1,153 research outputs found

    Nitrogen Acquisition and Utilization by Crops: Review of Different Approaches and Proposition of a Mechanistic Modeling

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    Natural relations among physical observables in the neutrino mass matrix

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    We find all possible relations among physical observables arising from neutrino mass matrices that describe in a natural way the currently observed pattern (tan_23 and tan_12 large, dm^2_Sun/dm^2_Atm and tan_13 small) in terms of a minimum number of parameters. Natural here means due only to the relative smallness (vanishing) of some parameters in the relevant lagrangian, without special relations or accidental cancellations among them.Comment: 14 pages, 1 eps figur

    Parameterization and Reconstruction of Quasi Static Universe

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    We study a possibility of the fate of universe, in which there is neither the rip singularity, which results in the disintegration of bound systems, nor the endless expansion, instead the universe will be quasi static. We discuss the parameterization of the corresponding evolution and the reconstruction of the scalar field model. We find, with the parameterization consistent with the current observation, that the current universe might arrive at a quasi static phase after less than 20Gyr.Comment: minor changes and Refs. added, publish in EPJ

    Prediction of Ue3U_{e3} in Neutrino Mass Matrix with Two Zeros

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    We have discussed predictions of Ue3|U_{e3}| and JCPJ_{CP} in the framework of the neutrino mass matrix with two zeros. In the case of the best fit values of tan2θ12\tan^2\theta_{12}, tan2θ23\tan^2\theta_{23}, Δmsun2\Delta m^2_{\rm sun} and Δmatm2\Delta m_{\rm atm}^2, the prediction of Ue3|U_{e3}| is 0.110.140.11\sim 0.14. The lower bound of Ue3|U_{e3}| is 0.05, which depends on tanθ12\tan\theta_{12} and tanθ23\tan\theta_{23}. We have investigated the stability of these predictions taking account of small corrections to zeros, which may come from radiative corrections or off-diagonal elements of the charged lepton massmatrix. The lower bound of Ue3|U_{e3}| comes down considerably due to the small corrections to zeros.Comment: Figures and discussions are adde

    Habitable Zones of Host Stars During the Post-MS Phase

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    A star will become brighter and brighter with stellar evolution, and the distance of its habitable zone will become farther and farther. Some planets outside the habitable zone of a host star during the main sequence phase may enter the habitable zone of the host star during other evolutionary phases. A terrestrial planet within the habitable zone of its host star is generally thought to be suited to life existence. Furthermore, a rocky moon around a giant planet may be also suited to life survive, provided that the planet-moon system is within the habitable zone of its host star. Using Eggleton's code and the boundary flux of habitable zone, we calculate the habitable zone of our Solar after the main sequence phase. It is found that Mars' orbit and Jupiter's orbit will enter the habitable zone of Solar during the subgiant branch phase and the red giant branch phase, respectively. And the orbit of Saturn will enter the habitable zone of Solar during the He-burning phase for about 137 million years. Life is unlikely at any time on Saturn, as it is a giant gaseous planet. However, Titan, the rocky moon of Saturn, may be suitable for biological evolution and become another Earth during that time. For low-mass stars, there are similar habitable zones during the He-burning phase as our Solar, because there are similar core masses and luminosities for these stars during that phase.Comment: 6 pages, 7 figures. Accepted by Ap & S

    Predictions of bedaquiline and pretomanid target attainment in lung lesions of tuberculosis patients using translational minimal physiologically based pharmacokinetic modeling

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    BACKGROUND\nMETHODS\nRESULTS\nCONCLUSIONS\nSite-of-action concentrations for bedaquiline and pretomanid from tuberculosis patients are unavailable. The objective of this work was to predict bedaquiline and pretomanid site-of-action exposures using a translational minimal physiologically based pharmacokinetic (mPBPK) approach to understand the probability of target attainment (PTA).\nA general translational mPBPK framework for the prediction of lung and lung lesion exposure was developed and validated using pyrazinamide site-of-action data from mice and humans. We then implemented the framework for bedaquiline and pretomanid. Simulations were conducted to predict site-of-action exposures following standard bedaquiline and pretomanid, and bedaquiline once-daily dosing. Probabilities of average concentrations within lesions and lungs greater than the minimum bactericidal concentration for non-replicating (MBCNR) and replicating (MBCR) bacteria were calculated. Effects of patient-specific differences on target attainment were evaluated.\nThe translational modeling approach was successful in predicting pyrazinamide lung concentrations from mice to patients. We predicted that 94% and 53% of patients would attain bedaquiline average daily PK exposure within lesions (Cavg-lesion) > MBCNR during the extensive phase of bedaquiline standard (2 weeks) and once-daily (8 weeks) dosing, respectively. Less than 5% of patients were predicted to achieve Cavg-lesion > MBCNR during the continuation phase of bedaquiline or pretomanid treatment, and more than 80% of patients were predicted to achieve Cavg-lung >MBCR for all simulated dosing regimens of bedaquiline and pretomanid.\nThe translational mPBPK model predicted that the standard bedaquiline continuation phase and standard pretomanid dosing may not achieve optimal exposures to eradicate non-replicating bacteria in most patients.Pharmacolog

    Model‐based dose optimization framework for bedaquiline, pretomanid, and linezolid for the treatment of drug‐resistant tuberculosis

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    AIM\nMETHODS\nRESULTS\nCONCLUSION\nBedaquiline, pretomanid, and linezolid combination (BPaL) treatment against Mycobacterium tuberculosis is promising yet safety and adherence concerns exist that motivates exploration of alternative dosing regimens. We developed a mechanistic modeling framework to compare the efficacy of the current and alternative BPaL treatment strategies.\nPharmacodynamic models for each drug in the BPaL combination treatment were developed using in vitro time-kill data. These models were combined with pharmacokinetic models, incorporating bodyweight, lesion volume, site-of-action distribution, bacterial susceptibility, and pharmacodynamic interactions to assemble the framework. The model was qualified by comparing the simulations against the observed clinical data. Simulations were performed evaluating bedaquiline and linezolid approved (bedaquiline 400mg once daily (QD) 14-days followed by 200mg three times a week, linezolid 1200mg QD) and alternative dosing regimens (bedaquiline 200mg QD, linezolid 600mg QD).\nThe framework adequately described the observed anti-bacterial activity data in patients following monotherapy for each drug and approved BPaL dosing. The simulations suggested a minor difference in median time to colony forming units (CFU)-clearance state with the bedaquiline alternative compared to the approved dosing and the linezolid alternative compared to the approved dosing. Median time to non-replicating-clearance state was predicted to be 15-days from the CFU-clearance state.\nThe model-based simulations suggested that comparable efficacy can be achieved using alternative bedaquiline and linezolid dosing, which may improve safety and adherence in drug-resistant tuberculosis patients. The framework can be utilized to evaluate treatment optimization approaches, including dosing regimen and duration of treatment predictions to eradicate both replicating- and non-replicating bacteria from lung and lesions.Pharmacolog

    Implications of the KamLAND Measurement on the Lepton Flavor Mixing Matrix and the Neutrino Mass Matrix

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    We explore some important implications of the KamLAND measurment on the lepton flavor mixing matrix VV and the neutrino mass matrix MM. The model-independent constraints on nine matrix elements of VV are obtained to a reasonable degree of accuracy. We find that nine two-zero textures of MM are compatible with current experimental data, but two of them are only marginally allowed. Instructive predictions are given for the absolute neutrino masses, Majorana phases of CP violation, effective masses of the tritium beta decay and neutrinoless double beta decay.Comment: RevTex 15 pages (4 PS figures included

    Magnetic Field Structures in a Facular Region Observed by THEMIS and Hinode

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    The main objective of this paper is to build and compare vector magnetic maps obtained by two spectral polarimeters, i.e. THEMIS/MTR and Hinode SOT/SP, using two inversion codes (UNNOFIT and MELANIE) based on the Milne-Eddington solar atmosphere model. To this end, we used observations of a facular region within active region NOAA 10996 on 23 May 2008, and found consistent results concerning the field strength, azimuth and inclination distributions. Because SOT/SP is free from the seeing effect and has better spatial resolution, we were able to resolve small magnetic polarities with sizes of 1" to 2", and we could detect strong horizontal magnetic fields, which converge or diverge in negative or positive facular polarities. These findings support models which suggest the existence of small vertical flux tube bundles in faculae. A new method is proposed to get the relative formation heights of the multi-lines observed by MTR assuming the validity of a flux tube model for the faculae. We found that the Fe 1 6302.5 \AA line forms at a greater atmospheric height than the Fe 1 5250.2 \AA line.Comment: 20 pages, 9 figures, 3 tables, accepted for publication in Solar Physic

    Leptogenesis in Neutrino Textures with Two Zeros

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    The leptogenesis is studied in the neutrino textures with two zeros, which reduce the number of independent phases of the CP violation. The phenomenological favored neutrino textures with two zeros are decomposed into the Dirac neutrino mass matrix and the right-handed Majorana one in the see-saw mechanism. Putting the condition to suppress the μeγ\mu \to e\gamma decay enough, the texture zeros of the Dirac neutrino mass matrix are fixed in the framework of the MSSM with right-handed neutrinos. These textures have only one CP violatig phase. The magnitude of each entry of the Dirac mass matrix is determined in order to explain the baryon asymmetry of the universe by solving the Boltzman equations. The relation between the leptogenesis and the low energy CP violation is presented in these textures.Comment: Latex file with 20 pages, 6 eps figure
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