פרסומים

Kolmogorov's setting for probability theory is given an original generalization to account for probabilities arising from Quantum Mechanics. The sample space has a central role in this presentation and random variables, i.e., observables, are defined in a natural way. The mystery presented by the algebraic equations satisfied by (non-commuting) observables that cannot be observed in the same states is elucidated

In the framework of Kohn-Sham density-functional theory, systems with ground-state densities that are not pure-state v-representable (PSVR) in the noninteracting reference system occur frequently. In the present contribution, an algorithm, which allows the solution of such systems, is proposed. It is shown that the use of densities which do not correspond to a ground state of their noninteracting reference system is forbidden. As a consequence, the proposed algorithm considers only noninteracting ensemble v-representable densities. The Fe atom, a well-known non-PSVR system, is used as an illustration. Finally, the problem is analyzed within finite-temperature density-functional theory, where the physical significance of fractional occupations is exposed and the question of why degenerate states can be unequally occupied is resolved.

Cross-linking proteins can mediate the emergence of rigid bundles from a dense branched network of actin filaments. To enable their binding, the filaments must first bend towards each other. We derive an explicit criterion for the onset of bundling, in terms of the initial length of filaments L, their spacing b, and cross-linker concentration f, reflecting the balance between bending and binding energies. Our model system contains actin, the branching complex Arp2/3 and the bundling protein fascin. In the first distinct stage, during which only actin and Arp2/3 are active, an entangled aster-like mesh of actin filaments is formed. Tens of seconds later, when filaments at the aster periphery are long and barely branched, a sharp transition takes place into a star-like structure, marking the onset of bundling. Now fascin and actin govern bundle growth; Arp2/3 plays no role. Using kinetic Monte Carlo simulations we calculate the temporal evolution of b and L, and predict the onset of bundling as a function of f. Our predictions are in good qualitative agreement with several new experiments that are reported herein and demonstrate how f controls the aster-star transition and bundle length. We also present two models for aster growth corresponding to different experimental realizations. The first treats filament and bundle association as an irreversible sequence of elongation-association steps. The second, applicable for low f, treats bundling as a reversible self-assembly process, where the optimal bundle size is dictated by the balance between surface and bending energies. Finally, we discuss the relevance of our conclusions for the lamellipodium to filopodia transition in living cells, noting that bundles are more likely nucleated by ‘‘tip complex’’ cross-linkers (e.g. mDia2 or Ena/VASP), whereas fascin is mainly involved in bundle maintenance.

"Game Engineering" deals with the application of game theoretic methods to interactive situations or systems in which the rules are well defined, or where the designer can himself specify the rules. This talk, which addressed a business-school audience with no specific knowledge of game theory, describes five examples of game engineering: two dealing with auctions, two with traffic systems, and one with arbitration. At the end of the talk there was a Q & A session, which, too, is recorded here.

The subset agreement problem generalizes all forms of two-sided matching. Two agents need to agree on some subset of a given

We produce carrier-envelope-phase-stable 15.7-fs (2-cycle) 740-μJ pulses at the 2.1-μm carrier wavelength, from a three-stage optical parametric chirped-pulse amplifier system, pumped by an optically synchronized 49-ps 11-mJ Nd:YLF laser. A novel seed pulse spectral shaping method is used to ascertain the true amplified seed energy and the parametric superfluorescence levels.

We investigate the generation of squeezing and entanglement for the motional degrees of freedom of ions in linear traps, confined by time-varying and oscillating potentials, comprised of a DC and an AC component. We show that high degrees of squeezing and entanglement can be obtained by controlling either the DC or the AC trapping component (or both), and by exploiting transient dynamics in regions where the ions’ motion is unstable, without any added optical control. Furthermore, we investigate the time-scales over which the potentials should be switched in order for the manipulations to be most effective.

An international sample of 130 working artists was divided into two domains: generators (writers, designers, choreographers, one composer) and interpreters (directors, actors, opera singers, dancers). The correlations between dissociation, trauma experiences, fantasy proneness, and affective states were examined, followed by a regression analysis to predict elevated levels of dissociation. Artists, regardless of creative domain, scored in the moderate range for dissociation and fantasy proneness. Both groups endorsed lower levels of affective variability than a normed group. Interpreters scored significantly higher than generators on total dissociation, absorption/imagination, absorption/changeability, and depersonalization/derealization. Additive factors of younger age, affective states of anger, sadness and spirituality, and higher scores on fantasy proneness and traumatic experiences predicted elevated levels of dissociation, with only sadness predicting pathological dissociative levels on the taxometric Dissociative Experiences Scale-II (DES-II) subscale. Given these findings, greater awareness about dissociation and the need for an elaborated model of affect regulation is recommended.

An international sample of 130 working artists was divided into two domains: generators (writers, designers, choreographers, one composer) and interpreters (directors, actors, opera singers, dancers). The correlations between dissociation, trauma experiences, fantasy proneness, and affective states were examined, followed by a regression analysis to predict elevated levels of dissociation. Artists, regardless of creative domain, scored in the moderate range for dissociation and fantasy proneness. Both groups endorsed lower levels of affective variability than a normed group. Interpreters scored significantly higher than generators on total dissociation, absorption/imagination, absorption/changeability, and depersonalization/derealization. Additive factors of younger age, affective states of anger, sadness and spirituality, and higher scores on fantasy proneness and traumatic experiences predicted elevated levels of dissociation, with only sadness predicting pathological dissociative levels on the taxometric Dissociative Experiences Scale-II (DES-II) subscale. Given these findings, greater awareness about dissociation and the need for an elaborated model of affect regulation is recommended.

Specific mutations in human LMNA or loss of ZMPSTE26 activity cause abnormal processing of lamin A and early aging diseases, including Hutchinson Gilford progeria syndrome (HGPS). HGPS fibroblasts in culture undergo age-dependent progressive changes in nuclear architecture. Treating these cells with farnesyl transferase inhibitors (FTIs) reverse these nuclear phenotypes and also extend lifespan of mice HGPS models. Dermal cells derived from healthy old humans also accumulate the abnormally processed lamin A. However, the effect of FTIs on normal aging cells was not tested. Aging adult C. elegans cells show changes in nuclear architecture similar to HGPS fibroblasts and down regulating lamin expression in adult C. elegans reduces their lifespan. Here, we show that nuclei of adult C. elegans, in which lamin is down-regulated, have similar phenotypes to normal aging nuclei, but at an earlier age. We further show that treating adult C. elegans with the FTI gliotoxin reverses nuclear phenotypes and improves motility of aging worms. However, the average lifespan of the gliotoxin-treated animals was similar to that of untreated animals. These results suggest that lamins are involved in the process of normal aging in C. elegans.