Protein misfolding thermodynamics

It is known that protein misfolding is governed by the hydrophobic effect of solutes at hydrophobic amino acid side chains. The hydrophobic force of nonaqueous solutes acts as a driving force for the spatial rearrangement of protein side chains, whose structural transitions need to be regulated in both time and space. Smaller hydrophobic solutes exert more effect at protein side chains, which involves the clustering of proteins into misfolded shapes. The consequences of misfolding are loss of protein function, gain of toxic function, or both. This is a physical process, whose result has been directly linked to a large number of human diseases

Thermodynamics of mechanopeptide sidechains

Biological systems are often exposed to mechanical perturbations, which may modulate many biochemical processes. Ligand binding involves a wide range of structural changes in the receptor protein, from hinge movement of entire domains to minor sidechain rearrangements in the binding pocket residues. Hydrophobic ligand binding to protein alters the system’s vibrational free energy, allowing different conformational states of allosteric proteins. Excess hydrophobicity in protein–ligand binding generates mechanical force along the peptide backbone through the hydrophobic effect. We describe mechanically strained peptide structures involved in protein aggregation to determine the transition between the initial condensation of hydrophobic polypeptide chains into ordered fibrillar structures. This transition is due to the excess attractive hydrophobic force by ligand binding within proteins into fibrillar assemblies. The process of fibrillar formation has a mechanosensitive nature, which significantly influences the pathogenesis of several neurodegenerative diseases

Entropy and Exact Matrix Product Representation of the Laughlin Wave Function

An analytical expression for the von Neumann entropy of the Laughlin wave function is obtained for any possible bipartition between the particles described by this wave function, for filling fraction nu=1. Also, for filling fraction nu=1/m, where m is an odd integer, an upper bound on this entropy is exhibited. These results yield a bound on the smallest possible size of the matrices for an exact representation of the Laughlin ansatz in terms of a matrix product state. An analytical matrix product state representation of this state is proposed in terms of representations of the Clifford algebra. For nu=1, this representation is shown to be asymptotically optimal in the limit of a large number of particles

Attracting Foreign Direct Investment in Bangladesh

This article seeks to depict the needs of Foreign Direct Investment (FDI) in Bangladesh along with the required determinants of congenial investment environments. In terms of the identified determinants of FDI, this study delineates the competitive and inductive factors other FDI recipient countries have in comparison to that of Bangladesh. The study also identifies the determinants of FDI that Bangladesh have. Reasons of why Bangladesh could not attract enough FDI have also been sought. The feasible attractive measures required in attracting the much-needed investment in the competitive FDI market have also been shown. In doing this, international competitors of FDI have been traced to locate the position of Bangladesh. Secondary published data from governments and other significant agencies have been comprehensively studied to get the required data in completing the study

Deformation of a Trapped Fermi Gas with Unequal Spin Populations

The real-space densities of a polarized strongly-interacting two-component Fermi gas of $^6$Li atoms reveal two low temperature regimes, both with a fully-paired core. At the lowest temperatures, the unpolarized core deforms with increasing polarization. Sharp boundaries between the core and the excess unpaired atoms are consistent with a phase separation driven by a first-order phase transition. In contrast, at higher temperatures the core does not deform but remains unpolarized up to a critical polarization. The boundaries are not sharp in this case, indicating a partially-polarized shell between the core and the unpaired atoms. The temperature dependence is consistent with a tricritical point in the phase diagram.Comment: Accepted for publication in Physical Review Letter

Analysis of a fully packed loop model arising in a magnetic Coulomb phase

The Coulomb phase of spin ice, and indeed the Ic phase of water ice, naturally realise a fully-packed two-colour loop model in three dimensions. We present a detailed analysis of the statistics of these loops, which avoid themselves and other loops of the same colour, and contrast their behaviour to an analogous two-dimensional model. The properties of another extended degree of freedom are also addressed, flux lines of the emergent gauge field of the Coulomb phase, which appear as "Dirac strings" in spin ice. We mention implications of these results for related models, and experiments.Comment: 5 pages, 4 figure

Localisation of 11β-Hydroxysteroid Dehydrogenase Type 2 in Mineralocorticoid Receptor Expressing Magnocellular Neurosecretory Neurones of the Rat Supraoptic and Paraventricular Nuclei

© 2015 British Society for Neuroendocrinology. An accumulating body of evidence suggests that the activity of the mineralocorticoid, aldosterone, in the brain via the mineralocorticoid receptor (MR) plays an important role in the regulation of blood pressure. MR was recently found in vasopressin and oxytocin synthesising magnocellular neurosecretory cells (MNCs) in both the paraventricular (PVN) and supraoptic (SON) nuclei in the hypothalamus. Considering the physiological effects of these hormones, MR in these neurones may be an important site mediating the action of aldosterone in blood pressure regulation within the brain. However, aldosterone activation of MR in the hypothalamus remains controversial as a result of the high binding affinity of glucocorticoids to MR at substantially higher concentrations compared to aldosterone. In aldosterone-sensitive epithelia, the enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) prevents glucocorticoids from binding to MR by converting glucocorticoids into inactive metabolites. The present study aimed to determine whether 11β-HSD2, which increases aldosterone selectivity, is expressed in MNCs. Specific 11β-HSD2 immunoreactivity was found in the cytoplasm of the MNCs in both the SON and PVN. In addition, double-fluorescence confocal microscopy demonstrated that MR-immunoreactivity and 11β-HSD2-in situ hybridised products are colocalised in MNCs. Lastly, single-cell reverse transcriptase-polymerase chain reaction detected MR and 11β-HSD2 mRNAs from cDNA libraries derived from single identified MNCs. These findings strongly suggest that MNCs in the SON and PVN are aldosterone-sensitive neurones

Racial Differences in the Use of Most Commonly Performed Medical Procedures in the United States

Objective: This study investigates racial disparities in the use of commonly performed medical procedures in U.S. hospitals. Methods: To examine racial disparities, we calculated age-adjusted rate of procedures used by all Whites, Blacks, Hispanics, Asians or Pacific Islanders and Native Americans and calculated corresponding Relative Risks(RRs) of White vs. all other races based on procedure utilizations and insurance types using 20% random sample of Nationwide Inpatient Sample (NIS) data between 2001 and2003. Results: Whites were significantly more likely to receive 3 of the study procedures than Blacks, 3 of the procedures than Hispanics, 2 of the procedures than Asians or Pacific Islanders and 4 of the procedures than Native Americans (p\u3c0.05). We also found racial disparities to receive medical procedures based on patients’ insurance status.However, only in a few cases were these differences substantial. Conclusion: Race plays a significantly important role in the use of commonly performed medical procedures in U.S. hospitals

A new binding geometry for an ortho-xylylene-linked bis(NHC)cyclophane: a ruthenium(II) complex with a chelating (g1-NHC)2:g6-arene ligand

Using two different reaction procedures, a Ru(II) complex has been isolated that contains an ortho-xylylene-linked bis(NHC)cyclophane (NHC = N-heterocyclic carbene) that binds to the Ru centre through two carbene carbons and one of the arene rings in an η6-mode

Elastic scattering of electrons and positrons from In-115 atoms over the energy range 1 eV-0.5 GeV

We present a theoretical study on the calculations of various cross sections related to the scattering of electrons and positrons from indium atoms. Our calculations cover the energy range 1 eV <= E-i <= 0.5 GeV. We have employed two approaches, applicable for two domains of energy, based on the Dirac partial-wave analysis. In one approach, we have used both the atomic and nuclear potentials to calculate the cross sections for the low and intermediate energies. The other approach, valid for the high-energy scattering, utilizes only the nuclear potential for the phase-shift analysis, and considers the magnetic scattering from the nucleus too. We report the calculations of differential, integral, momentum-transfer and viscosity cross sections along with the spin asymmetries for the elastic scattering of electrons and positrons. Moreover, we have analyzed the critical minima in the elastic differential cross sections, and also computed the absorption and total cross sections. Our results agree reasonably with the available experimental data and other calculations