We present new constraints on the neutrino oscillation parameters ∆m 2 21 , θ12, and θ13 from a three-flavor analysis of solar and KamLAND data. The KamLAND data set includes data acquired following a radiopurity upgrade and amounts to a total exposure of 3.49 × 10 32 target-proton-year. Under the assumption of CPT invariance, a two-flavor analysis (θ13 = 0) of the KamLAND and solar data yields the best-fit values tan 2 θ12 = 0.444 −0.016 . This θ13 interval is consistent with other recent work combining the CHOOZ, atmospheric and long-baseline accelerator experiments. We also present a new global θ13 analysis, incorporating the CHOOZ, atmospheric and accelerator data, which indicates sin 2 θ13 = 0.009 +0.013 −0.007 . A nonzero value is suggested, but only at the 79% C.L.
We present the results of a search for extraterrestrial electron antineutrinos (ν e 's) in the energy range 8.3 MeV < E ν e < 31.8 MeV using the KamLAND detector. In an exposure of 4.53 kton-year, we identify 25 candidate events. All of the candidate events can be attributed to background, most importantly neutral current atmospheric neutrino interactions, setting an upper limit on the probability of 8 B solar ν e 's converting into ν e 's at 5.3 × 10 −5 (90% CL), if we assume an undistorted ν e shape. This limit corresponds to a solar ν e flux of 93 cmor an event rate of 1.6 events (kton-year) −1 above the energy threshold (E ν e 8.3 MeV). The present data also allows us to set more stringent limits on the diffuse supernova neutrino flux and on the annihilation rates for light dark matter particles.
The Earth has cooled since its formation, yet the decay of radiogenic isotopes, and in particular uranium, thorium and potassium, in the planet's interior provides a continuing heat source. The current total heat flux from the Earth to space is 44.2 ± 1.0 TW, but the relative contributions from residual primordial heat and radiogenic decay remain uncertain. However, radiogenic decay can be estimated from the flux of geoneutrinos, electrically neutral particles that are emitted during radioactive decay and can pass through the Earth virtually unaffected. Here we combine precise measurements of the geoneutrino flux from the Kamioka Liquid-Scintillator Antineutrino Detector, Japan, with existing measurements from the Borexino detector, Italy. We find that decay of uranium-238 and thorium-232 together contribute 20.0 +8.8 −8.6 TW to Earth's heat flux. The neutrinos emitted from the decay of potassium-40 are below the limits of detection in our experiments, but are known to contribute 4 TW. Taken together, our observations indicate that heat from radioactive decay contributes about half of Earth's total heat flux. We therefore conclude that Earth's primordial heat supply has not yet been exhausted.
We report a measurement of the neutrino-electron elastic scattering rate from 8 B solar neutrinos based on a 123 kton-day exposure of KamLAND. The background-subtracted electron recoil rate, above a 5.5 MeV analysis threshold is 1.49±0.14(stat)±0.17(syst) events per kton-day. Interpreted as due to a pure electron flavor flux with a 8 B neutrino spectrum, this corresponds to a spectrum integrated flux of 2.77±0.26(stat)±0.32(syst) ×10 6 cm −2 s −1 . The analysis threshold is driven by 208 Tl present in the liquid scintillator, and the main source of systematic uncertainty is due to background from cosmogenic 11 Be. The measured rate is consistent with existing measurements and with Standard Solar Model predictions which include matter enhanced neutrino oscillation.
Predicting certain crop phenological stages is important for scheduling agricultural practices and predicting crop responses to climate change. In this study, we developed three different wheat phenological models, a polynomial model and two sigmoid and exponential mixed SEM models developed by different parameter determination methods the Nelder-Mead and augmented Lagrange multiplier methods , and determined which of these models is the most effective for predicting the flowering date in wheat. Five winter wheat cultivars were cropped in western Japan for four years; we split the cultivation data for model calibration and validation. The SEM models showed higher precision in root mean square error RMSE; 3-5 days than the polynomial model when using the validation data. The models developed using the Nelder-Mead and augmented Lagrange multiplier methods showed similar RMSE values Mean SD: 4.24 0.59 and 4.16 0.36, respectively . On the other hand, in the context of validity, the model developed using the Nelder-Mead method showed an unnatural development response to changes in environmental variables; thus, we found that the model developed using the augmented Lagrange multiplier method would be more realistic and effective to express the response of wheat growth to environmental factors. The results of our study shed new light on the optimization methods used in crop development models and on the advantages of using the augmented Lagrange multiplier method for determining the parameters of a non-linear crop development model.
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