83 research outputs found
Dense packing crystal structures of physical tetrahedra
We present a method for discovering dense packings of general convex hard
particles and apply it to study the dense packing behavior of a one-parameter
family of particles with tetrahedral symmetry representing a deformation of the
ideal mathematical tetrahedron into a less ideal, physical, tetrahedron and all
the way to the sphere. Thus, we also connect the two well studied problems of
sphere packing and tetrahedron packing on a single axis. Our numerical results
uncover a rich optimal-packing behavior, compared to that of other continuous
families of particles previously studied. We present four structures as
candidates for the optimal packing at different values of the parameter,
providing an atlas of crystal structures which might be observed in systems of
nano-particles with tetrahedral symmetry
Crystalline Assemblies and Densest Packings of a Family of Truncated Tetrahedra and the Role of Directional Entropic Forces
Polyhedra and their arrangements have intrigued humankind since the ancient
Greeks and are today important motifs in condensed matter, with application to
many classes of liquids and solids. Yet, little is known about the
thermodynamically stable phases of polyhedrally-shaped building blocks, such as
faceted nanoparticles and colloids. Although hard particles are known to
organize due to entropy alone, and some unusual phases are reported in the
literature, the role of entropic forces in connection with polyhedral shape is
not well understood. Here, we study thermodynamic self-assembly of a family of
truncated tetrahedra and report several atomic crystal isostructures, including
diamond, {\beta}-tin, and high- pressure lithium, as the polyhedron shape
varies from tetrahedral to octahedral. We compare our findings with the densest
packings of the truncated tetrahedron family obtained by numerical compression
and report a new space filling polyhedron, which has been overlooked in
previous searches. Interestingly, the self-assembled structures differ from the
densest packings. We show that the self-assembled crystal structures can be
understood as a tendency for polyhedra to maximize face-to-face alignment,
which can be generalized as directional entropic forces.Comment: Article + supplementary information. 23 pages, 10 figures, 2 table
Receptor Tyrosine Kinases in Osteosarcoma: 2019 Update
The primary conclusions of our 2014 contribution to this series were as follows:
Multiple receptor tyrosine kinases (RTKs) likely contribute to aggressive phenotypes in osteosarcoma and, therefore, inhibition of multiple RTKs is likely necessary for successful clinical outcomes.
Inhibition of multiple RTKs may also be useful to overcome resistance to inhibitors of individual RTKs as well as resistance to conventional chemotherapies.
Different combinations of RTKs are likely important in individual patients.
AXL, EPHB2, FGFR2, IGF1R, and RET were identified as promising therapeutic targets by our in vitro phosphoproteomic/siRNA screen of 42 RTKs in the highly metastatic LM7 and 143B human osteosarcoma cell lines.
This chapter is intended to provide an update on these topics as well as the large number of osteosarcoma clinical studies of inhibitors of multiple tyrosine kinases (multi-TKIs) that were recently published
From RealâWorld Patient Data to Individualized Treatment Effects Using Machine Learning: Current and Future Methods to Address Underlying Challenges
A Two-Part Framework for Estimating Individualized Treatment Rules From Semicontinuous Outcomes
A Semiparametric Instrumental Variable Approach to Optimal Treatment Regimes Under Endogeneity
Introduction to the Theory and Methods Special Issue on Precision Medicine and Individualized Policy Discovery
Machine Intelligence for Individualized Decision Making Under a Counterfactual World: A Rejoinder
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