172 research outputs found
The frequency-size scaling of non-volcanic tremors beneath the San Andreas Fault at Parkfield: Possible implications for seismic energy release
© 2019 Elsevier B.V. We analyse the frequency-size-distribution of non-volcanic tremors observed along the Parkfield section of the San Andreas Fault. We suggest that these non-volcanic tremors follow a power-law scaling typical of scale-invariant, stick slip tectonic earthquakes, but with an unusually high scaling exponent of more than 2.0 and a systematic depth-dependency. While each individual non-volcanic tremor releases only a minuscule amount of energy and slip, this is more than compensated by their sheer numbers. Consequently, the integrated contribution of this largely ‘invisible’ seismicity (non-volcanic tremors and nano-earthquakes) is non-negligible and could potentially account in selected patches along the San Andreas fault for up to 100% of the plate motion
Spatial distribution and energy release of nonvolcanic tremor at Parkfield, California
Nonvolcanic tremors (NVTs) are observed in transition zones between freely slipping andlocked sections of faults and normally occur below the seismogenic zone. Based on NVT recordings in theParkfield region of the San Andreas Fault, we provide a novel approach to assess the energy release of theseevents and assign magnitudes (Me) that are compatible with size estimates of small earthquakes in the sameregion. To assess the energy magnitude of a detected tremor, we refine the estimate of its duration andperform a spectral analysis that accounts for local attenuation. For the 218 NVTs that we were able to process,we resolveMevalues in the range of 0.67 to 0.84. For events, which we could not process using the spectralanalysis technique, we propose a statistical model to estimateMevalues using observable characteristics,such as peak amplitude, spectral velocity at the source corner frequency, and duration. We furthermoreprovide seismic moment and moment magnitude estimates and calculate stress drops in a range of 3–10 kPa.As a result of our spectral analyses, wefind strong indications regarding the ongoing debate aboutpotential NVT location hypotheses: the Parkfield NVTs have a higher probability to be located in the proposedthree-dimensional cloud-like cluster than in any other suggested location distributi
Measurement of Inverse Pion Photoproduction at Energies Spanning the N(1440) Resonance
Differential cross sections for the process pi^- p -> gamma n have been
measured at Brookhaven National Laboratory's Alternating Gradient Synchrotron
with the Crystal Ball multiphoton spectrometer. Measurements were made at 18
pion momenta from 238 to 748 MeV/c, corresponding to E_gamma for the inverse
reaction from 285 to 769 MeV. The data have been used to evaluate the gamma n
multipoles in the vicinity of the N(1440) resonance. We compare our data and
multipoles to previous determinations. A new three-parameter SAID fit yields 36
+/- 7 (GeV)^-1/2 X 10^-3 for the A^n_1/2 amplitude of the P_11.Comment: 14 pages, 8 figures, submitted to PR
Precision Pion-Proton Elastic Differential Cross Sections at Energies Spanning the Delta Resonance
A precision measurement of absolute pi+p and pi-p elastic differential cross
sections at incident pion laboratory kinetic energies from T_pi= 141.15 to
267.3 MeV is described. Data were obtained detecting the scattered pion and
recoil proton in coincidence at 12 laboratory pion angles from 55 to 155
degrees for pi+p, and six angles from 60 to 155 degrees for pi-p. Single arm
measurements were also obtained for pi+p energies up to 218.1 MeV, with the
scattered pi+ detected at six angles from 20 to 70 degrees. A flat-walled,
super-cooled liquid hydrogen target as well as solid CH2 targets were used. The
data are characterized by small uncertainties, ~1-2% statistical and ~1-1.5%
normalization. The reliability of the cross section results was ensured by
carrying out the measurements under a variety of experimental conditions to
identify and quantify the sources of instrumental uncertainty. Our lowest and
highest energy data are consistent with overlapping results from TRIUMF and
LAMPF. In general, the Virginia Polytechnic Institute SM95 partial wave
analysis solution describes our data well, but the older Karlsruhe-Helsinki PWA
solution KH80 does not.Comment: 39 pages, 22 figures (some with quality reduced to satisfy ArXiv
requirements. Contact M.M. Pavan for originals). Submitted to Physical Review
Modeling of graphite oxide
Based on density functional calculations, optimized structures of graphite
oxide are found for various coverage by oxygen and hydroxyl groups, as well as
their ratio corresponding to the minimum of total energy. The model proposed
describes well known experimental results. In particular, it explains why it is
so difficult to reduce the graphite oxide up to pure graphene. Evolution of the
electronic structure of graphite oxide with the coverage change is
investigated.Comment: 12 pages, 7 figures. Discussion about reduction to pure graphene and
several references added. Methodological part expanded. Accepted to J. Am.
Chem. So
Inclusive Jet and Hadron Suppression in a Multi-Stage Approach
We present a new study of jet interactions in the Quark-Gluon Plasma created
in high-energy heavy-ion collisions, using a multi-stage event generator within
the JETSCAPE framework. We focus on medium-induced modifications in the rate of
inclusive jets and high transverse momentum (high-) hadrons.
Scattering-induced jet energy loss is calculated in two stages: A high
virtuality stage based on the MATTER model, in which scattering of highly
virtual partons modifies the vacuum radiation pattern, and a second stage at
lower jet virtuality based on the LBT model, in which leading partons gain and
lose virtuality by scattering and radiation. Coherence effects that reduce the
medium-induced emission rate in the MATTER phase are also included. The
\trento\ model is used for initial conditions, and the (2+1)D VISHNU model is
used for viscous hydrodynamic evolution. Jet interactions with the medium are
modeled via 2-to-2 scattering with Debye screened potentials, in which the
recoiling partons are tracked, hadronized, and included in the jet clustering.
Holes left in the medium are also tracked and subtracted to conserve transverse
momentum. Calculations of the nuclear modification factor ()
for inclusive jets and high- hadrons are compared to
experimental measurements at RHIC and the LHC. Within this framework, we find
that two parameters for energy-loss, the coupling in the medium and the
transition scale between the stages of jet modification, suffice to
successfully describe these data at all energies, for central and semi-central
collisions, without re-scaling the jet transport coefficient .Comment: 33 pages, 23 figure
Multi-scale evolution of charmed particles in a nuclear medium
Parton energy-momentum exchange with the quark gluon plasma (QGP) is a
multi-scale problem. In this work, we calculate the interaction of charm quarks
with the QGP within the higher twist formalism at high virtuality and high
energy using the MATTER model, while the low virtuality and high energy portion
is treated via a (linearized) Boltzmann Transport (LBT) formalism. Coherence
effect that reduces the medium-induced emission rate in the MATTER model is
also taken into account. The interplay between these two formalisms is studied
in detail and used to produce a good description of the D-meson and charged
hadron nuclear modification factor RAA across multiple centralities. All
calculations were carried out utilizing the JETSCAPE framework
The role of war in deep transitions: exploring mechanisms, imprints and rules in sociotechnical systems
This paper explores in what ways the two world wars influenced the development of sociotechnical systems underpinning the culmination of the first deep transition. The role of war is an underexplored aspect in both the Techno-Economic Paradigms (TEP) approach and the Multi-level perspective (MLP) which form the two key conceptual building blocks of the Deep Transitions (DT) framework. Thus, we develop a conceptual approach tailored to this particular topic which integrates accounts of total war and mechanisms of war from historical studies and imprinting from organisational studies with the DT framework’s attention towards rules and meta-rules. We explore in what ways the three sociotechnical systems of energy, food, and transport were affected by the emergence of new demand pressures and logistical challenges during conditions of total war; how war impacted the directionality of sociotechnical systems; the extent to which new national and international policy capacities emerged during wartime in the energy, food, and transport systems; and the extent to which these systems were influenced by cooperation and shared sacrifice under wartime conditions. We then explore what lasting changes were influenced by the two wars in the energy, food, and transport systems across the transatlantic zone. This paper seeks to open up a hitherto neglected area in analysis on sociotechnical transitions and we discuss the importance of further research that is attentive towards entanglements of warfare and the military particularly in the field of sustainability transitions
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