The Amphorae of the Kerameikos Cemetery at Athens from the Submycenaean to the Protogeometric Period

The amphorae dating from the Submycenaean to the end of the Protogeometric period, brought to light in the Kerameikos cemetery, represent a high quality sample of Athenian output of the shape. The amphorae here researched are re-examined with the help of new drawings and by adopting the “envelope” method for their comparison. Undertaken with the assistance of the Institute for Aegean Prehistory.

Strong chemical tagging with APOGEE: 21 candidate star clusters that have dissolved across the Milky Way disc

ABSTRACT Chemically tagging groups of stars born in the same birth cluster is a major goal of spectroscopic surveys. To investigate the feasibility of such strong chemical tagging, we perform a blind chemical tagging experiment on abundances measured from APOGEE survey spectra. We apply a density-based clustering algorithm to the 8D chemical space defined by [Mg/Fe], [Al/Fe], [Si/Fe], [K/Fe], [Ti/Fe], [Mn/Fe], [Fe/H], and [Ni/Fe], abundances ratios which together span multiple nucleosynthetic channels. In a high-quality sample of 182 538 giant stars, we detect 21 candidate clusters with more than 15 members. Our candidate clusters are more chemically homogeneous than a population of non-member stars with similar [Mg/Fe] and [Fe/H], even in abundances not used for tagging. Group members are consistent with having the same age and fall along a single stellar-population track in log g versus Teff space. Each group’s members are distributed over multiple kpc, and the spread in their radial and azimuthal actions increases with age. We qualitatively reproduce this increase using N-body simulations of cluster dissolution in Galactic potentials that include transient winding spiral arms. Observing our candidate birth clusters with high-resolution spectroscopy in other wavebands to investigate their chemical homogeneity in other nucleosynthetic groups will be essential to confirming the efficacy of strong chemical tagging. Our initially spatially compact but now widely dispersed candidate clusters will provide novel limits on chemical evolution and orbital diffusion in the Galactic disc, and constraints on star formation in loosely bound groups.

Study of the departures from LTE in the unevolved stars infrared spectra

ABSTRACT We present a study of departures from Local Thermodynamic Equilibrium (LTE) in the formation of infrared (IR) lines of Na i, Mg i, Al i, S i, K i, and Sr ii in unevolved stars of spectral types F, G, K and metallicities around the solar metallicity. The purpose of this investigation is to identify lines of these species that can be safely treated with the LTE approximation in the IR spectra of these types of stars. We employ a set of 40 stars observed with the GIANO spectrograph at the 3.5 m Telescopio Nazionale Galileo and previously investigated by Caffau et al. We were able to identify many lines that can be treated in LTE for all the above-mentioned species, except for Sr ii. The latter species can only be studied using three lines in the J band, but all three of them display significant departures from LTE. With our small-size, but high-quality sample, we can determine robustly the trends of the abundance ratios with metallicity, confirming the trends apparent from a sample that is larger by several orders of magnitude, but of lower quality in terms of resolution and S/N ratio.

Stellar angular momentum distribution linked to galaxy morphology

ABSTRACT We study the spatially resolved stellar specific angular momentum j* in a high-quality sample of 24 Calar Alto Legacy Integral Field Area galaxies covering a broad range of visual morphology, accounting for stellar velocity and velocity dispersion. The shape of the spaxelwise probability density function of normalized s = j*/j*mean, PDF(s), deviates significantly from the near-universal initial distribution expected of baryons in a dark matter halo and can be explained by the expected baryonic effects in galaxy formation that remove and redistribute angular momentum. Further we find that the observed shape of the PDF(s) correlates significantly with photometric morphology, where late-type galaxies have a PDF(s) that is similar to a normal distribution, whereas early types have a strongly skewed PDF(s) resulting from an excess of low-angular momentum material. Galaxies that are known to host pseudo-bulges (bulge Sérsic index nb < 2.2) tend to have less skewed bulge PDF(s), with skewness (b1rb) ≲ 0.8. The PDF(s) encodes both kinematic and photometric information and appears to be a robust tracer of morphology. Its use is motivated by the desire to move away from traditional component-based classifications which are subject to observer bias, to classification on a galaxy’s fundamental (stellar mass and angular momentum) properties. In future, PDF(s) may also be useful as a kinematic decomposition tool.

Establishing and Maintaining a Robust Sample Management System

This paper has been written by the SLAS Sample Management Special Interest Group to serve as a guide to the best practices and methods in establishing and maintaining a high-quality sample management system. The topics covered are applicable to sample types ranging from small molecules to biologics to tissue samples. It has been put together using the collective experience of the authors in start-up companies, small pharma, agricultural research, IT, academia, biorepositories, and large pharma companies. Our hope is that sharing our experience will streamline the process of setting up a new sample management system and help others avoid some of the problems that we have encountered.

Correction of Stress Release During Sample Preparation for TEM CBED Measurements

In the vicinity of a through silicon via (TSV) used in 3D chip integration, the effect of dedicated strain engineering to enhance the carrier mobility in the channel of metal oxide semiconductor field effect transistors (MOSFETs) is superposed by a strain caused by cooling down from high process temperatures to room temperature. This additional strain influences the transistor characteristics, and consequently the product performance. The measurement of strain with high spatial resolution requires TEM-based methods. In this paper, convergent beam electron diffraction (CBED) is used for strain measurement. The strain state is significantly changed during the preparation of the TEM lamellae. The exact sample geometry and accurate materials parameters were used in FE modelling and strain simulation based on a physical model. The strain in silicon at several distances from the TSV were determined experimentally using TEM-CBED and compared with numerical simulations. High-quality sample preparation is crucial for reliable and reproducible TEM-based strain data, i.e., it is a necessary precondition for strain release correction based on FE modelling and simulation.