1,023 research outputs found
A Combined Control Systems and Machine Learning Approach to Forecasting Iceberg Flux off Newfoundland
Icebergs have long been a threat to shipping in the NW Atlantic and the iceberg season of February to late summer is monitored closely by the International Ice Patrol. However, reliable predictions of the severity of a season several months in advance would be useful for planning monitoring strategies and also for shipping companies in designing optimal routes across the North Atlantic for specific years. A seasonal forecast model of the build-up of seasonal iceberg numbers has recently become available, beginning to enable this longer-term planning of marine operations. Here we discuss extension of this control systems model to include more recent years within the trial ensemble sample set and also increasing the number of measures of the iceberg season that are considered within the forecast. These new measures include the seasonal iceberg total, the rate of change of the seasonal increase, the number of peaks in iceberg numbers experienced within a given season, and the timing of the peak(s). They are predicted by a range of machine learning tools. The skill levels of the new measures are tested, as is the impact of the extensions to the existing seasonal forecast model. We present a forecast for the 2021 iceberg season, predicting a medium iceberg year
Solitons in Five Dimensional Minimal Supergravity: Local Charge, Exotic Ergoregions, and Violations of the BPS Bound
We describe a number of striking features of a class of smooth solitons in
gauged and ungauged minimal supergravity in five dimensions. The solitons are
globally asymptotically flat or asymptotically AdS without any Kaluza-Klein
directions but contain a minimal sphere formed when a cycle pinches off in the
interior of the spacetime. The solutions carry a local magnetic charge and many
have rather unusual ergosurfaces. Perhaps most strikingly, many of the solitons
have more electric charge or, in the asymptotically AdS case, more electric
charge and angular momentum than is allowed by the usual BPS bound. We comment
on, but do not resolve, the new puzzle this raises for AdS/CFT.Comment: 60 pages, 12 figures, 3 table
Spin induced multipole moments for the gravitational wave flux from binary inspirals to third Post-Newtonian order
Using effective field theory techniques we calculate the source multipole
moments needed to obtain the spin contributions to the power radiated in
gravitational waves from inspiralling compact binaries to third Post-Newtonian
order (3PN). The multipoles depend linearly and quadratically on the spins and
include both spin(1)spin(2) and spin(1)spin(1) components. The results in this
paper provide the last missing ingredient required to determine the phase
evolution to 3PN including all spin effects which we will report in a separate
paper.Comment: 35 pages, 7 figures. Published versio
Three-Loop Electroweak Correction to the Rho Parameter in the Large Higgs Mass Limit
We present an analytical calculation of the leading three-loop radiative
correction to the rho-parameter in the Standard Model in the large Higgs mass
limit. This correction, of order g^6 m_H^4/M_W^4, is opposite in sign to the
leading two-loop correction of order g^4 m_H^2/M_W^2. The two corrections
cancel each other for a Higgs mass of approximately 480 GeV. The result shows
that it is extremely unlikely that a strongly interacting Higgs sector could
fit the data of electroweak precision measurements.Comment: 15 pages, late
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Quantitative plant proteomics using hydroponic isotope labeling of entire plants (HILEP)
Pressure dissociation of integration host factorāDNA complexes reveals flexibility-dependent structural variation at the proteināDNA interface
E. coli Integration host factor (IHF) condenses the bacterial nucleoid by wrapping DNA. Previously, we showed that DNA flexibility compensates for structural characteristics of the four consensus recognition elements associated with specific binding (Aeling et al., J. Biol. Chem. 281, 39236ā39248, 2006). If elements are missing, high-affinity binding occurs only if DNA deformation energy is low. In contrast, if all elements are present, net binding energy is unaffected by deformation energy. We tested two hypotheses for this observation: in complexes containing all elements, (1) stiff DNA sequences are less bent upon binding IHF than flexible ones; or (2) DNA sequences with differing flexibility have interactions with IHF that compensate for unfavorable deformation energy. Time-resolved Fƶrster resonance energy transfer (FRET) shows that global topologies are indistinguishable for three complexes with oligonucleotides of different flexibility. However, pressure perturbation shows that the volume change upon binding is smaller with increasing flexibility. We interpret these results in the context of Record and coworker's model for IHF binding (J. Mol. Biol. 310, 379ā401, 2001). We propose that the volume changes reflect differences in hydration that arise from structural variation at IHFāDNA interfaces while the resulting energetic compensation maintains the same net binding energy
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