Observation of electron neutrino appearance in a muon neutrino beam.

The T2K experiment has observed electron neutrino appearance in a muon neutrino beam produced 295 km from the Super-Kamiokande detector with a peak energy of 0.6 GeV. A total of 28 electron neutrino events were detected with an energy distribution consistent with an appearance signal, corresponding to a significance of 7.3σ when compared to 4.92±0.55 expected background events. In the Pontecorvo-Maki-Nakagawa-Sakata mixing model, the electron neutrino appearance signal depends on several parameters including three mixing angles θ12, θ23, θ13, a mass difference Δm(32)(2) and a CP violating phase δ(CP). In this neutrino oscillation scenario, assuming |Δm(32)(2)|=2.4×10(-3) eV(2), sin(2)θ(23)=0.5, and Δm322>0 (Δm(32)(2)<0), a best-fit value of sin(2)2θ(13)=0.140(-0.032)(+0.038) (0.170(-0.037)(+0.045)) is obtained at δ(CP)=0. When combining the result with the current best knowledge of oscillation parameters including the world average value of θ(13) from reactor experiments, some values of δ(CP) are disfavored at the 90% C.L.

Precise measurement of the neutrino mixing parameter θ23 from muon neutrino disappearance in an off-axis beam.

New data from the T2K neutrino oscillation experiment produce the most precise measurement of the neutrino mixing parameter θ23. Using an off-axis neutrino beam with a peak energy of 0.6 GeV and a data set corresponding to 6.57×10(20) protons on target, T2K has fit the energy-dependent νµ oscillation probability to determine oscillation parameters. The 68% confidence limit on sin(2)(θ23) is 0.514(-0.056)(+0.055) (0.511±0.055), assuming normal (inverted) mass hierarchy. The best-fit mass-squared splitting for normal hierarchy is Δm32(2)=(2.51±0.10)×10(-3) eV(2)/c(4) (inverted hierarchy: Δm13(2)=(2.48±0.10)×10(-3) eV(2)/c(4)). Adding a model of multinucleon interactions that affect neutrino energy reconstruction is found to produce only small biases in neutrino oscillation parameter extraction at current levels of statistical uncertainty.

Measurement of the inclusive electron neutrino charged current cross section on carbon with the T2K near detector.

The T2K off-axis near detector ND280 is used to make the first differential cross-section measurements of electron neutrino charged current interactions at energies ∼1 GeV as a function of electron momentum, electron scattering angle, and four-momentum transfer of the interaction. The total flux-averaged ν(e) charged current cross section on carbon is measured to be ⟨σ⟩(ϕ)=1.11±0.10(stat)±0.18(syst)×10⁻³8 cm²/nucleon. The differential and total cross-section measurements agree with the predictions of two leading neutrino interaction generators, NEUT and GENIE. The NEUT prediction is 1.23×10⁻³8 cm²/nucleon and the GENIE prediction is 1.08×10⁻³8 cm²/nucleon. The total ν(e) charged current cross-section result is also in agreement with data from the Gargamelle experiment.

Measurement of muon antineutrino quasielastic scattering on a hydrocarbon target at Eν ~ 3.5 GeV.

We have isolated ν(µ) charged-current quasielastic (QE) interactions occurring in the segmented scintillator tracking region of the MINERvA detector running in the NuMI neutrino beam at Fermilab. We measure the flux-averaged differential cross section, dσ/dQ², and compare to several theoretical models of QE scattering. Good agreement is obtained with a model where the nucleon axial mass, M(A), is set to 0.99 GeV/c² but the nucleon vector form factors are modified to account for the observed enhancement, relative to the free nucleon case, of the cross section for the exchange of transversely polarized photons in electron-nucleus scattering. Our data at higher Q² favor this interpretation over an alternative in which the axial mass is increased.

Measurement of muon neutrino quasielastic scattering on a hydrocarbon target at Eν ~ 3.5 GeV.

We report a study of ν(µ) charged-current quasielastic events in the segmented scintillator inner tracker of the MINERvA experiment running in the NuMI neutrino beam at Fermilab. The events were selected by requiring a µ- and low calorimetric recoil energy separated from the interaction vertex. We measure the flux-averaged differential cross section, dσ/dQ², and study the low energy particle content of the final state. Deviations are found between the measured dσ/dQ² and the expectations of a model of independent nucleons in a relativistic Fermi gas. We also observe an excess of energy near the vertex consistent with multiple protons in the final state.

Measurement of neutrino oscillation parameters from muon neutrino disappearance with an off-axis beam.

The T2K Collaboration reports a precision measurement of muon neutrino disappearance with an off-axis neutrino beam with a peak energy of 0.6 GeV. Near detector measurements are used to constrain the neutrino flux and cross section parameters. The Super-Kamiokande far detector, which is 295 km downstream of the neutrino production target, collected data corresponding to 3.01×10(20) protons on target. In the absence of neutrino oscillations, 205±17 (syst) events are expected to be detected while only 58 muon neutrino event candidates are observed. A fit to the neutrino rate and energy spectrum, assuming three neutrino flavors and normal mass hierarchy yields a best-fit mixing angle sin2(θ23)=0.514±0.082 and mass splitting |Δm(32)(2)|=2.44(-0.15)(+0.17)×10(-3) eV2/c4. Our result corresponds to the maximal oscillation disappearance probability.

Improved measurement of muon antineutrino disappearance in MINOS.

We report an improved measurement of ν(µ) disappearance over a distance of 735 km using the MINOS detectors and the Fermilab Main Injector neutrino beam in a ν(µ)-enhanced configuration. From a total exposure of 2.95×10(20) protons on target, of which 42% have not been previously analyzed, we make the most precise measurement of Δm2=[2.62(-0.28)(+0.31)(stat)±0.09(syst)]×10(-3) eV2 and constrain the ν(µ) mixing angle sin2(2θ)>0.75 (90% C.L.). These values are in agreement with Δm2 and sin2(2θ) measured for ν(µ), removing the tension reported in [P. Adamson et al. (MINOS), Phys. Rev. Lett. 107, 021801 (2011).].

Measurement of the neutrino mass splitting and flavor mixing by MINOS.

Measurements of neutrino oscillations using the disappearance of muon neutrinos from the Fermilab NuMI neutrino beam as observed by the two MINOS detectors are reported. New analysis methods have been applied to an enlarged data sample from an exposure of 7.25×10(20) protons on target. A fit to neutrino oscillations yields values of |Δm(2)|=(2.32(-0.08)(+0.12))×10(-3) eV(2) for the atmospheric mass splitting and sin(2)(2θ)>0.90 (90% C.L.) for the mixing angle. Pure neutrino decay and quantum decoherence hypotheses are excluded at 7 and 9 standard deviations, respectively.

Active to sterile neutrino mixing limits from neutral-current interactions in MINOS.

Results are reported from a search for active to sterile neutrino oscillations in the MINOS long-baseline experiment, based on the observation of neutral-current neutrino interactions, from an exposure to the NuMI neutrino beam of 7.07×10(20) protons on target. A total of 802 neutral-current event candidates is observed in the Far Detector, compared to an expected number of 754 ± 28(stat) ± 37(syst) for oscillations among three active flavors. The fraction f(s) of disappearing ν(µ) that may transition to ν(s) is found to be less than 22% at the 90% C.L.

First direct observation of muon antineutrino disappearance.

This Letter reports the first direct observation of muon antineutrino disappearance. The MINOS experiment has taken data with an accelerator beam optimized for ν(µ) production, accumulating an exposure of 1.71 × 10²° protons on target. In the Far Detector, 97 charged current ν(µ) events are observed. The no-oscillation hypothesis predicts 156 events and is excluded at 6.3σ. The best fit to oscillation yields |Δm²| = [3.36(-0.40)(+0.46)(stat) ± 0.06(syst)] × 10⁻³ eV², sin²(2θ) = 0.86(-0.12)(+0.11)(stat) ± 0.01(syst). The MINOS ν(µ) and ν(µ) measurements are consistent at the 2.0% confidence level, assuming identical underlying oscillation parameters.

Improved search for Muon-neutrino to electron-neutrino oscillations in MINOS.

We report the results of a search for ν(e) appearance in a ν(µ) beam in the MINOS long-baseline neutrino experiment. With an improved analysis and an increased exposure of 8.2 × 10(20) protons on the NuMI target at Fermilab, we find that 2 sin(2) (θ(23))sin(2)(2θ(13))<0.12(0.20) at 90% confidence level for δ = 0 and the normal (inverted) neutrino mass hierarchy, with a best-fit of 2sin(2) (θ(23))sin(2)(2θ(13)) = 0.041(-0.031)(+0.047) (0.079(-0.053) (+0.071)). The θ(13) = 0 hypothesis is disfavored by the MINOS data at the 89% confidence level.

Search for Lorentz invariance and CPT violation with the MINOS far detector.

We searched for a sidereal modulation in the MINOS far detector neutrino rate. Such a signal would be a consequence of Lorentz and CPT violation as described by the standard-model extension framework. It also would be the first detection of a perturbative effect to conventional neutrino mass oscillations. We found no evidence for this sidereal signature, and the upper limits placed on the magnitudes of the Lorentz and CPT violating coefficients describing the theory are an improvement by factors of 20-510 over the current best limits found by using the MINOS near detector.

Search for muon-neutrino to electron-neutrino transitions in MINOS.

This Letter reports on a search for nu(mu) --> nu(e) transitions by the MINOS experiment based on a 3.14x10(20) protons-on-target exposure in the Fermilab NuMI beam. We observe 35 events in the Far Detector with a background of 27+/-5(stat)+/-2(syst) events predicted by the measurements in the Near Detector. If interpreted in terms of nu(mu) --> nu(e) oscillations, this 1.5sigma excess of events is consistent with sin2(2theta(13)) comparable to the CHOOZ limit when |Delta m2|=2.43x10(-3) eV2 and sin2(2theta(23))=1.0 are assumed.

A plasmid-based self-amplifying Sindbis virus vector.

Sindbis virus was used as a self-amplifying eukaryotic expression vector. A recombinant cDNA genome of this (+)-strand RNA virus was placed under the transcriptional control of a Rous sarcoma virus LTR (RSV) promoter. Transfection of this plasmid construct into mammalian cell lines (3T3, HepG2, and 293 cells) resulted in expression of the luciferase reporter gene. High-expression levels were also measured after transfection into primary rat myoblasts. In differentiated myotubes, expression levels generated by the Sindbis virus vector were up to 200 times higher than those obtained with a conventional RSV expression vector. In vivo expression was detected after injection of plasmid DNA into mouse quadriceps. In vivo expression was transient and undetectable by day 16. This self-amplifying expression vector can be used for generating high-level expression of transgenes in vitro and in vivo. Its transient nature in vivo could allow for safe, short-term delivery of gene products in gene therapy protocols. It should facilitate the study of Sindbis and other RNA viruses.

Energy supply of the mitotic cell cycle and the Na+/H+-antiport in ascites tumors.

The activation of Na+ transport is due to the exchange of protons formed via glucose conversion into lactate for Na+, i.e., to the stimulation of the Na+/H+-antiport. Experimental results and theoretical calculations suggest that in glucose-containing medium the Na+ transport increases from 0.75 to 1.78 pmol/hour per cell. The permeability of plasma membranes for K+ increases 2.75 fold, while the passive flux of Na+ diminishes. The intensity of O2 adsorption by ascites tumor cells does not practically depend on the monovalent cation concentration gradient between the cells and the culture medium, whereas the rate of glycolysis decreases simultaneously with the diminution of the concentration gradient. In synchronized cultures at the beginning of the mitotic cycle, the bulk of ATP resynthesized via glycolysis is utilized for the synthesis of biopolymers, whereas that at the end of the S-phase and in the G2-phase is utilized for cation transport across plasma membranes. From 35 to 100% of the whole amount of ATP resynthesized via glycolysis is utilized for transport purposes. It is concluded that the observed increase in the Na+/K+ ratio in ascites tumor cells is connected with their enhanced ability to synthesize lactic acid. Presumably, glycolysis is one of the regulatory mechanisms of intracellular ratios of monovalent cations.

Ascitic tumor cell cycle metabolism and energetics.

Data are presented on Ehrlich ascitic tumor cells energetic metabolism, activities of the glycolytic enzymes and the pentose phosphate pathway enzymes, contents and synthesis rates of the macromolecules at various cell cycle stages. An attempt was made to correct the direct measurement by taking into consideration a systematic error introduced in the experiment by incomplete cells synchronization. Cell metabolism activation sharply increased at two mitotic cycle stages. At the first stage (end of G1-period, beginning of S-period) the processes associated with the preparation to reduplication and DNA synthesis were activated. The second activation wave (end of S-period, G2-period) was connected with cell preparation of mitosis. The coordination of cell metabolism variations during the cell cycle is shown.

Isolation of low molecular protein P-9 from nuclei of NK/Ly lymphoma and Guerin carcinoma.

Protein with molecular weight 9000 (protein-9) was found in nuclei of resting cells of NK/Ly lymphoma and Guerin carcinoma by electrophoresis in polyacrylamide gel. Method of preparative isolation P-9 concluding in fractionation of nuclei from phenol extract by acetone at different pH and following electrophoresis in polyacrylamide gel was made. Electrophoretically homogeneous preparation of protein P-9 from nuclei of NK/Ly lymphoma and Guerin carcinoma was obtained.

Intracellular ratio between monovalent cations (Na+/K+), and transcriptional activity of genes in tumour cells.

The effects of the intracellular Na+/K+ ratio on transcriptional activity of ribosomal, c-fos, beta-actin and histone genes of Ehrlich ascites tumour cells and P-388 leukaemia cells have been investigated. Optimum values of the Na+/K+ ratio for selective transcription of genes are shown, they are in accordance with the Na+/K+ ratio and mRNA content of respective genes during the cell cycle. Differential activation and repression of these genes do not correlate with the total synthesis rate of RNA during the cell cycle. The data indicate a selective nature of the action of monovalent cations on gene expression during the cell growth.

[Cytochemical analysis of polyamines in Ehrlich ascitic carcinoma cells during different phases of mitotic cycle under the effects of difluoromethylornithine]. / Tsitokhimicheskoe issledovanie poliaminov v kletkakh astsitnogo raka Erlikha v razlichnye fazy mitoticheskogo tsikla posle vozdeistviia diftormetilornitinom.

Mice bearing Ehrlich carcinoma cells received one 80 mg/kg dose of DFMO. After 20 hours the cells were extracted from the peritoneal cavity and separated by means of sedimentation of 1 g in saccharose gradient into 9 fractions depending on the mitotic cycle phase. The content of polyamines in the cells of each fraction was detected by the fluorescent method using fluorescamine. It was shown that the tumor cells during G1 phase mitotic cycle (13-15% cells blocked) and especially cells in the 1st half of S-phase (19-23% cells blocked) were most sensitive to inhibitory effect of DFMO.

[Effects of intracellular Na+/K+ ratio on expression of c-fos oncogene and beta-actin gene in ascitic cells of leukemia P-388 and Ehrlich tumor]. / Vliianie vnutrikletochnogo sootnosheniia Na+/K+ na ékspressiiu onkogena c-fos i gena beta-aktina v astsitnykh kletkakh leikoza P-388 i raka Erlikha.

The intracellular Na+/K+ ratio was studied for its effect on expression gene beta-actin and oncogene c-fos and activity of these genes during the mitotic cycle in ascites cells of leukemia P-388 and Ehrlich tumour. It was established that gene beta-actin was activated at high and low ratios of Na+/K+, while c-fos only at high ones. The expression of these genes during the mitotic cell cycle was due to changes in the intracellular Na+/K+ ratio. The obtained data showed an important role of intracellular homeostasis of monovalent cations in regulation of gene expression during the mitotic cell cycle.