Glassy Dynamics of Protein Folding

A coarse grained model of a random polypeptide chain, with only discrete torsional degrees of freedom and Hookean springs connecting pairs of hydrophobic residues is shown to display stretched exponential relaxation under Metropolis dynamics at low temperatures with the exponent $\beta\simeq 1/4$, in agreement with the best experimental results. The time dependent correlation functions for fluctuations about the native state, computed in the Gaussian approximation for real proteins, have also been found to have the same functional form. Our results indicate that the energy landscape exhibits universal features over a very large range of energies and is relatively independent of the specific dynamics.Comment: RevTeX, 4 pages, multicolumn, including 5 figures; larger computations performed, error bars improve

SAXS studies of the thermally-induced fusion of diblock copolymer spheres : formation of hybrid nanoparticles of intermediate size and shape

Dilute dispersions of poly(lauryl methacrylate)–poly(benzyl methacrylate) (PLMA–PBzMA) diblock copolymer spheres (a.k.a. micelles) of differing mean particle diameter were mixed and thermally annealed at 150 °C to produce spherical nanoparticles of intermediate size. The two initial dispersions were prepared via reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization of benzyl methacrylate in n-dodecane at 90 °C. Systematic variation of the mean degree of polymerization of the core-forming PBzMA block enabled control over the mean particle diameter: small-angle X-ray scattering (SAXS) analysis indicated that PLMA39–PBzMA97 and PLMA39–PBzMA294 formed well-defined, non-interacting spheres at 25 °C with core diameters of 21 ± 2 nm and 48 ± 5 nm, respectively. When heated separately, both types of nanoparticles regained their original dimensions during a 25–150–25 °C thermal cycle. However, the cores of the smaller nanoparticles became appreciably solvated when annealed at 150 °C, whereas the larger nanoparticles remained virtually non-solvated at this temperature. Moreover, heating caused a significant reduction in mean aggregation number for the PLMA39–PBzMA97 nanoparticles, suggesting their partial dissociation at 150 °C. Binary mixtures of PLMA39–PBzMA97 and PLMA39–PBzMA294 nanoparticles were then studied over a wide range of compositions. For example, annealing a 1.0% w/w equivolume binary mixture led to the formation of a single population of spheres of intermediate mean diameter (36 ± 4 nm). Thus we hypothesize that the individual PLMA39–PBzMA97 chains interact with the larger PLMA39–PBzMA294 nanoparticles to form the hybrid nanoparticles. Time-resolved SAXS studies confirm that the evolution in copolymer morphology occurs on relatively short time scales (within 20 min at 150 °C) and involves weakly anisotropic intermediate species. Moreover, weakly anisotropic nanoparticles can be obtained as a final copolymer morphology over a restricted range of compositions (e.g. for PLMA39–PBzMA97 volume fractions of 0.20–0.35) when heating dilute dispersions of such binary nanoparticle mixtures up to 150 °C. A mechanism involving both chain expulsion/insertion and micelle fusion/fission is proposed to account for these unexpected observations

Developmental parameters and physical fitness in preschool children with minor neurological dysfunction

Background. The preschool years constitute a critical period during which significant changes are experienced in the acquisition of locomotor skills due to maturation of the nervous system. Our aim was to investigate the developmental parameters and physical fitness in preschool children with Minor Neurological Dysfunction (MND). Methods. The study was carried out in 212 preschool children without any known health problems. Sociodemographic characteristics of children were recorded. Denver Developmental Screening Test (DDST) II, Touwen Neurological Examination, and Preschool Physical Fitness (PREFIT) test battery were used to assess developmental parameters, neurological status, and physical fitness, respectively. Results. There was a statistical difference in the physical fitness and developmental parameters in preschool children with MND compared with healthy peers (p<0.05). There was also a relationship between physical fitness and developmental parameters (p<0.05). Conclusions. Early identification of problems in developmental parameters and physical fitness in preschool children with MND might help to implement early supportive physiotherapy and rehabilitation. © 2021, Turkish National Pediatric Society. All rights reserved

Energy efficient power control and radio resource management in multi-connectivity framework

In this paper, CoMP (Coordinated Multi-Point Transmission and Reception) technique is studied to mitigate interference effects in cellular networks in which distributed antenna systems (DAS) are utilized. Power control and resource allocation problem is jointly optimized in a multi-user, multi-carrier downlink scenario where backhaul between base station and remote radio heads (antenna) are assumed lossless. Energy efficient radio resource management (RRM) algorithms are produced offering (sub)optimum solutions in a multi-connectivity framework providing user equipments connecting multiple access points simultaneously

A novel form of recessive limb girdle muscular dystrophy with mental retardation and abnormal expression of α-dystroglycan

The limb girdle muscular dystrophies are a heterogeneous group of conditions characterized by proximal muscle weakness and disease onset ranging from infancy to adulthood. We report here eight patients from seven unrelated families affected by a novel and relatively mild form of autosomal recessive limb girdle muscular dystrophy (LGMD2) with onset in the first decade of life and characterized by severe mental retardation but normal brain imaging. Immunocytochemical studies revealed a significant selective reduction of α-dystroglycan expression in the muscle biopsies. Linkage analysis excluded known loci for both limb girdle muscular dystrophy and congenital muscular dystrophies in the consanguineous families. We consider that this represents a novel form of muscular dystrophy with associated brain involvement. The biochemical studies suggest that it may belong to the growing number of muscular dystrophies with abnormal expression of α-dystroglycan. © 2003 Published by Elsevier B.V