트룰스티 츠비 교수

Rubisco (D-ribulose 1,5-bisphosphate carboxylase/oxygenase), probably the most abundant protein in the biosphere, performs an essential part in the process of carbon fixation through photosynthesis, thus facilitating life on earth. Despite the significant effect that Rubisco has on the fitness of plants and other photosynthetic organisms, this enzyme is known to have a low catalytic rate and a tendency to confuse its substrate, carbon dioxide, with oxygen. This apparent inefficiency is puzzling

A defect-induced, critical phase separation in dipolar fluids is predicted, which replaces the usual liquid-gas transition that is driven by the isotropic aggregation of particles and is absent in dipolar fluids due to strong chaining. The coexisting phases are a dilute gas of chain ends that coexists with a high-density liquid of chain branching points. Our model provides a unified explanation for the branched structures, the unusually low critical temperature and density, and the consequent tw

To perform recognition, molecules must locate and specifically bind their targets within a noisy biochemical environment with many look-alikes. Molecular recognition processes, especially the induced-fit mechanism, are known to involve conformational changes. This raises a basic question: Does molecular recognition gain any advantage by such conformational changes? By introducing a simple statistical-mechanics approach, we study the effect of conformation and flexibility on the quality of recogn

We present a new approach for determining optical gradient forces applied by strongly focused laser beams on dielectric particles. We show that when the electromagnetic field is focused to a diffraction limited spot a dipole approximation is valid for any particle size. We derive intuitive predictions for force-displacement curves, maximal trapping forces, and force constants. The theory fits well with recent measurements of particles trapped by laser tweezers. We also discuss effects of radiati

We predict theoretically the gradual formation of fluctuating, connected microemulsion networks from disconnected globules as the spontaneous curvature is varied, in agreement with recent direct measurements of these topological transitions. The connectivity induced instability together with emulsification failure of the network relate the ultralow tensions and wetting transition to the changing microstructure.

Density fluctuations and the Widom line are of great importance in understanding the critical phenomena and the behaviors of supercritical fluids (SCFs). We report on the direct classification of liquid-like and gas-like molecules coexisting in the SCF, identified by machine learning analysis on simulation data. The deltoid coexistence region encloses the Widom line and may therefore be termed the Widom delta. Number fractions of gas-like and liquid-like particles are found to undergo continuous

We introduce a model for microemulsions whose basic building blocks are cylindrical tubes connected by spherical junctions forming a network. The model predicts analytic scaling laws which quantitatively reproduce several prominent experimental features of the phase diagram, including the closed loops of 2-phase coexistence and the 3-phase body. The interfacial nature of our model, which takes into account only the curvature energy and the entropy of the interface, explains the observed water/oi

We examine bootstrap percolation in d-dimensional, directed metric graphs in the context of recent measurements of firing dynamics in 2D neuronal cultures. There are two regimes, depending on the graph size N. Large metric graphs are ignited by the occurrence of critical nuclei, which initially occupy an infinitesimal fraction, f_* -> 0, of the graph and then explode throughout a finite fraction. Smaller metric graphs are effectively random in the sense that their ignition requires the initial i

Abstract. We predict theoretically the gradual formation of fluctuating, connected microemulsion networks from disconnected cylinders as the spontaneous curvature and the radius are varied, in agreement with recent direct measurements of these topological transitions. We discuss the role of the topological defects, the network junction and the end-cap of the disconnected cylinders, in the connectivity transition. The optimal shapes and curvature energies of the junctions and end-caps are calcula

A relation between the multiplicity m of the second eigenvalue λ2 of a Laplacian ona graph G, tight mappings of G and a discrete analogue of Courant’s nodal line theorem is discussed.For a certain class of graphs, it is shown that the m-dimensional eigenspace of λ2 is tight and thusdefines a tight mapping of G into an m-dimensional Euclidean space. The tightness of the mappingis shown to set Colin de Verdi´ere’s upper bound on the maximal λ2-multiplicity, m ≤ chr(γ(G)) − 1,where chr(γ(G)) is the