84 research outputs found
Fiber-optic control and thermometry of single-cell thermosensation logic
Thermal activation of transient receptor potential (TRP) cation channels is one of the most striking examples of temperature-controlled processes in cell biology. As the evidence indicating the fundamental role of such processes in thermosensation builds at a fast pace, adequately accurate tools that would allow heat receptor logic behind thermosensation to be examined on a single-cell level are in great demand. Here, we demonstrate a specifically designed fiber-optic probe that enables thermal activation with simultaneous online thermometry of individual cells expressing genetically encoded TRP channels. This probe integrates a fiber-optic tract for the delivery of laser light with a two-wire microwave transmission line. A diamond microcrystal fixed on the fiber tip is heated by laser radiation transmitted through the fiber, providing a local heating of a cell culture, enabling a well-controlled TRP-assisted thermal activation of cells. Online local temperature measurements are performed by using the temperature-dependent frequency shift of optically detected magnetic resonance, induced by coupling the microwave field, delivered by the microwave transmission line, to nitrogen—vacancy centers in the diamond microcrystal. Activation of TRP channels is verified by using genetically encoded fluorescence indicators, visualizing an increase in the calcium flow through activated TRP channels
Search for a scalar or vector particle decaying into Zgamma in ppbar collisions at sqrt(s) = 1.96 TeV
We present a search for a narrow scalar or vector resonance decaying into
Zgamma with a subsequent Z decay into a pair of electrons or muons. The data
for this search were collected with the D0 detector at the Fermilab Tevatron
ppbar collider at a center of mass energy sqrt(s) = 1.96 TeV. Using 1.1 (1.0)
fb-1 of data, we observe 49 (50) candidate events in the electron (muon)
channel, in good agreement with the standard model prediction. From the
combination of both channels, we derive 95% C.L. upper limits on the cross
section times branching fraction (sigma x B) into Zgamma. These limits range
from 0.19 (0.20) pb for a scalar (vector) resonance mass of 600 GeV/c^2 to 2.5
(3.1) pb for a mass of 140 GeV/c^2.Comment: Published by Phys. Lett.
Measurement of the differential cross section for the production of an isolated photon with associated jet in ppbar collisions at sqrt(s)=1.96 TeV
The process ppbar -> photon + jet + X is studied using 1.0 fb^-1 of data
collected by the D0 detector at the Fermilab Tevatron ppbar collider at a
center-of-mass energy sqrt(s)=1.96 TeV. Photons are reconstructed in the
central rapidity region |y_gamma|<1.0 with transverse momenta in the range
30<Pt_gamma<400 GeV while jets are reconstructed in either the central
|y_jet|15 GeV.
The differential cross section d^3sigma/dPt_gamma dy_gamma dy_jet is measured
as a function of Pt_gamma in four regions, differing by the relative
orientations of the photon and the jet in rapidity. Ratios between the
differential cross sections in each region are also presented. Next-to-leading
order QCD predictions using different parameterizations of parton distribution
functions and theoretical scale choices are compared to the data. The
predictions do not simultaneously describe the measured normalization and
Pt_gamma dependence of the cross section in any of the four measured regions.Comment: 13 pages, 10 figure
Measurement of the ratio of the +-jet cross section to the inclusive +jets cross section
We present a measurement of the fraction of inclusive +jets events
produced with net charm quantum number , denoted +-jet, in
collisions at TeV using approximately 1~fb of
data collected by the D0 detector at the Fermilab Tevatron Collider. We
identify the +jets events via the leptonic boson decays. Candidate
+-jet events are selected by requiring a jet containing a muon in
association with a reconstructed boson and exploiting the charge
correlation between this muon and boson decay lepton to perform a nearly
model-independent background subtraction. We measure the fraction of
+-jet events in the inclusive +jets sample for jet GeV and
pseudorapidity to be
0.074(stat.)(syst.), in agreement with
theoretical predictions. The probability that background fluctuations could
produce the observed fraction of +-jet events is estimated to be
, which corresponds to a 3.5 statistical
significance.Comment: submitted to Physics Letters
Search for Supersymmetry in Di-Photon Final States at sqrt{s} = 1.96 TeV
We report results of a search for supersymmetry (SUSY) with gauge-mediated
symmetry breaking in di-photon events collected by the D0 experiment at the
Fermilab Tevatron Collider in 2002--2006. In 1.1 fb of data, we find no
significant excess beyond the background expected from the standard model and
set the most stringent lower limits to date for a standard benchmark model on
the lightest neutralino and chargino masses of 125 GeV and 229 GeV,
respectively, at 95% confidence
Search for scalar top quarks in the acoplanar charm jets and missing transverse energy final state in collisions at TeV
We present a search for the pair production of scalar top quarks,
, using 995 pb of data collected in collisions
with the D0 detector at the Fermilab Tevatron Collider at
TeV. Both scalar top quarks are assumed to decay into a charm quark and a
neutralino (), where is the
lightest supersymmetric particle. This leads to a final state with two
acoplanar charm jets and missing transverse energy. We find the yield of such
events to be consistent with the standard model expectation, and exclude sets
of and masses at the 95% C.L. that
substantially extend the domain excluded by previous searches.Comment: 10 pages, 5 figures, submitted to Physics Letters
Search for squarks and gluinos in events with jets and missing transverse energy using 2.1 fb-1 of ppbar collision data at sqrt(s)=1.96 TeV
A data sample corresponding to an integrated luminosity of 2.1 fb-1 collected
by the D0 detector at the Fermilab Tevatron Collider was analyzed to search for
squarks and gluinos produced in ppbar collisions at a center-of-mass energy of
1.96 TeV. No evidence for the production of such particles was observed in
topologies involving jets and missing transverse energy, and 95% C.L. lower
limits of 379 GeV and 308 GeV were set on the squark and gluino masses,
respectively, within the framework of minimal supergravity with tan(beta)=3,
A0=0, and mu<0. The corresponding previous limits are improved by 54 GeV and 67
GeV
Search for the lightest scalar top quark in events with two leptons in p-pbar collisions at sqrt(s) = 1.96 TeV
Data collected by the D0 detector at a p-pbar center-of-mass energy of 1.96
TeV at the Fermilab Tevatron Collider have been used to search for pair
production of the lightest supersymmetric partner of the top quark decaying
into . The search is performed in the
and final states. No evidence for this process has been found in data
samples of approximately 400 pb^-1. The domain in the
[] plane excluded at the 95% C.L. is
substantially extended by this search.Comment: 9 pages, 11 figures. Selection-cut layouts slightly different than in
PL
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