919 research outputs found
Determination of Reactivity and Neutron Flux Using Modified Neural Network for HTGR
Nuclear kinetic calculations based on point kinetic model have been generally applied as the standard method for neutronics codes. As the central control rod (C-CR) withdrawal test has demonstrated in a prismatic core type high-temperature gas-cooled reactor (HTGR) named High Temperature Engineering Test Reactor (HTTR), the transient calculation of kinetic parameter, reactivity, and neutron fluxes, requires a new method to shorten calculation-process time. Development of neural network method was applied to point kinetic model as the necessity of real-time calculation that could work in parallel with the digital reactivity meter. The combination of Time Delayed Neural Network (TDNN) and Jordan Recurrent Neural Network (Jordan RNN) named TD-Jordan RNN was the result of the modeling approach. The application of TD-Jordan RNN with adequate learning, tested offline, determined results accurately even when signal inputs were noisy. Furthermore, the preprocessing for neural network input utilized noise reduction as one of the equations to transform two of twelve time-delayed inputs into power corrected inputs
Crossing over is coupled to late meiotic prophase bivalent differentiation through asymmetric disassembly of the SC
Homologous chromosome pairs (bivalents) undergo restructuring during meiotic prophase to convert a configuration that promotes crossover recombination into one that promotes bipolar spindle attachment and localized cohesion loss. We have imaged remodeling of meiotic chromosome structures after pachytene exit in Caenorhabditis elegans. Chromosome shortening during diplonema is accompanied by coiling of chromosome axes and highly asymmetric departure of synaptonemal complex (SC) central region proteins SYP-1 and SYP-2, which diminish over most of the length of each desynapsing bivalent while becoming concentrated on axis segments distal to the single emerging chiasma. This and other manifestations of asymmetry along chromosomes are lost in synapsis-proficient crossover-defective mutants, which often retain SYP-1,2 along the full lengths of coiled diplotene axes. Moreover, a γ-irradiation treatment that restores crossovers in the spo-11 mutant also restores asymmetry of SYP-1 localization. We propose that crossovers or crossover precursors serve as symmetry-breaking events that promote differentiation of subregions of the bivalent by triggering asymmetric disassembly of the SC
Microscopic analysis of the chemical reaction between Fe(Te,Se) thin films and underlying CaF
To understand the chemical reaction at the interface of materials, we
performed a transmission electron microscopy (TEM) observation in four types of
Fe(Te,Se) superconducting thin films prepared on different types of substrates:
CaF2 substrate, CaF2 substrate with a CaF2 buffer layer, CaF2 substrate with a
FeSe buffer layer, and a LaAlO3 substrate with a CaF2 buffer layer. Based on
the energy-dispersive X-ray spectrometer (EDX) analysis, we found possible
interdiffusion between fluorine and selenium that has a strong influence on the
superconductivity in Fe(Te,Se) films. The chemical interdiffusion also plays a
significant role in the variation of the lattice parameters. The lattice
parameters of the Fe(Te,Se) thin films are primarily determined by the chemical
substitution of anions, and the lattice mismatch only plays a secondary role.Comment: 30 pages, 9 figur
Radiative type-I seesaw model with dark matter via U(1)_{B-L} gauge symmetry breaking at future linear colliders
We discuss phenomenology of the radiative seesaw model in which spontaneous
breaking of the U(1) gauge symmetry at the TeV scale gives the common
origin for masses of neutrinos and dark matter (Kanemura et al., 2012). In this
model, the stability of dark matter is realized by the global U(1)
symmetry which arises by the BL charge assignment. Right-handed neutrinos
obtain TeV scale Majorana masses at the tree level. Dirac masses of neutrinos
are generated via one-loop diagrams. Consequently, tiny neutrino masses are
generated at the two-loop level by the seesaw mechanism. This model gives
characteristic predictions, such as light decayable right-handed neutrinos,
Dirac fermion dark matter and an extra heavy vector boson. These new particles
would be accessible at collider experiments because their masses are at the TeV
scale. The U(1) vector boson may be found at the LHC, while the other
new particles could only be tested at future linear colliders. We find that the
dark matter can be observed at a linear collider with =500 GeV and
that light right-handed neutrinos can also be probed with =1 TeV.Comment: 15 pages, 8 figure
Pure nematic state in iron-based superconductor
Lattice and electronic states of thin FeSe films on LaAlO substrates are
investigated in the vicinity of the nematic phase transition. No evidence of
structural phase transition is found by x-ray diffraction below K, while results obtained from resistivity measurement and angle-resolved
photoemission spectroscopy clearly show the appearance of a nematic state.
These results indicate formation of a pure nematic state in the iron-based
superconductor and provide conclusive evidence that the nematic state
originates from the electronic degrees of freedom. This pure nematicity in the
thin film implies difference in the electron-lattice interaction from bulk FeSe
crystals. FeSe films provide valuable playgrounds for observing the pure
response of "bare" electron systems free from the electron-lattice interaction,
and should make important contribution to investigate nematicity and its
relationship with superconductivity
Efeito da adição de farinha de cotilédones de feijão-caupi nas propriedades tecnológicas de biscoitos.
Na publicação: Kaesel Jackson Damasceno-Silva
Dark matter wants Linear Collider
One of the main purposes of physics at the International Linear Collider (ILC) is to study the property of dark matter such as its mass, spin, quantum numbers, and interactions with particles of the standard model. We discuss how the property can or cannot be investigated at the ILC using two typical cases of dark matter scenario: i) most of new particles predicted in physics beyond the standard model are heavy and only dark matter is accessible at the ILC, and ii) not only dark matter but also other new particles are accessible at the ILC. We find that, as can be easily imagined, dark matter can be detected without any difficulties in the latter case. In the former case, it is still possible to detect dark matter when the mass of dark matter is less than a half mass of the higgs boson
Seesaw Neutrino Signals at the Large Hadron Collider
We discuss the scenario with gauge singlet fermions (right-handed neutrinos)
accessible at the energy of the Large Hadron Collider. The singlet fermions
generate tiny neutrino masses via the seesaw mechanism and also have sizable
couplings to the standard-model particles. We demonstrate that these two facts,
which are naively not satisfied simultaneously, are reconciled in the
five-dimensional framework in various fashions, which make the seesaw mechanism
observable. The collider signal of tri-lepton final states with transverse
missing energy is investigated for two explicit examples of the observable
seesaw, taking account of three types of neutrino mass spectrum and the
constraint from lepton flavor violation. We find by showing the significance of
signal discovery that the collider experiment has a potential to find signals
of extra dimensions and the origin of small neutrino masses.Comment: 27 pages, 4 figure
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