A cautionary lesson from Gaia systematics: the mono-metallic globular cluster NGC 5904

The study of the chemistry of the stellar populations in Globular Clusters (GCs) is a fundamental task to unveil their formation in the high-redshift universe and to reconstruct the build up of our Galaxy. Recently, using metallicity estimates from BP/RP low-resolution Gaia DR3 spectra, Piatti 2023 presented the surprising detection of two distinct stellar populations in the stellar stream of the GC NGC 5904, otherwise considered a mono-metallic system. The presence of these two populations, with [Fe/H]~-1.4 and [Fe/H]~-2.0 dex, was taken as the evidence of a merger origin of the cluster. In this Letter, using the same data set complemented by the new robust metallicity estimates by Andrae et al. 2023b, we carry out a detailed analysis of the metallicity distribution of stars belonging both to the cluster and to its stellar stream, explicitly focusing on the subtle effects of data systematics. We demonstrate that the population at [Fe/H]~-2.0 dex is a data artefact due to error systematics, affecting especially low-magnitude stars. The new higher quality metallicity sample corroborates this finding, and it indicates the presence of only a population of stars with metallicity of [Fe/H]~-1.3 dex, in agreement with previous literature studies. We, therefore, conclude that both NGC 5904 and its stellar stream are mono-metallic systems, and emphasize the need of carefully examining systematic effects in large and complex data bases.Comment: Submitted to MNRAS, 5 pages, 3 figures. Comments welcom

Metodi e strumenti di un progetto di valorizzazione delle riviste italiane di biblioteconomia in Wikidata

The authors of this study would aim at conducting a bibliometric analysis focusing on recent advancements in Italian library science and bibliographic studies. To achieve this objective, Wikidata was identified as a powerful tool for generating, processing, and scrutinizing data, but it lacks information concerning Italian library journals from the latest decades. In this case, the substantial volume of data to be uploaded onto Wikidata would necessitate considerable human resources. Consequently, this article looks into methods to streamline and manage the data uploading process efficiently. Moreover, the article investigates existing methods, tools, and techniques for accurate author identification within the dataset. Furthermore, it examines the potential for establishing synergies that promote project continuity and facilitate future advancements. Additionally, the research assesses procedures aimed at enhancing citation data quality. The study investigates also the feasibility of conducting bibliographic data analysis on a sample uploaded to Wikidata compared to other bibliometric tools, with a particular focus on Italian-language production. By shedding light on these vital aspects, this article provides valuable insights into conducting bibliometric research within the field of Italian library science and bibliographic studies. The findings not only contribute to the advancement of knowledge in this domain, but they pave the way for more efficient and effective bibliometric research.Gli autori di questo studio intendono condurre in futuro un’analisi bibliometrica incentrata sui recenti progressi della biblioteconomia e degli studi bibliografici italiani. Per raggiungere questo obiettivo, Wikidata è stato identificato come un potente strumento per la generazione, l’elaborazione e lo scrutinio dei dati, ma manca di informazioni riguardanti le riviste bibliotecarie italiane degli ultimi decenni. In questo caso, l’ingente volume di dati da caricare su Wikidata richiede notevoli risorse umane. Di conseguenza, questo articolo studia i metodi per snellire e gestire in modo efficiente il processo di caricamento dei dati. Inoltre, l’articolo analizza i metodi, gli strumenti e le tecniche esistenti per un’accurata identificazione degli autori all’interno del set di dati. In aggiunta, esso, esamina il potenziale per stabilire sinergie che promuovano la continuità del progetto e facilitino i progressi futuri. Oltre a ciò, la ricerca valuta le procedure volte a migliorare la qualità dei dati citazionali. Lo studio analizza anche la fattibilità dell’analisi dei dati bibliografici su un campione caricato su Wikidata rispetto ad altri strumenti bibliometrici, con particolare attenzione alla produzione in lingua italiana. Facendo luce su questi aspetti fondamentali, l’articolo fornisce indicazioni preziose per la conduzione di ricerche bibliometriche nel campo della biblioteconomia e degli studi bibliografici italiani. I risultati non solo contribuiscono all’avanzamento delle conoscenze in questo campo, ma aprono anche la strada a una ricerca bibliometrica più efficiente ed efficace

Isolation of an "early" transit amplifying keratinocyte population in human epidermis: a role for the low affinity neurotrophin receptor CD271

In the interfollicular epidermis (IFE), stem cells (KSC) generate transit amplifying (TA) cells that, after symmetric divisions, produce differentiating daughters. Here, we isolated and characterized the highly proliferative interfollicular epidermal basal cell population "early" TA (ETA) cells, based on their capacity to adhere to type IV collagen. Proliferation and colony-forming efficiency in ETA cells are lower than in KSC but higher than in "late" TA (LTA). Stemness, proliferation, and differentiation markers confirmed that ETA cells display a unique phenotype. Skin reconstructs derived from ETA cells present different features (epidermal thickness, Ki67, and Survivin expression), as compared to skin equivalents generated from either KSC or LTA cells. The low-affinity neurotrophin receptor CD271, which regulates the KSC to TA cell transition in the human epidermis through an on/off switch control mechanism, is predominantly expressed in ETA cells. Skin equivalents generated from siRNA CD271 ETA cells display a more proliferative and less differentiated phenotype, as compared to mock-derived reconstructs. Consistently, CD271 overexpression in LTA cells generates a more proliferative skin equivalent than mock LTA cells. Finally, the CD271 level declines with cellular senescence, while it induces a delay in p16INK4 expression. We conclude that ETA cells represent the first KSC progenitor with exclusive features. CD271 identifies and modulates ETA cells, thus participating in the early differentiation and regenerative capacity of the human epidermis