pinecone/core-2020-05-10-deduplication huggingface dataset:
Free fall and self-force: an historical perspective

Free fall has signed the greatest markings in the history of physics through
the leaning Pisa tower, the Cambridge apple tree and the Einstein lift. The
perspectives offered by the capture of stars by supermassive black holes are to
be cherished, because the study of the motion of falling stars will constitute
a giant step forward in the understanding of gravitation in the regime of
strong field. After an account on the perception of free fall in ancient times
and on the behaviour of a gravitating mass in Newtonian physics, this chapter
deals with last century debate on the repulsion for a Schwarzschild black hole
and mentions the issue of an infalling particle velocity at the horizon.
Further, black hole perturbations and numerical methods are presented, paving
the way to the introduction of the self-force and other back-action related
methods. The impact of the perturbations on the motion of the falling particle
is computed via the tail, the back-scattered part of the perturbations, or via
a radiative Green function. In the former approach, the self-force acts upon
the background geodesic; in the latter, the geodesic is conceived in the total
(background plus perturbations) field. Regularisation techniques (mode-sum and
Riemann-Hurwitz $z$ function) intervene to cancel divergencies coming from the
infinitesimal size of the particle. An account is given on the state of the
art, including the last results obtained in this most classical problem,
together with a perspective encompassing future space gravitational wave
interferometry and head-on particle physics experiments. As free fall is
patently non-adiabatic, it requires the most sophisticated techniques for
studying the evolution of the motion. In this scenario, the potential of the
self-consistent approach, by means of which the background geodesic is
continuously corrected by the self-force contribution, is examined.Comment: 43 pages; to appear in final form on "Mass and Motion in General
  Relativity" by Springer (L. Blanchet, A. Spallicci, B. Whiting Eds.) based on
  the lectures given at the CNRS School on Mass held the 23-25 June 2008 in
  Orl\'eans. http://www.springer.com/astronomy/cosmology/book/978-90-481-3014-
Mass and Angular Momentum in General Relativity

We present an introduction to mass and angular momentum in General
Relativity. After briefly reviewing energy-momentum for matter fields, first in
the flat Minkowski case (Special Relativity) and then in curved spacetimes with
or without symmetries, we focus on the discussion of energy-momentum for the
gravitational field. We illustrate the difficulties rooted in the Equivalence
Principle for defining a local energy-momentum density for the gravitational
field. This leads to the understanding of gravitational energy-momentum and
angular momentum as non-local observables that make sense, at best, for
extended domains of spacetime. After introducing Komar quantities associated
with spacetime symmetries, it is shown how total energy-momentum can be
unambiguously defined for isolated systems, providing fundamental tests for the
internal consistency of General Relativity as well as setting the conceptual
basis for the understanding of energy loss by gravitational radiation. Finally,
several attempts to formulate quasi-local notions of mass and angular momentum
associated with extended but finite spacetime domains are presented, together
with some illustrations of the relations between total and quasi-local
quantities in the particular context of black hole spacetimes. This article is
not intended to be a rigorous and exhaustive review of the subject, but rather
an invitation to the topic for non-experts. In this sense we follow essentially
the expositions in Szabados 2004, Gourgoulhon 2007, Poisson 2004 and Wald 84,
and refer the reader interested in further developments to the existing
literature, in particular to the excellent and comprehensive review by Szabados
(2004).Comment: 41 pages. Notes based on the lecture given at the C.N.R.S. "School on
  Mass" (June 2008) in Orleans, France. To appear as proceedings in the book
  "Mass and Motion in General Relativity", eds. L. Blanchet, A. Spallicci and
  B. Whiting. Some comments and references added
Modeling Slope Instability as Shear Rupture Propagation in a Saturated Porous Medium

When a region of intense shear in a slope is much thinner than other relevant geometric lengths, this shear failure may be approximated as localized slip, as in faulting, with strength determined by frictional properties of the sediment and effective stress normal to the failure surface. Peak and residual frictional strengths of submarine sediments indicate critical slope angles well above those of most submarine slopes—in contradiction to abundant failures. Because deformation of sediments is governed by effective stress, processes affecting pore pressures are a means of strength reduction. However, common methods of exami ning slope stability neglect dynamically variable pore pressure during failure. We examine elastic-plastic models of the capped Drucker-Prager type and derive approximate equations governing pore pressure about a slip surface when the adjacent material may deform plastically. In the process we identify an elastic-plastic hydraulic diffusivity with an evolving permeability and plastic storage term analogous to the elastic term of traditional poroelasticity. We also examine their application to a dynamically propagating subsurface rupture and find indications of downslope directivity.Earth and Planetary SciencesEngineering and Applied Science
Investigations on the Peach 4 Debrite, a Late Pleistocene Mass Movement on the Northwest British Continental Margin

The Peach 4 debrite is the most recent in a series of large scale Pleistocene MTDs within the Barra fan on the northwest British continental margin.  Geophysical data indicate that Peach 4 was formed through a combination of blocky and muddy debris flows and affects an area of ~ 700 km2.  BGS core sample 56 -10 36, located directly over the Peach 4 debrite, provides a minimum age of 14.68 ka cal BP for the last major failure.  An upwards fining turbidite sequence in BGS core sample 56 -10 239 is associ-ated with increased As and S concentrations, indicators of diagenetic pyrite which forms under anoxic conditions.  It is proposed that As and S concentrations may pro-vide a method of distinguishing between contourite and turbidite sedimentation, though further research is required
Mass transport events and their tsunami hazard

Mass transport events, such as those from submarine landslides, volcanic flank collapse at convergent margins and on oceanic islands, and subaerial failure are reviewed and found to be all potential tsunami sources. The intensity and frequency of the tsunamis resulting is dependent upon the source. Most historical records are of devastating tsunamis from volcanic collapse at convergent margins. Although the database is limited, tsunamis sourced from submarine landslides and collapse on oceanic volcanoes have a climate influence and may not be as hazardous as their frequency suggests. Conversely, tsunamis sourced from submarine landslides at convergent margins may be more frequent historically than previously recognized and, therefore, more hazardous
Mesoscopic interplay of superconductivity and ferromagnetism in
  ultra-small metallic grains

We review the effects of electron-electron interactions on the ground-state
spin and the transport properties of ultra-small chaotic metallic grains. Our
studies are based on an effective Hamiltonian that combines a superconducting
BCS-like term and a ferromagnetic Stoner-like term. Such terms originate in
pairing and spin exchange correlations, respectively. This description is valid
in the limit of a large dimensionless Thouless conductance. We present the
ground-state phase diagram in the fluctuation-dominated regime where the
single-particle mean level spacing is comparable to the bulk BCS pairing gap.
This phase diagram contains a regime in which pairing and spin exchange
correlations coexist in the ground-state wave function. We discuss the
calculation of the tunneling conductance for an almost-isolated grain in the
Coulomb-blockade regime, and present measurable signatures of the competition
between superconductivity and ferromagnetism in the mesoscopic fluctuations of
the conductance.Comment: 6 pages, 3 figures, To be published in the proceedings of the NATO
  Advance Research Workshop "Recent Advances in Nonlinear Dynamics and Complex
  System Physics.
Entanglement and localization of wavefunctions

We review recent works that relate entanglement of random vectors to their
localization properties. In particular, the linear entropy is related by a
simple expression to the inverse participation ratio, while next orders of the
entropy of entanglement contain information about e.g. the multifractal
exponents. Numerical simulations show that these results can account for the
entanglement present in wavefunctions of physical systems.Comment: 6 pages, 4 figures, to appear in the proceedings of the NATO Advanced
  Research Workshop 'Recent Advances in Nonlinear Dynamics and Complex System
  Physics', Tashkent, Uzbekistan, 200
Robot competence development by constructive learning

The final publication is available at Springer via: https://doi.org/10.1007/978-90-481-3177-8_2.This paper presents a constructive learning approach for developing sensor-motor mapping in autonomous systems. The system's adaptation to environment changes is discussed and three methods are proposed to deal with long term and short term changes. The proposed constructive learning allows autonomous systems to develop network topology and adjust network parameters. The approach is supported by findings from psychology and neuroscience especially during infants cognitive development at early stages. A growing radial basis function network is introduced as a computational substrate for sensory-motor mapping learning. Experiments are conducted on a robot eye/hand coordination testbed and results show the incremental development of sensory-motor mapping and its adaptation to changes such as in tool-use
Cinema and the ‘City of the Mind’: Using Motion Pictures to Explore Human-Environment Transactions in Planning Education.

This chapter examines the pedagogical use of film in planning education, specifically
as it relates to the teaching of environmental psychology. The intersections
between film, theory, and pedagogy are important because film is herein invested
with the power to represent – and more importantly interpret and challenge – our
understandings of human-environment transactions. I further suggest that planning
students may be undereducated in the nature of these transactions and that the
medium of the motion picture – combined with the neglected body of theory
represented by environmental psychology – offers an excellent synthesis to address
this need.https://link.springer.com/chapter/10.1007%2F978-90-481-3209-6_1
Substantive General Covariance: Another Decade of Dispute

John Earman's recent proposal that a substantive version of general covariance consists in the requirement that diffeomorphism invariance be a gauge symmetry is critically assessed.  I argue that such a principle does not serve to differentiate general relativity from pre-relativistic theories.  A model-theoretic characterization of two formulations of specially-relativistic theories is suggested.  Diffeomorphisms are symmetries of only one such style of formulation and, I argue, Earman's proposal does not provide a reason to deny diffeomorphisms the status of gauge transformations relative to this formulation.  Carlo Rovelli's distinction between "passive" and "active" diffeomorphism invariance is also clarified
Cyclic AMP signalling in pancreatic islets

Cyclic 3'5'AMP (cAMP) is an important physiological amplifier of glucose-induced insulin secretion by the pancreatic islet β-cell, where it is formed by the activity of adenylyl cyclases, which are stimulated by glucose, through elevation in intracellular calcium concentrations, and by the incretin hormones (GLP-1 and GIP). cAMP is rapidly degraded in the pancreatic islet β-cell by various cyclic nucleotide phosphodiesterase (PDE) enzymes. Many steps involved in glucose-induced insulin secretion are modulated by cAMP, which is also important in regulating pancreatic islet β-cell differentiation, growth and survival. This chapter discusses the formation, destruction and actions of cAMP in the islets with particular emphasis on the β-cell
Singular reference. A descriptivist perspective

Singular reference to ourselves and the ordinary objects surrounding us is a most crucial\ud
philosophical topic, for it looms large in any attempt to understand how language\ud
and mind connect to the world. This book explains in detail why in the past philosophers\ud
such as Frege, Russell and Reichenbach have favoured a descriptivist approach to this\ud
matter and why in more recent times Donnellan, Kripke, Kaplan and others have rather\ud
favoured a referentialist standpoint. The now dominant referentialist theories however\ud
still have a hard time in addressing propositional attitudes and empty singular terms.\ud
Here a way out of this difficulty emerges in an approach that incorporates aspects of the\ud
old-fashioned descriptivist views of Frege, Russell and Reichenbach without succumbing\ud
to the anti-descriptivist arguments that back up the current referentialist trend. The\ud
resulting theory features a novel approach to the semantics and pragmatics of determiner\ud
phrases, definite descriptions, proper names and indexicals, all treated in uniform\ud
fashion in both their anaphoric and non-anaphoric uses. This work will be of interest to\ud
researchers in philosophy of language, philosophy of mind and theoretical linguistics
Modeling eutrophication and oligotrophication of shallow-water marine systems: the importance of sediments under stratified and well-mixed conditions

A one-dimensional model that couples water-column physics with pelagic and benthic biogeochemistry in a 50-m-deep water column is used to demonstrate the importance of the sediment in the functioning of shallow systems, the eutrophication status of the system, and the system’s resilience to oligotrophication. Two physical scenarios, a well-mixed and a stratified water column, are considered and both are run along a gradient of increasing initial pelagic-dissolved inorganic nitrogen (DIN) concentration. Where the mixed layer extends to the bottom, more nutrients and less light are available for growth. Under low to moderately eutrophic conditions (pelagic DIN <30 mmol m−3), this leads to higher productivity in well-mixed waters, while the stratified system is more productive under highly eutrophic conditions. Under stratification, the build-up of nitrate and depletion of oxygen below the mixed layer does not notably change the functioning of the sediment as a sink for reactive nitrogen. In sediments underlying well-mixed waters, sedimentary denitrification, fueled mainly by in situ nitrification, is slightly more important (8–15% of total benthic mineralization) than under stratified waters (7–20%), where the influx of bottom-water nitrate is the most important nitrate source. As a consequence of this less efficient removal of reactive nitrogen, the winter DIN concentrations are higher in the stratified scenario. The model is used to estimate the long-term benefits of nutrient reduction scenarios and the timeframe under which the new steady-state condition is approached. It is shown that a 50% reduction in external nitrogen inputs ultimately results in a reduction of 60–70% of the original pelagic DIN concentration. However, as the efflux of nitrogen from the sediment compensates part of the losses in the water column, system oligotrophication is a slow process: after 20 years of reduced inputs, the pelagic DIN concentrations still remain 2.7 mmol m−3 (mixed) and 3.9 mmol m−3 (stratified) above the ultimate DIN concentrations.
A Hubble View of Star Forming Regions in the Magellanic Clouds

The Magellanic Clouds (MCs) offer an outstanding variety of young stellar
associations, in which large samples of low-mass stars (with masses less than 1
solar mass) currently in the act of formation can be resolved and explored
sufficiently with the Hubble Space Telescope. These pre-main sequence (PMS)
stars provide a unique snapshot of the star formation process, as it is being
recorded for the last 20 Myr, and they give important information on the
low-mass Initial Mass Function (IMF) of their host environments. We present the
latest results from observations with the Advanced Camera for Surveys (ACS) of
such star-forming regions in the MCs, and discuss the importance of Hubble}for
a comprehensive collection of substantial information on the most recent
low-mass star formation and the low-mass IMF in the MCs.Comment: To appear in the proceedings of the 41st ESLAB Symposium: The Impact
  of HST on European Astronomy, 4 pages, LaTeX ESA Publications style, 5
  Figure
Nuclear Star Clusters across the Hubble Sequence

Over the last decade, HST imaging studies have revealed that the centers of
most galaxies are occupied by compact, barely resolved sources. Based on their
structural properties, position in the fundamental plane, and spectra, these
sources clearly have a stellar origin. They are therefore called ``nuclear star
clusters'' (NCs) or ``stellar nuclei''. NCs are found in galaxies of all Hubble
types, suggesting that their formation is intricately linked to galaxy
evolution. In this contribution, I briefly review the results from recent
studies of NCs, touch on some ideas for their formation, and mention some open
issues related to the possible connection between NCs and supermassive black
holes.Comment: 6 page conference proceedings, to appear in "The impact of HST on
  European Astronomy" (41st ESLAB Symposium), pdflatex file, uses svmult.cls
  (included
The kinematics of Core and Cusp galaxies: comparing HST imaging and
  integral-field observations

In this proceeding we look at the relationship between the photometric
nuclear properties of early-type galaxies from Hubble Space Telescope imaging
and their overall kinematics as observed with the SAURON integral-field
spectrograph. We compare the inner slope of their photometric profiles and the
Slow/Fast rotator classes, defined by the amplitude of a newly defined LambdaR
parameter, to show that slow rotators tend to be more massive systems and
display shallower inner profiles and fast rotators steper ones. It is important
to remark, however, that there is not a one-to-one relationship between the two
photometric and kinematic groups.Comment: 4 pages, 2 figures, to appear in the Proceedings of the 41st ESLAB
  Symposium "The Impact of HST on European Astronomy", 29 May to 1 June 2007,
  ESTEC, Noordwijk, N
UV Spectroscopy of Metal-Poor Massive Stars in the Small Magellanic
  Cloud

The Hubble Space Telescope has provided the first clear evidence for weaker
winds of metal-poor massive stars in the Small Magellanic Cloud, confirming
theoretical predictions of the metallicity dependence of mass-loss rates and
wind terminal velocities. For lower luminosity O-type stars however, derived
mass-loss rates are orders of magnitude lower than predicted, and are at
present unexplained.Comment: 4 pages, 3 figures. To appear in 'The Impact of HST on European
  Astronomy', Eds., G. De Marchi & F.D. Macchetto, Astrophysics & Space
  Science, Springe
2D and 3D quantum rotors in a crystal field: critical points,
  metastability, and reentrance

An overview of results of models of coupled quantum rotors is presented. We
focus on rotors with dipolar and quadrupolar potentials in two and three
dimensions, potentials which correspond to approximate descriptions of real
molecules adsorbed on surfaces and in the solid phase. Particular emphasis is
placed on the anomalous reentrant phase transition which occurs in both two and
three-dimensional systems. The anomalous behaviour of the entropy, which
accompanies the reentrant phase transition, is also analyzed and is shown to be
present regardless if a phase transition is present or not. Finally, the
effects of the crystal field on the phase diagrams are also investigated. In
two-dimensions the crystal field causes the disappearance of the phase
transition, and ordering takes place via a continuous increase in the value of
the order parameter. This is also true in three dimensions for the dipolar
potential. For the quadrupolar potential in three dimensions turning on the
crystal field leads to the appearance of critical points where the phase
transition ceases, and ordering occurs via a continuous increase in the order
parameter. As the crystal field is increased the range of the coupling constant
over which metastable states are found decreases.Comment: submitted to the Proceedings of the NATO Advanced Research Workshop
  "Matastable Systems under Pressure: Platforms for New Technological and
  Environmental Application" (4 - 8 October, 2008, Odessa, Ukraine). To be
  publeshed by Springer Verla
AMDA, Automated Multi-Dataset Analysis: A Web-Based Service Provided by the CDPP

International audienceWe present AMDA (Automated Mutli-Dataset Analysis), a new service recently opened at CDPP. AMDA is a web-based facility for on line analysis of space physics data coming from either its local database or distant ones. This tool allows the user to perform on line classical manipulations such as data visualization, parameter computation or data extraction. AMDA also offers innovative functionalities such as event search on the content of the data in either visual or automated way, and the generation, use and management of time-tables. These time-tables can be seen as a brick of up-coming virtual observatories in space physics, and could be used as an input to extract data from other databases, Cluster Active Archive in particular
Critical interrelations between ICT and electricity system.

The widespread blackouts of 2003 have exposed the critical role of ICT systems in maintaining reliable operation of power systems. Fundamental errors in providing back-up and alarm function in the control room were one of the main contributing factors to the 2003 USA/Canada blackout. The lack of proper ICT infrastructure to enable proper communication and cooperation between system operators in Italy and Switzerland led to delayed remedial actions and the consequent blackout of Italy in 2003. Improved ICT systems would enable a better real-time cooperation and coordination between utilities in an interconnected power system but the main challenge is political: overcoming resistance of individual utilities to give up partially their interdependence and operate within the paradigm of a distributed, but coordinated, control. Emergence of GPS-synchronised Wide Area Measurement Systems (WAMS) holds a great promise for improved monitoring and control of modern power systems and therefore avoiding future blackouts