A measurement of electron antineutrino oscillation by the Daya Bay Reactor Neutrino Experiment is described in detail. Six 2.9-GWth nuclear power reactors of the Daya Bay and Ling Ao nuclear power facilities served as intense sources of ν e 's. Comparison of theν e rate and energy spectrum measured by antineutrino detectors far from the nuclear reactors (∼1500-1950 m) relative to detectors near the reactors (∼350-600 m) allowed a precise measurement ofν e disappearance. More than 2.5 millionν e inverse beta-decay interactions were observed, based on the combination of 217 days of operation of six antineutrino detectors (December, 2011-July, 2012) with a subsequent 1013 days using the complete configuration of eight detectors (October, 2012-July, 2015. Theν e rate observed at the far detectors relative to the near detectors showed a significant deficit, R ¼ 0.949 AE 0.002ðstatÞAE 0.002ðsystÞ. The energy dependence ofν e disappearance showed the distinct variation predicted by neutrino oscillation. Analysis using an approximation for the three-flavor oscillation probability yielded the flavor-mixing angle sin 2 2θ 13 ¼ 0.0841 AE 0.0027ðstatÞ AE 0.0019ðsystÞ and the effective neutrino mass-squared difference of jΔm 2 ee j ¼ ð2.50 AE 0.06ðstatÞ AE 0.06ðsystÞÞ × 10 −3 eV 2 . Analysis using the exact three-flavor probability found Δm

The positive transcription elongation factor b (P-TEFb), consisting of Cdk9 and cyclin T, stimulates RNA polymerase II elongation and cotranscriptional pre-mRNA processing. To accommodate different growth conditions and transcriptional demands, a reservoir of P-TEFb is kept in an inactive state in the multisubunit 7SK snRNP. Under certain stress or disease conditions, P-TEFb is released to activate transcription, although the signaling pathway(s) that controls this is largely unknown. Here, through analyzing the UV-or hexamethylene bisacetamide (HMBA)-induced release of P-TEFb from 7SK snRNP, an essential role for the calcium ion (Ca 2+ )-calmodulin-protein phosphatase 2B (PP2B) signaling pathway is revealed. However, Ca 2+ signaling alone is insufficient, and PP2B must act sequentially and cooperatively with protein phosphatase 1␣ (PP1␣) to disrupt 7SK snRNP. Activated by UV/HMBA and facilitated by a PP2B-induced conformational change in 7SK snRNP, PP1␣ releases P-TEFb through dephosphorylating phospho-Thr186 in the Cdk9 T-loop. This event is also necessary for the subsequent recruitment of P-TEFb by the bromodomain protein Brd4 to the preinitiation complex, where Cdk9 remains unphosphorylated and inactive until after the synthesis of a short RNA. Thus, through cooperatively dephosphorylating Cdk9 in response to Ca 2+ signaling, PP2B and PP1␣ alter the P-TEFb functional equilibrium through releasing P-TEFb from 7SK snRNP for transcription.[Keywords: P-TEFb; CDK activation; transcriptional elongation; Ca 2+ signal transduction; protein phosphatases] Supplemental material is available at http://www.genesdev.org. Received November 21, 2007; revised version accepted March 31, 2008. In eukaryotes, the transcription of protein-coding genes is performed by RNA polymerase (Pol) II in a cyclic process consisting of several tightly regulated stages (Sims et al. 2004). During the elongation stage, the C-terminal domain of the largest subunit of Pol II is phosphorylated by the positive transcription elongation factor b (P-TEFb) (Peterlin and Price 2006;Zhou and Yik 2006). This modification is crucial for Pol II to change from abortive to productive elongation and produce full-length RNA transcripts. Consisting of Cdk9 and cyclin T1 (or the minor forms T2 and K), P-TEFb is considered a general transcription factor required for the expression of a vast array of protein-coding genes (Chao and Price 2001;Shim et al. 2002). Not only is P-TEFb critical for cellular gene transcription, it is also a specific host cofactor for the HIV-1 Tat protein. Tat recruits P-TEFb to the TAR RNA element located at the 5Ј end of nascent viral transcripts, allowing P-TEFb to phosphorylate stalled Pol II and enhance HIV-1 elongation (Peterlin and Price 2006).However, not every P-TEFb in the nucleus is in a transcriptionally active state. A major reservoir of P-TEFb (∼50% of total P-TEFb in HeLa cells) actually exists in an inactive complex termed 7SK snRNP that also contains the 7SK snRNA (Nguyen et al. 2001;Yang et al. 2001) and three nuclear...

Reactor neutrino experiments play a crucial role in advancing our knowledge of neutrinos. A precise measurement of reactor electron antineutrino flux and spectrum evolution can be key inputs in improving the knowledge of neutrino mass and mixing as well as reactor nuclear physics and searching for physics beyond the standard model. In this work, the evolution of the flux and spectrum as a function of the reactor isotopic content is reported in terms of the inverse-beta-decay yield at Daya Bay with 1958 days of data and improved systematic uncertainties. These measurements are compared with two signature model predictions: the Huber-Mueller model based on the conversion method and the SM2018 model based on the summation method. The measured average flux and spectrum, as well as their evolution with the 239 Pu isotopic fraction, are inconsistent with the predictions of the Huber-Mueller model. In contrast, the SM2018 model is shown to agree with the average flux and its evolution but fails to describe the energy spectrum. Altering the predicted IBD spectrum from 239 Pu fission does not improve the agreement with the measurement for either model. The models can be brought into better agreement with the measurements if either the predicted spectrum due to 235 U fission is changed or the predicted 235 U, 238 U, 239 Pu, and 241 Pu spectra are changed in equal measure.

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