347 research outputs found
The Selfish Grandma Gene: The Roles of the X-Chromosome and Paternity Uncertainty in the Evolution of Grandmothering Behavior and Longevity
When considering inclusive fitness, it is expected that individuals will provide more care towards those with whom they are more closely related. Thus, if a selfish X-linked genetic element influenced care giving, we would expect care giving to vary with X-relatedness. Recent studies have shown that X-chromosome inheritance patterns may influence selection of traits affecting behavior and life-history. Sexually antagonistic (SA) zygotic drive could encourage individuals to help those with whom they are more likely to share genetic material at the expense of other relatives. We reanalyze previously reported data in light of this new idea. We also evaluate the effects of paternity uncertainty on SA-zygotic drive. Our evidence suggests that human paternal discrepancy is relatively low. Using published models, we find the effects of paternal discrepancy do not override opportunity for selection based on X-relatedness. Based on these results, longevity and grandmothering behaviors, including favoritism, may be more heavily influenced by selection on the X-chromosome than by paternity uncertainty
The Space Filling Curve Needle
The following slides are our contribution to the Meshing Contest of the International Meshing Roundtable 2022. We show a hybrid adaptively refined mesh of the Seattle Spaceneedle
Extensive air shower simulations at the highest energies
Air shower simulation programs are essential tools for the analysis of data from cosmic ray experiments and for planning the layout of new detectors. They are used to estimate the energy and mass of the primary particle. Unfortunately the model uncertainties translate directly into systematic errors in the energy and mass determination. Aiming at energies > 1019 eV, the models have to be extrapolated far beyond the energies available at accelerators. On the other hand, hybrid measurement of ground particle densities and calorimetric shower energy, as will be provided by the Pierre Auger Observatory, will strongly constrain shower models. While the main uncertainty of contemporary models comes from our poor knowledge of the (soft) hadronic interactions at high energies, also electromagnetic interactions, lowenergy hadronic interactions and the particle transport influence details of the shower development. We review here the physics processes and some of the computational techniques of air shower models presently used for highest energies, and discuss the properties and limitations of the models.Facultad de Ciencias Exacta
Calculations for Mirror Symmetry with D-branes
We study normal functions capturing D-brane superpotentials on several one-
and two-parameter Calabi-Yau hypersurfaces and complete intersections in
weighted projective space. We calculate in the B-model and interpret the
results using mirror symmetry in the large volume regime, albeit without
identifying the precise A-model geometry in all cases. We identify new classes
of extensions of Picard-Fuchs equations, as well as a novel type of topology
changing phase transition involving quantum D-branes. A 4-d domain wall which
is obtained in one region of closed string moduli space from wrapping a
four-chain interpolating between two Lagrangian submanifolds is, for other
values of the parameters, represented by a disk ending on a single Lagrangian.Comment: 42 page
Enabling hybrid tree-based Adaptive Mesh Refinement using Pyramids
We present a space-filling curve for pyramids to enable fully hybrid adaptive mesh refinement. The SFC is based on the tetrahedral Morton-curve. We show how to solve the difficulty, that a pyramid divides into pyramids and tetrahedral and how to reuse the already existing SFC for the tetrahedral children of a pyramid. Our results proof, that the algorithms scale very good and that our algorithms are efficient
An Optimized, Parallel Computation of the Ghost Layer for Adaptive Hybrid Forest Meshes
We discuss parallel algorithms to compute the ghost layer in computational, distributed memory, recursively adapted meshes. Its creation is a fundamental, necessary task in executing most parallel, element-based computer simulations. Common methods differ in that the ghost layer may either be inherently part of the mesh data structure that is maintained and modified, or kept separate and constructed/deleted as needed. In this work, we present a design following the latter approach, which we chose for its modularity of algorithms and data structures. We target arbitrary adaptive, nonconforming forest-of-trees meshes of mixed element shapes, such as cubes, prisms, and tetrahedra, and restrict ourselves to ghost elements across mesh faces. Our algorithm has low code complexity and redundancy since we reduce it to generic codimension-1 subalgorithms that can be flexibly combined. We recover older algorithms for cubic elements as special cases and optimize further using recursive, amortized tree searches and traversals
Dynamic Adaptive Refinement In Earth System Modelling
: Increasing the mesh resolution is one the most important tools for
increasing the accuracy of numerical simulations. However, increasing the mesh
resolution globally increases the amount of data and computational time
substantially. In the exascale-era sub-km meshes are becoming more and more
popular for atmospheric models, making it especially difficult to manage the vast
amount of data efficiently. With dynamic adaptive mesh refinement (AMR) we
locally control the resolution of a mesh in areas of interest, using a fine resolution
only where it is explicitely needed and keeping the mesh coarse elsewhere. Thus,
we concentrate the data and computing power and significantly reduce the
simulation costs while keeping the same numerical accuracy. Vice versa, the
resolution can be increased while keeping the same runtime. Managing adaptive
meshes induces new challenges such as load-balancing, mesh management,
ghost layer computation etc. Developments in the recent years have extended the
scalable and efficicient tree-based AMR approach from quadrilaterals/hexahedra
to various element shapes such as triangles, tetrahedra, pyramids or prisms and
have been implemented in our AMR library t8code. It is a third-party library that
adresses these challenges and can be integrated by solver environments in order
to enable AMR. In our presentation we will give an introduction to AMR and how
we use it for atmospheric simulations. We will give an overview of ongoing and
past projects, such as our contributions to PilotLab Exascale Earth Sytem
Modelling (Pl-ExaESM) or the lossy data compression for data coming from
atmospheric simulations. Furthermore, we will demonstrate the efficiency of our
methods with recent benchmark results on current supercomputers, showing that
t8code scales on up to at least 1 million MPI ranks and over 1 Trillion mesh
elements
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The selfish grandma gene: the roles of the x-chromosome and paternity uncertainty in the evolution of grandmothering behavior and longevity.
When considering inclusive fitness, it is expected that individuals will provide more care towards those with whom they are more closely related. Thus, if a selfish X-linked genetic element influenced care giving, we would expect care giving to vary with X-relatedness. Recent studies have shown that X-chromosome inheritance patterns may influence selection of traits affecting behavior and life-history. Sexually antagonistic (SA) zygotic drive could encourage individuals to help those with whom they are more likely to share genetic material at the expense of other relatives. We reanalyze previously reported data in light of this new idea. We also evaluate the effects of paternity uncertainty on SA-zygotic drive. Our evidence suggests that human paternal discrepancy is relatively low. Using published models, we find the effects of paternal discrepancy do not override opportunity for selection based on X-relatedness. Based on these results, longevity and grandmothering behaviors, including favoritism, may be more heavily influenced by selection on the X-chromosome than by paternity uncertainty.Peer Reviewe
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