לוח שנה משולב

Most every day materials can be described by a set of numbers that describe their properties – a resistor for example, is described by its resistance, a number that is useful in predicting how much current will flow through it under a given voltage. Some materials however, lack this basic characteristic. Under constant external conditions, their properties can change over many time scales, from fractions of a second to weeks and even years, without showing any sign of reaching equilibrium. Such behavior is exhibited in a strikingly similar way by very different systems, from materials such as polymers and glass to properties of interfaces leading to friction and even earthquakes. Perhaps the only common attribute to all this systems is that they are disordered. Yet, in spite of many studies that have been conducted on these recurring motifs across a broad range of systems, identifying the mechanisms underlying the unusual out-of-equilibrium dynamics of disordered systems remains an outstanding problem in condensed matter physics.
Here, I will describe several disordered soft-matter systems that exhibit a similar repertoire of far-from-equilibrium behavior, including logarithmic relaxation and the ability to hold a memory of previous conditions that can last for hours. At the same time, each one of these systems offers a way to track the evolution of the internal structure, presenting an opportunity to reveal and compare mechanisms across different systems.

Many natural structures are made of soft tissue that undergoes active growth. Non uniform growth of thin sheets can lead to the formation of elaborate three-dimensional configurations and to induce non trivial shape transformations. In particular, complicated configurations appear in thin sheets when growth leads to geometrical frustration.

I will present examples of different types of systems and discus different types of self-shaping principles, together with the theoretical framework of incompatible elasticity which is used to study such systems. Experimental methods for the construction of “programmed” responsive sheets will be reviewed and the connection of the topic to shape selection in chemical and biological systems, as well as to design and art, will be presented.

Research of neutron-rich exotic isotopes can generate significant contributions to the understanding of the astrophysical rapid neutron capture process (r-process) of nucleosynthesis, and the extension of nuclear models to regions far from stability. In this talk I present an initiative to start a research program of neutron-rich exotic isotopes
in Israel.

In the short term, the plan is to study specific processes and characteristics in relevant facilities in the world. I will discuss medium- and high-energy neutron-induced fission rates and fission products distributions of several actinides, which serve as input to quantify fission recycling in the r-process; and the probabilities of beta-delayed multi-neutron emission (of applicable isotopes), which affect the beta decay chains during "freeze out", thus changing the resulting stable isotopes r-process abundances.

For the longer term, I explore the possibility of constructing a neutron-rich exotic isotopes facility at SARAF Phase II, mainly based on medium- and high-energy induced fission. Neutron induced fission has the advantage of generating isotopes with a higher neutron number, thus extending our reach to regions farther from stability. Preliminary estimations indicate that such a facility will be potent in a world competitive manner.

Ubiquitin and ubiquitin-like protein post-translational modifications (PTMs) are implicated in every aspect of cellular regulation. Yet, we still lack comprehensive understanding of their broad functions and the range of their cellular targets. We developed a PTM profiling platform, which establishes a broadly applicable and systematic approach to study regulation of PTMs in various biological processes and human diseases. In my talk, I will introduce this system and focus primarily on one example in which we gained mechanistic insight of PTM-based regulation of cyclin B1, which is required for proper mitotic progression.

Proper performance of voluntary movements requires the integration of both spatial and temporal information about the ensuing movements. The timing of actions is often considered to be dictated by cerebellar output that is relayed to the motor cortex via the motor thalamus. We investigated the mechanisms by which the cerebellar-thalamo-cortical (CTC) system controls temporal properties of motor cortical activity.
We found that in primates the CTC pathway efficiently recruits motor cortical neurons in primary motor and premotor areas. Cortical responses to CTC activation were dominated by prolonged inhibition mediated by a feedforward mechanism. We further found that cortical cells that integrated CTC input fired transiently and synchronously at movement onset, when the timing of action is dictated. Moreover, when preventing the flow of information in the pathway the phasic firing at movement onset was reduced, but the preferred direction of the cells remained unchanged. These changes in neural firing were correlated with altered motor behavior: the monkeys were able to perform the task but with increased reaction and movement times.
These results suggest that the CTC system affects cortical firing by changing the excitation-inhibition balance at movement onset in an extensive network of TC-activated motor cortical neurons. In this manner, the temporal pattern of neural firing is shaped, and firing across groups of neurons is synchronized to generate transiently enhanced firing.