לוח שנה משולב

The geologically recent (~1 Gya) Rheasilvia basin on asteroid 4 Vesta is on of the most spectacular impact structures in the solar system, with a diameter nearly equal in size to that of Vesta itself. To date, much of the numerical modeling of this impact has concentrated on the morphology of the Rheasilvia basin. However, the stress wave produced by an impact of this size is capable of causing deformation at considerable distance from the basin itself. We use high resolution hydrocodes modeling coupled with a strain analysis routine in order to understand the modes and magnitudes of deformation expected globally on Vesta following the Rheasilvia impact. These simulations give insight into several interesting observations by NASA’s Dawn spacecraft. First, our results suggest that the major system of graben circling Vesta’s equator opened shortly after the passage of the Rheasilvia related impact shock wave. Secondly, we find that the deficiency of small craters at Vesta’s north pole is likely a result of antipodal focusing of Rheasilvia impact related stresses. The details behind both of these findings are dependent on material parameters of Vesta’s interior, including core strength, mantle porosity, and damage to the body from previous major impacts. By matching model output to observation, we can perform a crude sort of seismology and gain insight into both Vesta’s internal rheology as well as its impact history.

ההרצאה תעסוק בהפיכתה של פרדיגמת "עיבוד המידע" לפרדיגמה השליטה לא רק במדעי החיים, אלא גם בחלקים הולכים וגדלים של מדעי הרוח ומדעי החברה. החלק השני של ההרצאה יתמקד בהשלכות של זה על חקר המוח והתודעה. האם המוח הוא מערכת לעיבוד מידע? ואם כן, האם זה אומר שגם התודעה היא מערכת לעיבוד מידע? מה מפספסים כשמנסים להבין את העולם באמצעות הפרדיגמה של עיבוד מידע?

Extraordinary electron systems can be generated at well-defined interfaces between complex oxides [1]. These two-dimensional electron systems are characterized by properties that fundamentally differ from those of two-dimensional electron gases in semiconductor heterostructures, which provide the basis of the Quantum Hall Effect and are exploited in high electron mobility transistors.

In recent years, groundbreaking progress has been achieved in exploring and utilizing novel oxide electron systems. In the presentation I will provide an overview of their surprising properties (see, e.g., [2]) and explore the potential of electron liquids at oxide interfaces for the use in nanoscale electronic devices.

[1] A. Ohtomo et al., Nature 419, 378 (2002)

Hematopoietic stem cells (HSCs) and their subsequent progenitors produce blood cells, but the precise nature of this production is dogged by controversy. Cellular barcoding is a powerful experimental technique that simultaneously traces the in vivo differentiation of individual cells. Using cellular barcoding, we traced the progeny of hematopoietic progenitors and reconstituted the lineage relationship with single cell resolution. We show that individual multipotent progenitors are generally not multi-outcome; instead, they produce heterogeneous patterns of limited types of blood cells. Interestingly, we found that some progenitors produce dendritic cells without producing any lymphoid and myeloid cells, redefining dendritic cells as a third lineage of blood cells. We then developed a quantitative framework to infer the nature of the hematopoietic tree. With this approach, we showed that the classical model of hematopoiesis cannot explain our data and we propose an alternative model.