pinecone/core-2020-05-10-deduplication huggingface dataset:
South African foreign policy and China: converging visions, competing interests, contested identities

South Africa's burgeoning relationship with China exposes the increasing complexities of its post-apartheid international relations. On one hand bilateral relations have deepened since 1998, due to the increasing complementarities with South Africa's foreign policy priorities that emphasise developmental pragmatism and a Southward orientation within the broader African context. On the other hand this relationship emphasises the deeper schisms within South African society itself, where divergent and multi-layered perspectives on South Africa's post-apartheid identity and relationship with China, the country's largest trading partner, remains unresolved. This article maps out the nature of China–South Africa relations through a thematic approach. This allows for nuanced consideration of South Africa's contemporary foreign policy, one that remains compressed between a combination of external and domestic factors
Eroding dipoles and vorticity growth for Euler flows in $
  \scriptstyle{\mathbb{R}}^3$ I. Axisymmetric flow without swirl

A review of analyses based upon anti-parallel vortex structures suggests that
structurally stable vortex structures with eroding circulation may offer a path
to the study of rapid vorticity growth in solutions of Euler's equations in $
\scriptstyle{\mathbb{R}}^3$. We examine here the possible formation of such a
structure in axisymmetric flow without swirl, leading to maximal growth of
vorticity as $t^{4/3}$. Our study suggests that the optimizing flow giving the
$t^{4/3}$ growth mimics an exact solution of Euler's equations representing an
eroding toroidal vortex dipole which locally conserves kinetic energy. The
dipole cross-section is a perturbation of the classical Sadovskii dipole having
piecewise constant vorticity, which breaks the symmetry of closed streamlines.
The structure of this perturbed Sadovskii dipole is analyzed asymptotically at
large times, and its predicted properties are verified numerically.Comment: 33 pages, 11 figure
Surfaces containing two circles through each point

We find all analytic surfaces in space $\mathbb{R}^3$ such that through each
point of the surface one can draw two transversal circular arcs fully contained
in the surface. The problem of finding such surfaces traces back to the works
of Darboux from XIXth century. We prove that such a surface is an image of a
subset of one of the following sets under some composition of inversions:
  - the set $\{\,p+q:p\in\alpha,q\in\beta\,\}$, where $\alpha,\beta$ are two
circles in $\mathbb{R}^3$;
  - the set $\{\,2\frac{[p \times q]}{|p+q|^2}:p\in\alpha,q\in\beta,p+q\ne
0\,\}$, where $\alpha,\beta$ are two circles in ${S}^2$;
  - the set $\{\,(x,y,z): Q(x,y,z,x^2+y^2+z^2)=0\,\}$, where
$Q\in\mathbb{R}[x,y,z,t]$ has degree $2$ or $1$.
  The proof uses a new factorization technique for quaternionic polynomials.Comment: 7 pages, 1 figure; major simplification of the proof, equivalent
  restatement of Main Theorem 1.1, minor correction of Examples 1.6 and 1.
The B-ring's surface mass density from hidden density waves: Less than
  meets the eye?

Saturn's B ring is the most opaque ring in our solar system, but many of its
fundamental parameters, including its total mass, are not well constrained.
Spiral density waves generated by mean-motion resonances with Saturn's moons
provide some of the best constraints on the rings' mass density, but detecting
and quantifying such waves in the B ring has been challenging because of this
ring's high opacity and abundant fine-scale structure. Using a wavelet-based
analyses of 17 occultations of the star gamma Crucis observed by the Visual and
Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft, we are
able to examine five density waves in the B ring. Two of these waves are
generated by the Janus 2:1 and Mimas 5:2 Inner Lindblad Resonances at 96,427 km
and 101,311 km from Saturn's center, respectively. Both of these waves can be
detected in individual occultation profiles, but the multi-profile wavelet
analysis reveals unexpected variations in the pattern speed of the Janus 2:1
wave that might arise from the periodic changes in Janus' orbit. The other
three wave signatures are associated with the Janus 3:2, Enceladus 3:1 and
Pandora 3:2 Inner Lindblad Resonances at 115,959 km, 115,207 km and 108,546 km.
These waves are not visible in individual profiles, but structures with the
correct pattern speeds can be detected in appropriately phase-corrected average
wavelets. Estimates of the ring's surface mass density derived from these five
waves fall between 40 and 140 g/cm^2, even though the ring's optical depth in
these regions ranges from 1.5 to almost 5. This suggests that the total mass of
the B ring is most likely between one-third and two-thirds the mass of Saturn's
moon Mimas.Comment: 40 Pages, 21 Figures, Accepted for publication in Icarus, a few typos
  fixe
Search for dark matter particles in proton-proton collisions at sqrt(s)
  = 8 TeV using the razor variables

A search for dark matter particles directly produced in proton-proton
collisions recorded by the CMS experiment at the LHC is presented. The data
correspond to an integrated luminosity of 18.8 inverse femtobarns, at a
center-of-mass energy of 8 TeV. The event selection requires at least two jets
and no isolated leptons. The razor variables are used to quantify the
transverse momentum balance in the jet momenta. The study is performed
separately for events with and without jets originating from b quarks. The
observed yields are consistent with the expected backgrounds and, depending on
the nature of the production mechanism, dark matter production at the LHC is
excluded at 90% confidence level for a mediator mass scale Lambda below 1 TeV.
The use of razor variables yields results that complement those previously
published.Comment: Replaced with the published version. Added the journal reference and
  DOI. All the figures and tables can be at
  http://cms-results.web.cern.ch/cms-results/public-results/publications/EXO-14-004/index.htm
The development of egalitarianism, altruism, spite and parochialism in childhood and adolescence?

Available online 15 October 2013.We study how the distribution of other-regarding preferences develops with age. Based on a set of allocation choices, we classify each of 717 subjects, aged 8 to 17 years, as either egalitarian, altruistic, or spiteful. We find a strong decrease in spitefulness with increasing age. Egalitarianism becomes less frequent, and altruism much more prominent, with age. Females are more frequently classified as egalitarian than males, and less often as altruistic. By varying the allocation recipient as either an in-group or an out-group member, we also study how parochialism develops with age. Parochialism emerges significantly in the teenage years
The radiation condition at infinity for the high-frequency Helmholtz equation with source term: a wave packet approach

International audienceWe consider the high-frequency Helmholtz equation with a given source term, and a small absorption parameter $\a>0$. The high-frequency (or: semi-classical) parameter is $\eps>0$. We let $\eps$ and $\a$ go to zero simultaneously. We assume that the zero energy is non-trapping for the underlying classical flow. We also assume that the classical trajectories starting from the origin satisfy a transversality condition, a generic assumption. Under these assumptions, we prove that the solution $u^\eps$ radiates in the outgoing direction, {\bf uniformly} in $\eps$. In particular, the function $u^\eps$, when conveniently rescaled at the scale $\eps$ close to the origin, is shown to converge towards the {\bf outgoing} solution of the Helmholtz equation, with coefficients frozen at the origin. This provides a uniform version (in $\eps$) of the limiting absorption principle. Writing the resolvent of the Helmholtz equation as the integral in time of the associated semi-classical Schrödinger propagator, our analysis relies on the following tools: (i) For very large times, we prove and use a uniform version of the Egorov Theorem to estimate the time integral; (ii) for moderate times, we prove a uniform dispersive estimate that relies on a wave-packet approach, together with the above mentioned transversality condition; (iii) for small times, we prove that the semi-classical Schrödinger operator with variable coefficients has the same dispersive properties as in the constant coefficients case, uniformly in $\eps$
INTEGRAL/SPI data segmentation to retrieve sources intensity variations

International audienceContext. The INTEGRAL/SPI, X/γ-ray spectrometer (20 keV–8 MeV) is an instrument for which recovering source intensity variations is not straightforward and can constitute a difficulty for data analysis. In most cases, determining the source intensity changes between exposures is largely based on a priori information.Aims. We propose techniques that help to overcome the difficulty related to source intensity variations, which make this step more rational. In addition, the constructed “synthetic” light curves should permit us to obtain a sky model that describes the data better and optimizes the source signal-to-noise ratios.Methods. For this purpose, the time intensity variation of each source was modeled as a combination of piecewise segments of time during which a given source exhibits a constant intensity. To optimize the signal-to-noise ratios, the number of segments was minimized. We present a first method that takes advantage of previous time series that can be obtained from another instrument on-board the INTEGRAL observatory. A data segmentation algorithm was then used to synthesize the time series into segments. The second method no longer needs external light curves, but solely SPI raw data. For this, we developed a specific algorithm that involves the SPI transfer function.Results. The time segmentation algorithms that were developed solve a difficulty inherent to the SPI instrument, which is the intensity variations of sources between exposures, and it allows us to obtain more information about the sources’ behavior
Small data global existence for the semilinear wave equation with
  space-time dependent damping

In this paper we consider the critical exponent problem for the semilinear
wave equation with space-time dependent damping. When the damping is effective,
it is expected that the critical exponent agrees with that of only space
dependent coefficient case. We shall prove that there exists a unique global
solution for small data if the power of nonlinearity is larger than the
expected exponent. Moreover, we do not assume that the data are compactly
supported. However, it is still open whether there exists a blow-up solution if
the power of nonlinearity is smaller than the expected exponent
The Hawk-I UDS and GOODS Survey (HUGS): Survey design   and deep K-band number counts

International audienceWe present the results of a new, ultra-deep, near-infrared imaging survey executed with the Hawk-I imager at the ESO VLT, of which we make all the data (images and catalog) public. This survey, named HUGS (Hawk-I UDS and GOODS Survey), provides deep, high-quality imaging in the K and Y bands over the portions of the UKIDSS UDS and GOODS-South fields covered by the CANDELS HST WFC3/IR survey. In this paper we describe the survey strategy, the observational campaign, the data reduction process, and the data quality. We show that, thanks to exquisite image quality and extremely long exposure times, HUGS delivers the deepest K-band images ever collected over areas of cosmological interest, and in general ideally complements the CANDELS data set in terms of image quality and depth. In the GOODS-S field, the K-band observations cover the whole CANDELS area with a complex geometry made of 6 different, partly overlapping pointings, in order to best match the deep and wide areas of CANDELS imaging. In the deepest region (which includes most of the Hubble Ultra Deep Field) exposure times exceed 80 hours of integration, yielding a 1 − σ magnitude limit per square arcsec of ≃28.0 AB mag. The seeing is exceptional and homogeneous across the various pointings, confined to the range 0.38–0.43 arcsec. In the UDS field the survey is about one magnitude shallower (to match the correspondingly shallower depth of the CANDELS images) but includes also Y-band band imaging (which, in the UDS, was not provided by the CANDELS WFC3/IR imaging). In the K-band, with an average exposure time of 13 hours, and seeing in the range 0.37–0.43 arcsec, the 1 − σ limit per square arcsec in the UDS imaging is ≃27.3 AB mag. In the Y-band, with an average exposure time ≃8 h, and seeing in the range 0.45–0.5 arcsec, the imaging yields a 1 − σ limit per square arcsec of ≃28.3 AB mag. We show that the HUGS observations are well matched to the depth of the CANDELS WFC3/IR data, since the majority of even the faintest galaxies detected in the CANDELS H-band images are also detected in HUGS. Finally we present the K-band galaxy number counts produced by combining the HUGS data from the two fields. We show that the slope of the number counts depends sensitively on the assumed distribution of galaxy sizes, with potential impact on the estimated extra-galactic background light
Nonlinear disturbance evolution in a two-dimensional boundary layer along an elastic plate and induced radiated noise

International audienceThe interaction between a boundary-layer flow and an elastic plate is addressed by direct numerical simulation, taking into account the full coupling between the fluid flow and the flexible wall. The convectively unstable flow state is harmonically forced and two-dimensional nonlinearly saturated wavelike disturbances are computed along archetype-plates with respect to stiffness and natural frequencies. In the aim of determining the low-Mach number radiated sound for the system, the simulation data are used to solve the Lighthill equation in terms of a Green function in the wavenumber-frequency space. Different degrees of fluid-structure coupling are implemented in the radiated sound model and the resulting acoustic pressure levels are compared. The sound radiation levels are shown to be increased in the presence of flexible walls with however significant differences in the radiated pressure levels for different coupling assumptions
Combined inoculation with [i]Glomus intraradices[/i] and [i]Rhizobium tropici[/i] CIAT899 increases phosphorus use efficiency for symbiotic nitrogen fixation in common bean ([i]Phaseolus vulgaris[/i] L.)

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699This study compared the response of common bean (Phaseolus vulgaris L.) to arbuscular mycorrhizal fungi (AMF) and rhizobia strain inoculation. Two common bean genotypes i.e. CocoT and Flamingo varying in their effectiveness for nitrogen fixation were inoculated with Glomus intraradices and Rhizobium tropici CIAT899, and grown for 50 days in soil-sand substrate in glasshouse conditions. Inoculation of common bean plants with the AM fungi resulted in a significant increase in nodulation compared to plants without inoculation. The combined inoculation of AM fungi and rhizobia significantly increased various plant growth parameters compared to simple inoculated plants. In addition, the combined inoculation of AM fungi and rhizobia resulted in significantly higher nitrogen and phosphorus accumulation in the shoots of common bean plants and improved phosphorus use efficiency compared with their controls, which were not dually inoculated. It is concluded that inoculation with rhizobia and arbuscular mycorrhizal fungi could improve the efficiency in phosphorus use for symbiotic nitrogen fixation especially under phosphorus deficiency
VIMOS Ultra-Deep Survey (VUDS): Witnessing the assembly  of a massive cluster at z ~ 3.3

International audienceUsing new spectroscopic observations obtained as part of the VIMOS Ultra-Deep Survey (VUDS), we performed a systematic search for overdense environments in the early universe (z> 2) and report here on the discovery of Cl J0227-0421, a massive protocluster at z = 3.29. This protocluster is characterized by both the large overdensity of spectroscopically confirmed members, δgal = 10.5 ± 2.8, and a significant overdensity in photometric redshift members. The halo mass of this protocluster is estimated by a variety of methods to be ~3 × 1014ℳ⊙ at z ~ 3.3, which, evolved to z = 0 results in a halo mass rivaling or exceeding that of the Coma cluster. The properties of 19 spectroscopically confirmed member galaxies are compared with a large sample of VUDS/VVDS galaxies in lower density field environments at similar redshifts. We find tentative evidence for an excess of redder, brighter, and more massive galaxies within the confines of the protocluster relative to the field population, which suggests that we may be observing the beginning ofenvironmentally induced quenching. The properties of these galaxies are investigated, including a discussion of the brightest protocluster galaxy, which appears to be undergoing vigorous coeval nuclear and starburst activity. The remaining member galaxies appear to have characteristics that are largely similar to the field population. Though we find weaker evidence of the suppression of the median star formation rates among and differences in the stacked spectra of member galaxies with respect to the field, we defer any conclusions about these trends to future work with the ensemble of protostructures that are found in the full VUDS sample
Astronomy Astrophysics Evolution of the solar irradiance during the Holocene

International audienceContext. Long-term records of solar radiative output are vital for understanding solar variability and past climate change. Measurements of solar irradiance are available for only the last three decades, which calls for reconstructions of this quantity over longer time scales using suitable models. Aims. We present a physically consistent reconstruction of the total solar irradiance for the Holocene. Methods. We extend the SATIRE (Spectral And Total Irradiance REconstruction) models to estimate the evolution of the total (and partly spectral) solar irradiance over the Holocene. The basic assumption is that the variations of the solar irradiance are due to the evolution of the dark and bright magnetic features on the solar surface. The evolution of the decadally averaged magnetic flux is computed from decadal values of cosmogenic isotope concentrations recorded in natural archives employing a series of physics-based models connecting the processes from the modulation of the cosmic ray flux in the heliosphere to their record in natural archives. We then compute the total solar irradiance (TSI) as a linear combination of the jth and jth + 1 decadal values of the open magnetic flux. In order to evaluate the uncertainties due to the evolution of the Earth's magnetic dipole moment, we employ four reconstructions of the open flux which are based on conceptually different paleomagnetic models. Results. Reconstructions of the TSI over the Holocene, each valid for a different paleomagnetic time series, are presented. Our analysis suggests that major sources of uncertainty in the TSI in this model are the heritage of the uncertainty of the TSI since 1610 reconstructed from sunspot data and the uncertainty of the evolution of the Earth's magnetic dipole moment. The analysis of the distribution functions of the reconstructed irradiance for the last 3000 years, which is the period that the reconstructions overlap, indicates that the estimates based on the virtual axial dipole moment are significantly lower at earlier times than the reconstructions based on the virtual dipole moment. We also present a combined reconstruction, which represents our best estimate of total solar irradiance for any given time during the Holocene. Conclusions. We present the first physics-based reconstruction of the total solar irradiance over the Holocene, which will be of interest for studies of climate change over the last 11 500 years. The reconstruction indicates that the decadally averaged total solar irradiance ranges over approximately 1.5 W/m 2 from grand maxima to grand minima
Elasticity of (K,Na)AlSi(3)O(8) hollandite from lattice dynamics calculations

International audienceWe compute the elastic constants tensor and the seismic properties of KAlSi(3)O(8) and K(0.8)Na(0.2)AlSi(3)O(8) up to the ferroelastic transition using density-functional theory and density-functional perturbation theory in the ABINIT implementation. We observe a softening of the tetragonal shear with pressure that precedes the ferroelastic transition. The Reuss shear moduli become negative at respectively 23 GPa and 13 GPa for the two compositions considered in here. The ferroelastic transition is associated with a strong decrease of the horizontal shear wave velocities and a corresponding increase of the seismic anisotropy. The presence of Na enhances these features. (C) 2010 Elsevier B.V. All rights reserved
Multi-scale modeling of the mechanical behavior of polycrystalline ice under transient creep.

International audienceIce is a challenging material for understanding the overall behavior of polycrystalline materials and more specifically the coupling between elastic and viscous effects during transient creep. At the single crystal level, ice is an hexagonal material with a rather weak elastic anisotropy but with a strong viscoplastic anisotropy. The strain-stress curve of ice single crystals shows a softening behavior depending on the strain-rate. The strong viscous anisotropy of ice gives rise to the progressive development of intergranular and intragranular strain heterogeneities and to stress concentrations which play an important role in the understanding of the creep behavior of ice polycrystals. The single crystal constitutive relations of Castelnau et al [1] are slightly modified here for a better evolution of the reference resolved shear stress on the slip systems and to account for kinematic hardening at the single crystal level. These constitutive relations are then used in a full-field simulation performed by an elasto-viscoplastic FFT-based method. The material parameters of the model are determined by comparison with experimental data available for single crystals as well as for polycrystals
Fracture and debonding of a thin film on a stiff substrate: analytical and numerical solutions of a 1d variational model

International audienceWe study multifissuration and debonding phenomena of a thin film bonded to a stiff substrate us- ing the variational approach to fracture mechanics. We consider a reduced one-dimensional membrane model where the loading is introduced through uniform inelastic (e.g. thermal) strains in the film or imposed dis- placements of the substrate. Fracture phenomena are accounted for by adopting a Griffith model for debonding and transverse fracture. On the basis of energy minimization arguments, we recover the key qualitative prop- erties of the experimental evidences, like the periodicity of transverse cracks and the peripheral debonding of each regular segment. Phase diagrams relate the maximum number of transverse cracks that may be created before debonding takes place as a function of the material properties and the sample's geometry. The theo- retical results are illustrated with numerical simulations obtained through a finite element discretization and a regularized variational formulation of the Ambrosio-Tortorelli type, which is suited to further extensions in two-dimensional settings