Speaker Recognition In Noisy Conditions With Limited Training Data

In this paper we present a novel method for performing speaker recognition with very limited training data and in the presence of background noise. Similarity-based speaker recognition is considered so that speaker models can be created with limited training speech data. The proposed similarity is a form of cosine similarity used as a distance measure between speech feature vectors. Each speech frame is modelled using subband features, and into this framework, multicondition training and optimal feature selection are introduced, making the system capable of performing speaker recognition in the presence of realistic, time-varying noise, which is unknown during training. Speaker identi?cation experiments were carried out using the SPIDRE database. The performance of the proposed new system for noise compensation is compared to that of an oracle model; the speaker identi?cation accuracy for clean speech by the new system trained with limited training data is compared to that of a GMM trained with several minutes of speech. Both comparisons have demonstrated the effectiveness of the new model. Finally, experiments were carried out to test the new model for speaker identi?cation given limited training data and with differing levels and types of realistic background noise. The results have demonstrated the robustness of the new system.

Molecular dynamics studies of the STAT3 homodimer:DNA complex: relationships between STAT3 mutations and protein-DNA recognition.

Signal Transducers and Activators of Transcription (STAT) proteins are a group of latent cytoplasmic transcription factors involved in cytokine signaling. STAT3 is a member of the STAT family and is expressed at elevated levels in a large number of diverse human cancers and is now a validated target for anticancer drug discovery.. Understanding the dynamics of the STAT3 dimer interface, accounting for both protein-DNA and protein-protein interactions, with respect to the dynamics of the latent unphosphorylated STAT3 monomer, is important for designing potential small-molecule inhibitors of the activated dimer. Molecular dynamics (MD) simulations have been used to study the activated STAT3 homodimer:DNA complex and the latent unphosphorylated STAT3 monomer in an explicit water environment. Analysis of the data obtained from MD simulations over a 50 ns time frame has suggested how the transcription factor interacts with DNA, the nature of the conformational changes, and ways in which function may be affected. Examination of the dimer interface, focusing on the protein-DNA interactions, including involvement of water molecules, has revealed the key residues contributing to the recognition events involved in STAT3 protein-DNA interactions. This has shown that the majority of mutations in the DNA-binding domain are found at the protein-DNA interface. These mutations have been mapped in detail and related to specific protein-DNA contacts. Their structural stability is described, together with an analysis of the model as a starting-point for the discovery of novel small-molecule STAT3 inhibitors.

The effect of construction pattern and unit interlock on the structural behaviour of block pavements

The maintenance or even replacement of cracked pavements requires considerable financial resources and puts a large burden on the budgets of local councils. In addition to these costs, local councils also face liability claims arising from uneven or cracked pedestrian pavements. These currently cost the Manchester City Council and Preston City Council around £6 million a year each. Design procedures are empirical. A better understanding of the interaction between paving blocks, bedding sand and subbase was necessary in order to determine the mode of failure of pavements under load. Increasing applied stress was found to mobilise ‘‘rotational interlock’’, providing increased pavement stiffness and thus increased load dissipation resulting in lower transmitted stress on the subgrade. The indications from the literature
review were that pavements are designed to fail by excessive deformation and that paving blocks remained uncracked at failure. This was confirmed with experimental data which was obtained from tests on segments of pavements that were laid/constructed in a purpose built test frame in the laboratory.

Discovery and evolving history of two genetically related but phenotypically different viruses, porcine circoviruses 1 and 2

Porcine circoviruses (PCVs) belong to the genus Circovirus, family Circoviridae. and are the smallest non-enveloped, single stranded, negative sense, circular DNA viruses that replicate autonomously in mammalian cells. Two types of PCV have been characterised, PCV1 and PCV2 and these two viruses show 83% sequence identity at open reading frame (ORF) 1 and 67% identity at ORF2. PCV1 is a nonpathogenic virus of pigs. In contrast, PCV2 has emerged as a major pathogen of swine around the world. The discovery of PCV1 and how the subsequent studies on this virus eventually led to the recognition and characterisation of PCV2, and the disease scenarios associated with PCV2, serve as a model of how multidisciplinary collaboration among field veterinarians, diagnosticians and researchers can lead to the rapid characterisation and control of a globally important emerging disease. (C) 2011 Elsevier B.V. All rights reserved.

Isolation in cell cultures and initial characterisation of two novel bocavirus species from swine in Northern Ireland

We report the isolation in cell cultures of two novel bocavirus species in pigs from farms in Northern Ireland with clinical postweaning multisystemic wasting syndrome (PMWS). We have designated the isolates as porcine bocavirus-3 (PBoV3) and porcine bocavirus-4 (PBoV4). To date 5082 and 4125 bps of PBoV3 and PBoV4 have been sequenced, respectively. PBoV3 and PBoV4 show nucleotide homology to other known bocaviruses in swine and other organisms. Open reading frame (ORF) analysis has shown that these viruses have a third small ORF, equivalent to the NP1 ORF that distinguishes the bocaviruses from other parvoviruses.

Thermomechanical Response of Variable Stiffness Composite Panels

Analysis of non-traditional Variable Stiffness (VS) laminates, obtained by steering the fiber orientation as a spatial function of location, have shown to improve buckling load carrying capacity of flat rectangular panels under axial compressive loads. In some cases the buckling load of simply supported panels doubled compared to the best conventional laminate with straight fibers. Two distinct cases of stiffness variation, one due to fiber orientation variation in the direction of the loading, and the other one perpendicular to the loading direction, were identified as possible contributors to the buckling load improvements. In the first case, the increase was attributed to the favorable distribution of the transverse in-plane stresses over the panel platform. In the second case, a higher degree of improvement was obtained due to the re-distribution of the applied in-plane loads. Experimental results, however, showed substantially higher levels of buckling load improvements compared with theoretical predictions. The additional improvement was determined to be due to residual stresses introduced during curing of the laminates. The present paper provides a simplified thermomechanical analysis of residual stress state of variable stiffness laminates. Systematic parametric analyses of both cases of fiber orientation variations show that, indeed much higher buckling loads could result from the residual stresses present in such laminates.

Strong-field photodetachment of H- by few-cycle laser pulses

The recent adiabatic saddle-point method of Shearer et al. [ Phys. Rev. A 84 033409 (2011)] is applied to study strong-field photodetachment of H- by few-cycle linearly polarized laser pulses of frequencies near the two-photon detachment threshold. The behavior of the saddle points in the complex-time plane for a range of laser parameters is explored. A detailed analysis of the influence of laser intensities [(2×1011)–(6.5 × 1011) W/cm2], midinfrared laser wavelengths (1800–2700 nm), and various values of the carrier envelope phase (CEP) on (i) three-dimensional probability detachment distributions, (ii) photoangular distributions (PADs), (iii) energy spectra, and (iv) momentum distributions are presented. Examination of the probability distributions and PADs reveal main lobes and jetlike structures. Bifurcation phenomena in the probability distributions and PADs are also observed as the wavelength and intensity increase. Our simulations show that the (i) probability distributions, (ii) PADs, and (iii) energy spectra are extremely sensitive to the CEP and thus measuring such distributions provides a useful tool for determining this phase. The symmetrical properties of the electron momentum distributions are also found to be strongly correlated with the CEP and this provides an additional robust method for measuring the CEP of a laser pulse. Our calculations further show that for a three-cycle pulse inclusion of all eight saddle points is required in the evaluation of the transition amplitude to yield an accurate description of the photodetachment process. This is in contrast to recent results for a five-cycle pulse.

Epitaxial strain and electric boundary condition effects on the structural and ferroelectric properties of BiFeO3 films

The influence of both compressive and tensile epitaxial strain along with the electrical boundary conditions on the ferroelastic and ferroelectric domain patterns of bismuth ferrite films was studied. BiFeO3 films were grown on SrTiO3(001), DyScO3(110), GdScO3(110), and SmScO3(110) substrates to investigate the effect of room temperature in-plane strain ranging from -1.4% to +0.75%. Piezoresponse force microscopy, transmission electron microscopy, x-ray diffraction measurements, and ferroelectric polarization measurements were performed to study the properties of the films. We show that BiFeO3 films with and without SrRuO3 bottom electrode have different growth mechanisms and that in both cases reduction of the domain variants is possible. Without SrRuO3, stripe domains with reduced variants are formed on all rare earth scandate substrates because of their monoclinic symmetry. In addition, tensile strained films exhibit a rotation of the unit cell with increasing film thickness. On the other side, the presence of SrRuO3 promotes step flow growth of BiFeO3. In case of vicinal SrTiO3 and DyScO3 substrates with high quality SrRuO3 bottom electrode and a low miscut angle of approximate to 0.15 degrees we observed suppression of the formation of certain domain variants. The quite large in-plane misfit of SrRuO3 with GdScO3 and SmScO3 prevents the growth of high quality SrRuO3 films and subsequent domain variants reduction in BiFeO3 on these substrates, when SrRuO3 is used as a bottom electrode.

A spatio-temporal 2D-models framework for human pose recovery in monocular sequences

This paper addresses the pose recovery problem of a particular articulated object: the human body. In this model-based approach, the 2D-shape is associated to the corresponding stick figure allowing the joint segmentation and pose recovery of the subject observed in the scene. The main disadvantage of 2D-models is their restriction to the viewpoint. To cope with this limitation, local spatio-temporal 2D-models corresponding to many views of the same sequences are trained, concatenated and sorted in a global framework. Temporal and spatial constraints are then considered to build the probabilistic transition matrix (PTM) that gives a frame to frame estimation of the most probable local models to use during the fitting procedure, thus limiting the feature space. This approach takes advantage of 3D information avoiding the use of a complex 3D human model. The experiments carried out on both indoor and outdoor sequences have demonstrated the ability of this approach to adequately segment pedestrians and estimate their poses independently of the direction of motion during the sequence. (c) 2008 Elsevier Ltd. All rights reserved.

The rfaE gene from Escherichia coli encodes a bifunctional protein involved in biosynthesis of the lipopolysaccharide core precursor ADP-L-glycero-D-manno-heptose

The intermediate steps in the biosynthesis of the ADP-L-glycero-D-manno-heptose precursor of inner core lipopolysaccharide (LPS) are not yet elucidated. We isolated a mini-Tn10 insertion that confers a heptoseless LPS phenotype in the chromosome of Escherichia coli K-12. The mutation was in a gene homologous to the previously reported rfaE gene from Haemophilus influenzae. The E. coli rfaE gene was cloned into an expression vector, and an in vitro transcription-translation experiment revealed a polypeptide of approximately 55 kDa in mass. Comparisons of the predicted amino acid sequence with other proteins in the database showed the presence of two clearly separate domains. Domain I (amino acids 1 to 318) shared structural features with members of the ribokinase family, while Domain II (amino acids 344 to 477) had conserved features of the cytidylyltransferase superfamily that includes the aut gene product of Ralstonia eutrophus. Each domain was expressed individually, demonstrating that only Domain I could complement the rfaE::Tn10 mutation in E. coli, as well as the rfaE543 mutation of Salmonella enterica SL1102. DNA sequencing of the rfaE543 gene revealed that Domain I had one amino acid substitution and a 12-bp in-frame deletion resulting in the loss of four amino acids, while Domain II remained intact. We also demonstrated that the aut::Tn5 mutation in R. eutrophus is associated with heptoseless LPS, and this phenotype was restored following the introduction of a plasmid expressing the E. coli Domain II. Thus, both domains of rfaE are functionally different and genetically separable confirming that the encoded protein is bifunctional. We propose that Domain I is involved in the synthesis of D-glycero-D-manno-heptose 1-phosphate, whereas Domain II catalyzes the ADP transfer to form ADP-D-glycero-D-manno-heptose.

Construction and biochemical characterization of recombinant cytoplasmic forms of the IucD protein (lysine:N6-hydroxylase) encoded by the pColV-K30 aerobactin gene cluster

The aerobactin gene cluster in pColV-K30 consists of five genes (iucABCD iutA); four of these (iucABCD) are involved in aerobactin biosynthesis, whereas the fifth one (iutA) encodes the ferriaerobactin outer membrane receptor. iucD encodes lysine:N6-hydroxylase, which catalyzes the first step in aerobactin biosynthesis. Regardless of the method used for cell rupture, we have consistently found that IucD remains membrane bound, and repeated efforts to achieve a purified and active soluble form of the enzyme have been unsuccessful. To circumvent this problem, we have constructed recombinant IucD proteins with modified amino termini by creating three in-frame gene fusions of IucD to the amino-terminal amino acids of the cytoplasmic enzyme beta-galactosidase. Two of these constructs resulted in the addition to the iucD coding region of a hydrophilic leader sequence of 13 and 30 amino acids. The other construct involved the deletion of the first 47 amino acids of the IucD amino terminus and the addition of 19 amino acids of the amino terminus of beta-galactosidase. Cells expressing any of the three recombinant IucD forms were found to produce soluble N6-hydroxylysine. One of these proteins, IucD439, was purified to homogeneity from the soluble fraction of the cell lysates, and it was capable of participating in the biosynthesis of aerobactin, as determined in vitro by a cell-free system and in vivo by a cross-feeding bioassay. A medium ionic strength of 0.25 (250 mM NaCl) or higher was required to maintain the protein in a catalytically functional, tetrameric state.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of positron-atom interactions on the annihilation gamma spectra of molecules

Calculations of ?-spectra for positron annihilation on a selection of molecules, including methane and its fluoro-substitutes, ethane, propane, butane and benzene are presented. The annihilation ?-spectra characterise the momentum distribution of the electron-positron pair at the instant of annihilation. The contribution to the ?-spectra from individual molecular orbitals is obtained from electron momentum densities calculated using modern computational quantum chemistry density functional theory tools. The calculation, in its simplest form, effectively treats the low-energy (thermalised, room-temperature) positron as a plane wave and gives annihilation ?-spectra that are about 40% broader than experiment, although the main chemical trends are reproduced. We show that this effective 'narrowing' of the experimental spectra is due to the action of the molecular potential on the positron, chiefly, due to the positron repulsion from the nuclei. It leads to a suppression of the contribution of small positron-nuclear separations where the electron momentum is large. To investigate the effect of the nuclear repulsion, as well as that of short-range electron-positron and positron-molecule correlations, a linear combination of atomic orbital description of the molecular orbitals is employed. It facilitates the incorporation of correction factors which can be calculated from atomic many-body theory and account for the repulsion and correlations. Their inclusion in the calculation gives -spectrum linewidths that are in much better agreement with experiment. Furthermore, it is shown that the effective distortion of the electron momentum density, when it is observed through positron annihilation -spectra, can be approximated by a relatively simple scaling factor. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Chemical structural effects on γ-ray spectra of positron annihilation in fluorobenzenes

Spectra of ?-ray Doppler shifts for positron annihilation in benzene and its fluoro-derivatives are simulated using low energy plane wave positron (LEPWP) approximation. The results are compared with available measurements. It is found that the Doppler shifts in these larger aromatic compounds are dominated by the contributions of the valence electrons and that the LEPWP model overestimates the measurements by approximately 30%, in agreement with previous findings in noble gases and small molecules. It is further revealed that the halogen atoms not only switch the sign of the charges on carbon atoms that they bond to, but that they also polarize other C-H bonds in the molecule leading to a redistribution of the molecular electrostatic potentials. As a result, it is likely that the halogen atoms contribute more significantly to the annihilation process. The present study also suggests that, while the Doppler shifts are sensitive to the number of valence electrons in the molecules, they are less sensitive to the chemical structures of isomers that have the same numbers and type of atoms and, hence, the same numbers of electrons. Further investigation of this effect is warranted. © EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2012.