparison clusters under the same selection and identification criteria. The velocity dispersion of the member galaxies is 510 km s−1, which corresponds to a dark matter halo mass of 2.0$^{+1.9}_{-1.0}\times 10^{14}$ M⊙. The blue fraction of the cluster is more than 4.7σ beyond the standard theoretical predictions including semi-analytic models of galaxy formation. The probability to find such a high blue fraction in an individual cluster is only 0.003 per cent, which challenges the current standard frameworks of the galaxy formation and evolution in the ΛCDM universe. The spatial distribution of galaxies around the blue cluster suggests that filamentary cold gas streams can exist in massive haloes even in the local Universe. However these cold streams have already disappeared in the theoretically simulated local universes.
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Dissertations / Theses on the topic "Young cluster"

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Hußmann, Benjamin [Verfasser]. "The Quintuplet cluster : A young massive cluster study based on proper motion membership / Benjamin Hußmann." Bonn : Universitäts- und Landesbibliothek Bonn, 2014. http://d-nb.info/104762270X/34.

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Meyers-Rice, Barry Allan. "The dusty environment of the young galactic cluster NGC 2264." Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187282.

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This is a study of the young galactic cluster NGC 2264. In it 12-100 $\mu$m IRAS data are used to analyze emission from the cluster dust. This dust is warmed by the young point sources in the cluster. Images of the region were obtained in the V, R, and I bands, and the point source data extracted are combined with a pre-existing J-H-K database to produce a six-band photometric survey of the cluster. This 4900-entry catalogue and methods to eliminate spurious detections and non-cluster stars from it are discussed. The cluster is estimated to consist of 350-650 members. A device to produce polarimetric images was designed, built, and used to obtain data to explore star formation environments. The nature of one such region in NGC 2264 is discussed, and the sources responsible for illuminating this reflection nebula are identified. It is concluded that multiple scattering and a disk geometry can explain the features observed. Spectra of 361 stars in the cluster region were obtained and by extending the MK system to the red part of the spectrum their spectral types are determined. Many T Tauri stars are identified and aspects of their emission lines are analyzed. It is shown that the spectral lines of many cluster stars of types later than G9 are in emission while those of earlier-type stars show incipient emission diluted by stellar flux. An evolutionary sequence of stars based upon photometry and spectroscopy is proposed. Stars from this spectral survey are dereddened and the extinctions obtained are interpreted. Spectral energy distributions are produced for the dereddened stars, revealing infrared excesses in many. These excesses are modelled by disk-star systems, and it is shown that inner holes are required in the disks to explain the observed levels of short wavelength emission.
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Messa, M., A. Adamo, G. Östlin, D. Calzetti, K. Grasha, E. K. Grebel, F. Shabani, et al. "The young star cluster population of M51 with LEGUS – I. A comprehensive study of cluster formation and evolution." OXFORD UNIV PRESS, 2018. http://hdl.handle.net/10150/626277.

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Recently acquired WFC3 UV (F275W and F336W) imaging mosaics under the Legacy Extragalactic UV Survey (LEGUS), combined with archival ACS data of M51, are used to study the young star cluster (YSC) population of this interacting system. Our newly extracted source catalogue contains 2834 cluster candidates, morphologically classified to be compact and uniform in colour, for which ages, masses and extinction are derived. In this first work we study the main properties of the YSC population of the whole galaxy, considering a mass-limited sample. Both luminosity and mass functions follow a power-law shape with slope -2, but at high luminosities and masses a dearth of sources is observed. The analysis of the mass function suggests that it is best fitted by a Schechter function with slope -2 and a truncation mass at 1.00 +/- 0.12 x 10(5) M-circle dot . Through Monte Carlo simulations, we confirm this result and link the shape of the luminosity function to the presence of a truncation in the mass function. A mass limited age function analysis, between 10 and 200 Myr, suggests that the cluster population is undergoing only moderate disruption. We observe little variation in the shape of the mass function at masses above 1 x 10(4) M-circle dot over this age range. The fraction of star formation happening in the form of bound clusters in M51 is similar to 20 per cent in the age range 10-100 Myr and little variation is observed over the whole range from 1 to 200 Myr.
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Allen, Thomas S. "A Multi-wavelength survey of the Young Stellar Cluster Cep OB3b." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1404697742.

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Thurston, Mark Robert. "X-ray and optical observations of the young open cluster NGC 2516." Thesis, University of Birmingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366165.

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Dupree, A. K., A. Dotter, C. I. Johnson, A. F. Marino, A. P. Milone, J. I. Bailey, J. D. Crane, M. Mateo, and E. W. Olszewski. "NGC 1866: First Spectroscopic Detection of Fast-rotating Stars in a Young LMC Cluster." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/625815.

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High-resolution spectroscopic observations were taken of 29 extended main-sequence turnoff (eMSTO) stars in the young (similar to 200 Myr) Large Magellanic Cloud (LMC) cluster, NGC 1866, using the Michigan/Magellan Fiber System and MSpec spectrograph on the Magellan-Clay 6.5 m telescope. These spectra reveal the first direct detection of rapidly rotating stars whose presence has only been inferred from photometric studies. The eMSTO stars exhibit Ha emission (indicative of Be-star decretion disks), others have shallow broad H alpha absorption (consistent with rotation. greater than or similar to 150 km s(-1)), or deep Ha core absorption signaling lower rotation velocities (less than or similar to 150 km s(-1)). The spectra appear consistent with two populations of stars-one rapidly rotating, and the other, younger and slowly rotating.
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DE, LUCA MASSIMO. "The Vela molecular ridge young population: from pre-stellar condensations to young clusters." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2008. http://hdl.handle.net/2108/472.

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Scopo di questa tesi e' la caratterizzazione della popolazione proto-stellare di una regione di formazione stellare (circa un grado quadro) nel complesso di nubi molecolari giganti denominato Vela Molecular Ridge, con particolare riguardo per la correlazione tra oggetti giovani e caratteristiche fisiche e morfologiche del mezzo interstellare. Le nubi molecolari giganti contengono piu' dell'80% del contenuto di idrogeno della Galassia e sono considerate responsabili della maggior parte della formazione stellare. Esse rappresentano quindi i siti maggiormente promettenti nell'ambito della ricerca sulla nascita delle stelle. Analizzando la strutura su larga scala della nube, vengono descritte le condensazioni di gas e polvere dentro le quali si originano le stelle. Segue uno studio dettagliato, sia dell'emissione infrarossa proveniente da tali condensazioni, che dei fenomeni di perdita di massa (jet e outflow) associati agli oggetti piu' giovani. Cio' permette di trarre interessanti conclusioni riguardo le modalita' della formazione stellare, tanto all'interno di ciascuna condensazione, quanto, piu' in generale, nella nube, consentendo altresi' un raffronto con altre nubi Galattiche. I dati analizzati spaziano dal vicino infrarosso alle lunghezze d'onda millimetriche e sono stati ottenuti per mezzo di osservazioni da Terra e dallo spazio (vengono presentati anche i primi risultati dello studio tutt'ora in corso di mappe acquisite dal telescopio spaziale Spitzer). Il contributo fornito dal presente lavoro all'attuale attivita' di ricerca in formazione stellare riguarda principalmente: (i) la relazione spaziale tra siti dove le stelle hanno origine e distribuzione del mezzo interstellare, (ii) il legame tra distribuzione in massa delle condensazioni e funzione iniziale di massa, (iii) la statistica dei differenti stadi evolutivi delle proto-stelle in connessione con dette condensazioni, (iv) l'identificazione di sorgenti che meritano di essere osservate mediante strumentazione di nuova generazione in via di completamento (e.g. ALMA ed Herschel). Questo lavoro e' stato svolto nell'ambito del gruppo di astronomia infrarossa presso l'Osservatorio Astronomico di Roma, sotto la guida della Dott. Teresa Giannini, del Prof. Dario Lorenzetti, e presso l'Universita' di Roma "Tor Vergata", sotto la supervisione del prof. Roberto Buonanno.
The aim of this thesis is the characterization of the proto-stellar population of a star forming region (about one square degree) of the Vela Giant Molecular Cloud Complex, paying particular attention on the correlation between young objects and physical and morphological characteristics of the cloud interstellar medium. As a by-product, observational targets for new generation instrumentation have been also identified. Giant Molecular Clouds contain over 80% of the molecular hydrogen content of the Galaxy and are now considered responsible for most of the star birth. They thus represent the most promising sites for the research activity on star formation. By analysing the large-scale cloud structure we describe the gas-dust condensations inside which collapse into new stars begins. It follows a detailed inspection of both the infrared emission arising from such condensations and of the mass-loss phenomena (jets and outflows) associated with the youngest objects. This allows us to draw interesting conclusions regarding the star-forming modalities, both within each condensation and, more in general, within the cloud, enabling a comparison with other Galactic clouds. The large analysed database covers the range from Near-Infrared to millimeter wavelengths and has been obtained by means of both ground based and space-born facilities (we present also the first results of the on-going study of maps acquired by the Spitzer Space Telescope). The contribution given by this study to the present-day research activity on star formation mostly concerns the debates regarding: (i) the spatial relation between sites of star birth and interstellar material distribution, (ii) the link between the mass distribution of the cloud condensations and the Initial Mass Function, (iii) the statistics of different evolutionary stages of young objects within dust and molecular cores, (iv) the identification of interesting sources for a future investigation by means of more powerful instrumentation (e.g. ALMA and Herschel). This work has been carried out within the Infrared group of the Astronomical Observatory of Rome (INAF-OAR) under the supervision of Dr. Teresa Giannini, Prof. Dario Lorenzetti (INAF-OAR), and on the behalf of the University "Tor Vergata" of Rome (supervisor Prof. Roberto Buonanno).
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Lyo, A.-Ran Physical Environmental &amp Mathematical Sciences Australian Defence Force Academy UNSW. "The nearby young [special character] Chamaeleontis cluster as a laboratory for star formation and evolution." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Physical, Environmental and Mathematical Sciences, 2004. http://handle.unsw.edu.au/1959.4/38707.

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[Special characters cannot be displayed. Please see the pdf version of the Abstract for an accurate reproduction.] We studied the circumstellar discs, the initial mass function (IMF), mass distribution, binarity and the fundamental properties of the [special character] 9 Myr-old pre-main sequence (PMS) [special character] Chamaeleontis cluster. Using JHKL colour-colour and colour-excess diagrams, we found the circumstellar disc fraction to be [special character] 0.60 among the late-type members. Four stars with [special character] (K - L) > 0.4 were identified as experiencing ongoing accretion which was later confirmed by high-resolution spectroscopic study. Quantitative analysis of the H[special character] profiles found accretion in these four stars at rates comparable to that of two members of the similarly-aged TW Hydrae Association (TWA); rates 1 - 3 orders of magnitude lower than in younger classical T Tauri stars. Together these results suggest that, while the mass accretion rate decreases with age, PMS stars can retain their inner discs for [special character] 10 Myr. An optical photometric survey spanning 1.3 ?? 1.3 pc added two low-mass stars to the cluster inventory. Together with other recent surveys the population is likely to be significantly complete for primaries with masses M > 0.15M[special character]. The cluster now consists of 18 primaries and 9 confirmed and candidate secondaries, with [special character] 2-4 times higher multiplicity than seen in field dwarfs. The cluster IMF is consistent with that of rich young clusters and field stars. By extending the IMF to lower masses, we predict 20-29 low-mass stars and brown dwarfs may remain undiscovered. From study of the cluster???s spatial and mass distribution, we find the [special character] Cha cluster has significant mass segregation, with > 50 per cent of the stellar mass residing within the central 0.17 pc. Lastly we classified members of the cluster with low-resolution spectra, providing information about the fundamental properties of the PMS stars by comparison to standard dwarfs. Broadband VRI colours and pseudocontinuum indices derived for the cluster stars are indistinguishable from dwarfs at visual and red wavelengths. This suggests the temperature sequence for the PMS [special character] Cha cluster is similar to that of the dwarf sequence. Narrow-band spectral indices for the [special character] Cha cluster possibly indicate higher metallicity and strongly indicate lower surface gravity than the dwarf indices.
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Yusuf, H. "Preventing obesity by reducing soft drinks consumption among young people attending dental practices : a feasibility cluster RCT." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1470597/.

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Background: In England, 70% of young people consume soft drinks on a regular basis which increases the likelihood of obesity and dental caries. Many young people often visit the dentist; however primary dental care has been an underutilised research setting for delivering and evaluating dietary interventions. Motivational Interviewing (MI) has been shown to be effective in behaviour change. Therefore, this study provides an opportunity to assess an obesity intervention to reduce soft drinks consumption among young people attending NHS dental practices. Aims: To conduct a feasibility trial of an MI intervention to reduce soft drinks consumption among young people attending primary dental care practices in North Central London (Camden, Islington, and Haringey). Methods: The initial developmental phase explored dental teams’ attitudes, behaviours and perceived barriers in delivering prevention, using a mixed methods approach (focus groups followed by a questionnaire survey). A purposive sample of 11 out of 22 dental practices was selected from the study area for the four focus groups (two with dentists and two with dental care professionals). A cross-sectional survey of all NHS dentists was also conducted using a self-complete questionnaire. Descriptive analysis of the questionnaire data was undertaken and differences by the age and sex of the sample were assessed. A cluster feasibility trial with embedded process evaluation was then undertaken in the second phase of the study. Participants: Ten randomly allocated NHS dental practices recruited 39 overweight or obese young people (11-16 years). Intervention: 3-4 MI sessions. The three main outcomes were: mean daily consumption of sugary soft drinks using a 24 hour dietary recall, body mass index (BMI) and waist circumference. Outcomes were measured at baseline and at 6 month follow-up. Process evaluation outcomes: Recruitment, retention, fidelity and acceptability of the intervention were assessed using mixed methods. MI Fidelity was assessed using the Motivational Interviewing Treatment Integrity Code (MITI). Thematic analysis was used to analyse the qualitative data and descriptive analysis for the quantitative data. The study was approved by the local Ethics Committee (10/H0722/2). Results: Of the 300 eligible respondents, 164 questionnaires were returned (response rate: 54.7%). In Phase I, there were broad similarities in the themes that emerged from the four focus groups and the questionnaire survey. The majority of respondents strongly agreed that NHS dentists had a role to play in smoking cessation counselling, diet and alcohol advice. For dentists, prevention was viewed to be part of their ethical obligation. A high proportion of respondents 95.7% delivered oral hygiene advice, 85.4% provided diet advice, and 76.7% offered smoking cessation advice always or frequently. Barriers to delivering prevention included organisational factors (lack of adequate remuneration, bureaucracy), patient-related factors (motivation and compliance), and clinician-related factors (lack of training and resources). There was significant variation in providing prevention by the age and sex of dentists with female and younger dentists more likely to provide certain aspects of preventive care. Phase II- 10 dental practices were recruited (5 control and 5 intervention). Out of 149 potential participants, 39 (26.2%) conformed to the eligibility criteria, 5 (12.8%) withdrew from the study, and 3 (7.6%) were lost to follow-up, resulting in a retention rate of 79.5%. Facilitators of study implementation included the use of a screening questionnaire, support from the research team and incentives for young people and dental teams. In terms of acceptability, participants reported that the study had a positive impact on their knowledge or behaviours. At follow-up, soft drinks consumption decreased. Dental teams valued being involved in research. They recognised the challenges in recruiting young people and employed varying mechanisms to overcome them. Intervention fidelity revealed the MI practitioners to be proficient in MI and there was little variation in proficiency among the practitioners. Conclusions: Dentists in the study area were actively involved and had a generally positive attitude towards delivering prevention in primary dental care. The intervention was acceptable and feasible among dental teams and young people. MI is a feasible tool for reducing sugary soft drinks consumption among overweight young people attending dental practices. Further research is required to assess its effectiveness in primary dental care.
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Arévalo, Aura de Las Estrellas Ramírez. "The Red Supergiants in the Supermassive Stellar Cluster Westerlund 1." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/14/14131/tde-12092018-161841/.

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The purpose of this dissertation is to study the Red Supergiant stars (RSGs) in the supermassive young cluster Westerlund 1 through a photometric and spectral analysis. Due to its characteristics, Westerlund 1 is one of the most interesting young massive clusters in the Milky Way and has an impressive population of massive stars, with four RSGs among them. This represents a rare oportunity to study this type of stars in a cluster with well known distance and reddening. Apart from contributing to the general knowledge about RSGs, which parameters are poorly known due to their scarcity, an analysis of these four stars will contribute to solve the puzzle of the formation history of Westerlund 1. For the analysis presented here, photometric data of the four RSGs in Westerlund 1 were used, along with near infrared spectra covering the region from ~8400 Å to ~8900 Å, obtained at two different epochs with the 1.60 m telescope at Observatório do Pico dos Dias (OPD) and the Southern Astrophysical Research Telescope (SOAR). Magnitudes obtained with JHK band photometry were used to calculate effective temperatures and bolometric corrections at the K band through different methods involving the color indices (V-K)_0 and (J-K)_0, in order to determine the luminosities and locate the four RSGs in a Hertzsprung-Russell diagram (HRD). A spectral analysis was performed with the aim of estimating spectral types and the same stellar parameters calculated with the photomety. First, a visual comparison of the depth and strength of the main spectral features (TiO and VO bandheads, and CaT and Fe I lines) was carried out to classify the stars by spectral type. For this purpose, spectra of the four RSGs in the cluster were compared to a group of spectra from well studied reference stars, some of them also RSGs. Then, given their strong dependence on Teff, equivalent widths (EWs) of Fe I lines were measured in all the spectra available. By comparing the EWs measured on spectra of the four RSGs and the reference stars, the Teff\'s of the most similar reference stars were assigned to the RSGs in the cluster. With the Teff\'s obtained through the spectral analysis, new points were added to the initial HRD. The final objective of the present work was to estimate the initial masses and ages of the RSGs in Westerlund 1. This was accomplished by superimposing up to date evolutionary tracks and isochrones to the HRD. Masses and ages were determined for the cases with and without rotation, obtaining an average age for the RSGs of 8 Myr, thus doubling the age of the host cluster determined from the pre-main sequence (PMS). In the final part, it is presented a brief discussion about the discrepancy of the age of Westerlund 1 measured with the PMS isochrones and the age of the RSGs, as well as the uncertainties it raises regarding the formation history of the cluster.
O objetivo desta dissertação é estudar as estrelas Supergigantes Vermelhas (RSGs) no aglomerado jovem supermassivo Westerlund 1 através de uma análise fotométrica e espectral. Devido às suas características, Westerlund 1 é um dos aglomerados jovens mais interessantes da Via Láctea e tem uma população importante de estrelas massivas, com quatro RSGs entre elas. Isso representa uma oportunidade rara para estudar este tipo de estrelas em um aglomerado com a distância e avermelhamento bem conhecidos. Além de contribuir para o conhecimento geral sobre RSGs, cujos parâmetros são pouco conhecidos devido à sua escassez, uma análise dessas quatro estrelas contribuirá para resolver o enigma da história da formação de Westerlund 1. Para a análise apresentada aqui, foram utilizados dados fotométricos das quatro RSGs em Westerlund 1, juntamente com espectros no infravermelho próximo cobrindo a região de ~8400 Å a ~8900 Å, obtidos em duas épocas diferentes com o telescópio de 1.60 m do Observatório do Pico dos Dias (OPD) e o Southern Astrophysical Research Telescope (SOAR). Magnitudes obtidas com a fotometria nos filtros JHK foram usadas para calcular temperaturas efetivas e correções bolométricas na banda K através de diferentes métodos envolvendo os índices de cor (V-K)_0 e (J-K)_0, a fim de determinar as luminosidades e localizar as quatro RSGs em um diagrama de Hertzsprung-Russell (HRD). Uma análise espectral foi realizada com o objetivo de estimar os tipos espectrais e os mesmos parâmetros estelares calculados com a fotometria. Primeiramente, uma comparação visual da profundidade e força das principais características espectrais (as bandas moleculares de TiO e VO e as linhas de CaT e Fe I) foi realizada para classificar as estrelas por tipo espectral. Para este propósito, os espectros das quatro RSGs no aglomerado foram comparados com um grupo de espectros de estrelas de referência bem estudadas, algumas delas também RSGs. Depois, dada a sua forte dependência com a Teff, as larguras equivalentes (EWs) das linhas de Fe I foram medidas em todos os espectros disponíveis. Comparando as EWs medidas nos espectros das quatro RSGs e nos das estrelas de referência, as Teff das estrelas de referência mais similares foram atribuídas às RSGs do aglomerado. Com as Teff obtidas através da análise espectral, novos pontos foram adicionados ao HRD inicial. O objetivo final do presente trabalho foi estimar as massas iniciais e as idades das RSGs em Westerlund 1. Isto foi realizado através da sobreposição no HRD de caminhos evolutivos e de isócronas. Massas e idades foram determinadas para os casos com e sem rotação, obtendo-se uma média de idade para as RSGs de 8 milhões de anos, duplicando assim a idade do aglomerado ao que as RSGs pertencem, e que foi medida através de estrelas de pré-sequência principal (PMS). Na parte final, é apresentada uma breve discussão sobre a discrepância da idade de Westerlund 1 medida com as isócronas da PMS e a idade das RSGs, bem como as incertezas que isso suscita em relação à história da formação do aglomerado.
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Books on the topic "Young cluster"

1

S, Randich, and United States. National Aeronautics and Space Administration., eds. Lithium abundances in the young open cluster IC 2602. [Washington, DC: National Aeronautics and Space Administration, 1997.

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Thurston, Mark Robert. X-ray & optical observations of the young open cluster NGC 2516. Birmingham: University of Birmingham, 2000.

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Clarke, Cathie, Robert D. Mathieu, and Iain Neill Reid. Dynamics of Young Star Clusters and Associations. Edited by Michael R. Meyer, Laurent Eyer, and Cameron P. M. Bell. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-47290-3.

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Lamers, Henny J. G. L. M., 1941-, Smith Linda J, and Nota Antonella, eds. The formation and evolution of massive young star clusters: Proceedings of a meeting held in Cancun, Mexico, 17-21 November 2003. San Francisco, Calif: Astronomical Society of the Pacific, 2004.

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Tian ran qi li yong chan ye ji yue hua fa zhan li lun yu shi jian. Beijing: Ke xue chu ban she, 2013.

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James, David John. Rotation, activity and lithium depletion among late-type stars in young galactic open clusters. Birmingham: University of Birmingham, 1997.

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Ju lei suan fa zhong de you hua fang fa ying yong: JU LEI SUAN FA ZHONGDE YOUHUA FANGFA YINGYONG. Chengdu: Dian zi ke ji da xue chu ban she, 2014.

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Chuan Yu di qu tian ran qi li yong chan ye ji qun yan jiu. Beijing: Shi you gong ye chu ban she, 2013.

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A, Wilking B., and Ames Research Center, eds. Far-infrared observations of young clusters embedded in the R Coronae Austrinae and Rho Ophiuche dark clouds. Moffet Field, Calif: National Aeronautics and Space Administration, Ames Research Center, 1985.

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A, Wilking Bruce, and Ames Research Center, eds. Far-infrared observations of young clusters embedded in the R Coronae Austrinae and Rho Ophiuche dark clouds. Moffet Field, Calif: National Aeronautics and Space Administration, Ames Research Center, 1985.

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Book chapters on the topic "Young cluster"

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Schommer, R. A., and Doug Geisler. "Abundances of Young LMC Clusters." In The Harlow-Shapley Symposium on Globular Cluster Systems in Galaxies, 577–78. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-015-1104-9_114.

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de Grijs, Richard. "Star Cluster Evolution: From Young Massive Star Clusters to Old Globulars." In Globular Clusters - Guides to Galaxies, 353–56. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-76961-3_81.

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Poggianti, B. M., and G. Barbaro. "Determination of Young Population Ages in Cluster Galaxies." In Stellar Populations, 460. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0125-7_127.

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Clarke, Cathie J. "The Raw Material of Cluster Formation: Observational Constraints." In Dynamics of Young Star Clusters and Associations, 3–15. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-47290-3_1.

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Clarke, Cathie J. "The Numerical Tools for Star Cluster Formation Simulations." In Dynamics of Young Star Clusters and Associations, 17–30. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-47290-3_2.

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Clarke, Cathie J. "The Role of N-body Dynamics in Early Cluster Evolution." In Dynamics of Young Star Clusters and Associations, 73–87. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-47290-3_6.

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Ripepi, V., S. Leccia, A. Baglin, A. Ruoppo, S. Bernabei, K. Zwintz, F. Cusano, et al. "CoRoT observations of the young open cluster Dolidze 25." In Synergies between Solar and Stellar Modelling, 117–20. Dordrecht: Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-90-481-9198-7_19.

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Moneti, Andrea. "Infrared Photometry of the Young Cluster NGC 3603: First Results." In Infrared Astronomy with Arrays, 111–12. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-1070-9_29.

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Marco, A., G. Bernabeu, and I. Negueruela. "The Star Population of the Young Open Cluster NGC 1893." In Highlights of Spanish Astrophysics II, 157–60. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-017-1776-2_37.

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Wang, Jun-Jie, and Jing-Yao Hu. "Study of Reddening in the Young Open Cluster NGC 6913." In Stellar Astrophysics, 457–62. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-010-0878-5_57.

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Conference papers on the topic "Young cluster"

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Cavelan, Aurelien, Jiafan Li, Yves Robert, and Hongyang Sun. "When Amdahl Meets Young/Daly." In 2016 IEEE International Conference on Cluster Computing (CLUSTER). IEEE, 2016. http://dx.doi.org/10.1109/cluster.2016.17.

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Feng, Juan, Jie Zhao, and Guohua Zhan. "Content-based School Assignment Cluster Algorithm." In 2008 9th International Conference for Young Computer Scientists (ICYCS). IEEE, 2008. http://dx.doi.org/10.1109/icycs.2008.234.

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Semenov, Valeryi P., and Michael M. Garifullin. "Cluster model: Microeconomic approach." In 2018 IEEE Conference of Russian Young Researchers in Electrical and Electronic Engineering (EIConRus). IEEE, 2018. http://dx.doi.org/10.1109/eiconrus.2018.8317328.

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Xu, Sen, Zhimao Lu, and Guochang Gu. "An Efficient Spectral Method for Document Cluster Ensemble." In 2008 9th International Conference for Young Computer Scientists (ICYCS). IEEE, 2008. http://dx.doi.org/10.1109/icycs.2008.228.

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Lin, Chien-Cheng, Wen-Ping Chen, and Neelam Panwar. "Characterization of a young open cluster G144.9+0.4 in Cam OB1." In FIRST INTERNATIONAL CONFERENCE ON CHEMICAL EVOLUTION OF STAR FORMING REGION AND ORIGIN OF LIFE: Astrochem2012. AIP, 2013. http://dx.doi.org/10.1063/1.4812606.

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Cargile, P. A., D. J. James, C. P. Deliyannis, J. C. Mermilliod, I. Platais, A. Steinhauer, and Eric Stempels. "Rotation and Magnetic Activity in the Young Open Cluster Blanco 1." In COOL STARS, STELLAR SYSTEMS AND THE SUN: Proceedings of the 15th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun. AIP, 2009. http://dx.doi.org/10.1063/1.3099118.

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Franciosini, E., G. G. Sacco, R. Pallavicini, and Eric Stempels. "X-ray properties of the young open cluster around λ Orionis." In COOL STARS, STELLAR SYSTEMS AND THE SUN: Proceedings of the 15th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun. AIP, 2009. http://dx.doi.org/10.1063/1.3099182.

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Wang, Shuoping, Gaoyan Zhang, and Jun Liu. "Design of an Expandable Website Platform for Quality Course Cluster." In 2008 9th International Conference for Young Computer Scientists (ICYCS). IEEE, 2008. http://dx.doi.org/10.1109/icycs.2008.496.

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Stognii, Nadiia P., Nina S. Butenko, and Nataliya K. Sakhnenko. "Plasmonic properties of selfsimilar cluster of silver nanowires." In 2017 IEEE International Young Scientists Forum on Applied Physics and Engineering (YSF). IEEE, 2017. http://dx.doi.org/10.1109/ysf.2017.8126642.

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Che, ShaoPeng, Dongyan Nan, Pim Kamphuis, Xinvu Jin, and Jang Hyun Kim. "A Cluster Analysis of Lotte Young Plaza Using Semantic Network Analysis Method." In 2021 15th International Conference on Ubiquitous Information Management and Communication (IMCOM). IEEE, 2021. http://dx.doi.org/10.1109/imcom51814.2021.9377390.

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Reports on the topic "Young cluster"

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Nolan, Anne. Clusters of health behaviours among young adults in Ireland. ESRI, June 2020. http://dx.doi.org/10.26504/rs101.

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Oviedo, Daniel, Yisseth Scorcia, and Lynn Scholl. Ride-hailing and (dis)Advantage: Perspectives from Users and Non-users. Inter-American Development Bank, September 2021. http://dx.doi.org/10.18235/0003656.

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The introduction of ride-hailing in cities of Latin America and the Caribbean (LAC) remains a relatively new topic in regional research and a contentious issue in local policy and practice. Evidence regarding users and how do they differ from non-users is scarce, and there is little documented evidence about how user preferences and perceptions may influence the uptake of ride-hailing. This paper uses primary data from a survey collected from users and non-users of ride-hailing in Bogotá during 2019 to develop a Latent Class Analysis Model (LCA) to identify clusters of users and non-users of ride-hailing. The paper builds on results from the LCA to reflect on conditions of advantage and disadvantage that may make ride-hailing attractive and beneficial for particular social groups. The paper identifies four unique clusters: Carless middle-income ride-hailing users, Disadvantaged non-users, Young middle-class non-users, and Advantaged ride-hailing users. The research uses data on such perceptions to draw insights that may inform commercial and policy decisions. Findings suggest that issues such as the perception of legality in ride-hailing and aversion to crime play a significant role in the choice of such a mode in the context of Bogotá, particularly among socially and transport advantaged users.
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