500 research outputs found

    Large-Scale Pairwise Sequence Alignments on a Large-Scale GPU Cluster

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    This paper presents design of a GPU kernel for performing pairwise sequence alignments for large-scale short sequence datasets generated by nextgeneration sequencers. This kernel principally performs batch Needleman– Wunsch global alignments. When used with its MPI-based host software, the kernel is scalable and is capable of achieving high throughput alignment when run on a CPU-GPU cluster

    Kabul Times (April 11, 1964, vol. 3, no. 37)

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    High-resolution photon scattering experiments have been performed on the nucleus 45Sc at the Darmstadt superconducting electron accelerator S-DALINAC using bremsstrahlung beams with end point energies of 5.0 and 7.0MeV. Energies, absolute cross-sections and decay widths of 50 states, most of them previously unknown, have been determined. The results are compared to (γ,γ \gamma{^\prime}) experiments on the neighbouring closed proton shell isotope 44Ca

    Multilinear Wavelets: A Statistical Shape Space for Human Faces

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    We present a statistical model for 33D human faces in varying expression, which decomposes the surface of the face using a wavelet transform, and learns many localized, decorrelated multilinear models on the resulting coefficients. Using this model we are able to reconstruct faces from noisy and occluded 33D face scans, and facial motion sequences. Accurate reconstruction of face shape is important for applications such as tele-presence and gaming. The localized and multi-scale nature of our model allows for recovery of fine-scale detail while retaining robustness to severe noise and occlusion, and is computationally efficient and scalable. We validate these properties experimentally on challenging data in the form of static scans and motion sequences. We show that in comparison to a global multilinear model, our model better preserves fine detail and is computationally faster, while in comparison to a localized PCA model, our model better handles variation in expression, is faster, and allows us to fix identity parameters for a given subject.Comment: 10 pages, 7 figures; accepted to ECCV 201

    High count rate {\gamma}-ray spectroscopy with LaBr3:Ce scintillation detectors

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    The applicability of LaBr3:Ce detectors for high count rate {\gamma}-ray spectroscopy is investigated. A 3"x3" LaBr3:Ce detector is used in a test setup with radioactive sources to study the dependence of energy resolution and photo peak efficiency on the overall count rate in the detector. Digitized traces were recorded using a 500 MHz FADC and analysed with digital signal processing methods. In addition to standard techniques a pile-up correction method is applied to the data in order to further improve the high-rate capabilities and to reduce the losses in efficiency due to signal pile-up. It is shown, that {\gamma}-ray spectroscopy can be performed with high resolution at count rates even above 1 MHz and that the performance can be enhanced in the region between 500 kHz and 10 MHz by using pile-up correction techniques

    The decay of quadrupole-octupole 11^- states in 40^{40}Ca and 140^{140}Ce

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    Background: Two-phonon excitations originating from the coupling of two collective one-phonon states are of great interest in nuclear structure physics. One possibility to generate low-lying E1E1 excitations is the coupling of quadrupole and octupole phonons. Purpose: In this work, the γ\gamma-decay behavior of candidates for the (21+31)1(2_1^+\otimes 3_1^-)_{1^-} state in the doubly-magic nucleus 40^{40}Ca and in the heavier and semi-magic nucleus 140^{140}Ce is investigated. Methods: (γ,γ)(\vec{\gamma},\gamma') experiments have been carried out at the High Intensity γ\gamma-ray Source (HIγ{\gamma}S) facility in combination with the high-efficiency γ\gamma-ray spectroscopy setup γ3\gamma^3 consisting of HPGe and LaBr3_3 detectors. The setup enables the acquisition of γ\gamma-γ\gamma coincidence data and, hence, the detection of direct decay paths. Results: In addition to the known ground-state decays, for 40^{40}Ca the decay into the 313^-_1 state was observed, while for 140^{140}Ce the direct decays into the 21+2^+_1 and the 02+0^+_2 state were detected. The experimentally deduced transition strengths and excitation energies are compared to theoretical calculations in the framework of EDF theory plus QPM approach and systematically analyzed for N=82N=82 isotones. In addition, negative parities for two J=1J=1 states in 44^{44}Ca were deduced simultaneously. Conclusions: The experimental findings together with the theoretical calculations support the two-phonon character of the 111^-_1 excitation in the light-to-medium-mass nucleus 40^{40}Ca as well as in the stable even-even N=82N=82 nuclei.Comment: 11 pages, 6 figures, as accepted in Phys. Rev.

    Fragmentation and systematics of the Pygmy Dipole Resonance in the stable N=82 isotones

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    The low-lying electric dipole (E1) strength in the semi-magic nucleus 136Xe has been measured which finalizes the systematic survey to investigate the so-called pygmy dipole resonance (PDR) in all stable even N=82 isotones with the method of nuclear resonance fluorescence using real photons in the entrance channel. In all cases, a fragmented resonance-like structure of E1 strength is observed in the energy region 5 MeV to 8 MeV. An analysis of the fragmentation of the strength reveals that the degree of fragmentation decreases towards the proton-deficient isotones while the total integrated strength increases indicating a dependence of the total strength on the neutron-to-proton ratio. The experimental results are compared to microscopic calculations within the quasi-particle phonon model (QPM). The calculation includes complex configurations of up to three phonons and is able to reproduce also the fragmentation of the E1 strength which allows to draw conclusions on the damping of the PDR. Calculations and experimental data are in good agreement in the degree of fragmentation and also in the integrated strength if the sensitivity limit of the experiments is taken into account

    Investigation of octupole vibrational states in 150Nd via inelastic proton scattering (p,p'g)

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    Octupole vibrational states were studied in the nucleus 150Nd^{150}\mathrm{Nd} via inelastic proton scattering with \unit[10.9]{MeV} protons which are an excellent probe to excite natural parity states. For the first time in 150Nd^{150}\mathrm{Nd}, both the scattered protons and the γ\gamma rays were detected in coincidence giving the possibility to measure branching ratios in detail. Using the coincidence technique, the B(E1)B(E1) ratios of the decaying transitions for 10 octupole vibrational states and other negative-parity states to the yrast band were determined and compared to the Alaga rule. The positive and negative-parity states revealed by this experiment are compared with Interacting Boson Approximation (IBA) calculations performed in the (spdf) boson space. The calculations are found to be in good agreement with the experimental data, both for positive and negative-parity states

    Isospin properties of electric dipole excitations in 48Ca

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    Two different experimental approaches were combined to study the electric dipole strength in the doubly-magic nucleus 48Ca below the neutron threshold. Real-photon scattering experiments using bremsstrahlung up to 9.9 MeV and nearly mono-energetic linearly polarized photons with energies between 6.6 and 9.51 MeV provided strength distribution and parities, and an (\alpha,\alpha'\gamma) experiment at E_{\alpha}=136 MeV gave cross sections for an isoscalar probe. The unexpected difference observed in the dipole response is compared to calculations using the first-order random-phase approximation and points to an energy-dependent isospin character. A strong isoscalar state at 7.6 MeV was identified for the first time supporting a recent theoretical prediction.Comment: 6 pages, 5 figures, as accepted in Phys. Lett.
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