395 research outputs found
A novel role for proline- and acid-rich basic region leucine zipper (PAR bZIP) proteins in the transcriptional regulation of a BH3-only proapoptotic gene.
Proline- and acid-rich (PAR) basic region leucine zipper (bZIP) proteins thyrotroph embryonic factor (TEF), D-site-binding protein (DBP), and hepatic leukemia factor have been involved in neurotransmitter homeostasis and amino acid metabolism. Here we demonstrate a novel role for these proteins in the transcriptional control of a BH3-only gene. PAR bZIP proteins are able to transactivate the promoter of bcl-gS. This promoter is particularly responsive to TEF activation and is silenced by NFIL3, a repressor that shares the consensus binding site with PAR bZIP proteins. Consistently, transfection of TEF induces the expression of endogenous bcl-gS in cancer cells, and this induction is independent of p53. A naturally occurring variant of DBP (tDBP), lacking the transactivation domain, has been identified and shown to impede the formation of active TEF dimers in a competitive manner and to reduce the TEF-dependent induction of bcl-gS. Of note, treatment of cancer cells with etoposide induces TEF activation and promotes the expression of bcl-gS. Furthermore, blockade of bcl-gS or TEF expression by a small interfering RNA strategy or transfection with tDBP significantly reduces the etoposide-mediated apoptotic cell death. These findings represent the first described role for PAR bZIP proteins in the regulation of a gene involved in the execution of apoptosis
Sediment removal by prairie filter strips in row-cropped ephemeral watersheds
Twelve small watersheds in central Iowa were used to evaluate the effectiveness of prairie filter strips (PFS) in trapping sediment from agricultural runoff. Four treatments with PFS of different size and location (100% rowcrop, 10% PFS of total watershed area at footslope, 10% PFS at footslope and in contour strips, 20% PFS at footslope and in contour strips) arranged in a balanced incomplete block design were seeded in July 2007. All watersheds were in bromegrass ( L.) for at least 10 yr before treatment establishment. Cropped areas were managed under a no-till, 2-yr corn ( L.)-soybean [ (L.) Merr.] rotation beginning in 2007. About 38 to 85% of the total sediment export from cropland occurred during the early growth stage of rowcrop due to wet field conditions and poor ground cover. The greatest sediment load was observed in 2008 due to the initial soil disturbance and gradually decreased thereafter. The mean annual sediment yield through 2010 was 0.36 and 8.30 Mg ha for the watersheds with and without PFS, respectively, a 96% sediment trapping efficiency for the 4-yr study period. The amount and distribution of PFS had no significant impact on runoff and sediment yield, probably due to the relatively large width (37-78 m) of footslope PFS. The findings suggest that incorporation of PFS at the footslope position of annual rowcrop systems provides an effective approach to reducing sediment loss in runoff from agricultural watersheds under a no-till system
A Compact Beam Stop for a Rare Kaon Decay Experiment
We describe the development and testing of a novel beam stop for use in a
rare kaon decay experiment at the Brookhaven AGS. The beam stop is located
inside a dipole spectrometer magnet in close proximity to straw drift chambers
and intercepts a high-intensity neutral hadron beam. The design process,
involving both Monte Carlo simulations and beam tests of alternative beam-stop
shielding arrangements, had the goal of minimizing the leakage of particles
from the beam stop and the resulting hit rates in detectors, while preserving
maximum acceptance for events of interest. The beam tests consisted of
measurements of rates in drift chambers, scintilation counter hodoscopes, a gas
threshold Cherenkov counter, and a lead glass array. Measurements were also
made with a set of specialized detectors which were sensitive to low-energy
neutrons, photons, and charged particles. Comparisons are made between these
measurements and a detailed Monte Carlo simulation.Comment: 39 pages, 14 figures, submitted to Nuclear Instruments and Method
Vector-meson contributions do not explain the rate and spectrum in K_L -> pi0 gamma gamma
We analyze the recent NA48 data for the reaction K_L -> pi0 gamma gamma with
and without the assumption of vector meson dominance (VMD). We find that the
data is well described by a three-parameter expression inspired by O(p^6)
chiral perturbation theory. We also find that it is impossible to fit the shape
of the decay distribution and the overall rate simultaneously if one imposes
the VMD constraints on the three parameters. We comment on the different fits
and their implications for the CP-conserving component of the decay K_L -> pi0
e+ e-.Comment: Version accepted for publication on Phys. Rev. D. 19 pages, LaTeX, 8
figures, uses epsf.st
A straw drift chamber spectrometer for studies of rare kaon decays
We describe the design, construction, readout, tests, and performance of
planar drift chambers, based on 5 mm diameter copperized Mylar and Kapton
straws, used in an experimental search for rare kaon decays. The experiment
took place in the high-intensity neutral beam at the Alternating Gradient
Synchrotron of Brookhaven National Laboratory, using a neutral beam stop, two
analyzing dipoles, and redundant particle identification to remove backgrounds
Modelling of strain effects in manganite films
Thickness dependence and strain effects in films of
perovskites are analyzed in the colossal magnetoresistance regime. The
calculations are based on a generalization of a variational approach previously
proposed for the study of manganite bulk. It is found that a reduction in the
thickness of the film causes a decrease of critical temperature and
magnetization, and an increase of resistivity at low temperatures. The strain
is introduced through the modifications of in-plane and out-of-plane electron
hopping amplitudes due to substrate-induced distortions of the film unit cell.
The strain effects on the transition temperature and transport properties are
in good agreement with experimental data only if the dependence of the hopping
matrix elements on the bond angle is properly taken into account.
Finally variations of the electron-phonon coupling linked to the presence of
strain turn out important in influencing the balance of coexisting phases in
the filmComment: 7 figures. To be published on Physical Review
The Three Families from SM-like Chiral Models
We give a detailed description of the model construction procedures about our
new approach to the family structure of the standard model. SM-like chiral
fermion spectra, largely "derivable" from the gauge anomaly constraints, are
formulated in a symmetry
framework as an extension of the SM symmetry. The case gives naturally
three families as a result, with nontrivially embedded into the
. Such a spectrum has extra vector-like quarks and
leptons. We illustrate how an acceptable symmetry breaking pattern can be
obtained through a relatively simple scalar sector which gives naturally
hierarchical quark mass matrices. Compatibility with various FCNC constraints
and some interesting aspects of the possible phenomenological features are
discussed, from a non-model specific perspective. The question of incorporating
supersymmetry without putting in the Higgses as extra supermultiplet is also
addressed.Comment: 43 pages RevTex, including 9 tables and 3 figure
Time-integrated luminosity recorded by the BABAR detector at the PEP-II e+e- collider
This article is the Preprint version of the final published artcile which can be accessed at the link below.We describe a measurement of the time-integrated luminosity of the data collected by the BABAR experiment at the PEP-II asymmetric-energy e+e- collider at the Ï(4S), Ï(3S), and Ï(2S) resonances and in a continuum region below each resonance. We measure the time-integrated luminosity by counting e+e-âe+e- and (for the Ï(4S) only) e+e-âÎŒ+ÎŒ- candidate events, allowing additional photons in the final state. We use data-corrected simulation to determine the cross-sections and reconstruction efficiencies for these processes, as well as the major backgrounds. Due to the large cross-sections of e+e-âe+e- and e+e-âÎŒ+ÎŒ-, the statistical uncertainties of the measurement are substantially smaller than the systematic uncertainties. The dominant systematic uncertainties are due to observed differences between data and simulation, as well as uncertainties on the cross-sections. For data collected on the Ï(3S) and Ï(2S) resonances, an additional uncertainty arises due to Ïâe+e-X background. For data collected off the Ï resonances, we estimate an additional uncertainty due to time dependent efficiency variations, which can affect the short off-resonance runs. The relative uncertainties on the luminosities of the on-resonance (off-resonance) samples are 0.43% (0.43%) for the Ï(4S), 0.58% (0.72%) for the Ï(3S), and 0.68% (0.88%) for the Ï(2S).This work is supported by the US Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), the Commissariat Ă lâEnergie Atomique and Institut National de Physique NuclĂ©aire et de Physiquedes Particules (France), the Bundesministerium fĂŒr Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (The Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Ciencia e InnovaciĂłn (Spain), and the Science and Technology Facilities Council (United Kingdom). Individuals have received support from the Marie-Curie IEF program (European Union) and the A.P. Sloan Foundation (USA)
- âŠ