Integrated Calendar

Dark matter continues to pose one of the most important questions in modern cosmology. Gravitationally lensed multiple images of galaxies, quasars and stars provide several opportunities for testing the clumpiness of dark matter on small scales due to, for example, compact objects, axion mini-clusters and waves, or subhalos orbiting on galactic or cluster dark matter halos. The idea of using highly magnified stars by lensing clusters to probe this small-scale granularity in the dark matter will be discussed.

We describe two self-assembly pathways observed in micron-thick colloidal membranes that spontaneously assemble in mixtures of monodisperse colloidal rods and non-adsorbing polymer. In a first example, we study mechanisms by which membrane-embedded 2D liquid droplets acquire unusual non-spherical shapes, suggesting that the interfacial edge domain has spontaneous non-zero edge curvature. These experimental observations can be explained by a simple geometric argument which predicts that the edge curvature towards shorter rod domains softens the resistance of the edge to twist. In a second example, we study the 3D structure of membranes composed of miscible rod-like molecules of differing lengths. Above a critical concentration of shorter rods flat 2D membranes become unstable and assume a bewildering variety of different shapes and topologies. Simple arguments suggest that doping colloidal membranes with miscible shorter rods tunes the membrane’s Gaussian modulus, which in turn destabilizes flat 2D membranes.

The Acheulo-Yabrudian Cultural Complex (AYCC, ~420,000-200,000 years ago) is a local Levantine entity, characterized by a set of innovative human cultural and biological adaptations, including the habitual use of fire, technological innovations such as blade and Quina scraper production, and more. Qesem Cave (QC, central Israel) is one of the key sites of the AYCC. I will present the results of two recent studies, exploring the rich lithic assemblages yielded from this important site.
The first combines macroscopic classification of flint artefacts with a geological survey and petrographic and geochemical analyses, aimed at identifying patterns of flint acquisition and use. The results show that local Turonian flint was often brought and used at the cave, while flint from other, non-Turonian origins, was also used in noteworthy proportions, in specific categories, implying selectivity in flint procurement and exploitation through time.
The second study combines Raman spectroscopy and artificial intelligence (AI) to build temperature predictive models, aimed at identifying the temperatures to which flint artefacts were exposed. The results show that blades were heated at lower median temperatures (259℃) compared to flakes (413℃), suggesting the intentional and controlled heat treatment of flint specifically for blade production, more than 300,000 years ago.
Both datasets and their implications will be discussed in a broader perspective.