Speech segmentation using extrema based signal track length measure

We introduce a novel temporal feature of a signal, namely extrema-based signal track length (ESTL) for the problem of speech segmentation. We show that ESTL measure is sensitive to both amplitude and frequency of the signal. The short-time ESTL (ST_ESTL) shows a promising way to capture the significant segments of speech signal, where the segments correspond to acoustic units of speech having distinct temporal waveforms. We compare ESTL based segmentation with ML and STM methods and find that it is as good as spectral feature based segmentation, but with lesser computational complexity.

Investigating Diproline Segments in Proteins: Occurrences, Conformation and Classification

The covalent linkage between the side-chain and the backbone nitrogen atom of proline leads to the formation of the five-membered pyrrolidine ring and hence restriction of the backbone torsional angle phi to values of -60 degrees +/- 30 degrees for the L-proline. Diproline segments constitute a chain fragment with considerably reduced conformational choices. In the current study, the conformational states for the diproline segment ((L)Pro-(L)Pro) found in proteins has been investigated with an emphasis on the cis and trans states for the Pro-Pro peptide bond. The occurrence of diproline segments in turns and other secondary structures has been studied and compared to that of Xaa-Pro-Yaa segments in proteins which gives us a better understanding on the restriction imposed on other residues by the diproline segment and the single proline residue. The study indicates that P(II)-P(II) and P(II)-alpha are the most favorable conformational states for the diproline segment. The analysis on Xaa-Pro-Yaa sequences reveals that the XaaPro peptide bond exists preferably as the trans conformer rather than the cis conformer. The present study may lead to a better understanding of the behavior of proline occurring in diproline segments which can facilitate various designed diproline-based synthetic templates for biological and structural studies. (C) 2011 Wiley Periodicals, Inc. Biopolymers 97: 54-64, 2012.

Length of near-wall plumes in turbulent convection

We present planforms of line plumes formed on horizontal surfaces in turbulent convection, along with the length of line plumes measured from these planforms, in a six decade range of Rayleigh numbers (10(5) < Ra < 10(11)) and at three Prandtl numbers (Pr = 0.7, 5.2, 602). Using geometric constraints on the relations for the mean plume spacings, we obtain expressions for the total length of near-wall plumes on horizontal surfaces in turbulent convection. The plume length per unit area (L(p)/A), made dimensionless by the near-wall length scale in turbulent convection (Z(w)), remains constant for a given fluid. The Nusselt number is shown to be directly proportional to L(p)H/A for a given fluid layer of height H. The increase in Pr has a weak influence in decreasing L(p)/A. These expressions match the measurements, thereby showing that the assumption of laminar natural convection boundary layers in turbulent convection is consistent with the observed total length of line plumes. We then show that similar relationships are obtained based on the assumption that the line plumes are the outcome of the instability of laminar natural convection boundary layers on the horizontal surfaces.

Extending the Supramolecular Synthon Based Fragment Approach (SBFA) for Transferability of Multipole Charge Density Parameters to Monofluorobenzoic Acids and their Cocrystals with Isonicotinamide: Importance of C-H center dot center dot center dot O, C-H center dot center dot center dot F, and F center dot center dot center dot F Intermolecular Regions

An extension of the supramolecular synthon-based fragment approach (SBFA) method for transferability of multipole charge density parameters to include weak supramolecular synthons is proposed. In particular, the SBFA method is applied to C-H center dot center dot center dot O, C-H center dot center dot center dot F, and F center dot center dot center dot F containing synthons. A high resolution charge density study has been performed on 4-fluorobenzoic acid to build a synthon library for C-H center dot center dot center dot F infinite chain interactions. Libraries for C-H center dot center dot center dot O and F center dot center dot center dot F synthons were taken from earlier work. The SBFA methodology was applied successfully to 2- and 3-fluorobenzoic acids, data sets for which were collected in a routine manner at 100 K, and the modularity of the synthons was demonstrated. Cocrystals of isonicotinamide with all three fluorobenzoic acids were also studied with the SBFA method. The topological analysis of inter- and intramolecular interaction regions was performed using Bader's AIM approach. This study shows that the SBFA method is generally applicable to generate charge density maps using information from multiple intermolecular regions.

Performance of Tuned Half-Wave-Length Power Transmission Lines

The basic concepts of tuned half-wave lines were covered by Hubert and Gent [1]. In this paper the problem of overvoltages during faults and the stability of the system incorporating such tuned lines are discussed. The type of tuning bank and the line arrangements that will be satisfactory from the point of view of stability are suggested. The behavior of a line tuned by distributed capacitor is analyzed, and its performance is compared with the other type of tuned line.

Analysis of Natural Half-Wave-Length Power Transmission Lines

This paper provides additional theoretical information on half-wave-length power transmission. The analysis is rendered more general by consideration of a natural half-wave line instead of a short line tuned to half-wave. The effects of line loading and its power factor on the voltage and current profiles of the line and ganerator excitation have been included. Some of the operating problems such as charging of the line and synchronization of the half-wave system are also discussed. The inevitability of power-frequency overvoltages during faults is established. Stability studies have indicated that the use of switching stations is not beneficial. Typical swing curves are also presented.

Triclabendazole: An Intriguing Case of Co-existence of Conformational and Tautomeric Polymorphism

The crystal polymorphism of the anthelmintic drug, triclabendazole (TCB), is described. Two anhydrates (Forms I and II), three solvates, and an amorphous form have been previously mentioned. This study reports the crystal structures of Forms I (1) and II (2). These structures illustrate the uncommon phenomenon of tautomeric polymorphism. TCB exists as two tautomers A and B. Form I (Z'=2) is composed of two molecules of tautomer A while Form II (Z'=1) contains a 1:1 mixture of A and B. The polymorphs are also characterized by using other solid-state techniques (differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), PXRD, FT-IR, and NMR spectroscopy). Form I is the higher melting form (m.p.: 177 degrees C, Delta Hf=approximate to 105 +/- 4 Jg-1) and is the more stable form at room temperature. Form II is the lower melting polymorph (m.p.: 166 degrees C, Delta Hf=approximate to 86 +/- 3 Jg-1) and shows high kinetic stability on storage in comparison to the amorphous form but it transforms readily into Form I in a solution-mediated process. Crystal structure analysis of co-crystals 3-11 further confirms the existence of tautomeric polymorphism in TCB. In 3 and 11, tautomer A is present whereas in 4-10 the TCB molecule exists wholly as tautomer B. The DFT calculations suggest that the optimized tautomers A and B have nearly the same energies. Single point energy calculations reveal that tautomer A (in Form I) exists in two low-energy conformations, whereas in Form II both tautomers A and B exist in an unfavorable high-energy conformation, stabilized by a five-point dimer synthon. The structural and thermodynamic features of 1-11 are discussed in detail. Triclabendazole is an intriguing case in which tautomeric and conformational variations co-exist in the polymorphs.

Mechanistic insights into type III restriction enzymes

Type III restriction-modification (R-M) enzymes need to interact with two separate unmethylated DNA sequences in indirectly repeated, head-to-head orientations for efficient cleavage to occur at a defined location next to only one of the two sites. However, cleavage of sites that are not in head-to-head orientation have been observed to occur under certain reaction conditions in vitro. ATP hydrolysis is required for the long-distance communication between the sites prior to cleavage. Type III R-M enzymes comprise two subunits, Res and Mod that form a homodimeric Mod(2) and a heterotetrameric Res(2)Mod(2) complex. The Mod subunit in M-2 or R2M2 complex recognizes and methylates DNA while the Res subunit in R2M2 complex is responsible for ATP hydrolysis, DNA translocation and cleavage. A vast majority of biochemical studies on Type III R-M enzymes have been undertaken using two closely related enzymes, EcoP1I and EcoP15I. Divergent opinions about how the long-distance interaction between the recognition sites exist and at least three mechanistic models based on 1D- diffusion and/or 3D-DNA looping have been proposed.

NMR Structure Implications of Enhanced Efficacy of Obestatin Fragment Analogs

Obestatin is a more recently discovered hormone that is encoded by the ghrelin gene and produced in the stomach and gut. We report NMR analysis on synthetic Obestatin (OB23), a 23 residue peptide, along with three overlapping fragments of the same in methanol solvent as a first step towards structure activity relationship. Selective substitutions on the promising N-terminal and middle fragments of obestatin have been carried out in order to improve the efficacy and potency. In the N-terminal fragment two peptides were obtained by the replacement of Gly (8) with a-aminoisobutyric acid (Aib, U) and Phe (F5) with Cyclohexylalanine (Cha). In case of the middle fragment both Gly (3) and Gly (8) were replaced with Aib residues. The rationale being, these unusual amino acids could provide protection from immediate degradation and aid structure stabilization. Our previous studies showed that the N-terminal and the middle fragment were unstructured and hence this substitution would directly evaluate the effect of structure on the activity of these fragment analogs. Detailed NMR analysis clearly demonstrates formation of helical secondary structure in all the peptide analogues and provides justification for relative activities reported by our group previously (Nagaraj et al. 2009).