We present a search for the decay B + → ℓ + ν ℓ (ℓ = τ, µ, or e) in (458.9±5.1)×10 6 Υ (4S) decays recorded with the BABAR detector at the SLAC PEP-II B-Factory. A sample of events with one reconstructed exclusive semi-leptonic B decay (B − → D 0 ℓ −ν X) is selected, and in the recoil a search for B + → ℓ + ν ℓ signal is performed. The τ is identified in the following channels: τ + → e + ν e ν τ , τ + → µ + ν µ ν τ , τ + → π + ν τ , and τ + → π + π 0 ν τ . The analysis strategy and the statistical procedure is set up for branching fraction extraction or upper limit determination. We determine from the dataset a preliminary measurement of B(B + → τ + ν τ ) = (1.8 ± 0.8 ± 0.1) × 10 −4 , which excludes zero at 2.4σ, and f B = 230 ± 57 MeV. Combination with the hadronically tagged measurement yields B(B + → τ + ν τ ) = (1.8 ± 0.6) × 10 −4 . We also set preliminary limits on the branching fractions at B(B + → e + ν e ) < 7.7 × 10 −6 (90% C.L.), B(B + → µ + ν µ ) < 11 × 10 −6 (90% C.L.), and B(B + → τ + ν τ ) < 3.2 × 10 −4 (90% C.L.).

Context The value of all the ultimate goods and services that the ecosystem provides for human welfare and long-term economic and social development is known as the gross ecosystem product (GEP). For the study of GEP accounting, the suggested water-energy-food (WEF) nexus offers a fresh viewpoint. Objectives The aim of this work is to build a GEP accounting index system based on WEF, investigate its spatiotemporal evolution characteristics, and assess trade-offs and synergies between and within water, energy, and food subsystems. Methods We used the Biophysical & monetary method to calculate the GEP amount based on WEF in five time periods (2005, 2009, 2013, 2017, 2021) and ArcGIS for spatial mapping. Functional quantity value of ecosystem services interactions were identified by statistically analyzing the spatiotemporal pattern. Results Considering the passage of time, the GEP based on WEF in the TGRA displayed an increase trend. From the standpoint of spatial evolution, the spatial distribution pattern of GEP based on WEF showed a spatial pattern of "high in the east and west, low in the middle". The GEP trade-offs based on WEF was dominating. It was discovered that the distribution space of cold and hot areas of a single ecosystem service function value in the three subsystems had spatial variances. Conclusions This study demonstrated that GEP based on WEF presents spatial heterogeneity, and the water subsystem contributed the highest proportion of ecosystem service value, and the tradeoffs/synergies of ecosystem service value were different at different times, as a whole and locally.