Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant to Part-per-Million Precision

We report a measurement of the positive muon lifetime to a precision of 1.0 parts per million (ppm); it is the most precise particle lifetime ever measured. The experiment used a time-structured, low-energy muon beam and a segmented plastic scintillator array to record more than 2 x 10^{12} decays. Two different stopping target configurations were employed in independent data-taking periods. The combined results give tau_{mu^+}(MuLan) = 2196980.3(2.2) ps, more than 15 times as precise as any previous experiment. The muon lifetime gives the most precise value for the Fermi constant: G_F(MuLan) = 1.1663788 (7) x 10^-5 GeV^-2 (0.6 ppm). It is also used to extract the mu^-p singlet capture rate, which determines the proton's weak induced pseudoscalar coupling g_P.Comment: Accepted for publication in Phys. Rev. Let

Improved Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant

The mean life of the positive muon has been measured to a precision of 11 ppm using a low-energy, pulsed muon beam stopped in a ferromagnetic target, which was surrounded by a scintillator detector array. The result, tau_mu = 2.197013(24) us, is in excellent agreement with the previous world average. The new world average tau_mu = 2.197019(21) us determines the Fermi constant G_F = 1.166371(6) x 10^-5 GeV^-2 (5 ppm). Additionally, the precision measurement of the positive muon lifetime is needed to determine the nucleon pseudoscalar coupling g_P.Comment: As published version (PRL, July 2007

Histone Deacetylase Inhibitors Globally Enhance H3/H4 Tail Acetylation Without Affecting H3 Lysine 56 Acetylation

Histone deacetylase inhibitors (HDACi) represent a promising avenue for cancer therapy. We applied mass spectrometry (MS) to determine the impact of clinically relevant HDACi on global levels of histone acetylation. Intact histone profiling revealed that the HDACi SAHA and MS-275 globally increased histone H3 and H4 acetylation in both normal diploid fibroblasts and transformed human cells. Histone H3 lysine 56 acetylation (H3K56ac) recently elicited much interest and controversy due to its potential as a diagnostic and prognostic marker for a broad diversity of cancers. Using quantitative MS, we demonstrate that H3K56ac is much less abundant than previously reported in human cells. Unexpectedly, in contrast to H3/H4 N-terminal tail acetylation, H3K56ac did not increase in response to inhibitors of each class of HDACs. In addition, we demonstrate that antibodies raised against H3K56ac peptides cross-react against H3 N-terminal tail acetylation sites that carry sequence similarity to residues flanking H3K56

Assessment of exposure to DDT and metabolites after indoor residual spraying through the analysis of thatch material from rural African dwellings

This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.[Introduction] We report on the analysis of 4,4′-dichlorodiphenyltrichloroethane (4,4′-DDT) and its metabolites in thatch and branch samples constituting the wall materials of dwellings from South African subtropical areas. This approach was used to assess the exposure to DDT in the residents of the dwellings after indoor residual spraying (IRS) following recommended sanitation practices against malaria vectors.[Discussion] Examination of the distributions of DDT compounds (2,4′-DDT, 4,4′-DDT and its metabolites) in 43 dwellings from the area of Manhiça (Mozambique) has shown median concentrations of 19, 130, and 23 ng/g for 2,4′-DDT, 4,4′-DDT, and 4,4′-DDE, respectively, in 2007 when IRS implementation was extensive. The concentrations of these compounds at the onset of the IRS campaign (n = 48) were 5. 5, 47, and 2. 2 ng/g, respectively. The differences were statistically significant and showed an increase in the concentration of this insecticide and its metabolites. Calculation of 4,4′-DDT in the indoor air resulting from the observed concentrations in the wall materials led to the characteristic values of environments polluted with this insecticide. © 2011 The Author(s).Funding was received from MICINN (INMA G03/176, Consolider Ingenio GRACCIE, CSD2007-00067), CSIC (PIF06-053), and ArcRisk EU Project (FP7-ENV-2008-1-226534).Peer reviewe