17,540 research outputs found
Pulse-like and crack-like ruptures in experiments mimicking crustal earthquakes
Theoretical studies have shown that the issue of rupture modes has important implications for fault constitutive laws, stress conditions on faults, energy partition and heat generation during earthquakes, scaling laws, and spatiotemporal complexity of fault slip. Early theoretical models treated earthquakes as crack-like ruptures, but seismic inversions indicate that earthquake ruptures may propagate in a self-healing pulse-like mode. A number of explanations for the existence of slip pulses have been proposed and continue to be vigorously debated. This study presents experimental observations of spontaneous pulse-like ruptures in a homogeneous linear-elastic setting that mimics crustal earthquakes; reveals how different rupture modes are selected based on the level of fault prestress; demonstrates that both rupture modes can transition to supershear speeds; and advocates, based on comparison with theoretical studies, the importance of velocity-weakening friction for earthquake dynamics
User benefits and funding strategies
The justification, economic and technological benefits of NASA Space Programs (aside from pure scientific objectives), in improving the quality of life in the United States is discussed and outlined. Specifically, a three-step, systematic method is described for selecting relevant and highly beneficial payloads and instruments for the Interim Upper Stage (IUS) that will be used with the space shuttle until the space tug becomes available. Viable Government and private industry cost-sharing strategies which would maximize the number of IUS payloads, and the benefits obtainable under a limited NASA budget were also determined. Charts are shown which list the payload instruments, and their relevance in contributing to such areas as earth resources management, agriculture, weather forecasting, and many others
Universality of residence-time distributions in non-adiabatic stochastic resonance
We present mathematically rigorous expressions for the residence-time and
first-passage-time distributions of a periodically forced Brownian particle in
a bistable potential. For a broad range of forcing frequencies and amplitudes,
the distributions are close to periodically modulated exponential ones.
Remarkably, the periodic modulations are governed by universal functions,
depending on a single parameter related to the forcing period. The behaviour of
the distributions and their moments is analysed, in particular in the low- and
high-frequency limits.Comment: 8 pages, 1 figure New version includes distinction between
first-passage-time and residence-time distribution
Partnership practice as collaborative knowledge work: Overcoming common dilemmas through an augmented view of professional expertise
Purpose - The purpose of this paper is to shed new light on how partnership practices that build resilience in families work. Two broad questions are explored: first, what are the forms of expertise required in practices that effectively build resilience through partnership; and second, how can some of the challenges practitioners experience when working in partnership be addressed Design/methodology/approach - A theoretical approach is taken, framing partnership as collaborative knowledge work between practitioners and clients. Concepts of relational expertise, common knowledge and relational agency are explored as means to understand the forms of expertise involved in partnership. An empirical example is provided from practices guided by The Family Partnership Model, an approach that has been widely implemented. Findings - These concepts help to address three key challenges experienced by practitioners: client readiness for change, maintaining focus and purpose and using specialist expertise in partnership. This approach elucidates features of partnership practice that distinguish it from expert-led models, while highlighting diverse forms of expertise in play. Originality/value - The framework presented in this paper is distinctive and can be used to identify how practitioners can avoid common dilemmas, even in challenging circumstances with vulnerable families where practitioner-client relationships may be perceived as fragile. It counters the idea that partnership work dilutes professional expertise. Instead, an enriched and augmented view of professional expertise is presented
Lattice congruences of the weak order
We study the congruence lattice of the poset of regions of a hyperplane
arrangement, with particular emphasis on the weak order on a finite Coxeter
group. Our starting point is a theorem from a previous paper which gives a
geometric description of the poset of join-irreducibles of the congruence
lattice of the poset of regions in terms of certain polyhedral decompositions
of the hyperplanes. For a finite Coxeter system (W,S) and a subset K of S, let
\eta_K:w \mapsto w_K be the projection onto the parabolic subgroup W_K. We show
that the fibers of \eta_K constitute the smallest lattice congruence with
1\equiv s for every s\in(S-K). We give an algorithm for determining the
congruence lattice of the weak order for any finite Coxeter group and for a
finite Coxeter group of type A or B we define a directed graph on subsets or
signed subsets such that the transitive closure of the directed graph is the
poset of join-irreducibles of the congruence lattice of the weak order.Comment: 26 pages, 4 figure
Two types of nematicity in the phase diagram of the cuprate superconductor YBaCuO
Nematicity has emerged as a key feature of cuprate superconductors, but its
link to other fundamental properties such as superconductivity, charge order
and the pseudogap remains unclear. Here we use measurements of transport
anisotropy in YBaCuO to distinguish two types of nematicity. The
first is associated with short-range charge-density-wave modulations in a
doping region near . It is detected in the Nernst coefficient, but
not in the resistivity. The second type prevails at lower doping, where there
are spin modulations but no charge modulations. In this case, the onset of
in-plane anisotropy - detected in both the Nernst coefficient and the
resistivity - follows a line in the temperature-doping phase diagram that
tracks the pseudogap energy. We discuss two possible scenarios for the latter
nematicity.Comment: 8 pages and 7 figures. Main text and supplementary material now
combined into single articl
On the noise-induced passage through an unstable periodic orbit II: General case
Consider a dynamical system given by a planar differential equation, which
exhibits an unstable periodic orbit surrounding a stable periodic orbit. It is
known that under random perturbations, the distribution of locations where the
system's first exit from the interior of the unstable orbit occurs, typically
displays the phenomenon of cycling: The distribution of first-exit locations is
translated along the unstable periodic orbit proportionally to the logarithm of
the noise intensity as the noise intensity goes to zero. We show that for a
large class of such systems, the cycling profile is given, up to a
model-dependent change of coordinates, by a universal function given by a
periodicised Gumbel distribution. Our techniques combine action-functional or
large-deviation results with properties of random Poincar\'e maps described by
continuous-space discrete-time Markov chains.Comment: 44 pages, 4 figure
Prospective regenerative medicine therapies for obstetric trauma-induced fecal incontinence.
Fecal incontinence is a major public health issue that has yet to be adequately addressed. Obstetric trauma and injury to the anal sphincter muscles are the most common cause of fecal incontinence. New therapies are emerging aimed at repair or regeneration of sphincter muscle and restoration of continence. While regenerative medicine offers an attractive option for fecal incontinence there are currently no validated techniques using this approach. Although many challenges are yet to be resolved, the advent of regenerative medicine is likely to offer disruptive technologies to treat and possibly prevent the onset of this devastating condition. This article provides a review on regenerative medicine approaches for treating fecal incontinence and a critique of the current landscape in this area
Anisotropy of the Seebeck Coefficient in the Cuprate Superconductor YBaCuO: Fermi-Surface Reconstruction by Bidirectional Charge Order
The Seebeck coefficient of the cuprate YBaCuO was
measured in magnetic fields large enough to suppress superconductivity, at hole
dopings and , for heat currents along the and
directions of the orthorhombic crystal structure. For both directions,
decreases and becomes negative at low temperature, a signature that the Fermi
surface undergoes a reconstruction due to broken translational symmetry. Above
a clear threshold field, a strong new feature appears in , for
conduction along the axis only. We attribute this feature to the onset of
3D-coherent unidirectional charge-density-wave modulations seen by x-ray
diffraction, also along the axis only. Because these modulations have a
sharp onset temperature well below the temperature where starts to drop
towards negative values, we infer that they are not the cause of Fermi-surface
reconstruction. Instead, the reconstruction must be caused by the quasi-2D
bidirectional modulations that develop at significantly higher temperature.Comment: 7 pages, 5 figure
Reliability and Validity of Self-Reported Questionnaires Related to Adolescent Violence and Consequences, Thailand
Copyright © 2013 Wongtonkam et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.In Thailand physical violence among male adolescents is considered a significant public health issue, although there has been little published research into the aetiology and functions of violence in Thai youth. Research in this area has been hampered by a lack of psychometrically sound tools that have been validated to assess problem behaviours in Asian youth. The purpose of this paper is to provide validity and reliability data on an instrument to measure violence in Thai youth. In this study, reliability and validity data for a sample of adolescent Thai youth are reported for the Communities That Care Youth Survey (CTC-YS), a measure of risk and protective factors for violent behaviour, and the STAXI-II, a measure of angry experience and expression. The findings showed overall high internal consistency for both questionnaires, and there was evidence of construct validity. It is concluded that these measures are appropriate for use in research that seeks to investigate youth violence among adolescents in Thailand
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