L1CAM binds ErbB receptors through Ig-like domains coupling cell adhesion and neuregulin signalling.

During nervous system development different cell-to-cell communication mechanisms operate in parallel guiding migrating neurons and growing axons to generate complex arrays of neural circuits. How such a system works in coordination is not well understood. Cross-regulatory interactions between different signalling pathways and redundancy between them can increase precision and fidelity of guidance systems. Immunoglobulin superfamily proteins of the NCAM and L1 families couple specific substrate recognition and cell adhesion with the activation of receptor tyrosine kinases. Thus it has been shown that L1CAM-mediated cell adhesion promotes the activation of the EGFR (erbB1) from Drosophila to humans. Here we explore the specificity of the molecular interaction between L1CAM and the erbB receptor family. We show that L1CAM binds physically erbB receptors in both heterologous systems and the mammalian developing brain. Different Ig-like domains located in the extracellular part of L1CAM can support this interaction. Interestingly, binding of L1CAM to erbB enhances its response to neuregulins. During development this may synergize with the activation of erbB receptors through L1CAM homophilic interactions, conferring diffusible neuregulins specificity for cells or axons that interact with the substrate through L1CAM

Advancing COVID-19 response through community participation: Lessons learned from community–academic research partnerships for health

Community Health Sciences, Counseling and Counseling Psycholog

The Spitzer South Pole Telescope Deep Field Survey: Linking galaxies and halos at z=1.5

We present an analysis of the clustering of high-redshift galaxies in the recently completed 94 deg$^2$ Spitzer-SPT Deep Field survey. Applying flux and color cuts to the mid-infrared photometry efficiently selects galaxies at $z\sim1.5$ in the stellar mass range $10^{10}-10^{11}M_\odot$, making this sample the largest used so far to study such a distant population. We measure the angular correlation function in different flux-limited samples at scales $>6^{\prime \prime}$ (corresponding to physical distances $>0.05$ Mpc) and thereby map the one- and two-halo contributions to the clustering. We fit halo occupation distributions and determine how the central galaxy's stellar mass and satellite occupation depend on the halo mass. We measure a prominent peak in the stellar-to-halo mass ratio at a halo mass of $\log(M_{\rm halo} / M_\odot) = 12.44\pm0.08$, 4.5 times higher than the $z=0$ value. This supports the idea of an evolving mass threshold above which star formation is quenched. We estimate the large-scale bias in the range $b_g=2-4$ and the satellite fraction to be $f_\mathrm{sat}\sim0.2$, showing a clear evolution compared to $z=0$. We also find that, above a given stellar mass limit, the fraction of galaxies that are in similar mass pairs is higher at $z=1.5$ than at $z=0$. In addition, we measure that this fraction mildly increases with the stellar mass limit at $z=1.5$, which is the opposite of the behavior seen at low-redshift.Comment: 32 pages, 22 figures. Published in MNRA

Drift of a polymer chain in disordered media

We consider the drift of a polymer chain in a disordered medium, which is caused by a constant force applied to the one end of the polymer, under neglecting the thermal fluctuations. In the lowest order of the perturbation theory we have computed the transversal fluctuations of the centre of mass of the polymer, the transversal and the longitudinal size of the polymer, and the average velocity of the polymer. The corrections to the quantities under consideration, which are due to the interplay between the motion and the quenched forces, are controlled by the driving force and the degree of polymerization. The transversal fluctuations of the Brownian particle and of the centre of mass of the polymer are obtained to be diffusive. The transversal fluctuations studied in the present Letter may also be of relevance for the related problem of the drift of a directed polymer in disordered media and its applications.Comment: 11 pages, RevTex, Accepted for publication in Europhysics Letter

On time and the quantum-to-classical transition in Jordan-Brans-Dicke quantum gravity

Any quantum theory of gravity which treats the gravitational constant as a dynamical variable has to address the issue of superpositions of states corresponding to different eigenvalues. We show how the unobservability of such superpositions can be explained through the interaction with other gravitational degrees of freedom (decoherence). The formal framework is canonically quantized Jordan-Brans-Dicke theory. We discuss the concepts of intrinsic time and semiclassical time as well as the possibility of tunneling into regions corresponding to a negative gravitational constant. We calculate the reduced density matrix of the Jordan-Brans-Dicke field and show that the off-diagonal elements can be sufficiently suppressed to be consistent with experiments. The possible relevance of this mechanism for structure formation in extended inflation is briefly discussed.Comment: 10 pages, Latex, ZU-TH 15/93, BUTP-93/1

DIFFERENTIAL EVOLUTION ALGORITHM APPLIED IN A NUMERICAL COST OPTIMIZATION DESIGN OF A SHELL AND-TUBE HEAT EXCHANGER

Shell-and-tube heat exchangers are the most common heat exchangers that can be found in several industrial applications. The reduction of the investment cost and the operation of this equipment it’s one of main industrial designers and entrepreneurs aim. With the intention of reducing total costs of a shell-and-tube heat exchangers, as proposed by Caputo et al. (2008), employed in this present study the optimization technique called Differential Evolution (DE), which basically consists in a calculation mechanism, supported on operators of “crossing” and “mutation” differential, through mathematical and heuristics arguments that indicate your adequacy for function optimization. This study is defined as a mono-objective optimization problem and the total cost of a shell-and-tube heat exchanger is the objective function. To this, it was taken as a design variable intern diameter tube, the outer diameter of the shell and the spacing between baffles or deflectors. The results reached in this work were compared with the same problem when used GA (Genetics Algorithms), PSO (Particle Swarm Optimization), QPSO (Quantum Particle Swarm Optimization) and QPSOZ (Quantum Particle Swarm Optimization by Zaslavskii). Regarding the literature, the capital investment in the heat exchange reduces corresponding in 15.2% and consequently the depreciation charge of the equipment decrease approximately 12.5%. In general, the total cost of the shell-and-tube heat exchange in analysis, presented a reduction of 15%, showing the potential of applied method in this study, the technique DE

Stochastics theory of log-periodic patterns

We introduce an analytical model based on birth-death clustering processes to help understanding the empirical log-periodic corrections to power-law scaling and the finite-time singularity as reported in several domains including rupture, earthquakes, world population and financial systems. In our stochastics theory log-periodicities are a consequence of transient clusters induced by an entropy-like term that may reflect the amount of cooperative information carried by the state of a large system of different species. The clustering completion rates for the system are assumed to be given by a simple linear death process. The singularity at t_{o} is derived in terms of birth-death clustering coefficients.Comment: LaTeX, 1 ps figure - To appear J. Phys. A: Math & Ge