4,115 research outputs found
A Performance-Portable SYCL Implementation of CRK-HACC for Exascale
The first generation of exascale systems will include a variety of machine
architectures, featuring GPUs from multiple vendors. As a result, many
developers are interested in adopting portable programming models to avoid
maintaining multiple versions of their code. It is necessary to document
experiences with such programming models to assist developers in understanding
the advantages and disadvantages of different approaches.
To this end, this paper evaluates the performance portability of a SYCL
implementation of a large-scale cosmology application (CRK-HACC) running on
GPUs from three different vendors: AMD, Intel, and NVIDIA. We detail the
process of migrating the original code from CUDA to SYCL and show that
specializing kernels for specific targets can greatly improve performance
portability without significantly impacting programmer productivity. The SYCL
version of CRK-HACC achieves a performance portability of 0.96 with a code
divergence of almost 0, demonstrating that SYCL is a viable programming model
for performance-portable applications.Comment: 12 pages, 13 figures, 2023 International Workshop on Performance,
Portability & Productivity in HP
Minimal Model Holography for SO(2N)
A duality between the large N 't Hooft limit of the WD_N minimal model CFTs
and a higher spin gravity theory on AdS3 is proposed. The gravity theory has
massless spin fields of all even spins s=2,4,6,..., as well as two real scalar
fields whose mass is determined by the 't Hooft parameter of the CFT. We show
that, to leading order in the large N limit, the 1-loop partition function of
the higher spin theory matches precisely with the CFT partition function.Comment: 21 pages, LaTe
Bis{tris[3-(2-pyridyl)-1H-pyrazole]manganese(II)} dodecamolybdo(V,VI)phosphate hexahydrate
The asymmetric unit of the title compound, [Mn(C8H7N3)3]2[PMo12O40]·6H2O, consists of a complex [Mn(C8H7N3)3]2+ cation, half of a mixed-valent MoV,VI α-Keggin-type [PMo12O40]4− heteropolyanion, and three uncoordinated water molecules. The Mn2+ cation is surrounded by six N atoms from three chelating 3-(2-pyridyl)-1H-pyrazole ligands in a distorted octahedral coordination. In the heteropolyanion, two O atoms of the central PO4 group ( symmetry) are equally disordered about an inversion centre. N—H⋯O and O—H⋯O hydrogen bonding between the cations, anions and the uncoordinated water molecules leads to a consolidation of the structure
Quantum Criticality and Holographic Superconductors in M-theory
We present a consistent Kaluza-Klein truncation of D=11 supergravity on an
arbitrary seven-dimensional Sasaki-Einstein space (SE_7) to a D=4 theory
containing a metric, a gauge-field, a complex scalar field and a real scalar
field. We use this D=4 theory to construct various black hole solutions that
describe the thermodynamics of the d=3 CFTs dual to skew-whiffed AdS_4 X SE_7
solutions. We show that these CFTs have a rich phase diagram, including
holographic superconductivity with, generically, broken parity and time
reversal invariance. At zero temperature the superconducting solutions are
charged domain walls with a universal emergent conformal symmetry in the far
infrared.Comment: 52 pages, 16 figures, 3 appendices; minor changes, version to be
published in JHE
Quantum W-symmetry in AdS_3
It has recently been argued that, classically, massless higher spin theories
in AdS_3 have an enlarged W_N-symmetry as the algebra of asymptotic isometries.
In this note we provide evidence that this symmetry is realised
(perturbatively) in the quantum theory. We perform a one loop computation of
the fluctuations for a massless spin field around a thermal AdS_3
background. The resulting determinants are evaluated using the heat kernel
techniques of arXiv:0911.5085. The answer factorises holomorphically, and the
contributions from the various spin fields organise themselves into vacuum
characters of the W_N symmetry. For the case of the hs(1,1) theory consisting
of an infinite tower of massless higher spin particles, the resulting answer
can be simply expressed in terms of (two copies of) the MacMahon function.Comment: 23 pages; v2: References adde
Rossby wave dynamics of the North Pacific extra-tropical response to El Niño: importance of the basic state in coupled GCMs
The extra-tropical response to El Nino in a "low" horizontal resolution coupled climate model, typical of the Intergovernmental Panel on Climate Change fourth assessment report simulations, is shown to have serious systematic errors. A high resolution configuration of the same model has a much improved response that is similar to observations. The errors in the low resolution model are traced to an incorrect representation of the atmospheric teleconnection mechanism that controls the extra-tropical sea surface temperatures (SSTs) during El Nino. This is due to an unrealistic atmospheric mean state, which changes the propagation characteristics of Rossby waves. These erroneous upper tropospheric circulation anomalies then induce erroneous surface circulation features over the North Pacific. The associated surface wind speed and direction errors create erroneous surface flux and upwelling anomalies which finally lead to the incorrect extra-tropical SST response to El Nino in the low resolution model. This highlights the sensitivity of the climate response to a single link in a chain of complex climatic processes. The correct representation of these processes in the high resolution model indicates the importance of horizontal resolution in resolving such processes
Out of the empirical box: A mixed-methods study of tool innovation among Congolese BaYaka forager and Bondongo fisher–farmer children
© 2021 The Authors. Tool innovation has played a crucial role in human adaptation. Yet, this capacity seems to arise late in development. Before 8 years of age, many children struggle to solve the hook task, a common measure of tool innovation that requires modification of a straight pipe cleaner into a hook to extract a prize. Whether these findings are generalizable beyond postindustrialized Western children remains unclear. In many small-scale subsistence societies, children engage in daily tool use and modification, experiences that theoretically could enhance innovative capabilities. Although two previous studies found no differences in innovative ability between children from Western and small-scale subsistence societies, these did not account for the latter’s inexperience with pipe cleaners. Thus, the current study investigated how familiarity with pipe cleaners affected hook task success in 132 Congolese BaYaka foragers (57 girls) and 59 Bondongo fisher–farmers (23 girls) aged 4–12 years. We contextualized these findings within children’s interview responses and naturalistic observations of how pipe cleaners were incorporated into daily activities. Counter to our expectation, prior exposure did not improve children’s performance during the hook task. Bondongo children innovated significantly more hooks than BaYaka children, possibly because they participate in hook-and-line fishing. Observations and interviews showed that children imagined and innovated novel uses for pipe cleaners outside the experimental context, including headbands, bracelets, and suspenders. We relate our findings to ongoing debates regarding systematic versus unsystematic tool innovation, the importance of prior experience for the ontogeny of tool innovation, and the external validity of experimental paradigms
Asymptotic W-symmetries in three-dimensional higher-spin gauge theories
We discuss how to systematically compute the asymptotic symmetry algebras of
generic three-dimensional bosonic higher-spin gauge theories in backgrounds
that are asymptotically AdS. We apply these techniques to a one-parameter
family of higher-spin gauge theories that can be considered as large N limits
of SL(N) x SL(N) Chern-Simons theories, and we provide a closed formula for the
structure constants of the resulting infinite-dimensional non-linear
W-algebras. Along the way we provide a closed formula for the structure
constants of all classical W_N algebras. In both examples the higher-spin
generators of the W-algebras are Virasoro primaries. We eventually discuss how
to relate our basis to a non-primary quadratic basis that was previously
discussed in literature.Comment: 61 page
Symmetries of Holographic Minimal Models
It was recently proposed that a large N limit of a family of minimal model
CFTs is dual to a certain higher spin gravity theory in AdS_3, where the 't
Hooft coupling constant of the CFT is related to a deformation parameter of the
higher spin algebra. We identify the asymptotic symmetry algebra of the higher
spin theory for generic 't Hooft parameter, and show that it coincides with a
family of W-algebras previously discovered in the context of the KP hierarchy.
We furthermore demonstrate that this family of W-algebras controls the
representation theory of the minimal model CFTs in the 't Hooft limit. This
provides a non-trivial consistency check of the proposal and explains part of
the underlying mechanism.Comment: 25 pages; references added and minor corrections (published version
The Prevalence and Characteristics of Performance-Enhancing Drug Use Among Bodybuilding Athletes in the South of Iran, Bushehr
Background: Several reports have implied progressive increase of performance-enhancing drug (PED) use among Iranian athletes.
More importantly, most of the previous research in the Iranian population had mainly focused on the anabolic steroid abuse, and
ignored other agents.
Objectives: The aim of this study was to investigate the prevalence and characteristics of PED use among bodybuilding athletes in
Bushehr, south of Iran.
Methods: Four hundred and fifty three male bodybuilding athletes were recruited from Bushehr gyms between February and May
of 2015. Men were eligible to participate in the survey if they had regularly participated in the strength-training exercise (minimum
of 1 year and 4 hour/week). Data were collected via a face-to-face interview. The survey consisted of three separate parts including
demographic data, exercise pattern and PED use.
Results: According to this study, 234 (51.7%) of bodybuilding athletes had used PEDs. The PED users reported an average of 3.80 �
4.52 agents’ use in their programs and they had used PEDs for the average of 3.24 � 3.99 years. The most prevalent agents which
had been abused by the athletes were anabolic steroids (used by 185 athletes (79.4% of athletes). Furthermore, 110 (47%) of athletes
reported stimulant agents’ use during their routines. The most prevalent motivation for using PEDs was increasing muscle mass
that was reported by 164 (70.1%) of PED users. In addition, sexual and dermatologic effects were the most prevalent adverse effects
reported by the PED user athletes (114 (49.4%) and 103 (44.2%), respectively).
Conclusions: This study showed the high rate of PED use among recreational and professional Iranian bodybuilding athletes that
can expose them to the serious side effects of these agents
- …