TY - JOUR AB - High carrier mobility is critical to improving thermoelectric performance over a broad temperature range. However, traditional doping inevitably deteriorates carrier mobility. Herein, we develop a strategy for fine tuning of defects to improve carrier mobility. To begin, n-type PbTe is created by compensating for the intrinsic Pb vacancy in bare PbTe. Excess Pb2+ reduces vacancy scattering, resulting in a high carrier mobility of ∼3400 cm2 V–1 s–1. Then, excess Ag is introduced to compensate for the remaining intrinsic Pb vacancies. We find that excess Ag exhibits a dynamic doping process with increasing temperatures, increasing both the carrier concentration and carrier mobility throughout a wide temperature range; specifically, an ultrahigh carrier mobility ∼7300 cm2 V–1 s–1 is obtained for Pb1.01Te + 0.002Ag at 300 K. Moreover, the dynamic doping-induced high carrier concentration suppresses the bipolar thermal conductivity at high temperatures. The final step is using iodine to optimize the carrier concentration to ∼1019 cm–3. Ultimately, a maximum ZT value of ∼1.5 and a large average ZTave value of ∼1.0 at 300–773 K are obtained for Pb1.01Te0.998I0.002 + 0.002Ag. These findings demonstrate that fine tuning of defects with <0.5% impurities can remarkably enhance carrier mobility and improve thermoelectric performance. AU - Wang, Siqi AU - Chang, Cheng AU - Bai, Shulin AU - Qin, Bingchao AU - Zhu, Yingcai AU - Zhan, Shaoping AU - Zheng, Junqing AU - Tang, Shuwei AU - Zhao, Li Dong ID - 12331 IS - 2 JF - Chemistry of Materials SN - 0897-4756 TI - Fine tuning of defects enables high carrier mobility and enhanced thermoelectric performance of n-type PbTe VL - 35 ER - TY - JOUR AB - A simple drawing D(G) of a graph G is one where each pair of edges share at most one point: either a common endpoint or a proper crossing. An edge e in the complement of G can be inserted into D(G) if there exists a simple drawing of G+e extending D(G). As a result of Levi’s Enlargement Lemma, if a drawing is rectilinear (pseudolinear), that is, the edges can be extended into an arrangement of lines (pseudolines), then any edge in the complement of G can be inserted. In contrast, we show that it is NP-complete to decide whether one edge can be inserted into a simple drawing. This remains true even if we assume that the drawing is pseudocircular, that is, the edges can be extended to an arrangement of pseudocircles. On the positive side, we show that, given an arrangement of pseudocircles A and a pseudosegment σ, it can be decided in polynomial time whether there exists a pseudocircle Φσ extending σ for which A∪{Φσ} is again an arrangement of pseudocircles. AU - Arroyo Guevara, Alan M AU - Klute, Fabian AU - Parada, Irene AU - Vogtenhuber, Birgit AU - Seidel, Raimund AU - Wiedera, Tilo ID - 11999 JF - Discrete and Computational Geometry SN - 0179-5376 TI - Inserting one edge into a simple drawing is hard VL - 69 ER - TY - JOUR AB - The design and implementation of efficient concurrent data structures has seen significant attention. However, most of this work has focused on concurrent data structures providing good worst-case guarantees, although, in real workloads, objects are often accessed at different rates. Efficient distribution-adaptive data structures, such as splay-trees, are known in the sequential case; however, they often are hard to translate efficiently to the concurrent case. We investigate distribution-adaptive concurrent data structures, and propose a new design called the splay-list. At a high level, the splay-list is similar to a standard skip-list, with the key distinction that the height of each element adapts dynamically to its access rate: popular elements “move up,” whereas rarely-accessed elements decrease in height. We show that the splay-list provides order-optimal amortized complexity bounds for a subset of operations, while being amenable to efficient concurrent implementation. Experiments show that the splay-list can leverage distribution-adaptivity for performance, and can outperform the only previously-known distribution-adaptive concurrent design in certain workloads. AU - Aksenov, Vitalii AU - Alistarh, Dan-Adrian AU - Drozdova, Alexandra AU - Mohtashami, Amirkeivan ID - 12330 JF - Distributed Computing SN - 0178-2770 TI - The splay-list: A distribution-adaptive concurrent skip-list VL - 36 ER - TY - JOUR AB - The term “haplotype block” is commonly used in the developing field of haplotype-based inference methods. We argue that the term should be defined based on the structure of the Ancestral Recombination Graph (ARG), which contains complete information on the ancestry of a sample. We use simulated examples to demonstrate key features of the relationship between haplotype blocks and ancestral structure, emphasizing the stochasticity of the processes that generate them. Even the simplest cases of neutrality or of a “hard” selective sweep produce a rich structure, often missed by commonly used statistics. We highlight a number of novel methods for inferring haplotype structure, based on the full ARG, or on a sequence of trees, and illustrate how they can be used to define haplotype blocks using an empirical data set. While the advent of new, computationally efficient methods makes it possible to apply these concepts broadly, they (and additional new methods) could benefit from adding features to explore haplotype blocks, as we define them. Understanding and applying the concept of the haplotype block will be essential to fully exploit long and linked-read sequencing technologies. AU - Shipilina, Daria AU - Pal, Arka AU - Stankowski, Sean AU - Chan, Yingguang Frank AU - Barton, Nicholas H ID - 12159 IS - 6 JF - Molecular Ecology KW - Genetics KW - Ecology KW - Evolution KW - Behavior and Systematics SN - 0962-1083 TI - On the origin and structure of haplotype blocks VL - 32 ER - TY - JOUR AB - Probing the dynamics of aromatic side chains provides important insights into the behavior of a protein because flips of aromatic rings in a protein’s hydrophobic core report on breathing motion involving a large part of the protein. Inherently invisible to crystallography, aromatic motions have been primarily studied by solution NMR. The question how packing of proteins in crystals affects ring flips has, thus, remained largely unexplored. Here we apply magic-angle spinning NMR, advanced phenylalanine 1H-13C/2H isotope labeling and MD simulation to a protein in three different crystal packing environments to shed light onto possible impact of packing on ring flips. The flips of the two Phe residues in ubiquitin, both surface exposed, appear remarkably conserved in the different crystal forms, even though the intermolecular packing is quite different: Phe4 flips on a ca. 10–20 ns time scale, and Phe45 are broadened in all crystals, presumably due to µs motion. Our findings suggest that intramolecular influences are more important for ring flips than intermolecular (packing) effects. AU - Gauto, Diego F. AU - Lebedenko, Olga O. AU - Becker, Lea Marie AU - Ayala, Isabel AU - Lichtenecker, Roman AU - Skrynnikov, Nikolai R. AU - Schanda, Paul ID - 12114 JF - Journal of Structural Biology: X KW - Structural Biology SN - 2590-1524 TI - Aromatic ring flips in differently packed ubiquitin protein crystals from MAS NMR and MD VL - 7 ER -