Thermodynamic entropy of a many body energy eigenstate

It is argued that a typical many body energy eigenstate has a well defined thermodynamic entropy and that individual eigenstates possess thermodynamic characteristics analogous to those of generic isolated systems. We examine large systems with eigenstate energies equivalent to finite temperatures. When quasi-static evolution of a system is adiabatic (in the quantum mechanical sense), two coupled subsystems can transfer heat from one subsystem to another yet remain in an energy eigenstate. To explicitly construct the entropy from the wave function, degrees of freedom are divided into two unequal parts. It is argued that the entanglement entropy between these two subsystems is the thermodynamic entropy per degree of freedom for the smaller subsystem. This is done by tracing over the larger subsystem to obtain a density matrix, and calculating the diagonal and off-diagonal contributions to the entanglement entropy.Comment: 18 page

Arabidopsis RTNLB1 and RTNLB2 reticulon-like proteins regulate intracellular trafficking and activity of the FLS2 immune receptor

Receptors localized at the plasma membrane are critical for the recognition of pathogens. The molecular determinants that regulate receptor transport to the plasma membrane are poorly understood. In a screen for proteins that interact with the FLAGELIN-SENSITIVE2 (FLS2) receptor using Arabidopsis thaliana protein microarrays, we identified the reticulon-like protein RTNLB1. We showed that FLS2 interacts in vivo with both RTNLB1 and its homolog RTNLB2 and that a Ser-rich region in the N-terminal tail of RTNLB1 is critical for the interaction with FLS2. Transgenic plants that lack RTNLB1 and RTNLB2 (rtnlb1 rtnlb2) or overexpress RTNLB1 (RTNLB1ox) exhibit reduced activation of FLS2-dependent signaling and increased susceptibility to pathogens. In both rtnlb1 rtnlb2 and RTNLB1ox, FLS2 accumulation at the plasma membrane was significantly affected compared with the wild type. Transient overexpression of RTNLB1 led to FLS2 retention in the endoplasmic reticulum (ER) and affected FLS2 glycosylation but not FLS2 stability. Removal of the critical N-terminal Serrich region or either of the two Tyr-dependent sorting motifs from RTNLB1 causes partial reversion of the negative effects of excess RTNLB1 on FLS2 transport out of the ER and accumulation at the membrane. The results are consistent with a model whereby RTNLB1 and RTNLB2 regulate the transport of newly synthesized FLS2 to the plasma membrane. © 2011 American Society of Plant Biologists. All rights reserved

Reversed Janus Micro/Nanomotors with Internal Chemical Engine

Self-motile Janus colloids are important for enabling a wide variety of microtechnology applications as well as for improving our understanding of the mechanisms of motion of artificial micro- and nanoswimmers. We present here micro/nanomotors which possess a reversed Janus structure of an internal catalytic "chemical engine". The catalytic material (here platinum (Pt)) is embedded within the interior of the mesoporous silica (mSiO(2))-based hollow particles and triggers the decomposition of H2O2 when suspended in an aqueous peroxide (H2O2) solution. The pores/gaps at the noncatalytic (Pt) hemisphere allow the exchange of chemical species in solution between the exterior and the interior of the particle. By varying the diameter of the particles, we observed size-dependent motile behavior in the form of enhanced diffusion for 500 nm particles, and self-phoretic motion, toward the nonmetallic part, for 1.5 and 3 mu m ones. The direction of motion was rationalized, by a theoretical model based on self-phoresis. For the 3 mu m particles, a change in the morphology of the porous part is observed, which is accompanied by a change in the mechanism of propulsion via bubble nucleation and ejection as well as a change in the direction of motion.1128Ysciescopu

The foundations of statistical mechanics from entanglement: Individual states vs. averages

We consider an alternative approach to the foundations of statistical mechanics, in which subjective randomness, ensemble-averaging or time-averaging are not required. Instead, the universe (i.e. the system together with a sufficiently large environment) is in a quantum pure state subject to a global constraint, and thermalisation results from entanglement between system and environment. We formulate and prove a "General Canonical Principle", which states that the system will be thermalised for almost all pure states of the universe, and provide rigorous quantitative bounds using Levy's Lemma.Comment: 12 pages, v3 title changed, v2 minor change

Telocytes and putative stem cells in the lungs: electron microscopy, electron tomography and laser scanning microscopy

This study describes a novel type of interstitial (stromal) cell — telocytes (TCs) — in the human and mouse respiratory tree (terminal and respiratory bronchioles, as well as alveolar ducts). TCs have recently been described in pleura, epicardium, myocardium, endocardium, intestine, uterus, pancreas, mammary gland, etc. (see www.telocytes.com). TCs are cells with specific prolongations called telopodes (Tp), frequently two to three per cell. Tp are very long prolongations (tens up to hundreds of μm) built of alternating thin segments known as podomers (≤ 200 nm, below the resolving power of light microscope) and dilated segments called podoms, which accommodate mitochondria, rough endoplasmic reticulum and caveolae. Tp ramify dichotomously, making a 3-dimensional network with complex homo- and heterocellular junctions. Confocal microscopy reveals that TCs are c-kit- and CD34-positive. Tp release shed vesicles or exosomes, sending macromolecular signals to neighboring cells and eventually modifying their transcriptional activity. At bronchoalveolar junctions, TCs have been observed in close association with putative stem cells (SCs) in the subepithelial stroma. SCs are recognized by their ultrastructure and Sca-1 positivity. Tp surround SCs, forming complex TC-SC niches (TC-SCNs). Electron tomography allows the identification of bridging nanostructures, which connect Tp with SCs. In conclusion, this study shows the presence of TCs in lungs and identifies a TC-SC tandem in subepithelial niches of the bronchiolar tree. In TC-SCNs, the synergy of TCs and SCs may be based on nanocontacts and shed vesicles

Cardiac telocytes — their junctions and functional implications

Telocytes (TCs) form a cardiac network of interstitial cells. Our previous studies have shown that TCs are involved in heterocellular contacts with cardiomyocytes and cardiac stem/progenitor cells. In addition, TCs frequently establish ‘stromal synapses’ with several types of immunoreactive cells in various organs (www.telocytes.com). Using electron microscopy (EM) and electron microscope tomography (ET), we further investigated the interstitial cell network of TCs and found that TCs form ‘atypical’ junctions with virtually all types of cells in the human heart. EM and ET showed different junction types connecting TCs in a network (puncta adhaerentia minima, processus adhaerentes and manubria adhaerentia). The connections between TCs and cardiomyocytes are ‘dot’ junctions with nanocontacts or asymmetric junctions. Junctions between stem cells and TCs are either ‘stromal synapses’ or adhaerens junctions. An unexpected finding was that TCs have direct cell–cell (nano)contacts with Schwann cells, endothelial cells and pericytes. Therefore, ultrastructural analysis proved that the cardiac TC network could integrate the overall ‘information’ from vascular system (endothelial cells and pericytes), nervous system (Schwann cells), immune system (macrophages, mast cells), interstitium (fibroblasts, extracellular matrix), stem cells/progenitors and working cardiomyocytes. Generally, heterocellular contacts occur by means of minute junctions (point contacts, nanocontacts and planar contacts) and the mean intermembrane distance is within the macromolecular interaction range (10–30 nm). In conclusion, TCs make a network in the myocardial interstitium, which is involved in the long-distance intercellular signaling coordination. This integrated interstitial system appears to be composed of large homotropic zones (TC–TC junctions) and limited (distinct) heterotropic zones (heterocellular junctions of TCs)

de Branges-Rovnyak spaces: basics and theory

For $S$ a contractive analytic operator-valued function on the unit disk ${\mathbb D}$, de Branges and Rovnyak associate a Hilbert space of analytic functions ${\mathcal H}(S)$ and related extension space ${\mathcal D(S)}$ consisting of pairs of analytic functions on the unit disk ${\mathbb D}$. This survey describes three equivalent formulations (the original geometric de Branges-Rovnyak definition, the Toeplitz operator characterization, and the characterization as a reproducing kernel Hilbert space) of the de Branges-Rovnyak space ${\mathcal H}(S)$, as well as its role as the underlying Hilbert space for the modeling of completely non-isometric Hilbert-space contraction operators. Also examined is the extension of these ideas to handle the modeling of the more general class of completely nonunitary contraction operators, where the more general two-component de Branges-Rovnyak model space ${\mathcal D}(S)$ and associated overlapping spaces play key roles. Connections with other function theory problems and applications are also discussed. More recent applications to a variety of subsequent applications are given in a companion survey article

Magnified image spatial spectrum (MISS) microscopy for nanometer and millisecond scale label-free imaging

Label-free imaging of rapidly moving, sub-diffraction sized structures has important applications in both biology and material science, as it removes the limitations associated with fluorescence tagging. However, unlabeled nanoscale particles in suspension are difficult to image due to their transparency and fast Brownian motion. Here we describe a novel interferometric imaging technique referred to as Magnified Image Spatial Spectrum (MISS) microscopy, which overcomes these challenges. The MISS microscope provides quantitative phase information and enables dynamic light scattering investigations with an overall optical path length sensitivity of 0.95 nm at 833 frames per second acquisition rate. Using spatiotemporal filtering, we find that the sensitivity can be further pushed down to 10−3-10−2 nm. We demonstrate the instrument???s capability through colloidal nanoparticle sizing down to 20 nm diameter and measurements of live neuron membrane dynamics. MISS microscopy is implemented as an upgrade module to an existing microscope, which converts it into a powerful light scattering instrument. Thus, we anticipate that MISS will be adopted broadly for both material and life sciences applications