Spectral measurement of electron antineutrino oscillation amplitude and frequency at Daya Bay.

A measurement of the energy dependence of antineutrino disappearance at the Daya Bay reactor neutrino experiment is reported. Electron antineutrinos (ν¯(e)) from six 2.9 GW(th) reactors were detected with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls. Using 217 days of data, 41 589 (203 809 and 92 912) antineutrino candidates were detected in the far hall (near halls). An improved measurement of the oscillation amplitude sin(2)2θ(13)=0.090(-0.009)(+0.008) and the first direct measurement of the ν¯(e) mass-squared difference |Δm(ee)2|=(2.59(-0.20)(+0.19))×10(-3) eV2 is obtained using the observed ν¯(e) rates and energy spectra in a three-neutrino framework. This value of |Δm(ee)2| is consistent with |Δm(µµ)2| measured by muon neutrino disappearance, supporting the three-flavor oscillation model.

Measurement of the total active 8B solar neutrino flux at the Sudbury Neutrino Observatory with enhanced neutral current sensitivity.

The Sudbury Neutrino Observatory has precisely determined the total active (nu(x)) 8B solar neutrino flux without assumptions about the energy dependence of the nu(e) survival probability. The measurements were made with dissolved NaCl in heavy water to enhance the sensitivity and signature for neutral-current interactions. The flux is found to be 5.21 +/- 0.27(stat)+/-0.38(syst) x 10(6) cm(-2) s(-1), in agreement with previous measurements and standard solar models. A global analysis of these and other solar and reactor neutrino results yields Deltam(2)=7.1(+1.2)(-0.6) x 10(-5) eV(2) and theta=32.5(+2.4)(-2.3) degrees. Maximal mixing is rejected at the equivalent of 5.4 standard deviations.

Constraints on nucleon decay via invisible modes from the Sudbury Neutrino Observatory.

Data from the Sudbury Neutrino Observatory have been used to constrain the lifetime for nucleon decay to "invisible" modes, such as n-->3nu. The analysis was based on a search for gamma rays from the deexcitation of the residual nucleus that would result from the disappearance of either a proton or neutron from 16O. A limit of tau(inv)>2 x 10(29) yr is obtained at 90% confidence for either neutron- or proton-decay modes. This is about an order of magnitude more stringent than previous constraints on invisible proton-decay modes and 400 times more stringent than similar neutron modes.

Binding analysis of antibodies produced by precursor and branchpoint intermediates of an anti-influenza hemagglutinin B cell clone. Parallel replacement mutations do not confer increased avidity for hemagglutinin.

We have previously described a set of secondary (2 degrees) hybridomas that are specific for the Sb site of influenza hemagglutinin (HA(Sb)) and share the H37-68 ld (68ld). Cells producing 68ld Abs dominated the 2 degree response of one BALB/c mouse, but were virtually absent from the primary (1 degree) and 2 degree responses of other BALB/c mice. To understand the basis for the idiosyncratic nature of this response, we have assessed the functional importance of a conserved DJ junctional sequence. We find that substitutions of conserved residues within this sequence drastically reduced HA(Sb) binding, providing an explanation for the absence of this ld from 1 degree responses. We have also examined intraclonal affinity maturation by generating Abs inferred to have been produced by the unmutated precursors and branchpoint intermediates of the largest 68ld clone. Interestingly, unmutated Abs of this clone bound HA(Sb) well, comparable to that of some 2 degree 68ld hybridoma Abs. Abs produced by branchpoint intermediates of this clone have a lower affinity for HA(Sb) than their unmutated precursor, despite containing parallel amino acid replacement mutations. Thus, expansion of this clone did not follow the paradigm of stepwise increases in affinity. Together, these data underscore the interconnective nature of precursor frequency and somatic mutation in the formation of the 2 degree response to a given Ag.

Direct determination of ionic solvation from neutron diffraction.

Much information on ionic solvation in electrolyte solutions has been inferred from macroscopic thermodynamic and transport properties and from spectroscopy. These ion-water interactions can now be probed directly and unambiguously by neutron diffraction. Such measurements have been done with neodymium trichloride solutions in heavy water that are identical in every respect except the isotopic state of the neodymium ions; these experiments yield in a straightforward manner the distribution of oxygen and deuterium atoms from the water molecules in the first hydration sphere of the neodymium ion. Each ion is surrounded by 8.6 oxygen atoms at a distance of 2.48 angstroms and 16.7 deuterium atoms at 3.13 angstroms indicating a well-defined first hydration sphere of water molecules, the deuterium atoms pointing away from the cation.

Lithium kinetics in single daily dosing.

The feasibility of single daily dosing of lithium carbonate was tested in eight recurrent manic-depressives being treated with lithium prophylaxis. The patients received their entire 24-h maintenance dose at 8:00 p.m. for 12 consecutive days. The suitability of single daily dosing was determined by comparing 1) lithium through levels; 2) lithium kinetic parameters of half-life, clearance, and volume of distribution; and 3) renal function parameters of serum creatinine, creatinine clearance, and mean 24-h urine output during the initial divided daily dosage trial and the subsequent single daily dosage trial. The observation of no significant changes in either serum half-lives or renal lithium clearance levels supports the conclusion that the average steady-state lithium serum concentration (Cpss) is unchanged by conversion to single daily doses. No significant changes were observed in either serum creatinine or creatinine clearance. However, a significant decrease in the 24-h urine output was noted on the single daily dose.