Shape selection of surface-bound helical filaments: biopolymers on curved membranes

Motivated to understand the behavior of biological filaments interacting with membranes of various types, we study a theoretical model for the shape and thermodynamics of intrinsically-helical filaments bound to curved membranes. We show filament-surface interactions lead to a host of non-uniform shape equilibria, in which filaments progressively unwind from their native twist with increasing surface interaction and surface curvature, ultimately adopting uniform-contact curved shapes. The latter effect is due to non-linear coupling between elastic twist and bending of filaments on anisotropically-curved surfaces, such as the cylindrical surfaces considered here. Via a combination of numerical solutions and asymptotic analysis of shape equilibria we show that filament conformations are critically sensitive to the surface curvature in both the strong- and weak-binding limits. These results suggest that local structure of membrane-bound chiral filaments is generically sensitive to the curvature-radius of the surface to which it is bound, even when that radius is much larger than the filament intrinsic pitch. Typical values of elastic parameters and interaction energies for several prokaryotic and eukaryotic filaments indicate that biopolymers are inherently very sensitive to the coupling between twist, interactions and geometry and that this could be exploited for regulation of a variety of processes such as the targeted exertion of forces, signaling and self-assembly in response to geometric cues including the local mean and Gaussian curvatures

The electronic structure and localized molecular orbitals in S<SUB>4</SUB>N<SUB>4</SUB> by the CNDO/BW theory

The energies calculated for tetranitrogen tetrasulfide, S4N4, by the CNDO/BW theory favor a structure with coplanar nitrogen atoms and not a structure with coplanar sulfur atoms. Both structures have been proposed from experimental studies. Localized molecular orbitals are calculated for S4N4 and used to choose the appropriate Lewis structure for the molecule. The hybridization at the nitrogen and sulfur atoms is discussed. There is electron delocalization in the molecule, the S-N bond is a bent bond involving pure p-orbitals on the sulfur and nitrogen atoms and there is a pure p-bent bond between the sulfur atoms on the same side of the coplanar nitrogen atoms. There is no N-N bond in S4N4

A Study on Image Enhancement Techniques using YCbCr Color Space Methods

We propose an image enhancement scheme by using YCBCR color space method. It shows the better feature of the processed input image. The acquired images are classified into three types, word document image, MRI image and scenery image. At first, the acquired inputs are converted to the gray scale to plot with the normalized histogram. Then, using the color space methods, the images are converted into YCBCR characteristics and there components are separated into individual modules(Y, CB, CR components). The processed image separates its in-features of luminance and chrominance components such as Y component, CB component and CR component. In Gray scale image, the Y is said to be the luminance feature also known as single component. In Color image, CB and CR is said to be the chromaticity of blue and red components. Further we find Hue, Saturation and Intensity components are classified from the same samples. Then the proposed technique shows its better performance than the other methods in the enhancement of images corrupted by Gaussian noise. The Experimental result shows that the proposed methods makes good enhancement in visual quality

On the evidence of deterministic chaos in ECG: surrogate and predictability analysis

The question whether the human cardiac system is chaotic or not has been an open one. Recent results in chaos theory have shown that the usual methods, such as saturation of correlation dimension D2 or the existence of positive Lyapunov exponent, alone do not provide sufficient evidence to confirm the presence of deterministic chaos in an experimental system. The results of surrogate data analysis together with the short-term prediction analysis can be used to check whether a given time series is consistent with the hypothesis of deterministic chaos. In this work nonlinear dynamical tools such as surrogate data analysis, short-term prediction, saturation of D2 and positive Lyapunov exponent have been applied to measured ECG data for several normal and pathological cases. The pathology presently studied are PVC (Premature Ventricular Contraction), VTA (Ventricular Tachy Arrhythmia), AV (Atrio-Ventricular) block and VF (Ventricular Fibrillation). While these results do not prove that ECG time series is definitely chaotic, they are found to be consistent with the hypothesis of chaotic dynamics

A study on prevalence and co-morbidity of bipolar and anxiety disorders in chronic headache patients

Background: Co morbidity between headache and psychiatric disorders is more prevalent in chronic headache patients. The bipolar disorders and anxiety disorders are predominant in migraine and TTH respectively. This co morbidities have a poor reflection and impact on quality and outcome of chronic headache patients and results in worst prognosis and poor response to medical treatment.Methods: The chronic headache patients especially migraine and tension type of headache were analyzed with following materials such as the structured psychiatric clinical interview with ICD-10 mental and behavioural disorder, DSM-5 criteria. HAM-A, HAM-D, BDI-2, BPRS, young mania rating scale, Yale-Brown Obsessive Compulsive Scale (Y-BOCS) and panic disorder scale.Results: Various subsets of bipolar disorder and anxiety disorder were found as follows: 74% of migraineurs are associated with psychiatric disorders in which bipolar affective disorder 6%, depressive episode 48%, dysthymia 30%, GAD 10% and Panic disorder 6%. 52% of TTH are associated with psychiatric disorders as follows: major depressive episode 52%, GAD 30%, separation anxiety disorder 6%, PTSD 7%, OCD 3% and panic disorder 2%.Conclusions: From previous and future studies the headache can be identified according to subsets of headache with psychiatric disorders make easier to provide appropriate pharmacological and psychological treatment which may reduce the chronicity and intractability of headache

Protein synthesis in Mycobacterium tuberculosis H37Rv and the effect of streptomycin in Streptomycin-Susceptible and -resistant Strains

An efficient in vitro amino acid-incorporating system from Mycobacterium tuberculosis H37Rv was standardized. Ribonucleic acid (RNA) isolated from phage-infected M. smegmatis cells served as natural messenger RNA and directed the incorporation of 14C-amino acids into protein. The effects of various antitubercular drugs and "known inhibitors" of protein synthesis on amino acid incorporation were studied. Antibiotics like chloramphenicol and tetracycline inhibited mycobacterial protein synthesis, though they failed to prevent the growth of the organism. This failure was shown to be due to the impermeability of mycobacteria to these drugs by use of "membrane-active" agents along with the antibiotics in growth inhibition studies. Several independent streptomycin-resistant mutants of M. tuberculosis H37Rv were isolated. Streptomycin inhibited the incorporation of 14C-amino acids into proteins by whole cells of a streptomycin-susceptible strain by more than 90%, whereas very little or no inhibition was observed in either high-level or low-level streptomycin-resistant strains. In vitro, streptomycin was an effective inhibitor of susceptible strains, whereas in streptomycin-resistant strains the concentration of streptomycin at which half-maximal inhibition was produced varied according to the resistance of whole cells, and there was a correlation between the two. In one low-level streptomycin-resistant mutant, the in vitro amino acid-incorporating system was as sensitive to various concentrations of streptomycin as the parental type, and a possible involvement of a membrane site in the development of low-level resistance was indicated. Streptomycin susceptibility and high-level resistance were shown to be ribosomal in nature

Modeling the formation of in vitro filopodia

Filopodia are bundles of actin filaments that extend out ahead of the leading edge of a crawling cell to probe its upcoming environment. {\it In vitro} experiments [D. Vignjevic {\it et al.}, J. Cell Biol. {\bf 160}, 951 (2003)] have determined the minimal ingredients required for the formation of filopodia from the dendritic-like morphology of the leading edge. We model these experiments using kinetic aggregation equations for the density of growing bundle tips. In mean field, we determine the bundle size distribution to be broad for bundle sizes smaller than a characteristic bundle size above which the distribution decays exponentially. Two-dimensional simulations incorporating both bundling and cross-linking measure a bundle size distribution that agrees qualitatively with mean field. The simulations also demonstrate a nonmonotonicity in the radial extent of the dendritic region as a function of capping protein concentration, as was observed in experiments, due to the interplay between percolation and the ratcheting of growing filaments off a spherical obstacle.Comment: 22 pages, 16 figure

Training manual on phytoplankton identification/taxonomy

The term 'plankton' was coined by Victor Hensen in 1887, denotes collectively all free floating and suspended bodies, both plants and animals, living or dead, that essentially move passively in a body of water. The phytoplankters are the microscopic plant life of the sea, which constitute the primary producers synthesizing the basic food. It belongs to the class Algae, which besides chlorophylls posses other characteristic pigments. The important components of phytoplankton are Diatoms (Bacillariophyceae), Dinoflagellates (Dinophyceae), Blue-green algae (Cyanophyceae), Phytoflagellates (Xanthophyceae, Chrysophyceae, Haptophyceae, Cryptophyceae) and Nannoplankters (Chlorella, Nannochloropsis etc.). In addition to these, two other Classes namely Silicoflagellates and Coccolithophores also belong to the category of phytoplankton

The quantum chemistry of valency

It is shown that the chemist's concept of valency can be put in quantum mechanical language. Such a quantification of valency opens up possibilities of new applications which are briefly reviewed. Valency is related to the equilibrium geometry of the molecule through a maximum valency principle. This principle, combined with the idea of molecular orbital valencies, provides a theoretical foundation for the well known Walsh diagrams. Valency can be used as an index of chemical reactivity and valency changes in a reaction can be used to determine the radical nature of intermediates and transition states as well as to indicate the allowed or forbidden nature of reaction paths. Molecular strain may be related to the loss of sigma valency