491 research outputs found
Ethylene-regulated gene expression in tomato fruit: characterization of novel ethylene-responsive and ripeningrelated genes isolated by differential display.
Differential display was used to isolate early ethyleneregulated genes from late immature green tomato fruit in order to obtain a broader understanding of the molecular basis by which ethylene coordinates the ripening process. Nineteen novel ethylene-responsive (ER) cDNA clones were isolated that fell into three classes: (i) ethylene up-regulated (ii) ethylene downregulated, and (iii) transiently induced. Expression analysis revealed that ethylene-dependent changes in mRNA accumulation occurred rapidly (15 min) for most of the ER clones. The predicted proteins encoded by the ER genes are putatively involved in processes as diverse as primary metabolism, hormone signalling and stress responses. Although a number of the isolated ER clones correspond to genes already documented in other species, their responsiveness to ethylene is described here for the ®rst time. Among the ER clones sharing high homology with regulatory genes, ER43, a putative GTP-binding protein, and ER50, a CTR1-like clone, are potentially involved in signal transduction. ER24 is homologous to the multiprotein bridging factor MBF1 involved in transcriptional activation, and ®nally, two clones are homologous to genes involved in post-transcriptional regulation: ER49, a putative translational elongation factor, and ER68, a mRNA helicase-like gene. Six ER clones correspond to as yet unidenti®ed genes. The expression studies indicated that all the ER genes are ripening-regulated, and, depending on the clone, show changes in transcript accumulation either at the breaker, turning, or red stage. Analysis of transcript accumulation in different organs indicated a strong bias towards expression in the fruit for many of the clones. The potential roles for some of the ER clone
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Structure Loaded Vacuum Laser-Driven Particle Acceleration Experiments at SLAC
We present an overview of the future laser-driven particle acceleration experiments. These will be carried out at the E163 facility at SLAC. Our objectives include a reconfirmation of the proof-of-principle experiment, a staged buncher laser-accelerator experiment, and longer-term future experiments that employ dielectric laser-accelerator microstructures
Effects of follicular phase exercise on luteinizing hormone pulse characteristics in sedentary eumenorrhoeic women
OBJECTIVE Current studies reveal little regarding the Inception of exercise-induced LH changes during physical training. This study aimed to assess the susceptibility of the hypothalamic–pituitary axis to the acute physical stress of exercise in untrained, physically inactive women. The acute effects of submaximal endurance exercise upon the pulsatile LH secretion in the follicular phase were compared with those accompanying leisurely strolling for a similar time period. SUBJECTS All subjects were eumenorrhoelc, as determined by biphasic temperature patterns, detection of the urinary LH surge, and mid-luteal serum progesterone levels. Subjects were not physically active and had little history of strenuous exercise ( V o 2 max = 38·0 ± 1·8) (mean ± SEM) ml/kg/min). DESIGN All women completed a 13·5-hour pulsatility test which included three consecutive 20-minute runs on a treadmill at 50, 60 and 70% of the subjects’maximum oxygen uptake ( n = 16). Six of these same subjects completed a separate test on another occasion in which one hour of leisurely strolling was substituted for exercise. Blood was sampled every 10 minutes via an indwelling cannula for 4·5 hours before and 8 hours after one hour of exercise and or strolling. MEASUREMENTS A pulse algorithm (Pulsar) was used to quantify LH pulse characteristics. RESULTS Exercise produced no significant effects upon LH pulse frequency or mean serum LH concentration. However, exercise of moderate intensity caused a significant increase in LH pulse amplitude ( P < 0·05). Strolling produced no significant changes in LH secretion. CONCLUSION Acute exercise of moderate intensity in the follicular phase of untrained women is an insufficient stimulus to inhibit the GnRH pulse generator in the post-exercise period, yet may produce a slight stimulatory effect on the amount of LH released per pulsePeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73507/1/j.1365-2265.1994.tb02794.x.pd
Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV
A search for a Higgs boson decaying into two photons is described. The
analysis is performed using a dataset recorded by the CMS experiment at the LHC
from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an
integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross
section of the standard model Higgs boson decaying to two photons. The expected
exclusion limit at 95% confidence level is between 1.4 and 2.4 times the
standard model cross section in the mass range between 110 and 150 GeV. The
analysis of the data excludes, at 95% confidence level, the standard model
Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The
largest excess of events above the expected standard model background is
observed for a Higgs boson mass hypothesis of 124 GeV with a local significance
of 3.1 sigma. The global significance of observing an excess with a local
significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is
estimated to be 1.8 sigma. More data are required to ascertain the origin of
this excess.Comment: Submitted to Physics Letters
Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV
Results are presented from a search for a W' boson using a dataset
corresponding to 5.0 inverse femtobarns of integrated luminosity collected
during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV.
The W' boson is modeled as a heavy W boson, but different scenarios for the
couplings to fermions are considered, involving both left-handed and
right-handed chiral projections of the fermions, as well as an arbitrary
mixture of the two. The search is performed in the decay channel W' to t b,
leading to a final state signature with a single lepton (e, mu), missing
transverse energy, and jets, at least one of which is tagged as a b-jet. A W'
boson that couples to fermions with the same coupling constant as the W, but to
the right-handed rather than left-handed chiral projections, is excluded for
masses below 1.85 TeV at the 95% confidence level. For the first time using LHC
data, constraints on the W' gauge coupling for a set of left- and right-handed
coupling combinations have been placed. These results represent a significant
improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
Measurement of isolated photon production in pp and PbPb collisions at sqrt(sNN) = 2.76 TeV
Isolated photon production is measured in proton-proton and lead-lead
collisions at nucleon-nucleon centre-of-mass energies of 2.76 TeV in the
pseudorapidity range |eta|<1.44 and transverse energies ET between 20 and 80
GeV with the CMS detector at the LHC. The measured ET spectra are found to be
in good agreement with next-to-leading-order perturbative QCD predictions. The
ratio of PbPb to pp isolated photon ET-differential yields, scaled by the
number of incoherent nucleon-nucleon collisions, is consistent with unity for
all PbPb reaction centralities.Comment: Submitted to Physics Letters
Measurement of the Lambda(b) cross section and the anti-Lambda(b) to Lambda(b) ratio with Lambda(b) to J/Psi Lambda decays in pp collisions at sqrt(s) = 7 TeV
The Lambda(b) differential production cross section and the cross section
ratio anti-Lambda(b)/Lambda(b) are measured as functions of transverse momentum
pt(Lambda(b)) and rapidity abs(y(Lambda(b))) in pp collisions at sqrt(s) = 7
TeV using data collected by the CMS experiment at the LHC. The measurements are
based on Lambda(b) decays reconstructed in the exclusive final state J/Psi
Lambda, with the subsequent decays J/Psi to an opposite-sign muon pair and
Lambda to proton pion, using a data sample corresponding to an integrated
luminosity of 1.9 inverse femtobarns. The product of the cross section times
the branching ratio for Lambda(b) to J/Psi Lambda versus pt(Lambda(b)) falls
faster than that of b mesons. The measured value of the cross section times the
branching ratio for pt(Lambda(b)) > 10 GeV and abs(y(Lambda(b))) < 2.0 is 1.06
+/- 0.06 +/- 0.12 nb, and the integrated cross section ratio for
anti-Lambda(b)/Lambda(b) is 1.02 +/- 0.07 +/- 0.09, where the uncertainties are
statistical and systematic, respectively.Comment: Submitted to Physics Letters
Search for new physics in events with opposite-sign leptons, jets, and missing transverse energy in pp collisions at sqrt(s) = 7 TeV
A search is presented for physics beyond the standard model (BSM) in final
states with a pair of opposite-sign isolated leptons accompanied by jets and
missing transverse energy. The search uses LHC data recorded at a
center-of-mass energy sqrt(s) = 7 TeV with the CMS detector, corresponding to
an integrated luminosity of approximately 5 inverse femtobarns. Two
complementary search strategies are employed. The first probes models with a
specific dilepton production mechanism that leads to a characteristic kinematic
edge in the dilepton mass distribution. The second strategy probes models of
dilepton production with heavy, colored objects that decay to final states
including invisible particles, leading to very large hadronic activity and
missing transverse energy. No evidence for an event yield in excess of the
standard model expectations is found. Upper limits on the BSM contributions to
the signal regions are deduced from the results, which are used to exclude a
region of the parameter space of the constrained minimal supersymmetric
extension of the standard model. Additional information related to detector
efficiencies and response is provided to allow testing specific models of BSM
physics not considered in this paper.Comment: Replaced with published version. Added journal reference and DO
The RESET project: constructing a European tephra lattice for refined synchronisation of environmental and archaeological events during the last c. 100 ka
This paper introduces the aims and scope of the RESET project (. RESponse of humans to abrupt Environmental Transitions), a programme of research funded by the Natural Environment Research Council (UK) between 2008 and 2013; it also provides the context and rationale for papers included in a special volume of Quaternary Science Reviews that report some of the project's findings. RESET examined the chronological and correlation methods employed to establish causal links between the timing of abrupt environmental transitions (AETs) on the one hand, and of human dispersal and development on the other, with a focus on the Middle and Upper Palaeolithic periods. The period of interest is the Last Glacial cycle and the early Holocene (c. 100-8 ka), during which time a number of pronounced AETs occurred. A long-running topic of debate is the degree to which human history in Europe and the Mediterranean region during the Palaeolithic was shaped by these AETs, but this has proved difficult to assess because of poor dating control. In an attempt to move the science forward, RESET examined the potential that tephra isochrons, and in particular non-visible ash layers (cryptotephras), might offer for synchronising palaeo-records with a greater degree of finesse. New tephrostratigraphical data generated by the project augment previously-established tephra frameworks for the region, and underpin a more evolved tephra 'lattice' that links palaeo-records between Greenland, the European mainland, sub-marine sequences in the Mediterranean and North Africa. The paper also outlines the significance of other contributions to this special volume: collectively, these illustrate how the lattice was constructed, how it links with cognate tephra research in Europe and elsewhere, and how the evidence of tephra isochrons is beginning to challenge long-held views about the impacts of environmental change on humans during the Palaeolithic. © 2015 Elsevier Ltd.RESET was funded through Consortium Grants awarded by the Natural Environment Research Council, UK, to a collaborating team drawn from four institutions: Royal Holloway University of London (grant reference NE/E015905/1), the Natural History Museum, London (NE/E015913/1), Oxford University (NE/E015670/1) and the University of Southampton, including the National Oceanography Centre (NE/01531X/1). The authors also wish to record their deep gratitude to four members of the scientific community who formed a consultative advisory panel during the lifetime of the RESET project: Professor Barbara Wohlfarth (Stockholm University), Professor Jørgen Peder Steffensen (Niels Bohr Institute, Copenhagen), Dr. Martin Street (Romisch-Germanisches Zentralmuseum, Neuwied) and Professor Clive Oppenheimer (Cambridge University). They provided excellent advice at key stages of the work, which we greatly valued. We also thank Jenny Kynaston (Geography Department, Royal Holloway) for construction of several of the figures in this paper, and Debbie Barrett (Elsevier) and Colin Murray Wallace (Editor-in-Chief, QSR) for their considerable assistance in the production of this special volume.Peer Reviewe
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