97,944 research outputs found
Investigation of Frame Alignments for GMM-based Digit-prompted Speaker Verification
Frame alignments can be computed by different methods in GMM-based speaker
verification. By incorporating a phonetic Gaussian mixture model (PGMM), we are
able to compare the performance using alignments extracted from the deep neural
networks (DNN) and the conventional hidden Markov model (HMM) in digit-prompted
speaker verification. Based on the different characteristics of these two
alignments, we present a novel content verification method to improve the
system security without much computational overhead. Our experiments on the
RSR2015 Part-3 digit-prompted task show that, the DNN based alignment performs
on par with the HMM alignment. The results also demonstrate the effectiveness
of the proposed Kullback-Leibler (KL) divergence based scoring to reject speech
with incorrect pass-phrases.Comment: accepted by APSIPA ASC 201
THE LONG RUN OUTLOOK FOR WORLD FOOD PRODUCTION
Food Security and Poverty,
4.6 billion year old aragonite and its implications for understanding the geological record of Ca-carbonate
Owing to its diagenetic instability, aragonite is rare in the geological record and almost entirely absent from pre-carboniferous sedimentary rocks. The former presence of this mineral in older deposits has to be inferred from petrographic, chemical or isotopic proxies. Crystals of aragonite that formed around 4563 million years ago occur in carbonaceous chondrite meteorites, showing that under certain conditions, the orthorhombic polymorph of Ca-carbonate can survive essentially indefinitely. Together with other carbonate minerals, phyllosilicates and sulphides, this aragonite formed by low-temperature water-mediated alteration of anhydrous minerals and glass in the interior of the meteorite’s parent asteroid(s). The survival of aragonite for such a long time can be attributed to the loss of free water by its incorporation into phyllosilicates, and to the very low permeability of the fine-grained and organic-rich rock matrix that prevented the ingress of fresh solutions via intergranular flow. By analogy with these meteorites, terrestrial aragonite is likely to survive where it has been similarly isolated from liquid water, particularly in organic-rich mudrocks, and such deposits may provide important new evidence for deducing the original mineralogy of skeletal and non-skeletal carbonates in deep-time
Two Single-Reference Approaches to Singlet Biradicaloid Problems: Complex, Restricted Orbitals and Approximate Spin-Projection Combined With Regularized Orbital-Optimized M{\o}ller-Plesset Perturbation Theory
We present a comprehensive study of two single-reference approaches to
singlet biradicaloids. These two approaches are based on the recently developed
regularized orbital-optimized M{\o}ller-Plesset method (-OOMP2). The
first approach is to combine the Yamaguchi's approximate projection (AP) scheme
and -OOMP2 with unrestricted (U) orbitals (-UOOMP2). By
capturing only essential symmetry breaking, -UOOMP2 can serve as a
suitable basis for AP. The second approach is -OOMP2 with complex,
restricted (cR) orbitals (-cROOMP2). Though its applicability is more
limited due to the comparative rarity of cR solutions, -cROOMP2 offers
a simple framework for describing singlet biradicaloids with complex
polarization while removing artificial spatial symmetry breaking. We compare
the scope of these two methods with numerical studies. We show that
AP+-UOOMP2 and -cROOMP2 can perform similarly well in the TS12
set, a data set that includes 12 data points for triplet-singlet gaps of
several atoms and diatomic molecules with a triplet ground state. This was also
found to be true for the barrier height of a reaction involving attack on a
cysteine ion by a singlet oxygen molecule. However, we also demonstrate that in
highly symmetric systems like ()
-cROOMP2 is more suitable as it conserves spatial symmetry. Lastly, we
present an organic biradicaloid that does not have a -cROOMP2 solution
in which case only AP+-UOOMP2 is applicable. We recommend
-cROOMP2 whenever complex polarization is essential and
AP+-UOOMP2 for biradicaloids without essential complex polarization but
with essential spin-polarization
Diffusion-controlled and replacement microtextures in alkali feldspars from two pegmatites: Perth, Ontario and Keystone, South Dakota
Macro- and micro-perthitic microclines from pegmatites from Perth, Ontario (Wards catalogue 46 E 0510) and Keystone, South Dakota (Wards 46 E 5125) have been studied using light and electron microscopy. A sample of the type perthite from Perth, Ontario (Hunterian Museum, Glasgow, M2361) was compared using light microscopy. It differs in bulk composition and microtexture from the Wards sample. The Perth sample from Wards is a mesoperthite, with sub-periodic ~mm-thick albite veins near (100), with irregular surfaces. The microcline has regular tartan twins and formed from orthoclase by a continuous process. The Keystone sample is a microperthite, with non-periodic albite veins mainly in {110}. Irregular tartan twins, volumes of irregular microcline and subgrains suggest that the microcline formed by dissolution–reprecipitation. Microcline in both samples contains semicoherent cryptoperthitic albite films that formed after the development of tartan twins. The bulk compositions of these intergrowths imply exsolution below ~400°C. Diffusion parameters imply sustained heating for between 0.11 My at 400°C, 1.5 GPa and 8.4 My at 300°C, 1 GPa. Unrealistic times are required at 200°C. Subsequently, the crystals reacted with a fluid leading to replacive growth of the vein perthites. Unusually, Albite twin composition planes in replacive subgrains have sub-periodic dislocations, formed by coalescence of advancing growth twins. Processes that might lead to periodic, replacive intergrowths are discussed. The Perth and Keystone feldspars have been used for experimental work on dissolution during weathering and on anomalous thermoluminescence fading. Their microtextures make them unsuitable for obtaining properties that can be extrapolated to feldspars in general
Particles accelerated by shocks in the heliosphere
The populations of energetic ions accelerated by shocks in the heliosphere are reviewed briefly. Characteristic spectra and representative fluxes are given
Revealing the z~2.5 Cosmic Web With 3D Lyman-Alpha Forest Tomography: A Deformation Tensor Approach
Studies of cosmological objects should take into account their positions
within the cosmic web of large-scale structure. Unfortunately, the cosmic web
has only been extensively mapped at low-redshifts (), using galaxy
redshifts as tracers of the underlying density field. At , the required
galaxy densities are inaccessible for the foreseeable future, but 3D
reconstructions of Lyman- forest absorption in closely-separated
background QSOs and star-forming galaxies already offer a detailed window into
large-scale structure. We quantify the utility of such maps for
studying the cosmic web by using realistic Ly forest
simulations matched to observational properties of upcoming surveys. A
deformation tensor-based analysis is used to classify voids, sheets, filaments
and nodes in the flux, which is compared to those determined from the
underlying dark matter field. We find an extremely good correspondence, with
of the volume in the flux maps correctly classified relative to the dark
matter web, and classified to within 1 eigenvalue. This compares
favorably to the performance of galaxy-based classifiers with even the highest
galaxy densities at low-redshift. We find that narrow survey geometries can
degrade the cosmic web recovery unless the survey is or on the sky. We also
examine halo abundances as a function of the cosmic web, and find a clear
dependence as a function of flux overdensity, but little explicit dependence on
the cosmic web. These methods will provide a new window on cosmological
environments of galaxies at this very special time in galaxy formation, "high
noon", and on overall properties of cosmological structures at this epoch.Comment: 10 pages, 8 figures. Accepted by Ap
Bases of quasisimple linear groups
Let be a vector space of dimension over , a finite field of
elements, and let be a linear group. A base of
is a set of vectors whose pointwise stabiliser in is trivial. We prove that
if is a quasisimple group (i.e. is perfect and is simple)
acting irreducibly on , then excluding two natural families, has a base
of size at most 6. The two families consist of alternating groups
acting on the natural module of dimension or , and classical
groups with natural module of dimension over subfields of
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