6,877 research outputs found

    Chiral phase transition at high temperature and density in the QCD-like theory

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    The chiral phase transition at finite temperature T and/or chemical potential μ\mu is studied using the QCD-like theory with a variational approach. The ``QCD-like theory'' means the improved ladder approximation with an infrared cutoff in terms of a modified running coupling. The form of Cornwall-Jackiw-Tomboulis effective potential is modified by the use of the Schwinger-Dyson equation for generally nonzero current quark mass. We then calculate the effective potential at finite T and/or μ\mu and investigate the phase structure in the chiral limit. We have a second-order phase transition at Tc=129T_c=129 MeV for μ=0\mu=0 and a first-order one at μc=422\mu_c=422 MeV for T=0. A tricritical point in the T-μ\mu plane is found at T=107 MeV, μ=210\mu=210 MeV. The position is close to that of the random matrix model and some version of the Nambu-Jona-Lasinio model.Comment: 10 pages, 6 figures. Accepted for publication in Physical Review

    Fast, Simple Calcium Imaging Segmentation with Fully Convolutional Networks

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    Calcium imaging is a technique for observing neuron activity as a series of images showing indicator fluorescence over time. Manually segmenting neurons is time-consuming, leading to research on automated calcium imaging segmentation (ACIS). We evaluated several deep learning models for ACIS on the Neurofinder competition datasets and report our best model: U-Net2DS, a fully convolutional network that operates on 2D mean summary images. U-Net2DS requires minimal domain-specific pre/post-processing and parameter adjustment, and predictions are made on full 512×512512\times512 images at \approx9K images per minute. It ranks third in the Neurofinder competition (F1=0.569F_1=0.569) and is the best model to exclusively use deep learning. We also demonstrate useful segmentations on data from outside the competition. The model's simplicity, speed, and quality results make it a practical choice for ACIS and a strong baseline for more complex models in the future.Comment: Accepted to 3rd Workshop on Deep Learning in Medical Image Analysis (http://cs.adelaide.edu.au/~dlmia3/

    Isoscalar Giant Quadrupole Resonance State in the Relativistic Approach with the Momentum-Dependent Self-Energies

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    We study the excited energy of the isoscalar giant quadrupole resonance with the scaling method in the relativistic many-body framework. In this calculation we introduce the momentum-dependent parts of the Dirac self-energies arising from the one-pion exchange on the assumption of the pseudo-vector coupling with nucleon field. It is shown that this momentum-dependence enhances the Landau mass significantly and thus suppresses the quadrupole resonance energy even giving the small Dirac effective mass which causes a problem in the momentum-independent mean-field theory.Comment: 12pages, 2 Postscript figure

    Sensory neurons are required for migration and axon pathfinding of relay motor neurons

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    The confluence Genil-Guadalquivir in Palma del Río (Córdoba), shows a system composed by four terraces of the Upper and Middle Pleistocene and two episodes of colluvial deposits. The Paleolithic sites (Acheulean and Middle Paleolithic) are linked to lateral bars and colluviums

    Improved ESP-index: a practical self-index for highly repetitive texts

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    While several self-indexes for highly repetitive texts exist, developing a practical self-index applicable to real world repetitive texts remains a challenge. ESP-index is a grammar-based self-index on the notion of edit-sensitive parsing (ESP), an efficient parsing algorithm that guarantees upper bounds of parsing discrepancies between different appearances of the same subtexts in a text. Although ESP-index performs efficient top-down searches of query texts, it has a serious issue on binary searches for finding appearances of variables for a query text, which resulted in slowing down the query searches. We present an improved ESP-index (ESP-index-I) by leveraging the idea behind succinct data structures for large alphabets. While ESP-index-I keeps the same types of efficiencies as ESP-index about the top-down searches, it avoid the binary searches using fast rank/select operations. We experimentally test ESP-index-I on the ability to search query texts and extract subtexts from real world repetitive texts on a large-scale, and we show that ESP-index-I performs better that other possible approaches.Comment: This is the full version of a proceeding accepted to the 11th International Symposium on Experimental Algorithms (SEA2014

    Magnetic aftereffect in rare earth-iron-boron magnets

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    The temperature dependences of the aftereffect coefficient Sv and the coercive force iHc have been measured from 4.2K to 300K on two specimens prepared from sintered magnets of Pr8Y7Fe77B8(sintered at 1060°C and 1100°C). The latter has higher maximum energy products. The Sv values of both have a maximum at 60K and 150K respectively. This is a new behavior which can not be explained by any theory proposed until now. </p

    Detecting mode entanglement: The role of coherent states, superselection rules and particle statistics

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    We discuss the possibility of observing quantum nonlocality using the so-called mode entanglement, analyzing the differences between different types of particles in this context. We first discuss the role of coherent states in such experiments, and we comment on the existence of coherent states in nature. The discussion of coherent states naturally raises questions about the role of particle statistics in this problem. Although the Pauli exclusion principle precludes coherent states with a large number of fermionic particles, we find that a large number of fermionic coherent states, each containing at most one particle, can be used to achieve the same effect as a bosonic coherent state for the purposes of this problem. The discussion of superselection rules arises naturally in this context, because their applicability to a given situation prohibits the use of coherent states. This limitation particularly affects the scenario that we propose for detecting the mode entanglement of fermionic particles.Comment: 7 pages (two-column

    Symmetric hysteresis curves of rare earth-cobalt magnets measured by high magnetic fields

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    Constraint Molecular Dynamics approach to Fermionic systems

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    We propose a Constraint Molecular Dynamics model for Fermionic system. In this approach the equations of motion of wave packets for the nuclear many-body problem are solved by imposing that the one-body occupation probability fˉ(r,p,t)\bar{f}(r,p,t) can assume only values less or equal to 1. This condition reflects the Fermionic nature of the studied systems and it is implemented with a fast algorithm which allows also the study of the heaviest colliding system. The parameters of the model have been chosen to reproduce the average binding energy and radii of nuclei in the mass region A=30208A=30\sim 208. Some comparison to data is given.Comment: 11 pages and 6 figure
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