1,123 research outputs found
Cohomology of bundles on homological Hopf manifold
We discuss the properties of complex manifolds having rational homology of
including those constructed by Hopf, Kodaira and
Brieskorn-van de Ven. We extend certain previously known vanishing properties
of cohomology of bundles on such manifolds.As an application we consider
degeneration of Hodge-deRham spectral sequence in this non Kahler setting.Comment: To appear in Proceedings of 2007 conference on Several complex
variables and Complex Geometry. Xiamen. Chin
WS2.8 Slc26a9-mediated Clâ secretion is enhanced in allergic airway inflammation and prevents mucus obstruction in mouse airways
The K+ Channel Opener 1-EBIO Potentiates Residual Function of Mutant CFTR in Rectal Biopsies from Cystic Fibrosis Patients
BACKGROUND: The identification of strategies to improve mutant CFTR function remains a key priority in the development of new treatments for cystic fibrosis (CF). Previous studies demonstrated that the Kâș channel opener 1-ethyl-2-benzimidazolone (1-EBIO) potentiates CFTR-mediated Clâ» secretion in cultured cells and mouse colon. However, the effects of 1-EBIO on wild-type and mutant CFTR function in native human colonic tissues remain unknown. METHODS: We studied the effects of 1-EBIO on CFTR-mediated Clâ» secretion in rectal biopsies from 47 CF patients carrying a wide spectrum of CFTR mutations and 57 age-matched controls. Rectal tissues were mounted in perfused micro-Ussing chambers and the effects of 1-EBIO were compared in control tissues, CF tissues expressing residual CFTR function and CF tissues with no detectable Clâ» secretion. RESULTS: Studies in control tissues demonstrate that 1-EBIO activated CFTR-mediated Clâ» secretion in the absence of cAMP-mediated stimulation and potentiated cAMP-induced Clâ» secretion by 39.2±6.7% (P<0.001) via activation of basolateral CaÂČâș-activated and clotrimazole-sensitive KCNN4 Kâș channels. In CF specimens, 1-EBIO potentiated cAMP-induced Clâ» secretion in tissues with residual CFTR function by 44.4±11.5% (P<0.001), but had no effect on tissues lacking CFTR-mediated Clâ» conductance. CONCLUSIONS: We conclude that 1-EBIO potentiates Clâ»secretion in native CF tissues expressing CFTR mutants with residual Clâ» channel function by activation of basolateral KCNN4 Kâș channels that increase the driving force for luminal Clâ» exit. This mechanism may augment effects of CFTR correctors and potentiators that increase the number and/or activity of mutant CFTR channels at the cell surface and suggests KCNN4 as a therapeutic target for CF
The CPLEAR Electromagnetic Calorimeter
A large-acceptance lead/gas sampling electromagnetic calorimeter (ECAL) was constructed for the CPLEAR experiment to detect photons from decays of s with momentum MeV. The main purpose of the ECAL is to determine the decay vertex of neutral-kaon decays \ko \rightarrow \pi^0\pi^0 \rightarrow 4 \gamma and \ko \rightarrow \pi^0\pi^0\pi^0 \rightarrow 6 \gamma. This requires a position-sensitive photon detector with high spatial granularity in -, -, and -coordinates. The ECAL --- a barrel without end-caps located inside a magnetic field of 0.44 T --- consists of 18 identical concentric layers. Each layer of radiation length (X) contains a converter plate followed by small cross-section high-gain tubes of 2640 mm active length which are sandwiched by passive pick-up strip plates. The ECAL, with a total of X, has an energy resolution of and a position resolution of 4.5 mm for the shower foot. The shower topology allows separation of electrons from pions. The design, construction, read-out electronics, and performance of the detector are described
Observation of charge-dependent azimuthal correlations and possible local strong parity violation in heavy ion collisions
Parity-odd domains, corresponding to non-trivial topological solutions of the
QCD vacuum, might be created during relativistic heavy-ion collisions. These
domains are predicted to lead to charge separation of quarks along the orbital
momentum of the system created in non-central collisions. To study this effect,
we investigate a three particle mixed harmonics azimuthal correlator which is a
\P-even observable, but directly sensitive to the charge separation effect. We
report measurements of this observable using the STAR detector in Au+Au and
Cu+Cu collisions at =200 and 62~GeV. The results are presented
as a function of collision centrality, particle separation in rapidity, and
particle transverse momentum. A signal consistent with several of the
theoretical expectations is detected in all four data sets. We compare our
results to the predictions of existing event generators, and discuss in detail
possible contributions from other effects that are not related to parity
violation.Comment: 17 pages, 14 figures, as accepted for publication in Physical Review
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Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV
A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay
channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7
TeV is presented. The data were collected at the LHC, with the CMS detector,
and correspond to an integrated luminosity of 4.6 inverse femtobarns. No
significant excess is observed above the background expectation, and upper
limits are set on the Higgs boson production cross section. The presence of the
standard model Higgs boson with a mass in the 270-440 GeV range is excluded at
95% confidence level.Comment: Submitted to JHE
Studying Parton Energy Loss in Heavy-Ion Collisions via Direct-Photon and Charged-Particle Azimuthal Correlations
Charged-particle spectra associated with direct photon () and
are measured in + and Au+Au collisions at center-of-mass energy
GeV with the STAR detector at RHIC. A hower-shape
analysis is used to partially discriminate between and .
Assuming no associated charged particles in the direction (near
side) and small contribution from fragmentation photons (), the
associated charged-particle yields opposite to (away side) are
extracted. At mid-rapidity () in central Au+Au collisions,
charged-particle yields associated with and at high
transverse momentum ( GeV/) are suppressed by a factor
of 3-5 compared with + collisions. The observed suppression of the
associated charged particles, in the kinematic range and GeV/, is similar for and , and
independent of the energy within uncertainties. These
measurements indicate that the parton energy loss, in the covered kinematic
range, is insensitive to the parton path length.Comment: submitted to Phys. Rev. Lett, 6 pages, 4 figure
An Experimental Exploration of the QCD Phase Diagram: The Search for the Critical Point and the Onset of De-confinement
The QCD phase diagram lies at the heart of what the RHIC Physics Program is
all about. While RHIC has been operating very successfully at or close to its
maximum energy for almost a decade, it has become clear that this collider can
also be operated at lower energies down to 5 GeV without extensive upgrades. An
exploration of the full region of beam energies available at the RHIC facility
is imperative. The STAR detector, due to its large uniform acceptance and
excellent particle identification capabilities, is uniquely positioned to carry
out this program in depth and detail. The first exploratory beam energy scan
(BES) run at RHIC took place in 2010 (Run 10), since several STAR upgrades,
most importantly a full barrel Time of Flight detector, are now completed which
add new capabilities important for the interesting physics at BES energies. In
this document we discuss current proposed measurements, with estimations of the
accuracy of the measurements given an assumed event count at each beam energy.Comment: 59 pages, 78 figure
Search for anomalous t t-bar production in the highly-boosted all-hadronic final state
A search is presented for a massive particle, generically referred to as a
Z', decaying into a t t-bar pair. The search focuses on Z' resonances that are
sufficiently massive to produce highly Lorentz-boosted top quarks, which yield
collimated decay products that are partially or fully merged into single jets.
The analysis uses new methods to analyze jet substructure, providing
suppression of the non-top multijet backgrounds. The analysis is based on a
data sample of proton-proton collisions at a center-of-mass energy of 7 TeV,
corresponding to an integrated luminosity of 5 inverse femtobarns. Upper limits
in the range of 1 pb are set on the product of the production cross section and
branching fraction for a topcolor Z' modeled for several widths, as well as for
a Randall--Sundrum Kaluza--Klein gluon. In addition, the results constrain any
enhancement in t t-bar production beyond expectations of the standard model for
t t-bar invariant masses larger than 1 TeV.Comment: Submitted to the Journal of High Energy Physics; this version
includes a minor typo correction that will be submitted as an erratu
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