| 1. |
- Ghafoor, Naureen, et al.
(författare)
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Self-organized anisotropic (Zr1-xSix)N-y nanocomposites grown by reactive sputter deposition
- 2015
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Ingår i: Acta Materialia. - : Elsevier. - 1359-6454 .- 1873-2453. ; 82, s. 179-189
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Tidskriftsartikel (refereegranskat)abstract
- The physical properties of hard and superhard nanocomposite thin films are strongly dependent on their nanostructure. Here, we present the results of an investigation of nanostructural evolution and the resulting mechanical properties of (Zr1-xSix)N-y films, with 0 less than= x less than= 1 and 1 less than= y less than= 1.27, grown on MgO(0 0 1) and Al2O3(0 0 0 1) substrates at temperatures T-s = 500-900 degrees C by reactive magnetron sputter deposition from Zr and Si targets. X-ray diffraction and transmission electron microscopy (TEM) results show that there is a T-s/composition window in which stoichiometric Zr-Si-N and amorphous a-Si3N4 phases mutually segregate and self-organize into encapsulated 3-5 um wide ZrN-rich (Zr1-xSix)N columns which extend along the growth direction with a strong (002) texture. Lattice-resolved scanning TEM and energy-dispersive X-ray spectroscopy reveal that the (Zr1-xSix)N-y nanocolumns are separated by a bilayer tissue phase consisting of a thin crystalline SiNy-rich (Zr1-xSix)N-y layer with an a-Si3N4 overlayer. Incorporation of metastable SiN into NaCl-structure ZrN leads to an enhanced nanoindentation hardness H which is a function of T-s and film composition. For nanocomposites with composition (Zr(0.8)Sio(0.2))N-1.14 (10 at.% Si) H, increases from 26 GPa at 500 degrees C to 37 GPa at 900 degrees C. For comparison, the hardness of epitaxial ZrN/MgO(0 0 1) layers grown at T-s = 800 degrees C is 24 GPa. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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| 2. |
- Glemin, Sylvain, et al.
(författare)
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Quantification of GC-biased gene conversion in the human genome
- 2015
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Ingår i: Genome Research. - : Cold Spring Harbor Laboratory. - 1088-9051 .- 1549-5469. ; 25:8, s. 1215-1228
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Tidskriftsartikel (refereegranskat)abstract
- Much evidence indicates that GC-biased gene conversion (gBGC) has a major impact on the evolution of mammalian genomes. However, a detailed quantification of the process is still lacking. The strength of gBGC can be measured from the analysis of derived allele frequency spectra (DAF), but this approach is sensitive to a number of confounding factors. In particular, we show by simulations that the inference is pervasively affected by polymorphism polarization errors and by spatial heterogeneity in gBGC strength. We propose a new general method to quantify gBGC from DAF spectra, incorporating polarization errors, taking spatial heterogeneity into account, and jointly estimating mutation bias. Applying it to human polymorphism data from the 1000 Genomes Project, we show that the strength of gBGC does not differ between hypermutable CpG sites and non-CpG sites, suggesting that in humans gBGC is not caused by the base-excision repair machinery. Genome-wide, the intensity of gBGC is in the nearly neutral area. However, given that recombination occurs primarily within recombination hotspots, 1%-2% of the human genome is subject to strong gBGC. On average, gBGC is stronger in African than in non-African populations, reflecting differences in effective population sizes. However, due to more heterogeneous recombination landscapes, the fraction of the genome affected by strong gBGC is larger in non-African than in African populations. Given that the location of recombination hotspots evolves very rapidly, our analysis predicts that, in the long term, a large fraction of the genome is affected by short episodes of strong gBGC.
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| 3. |
- Petrov, Vitaly, et al.
(författare)
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ON UNIFIED VEHICULAR COMMUNICATIONS AND RADAR SENSING IN MILLIMETER-WAVE AND LOW TERAHERTZ BANDS
- 2019
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Ingår i: IEEE wireless communications. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1536-1284 .- 1558-0687. ; 26:3, s. 146-153
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Tidskriftsartikel (refereegranskat)abstract
- Future smart vehicles will incorporate high-data-rate communications and high-resolution radar sensing capabilities operating in the millimeter-wave and higher frequencies. These two systems are preparing to share and reuse many common functionalities, such as steerable millimeter-wave antenna arrays. Motivated by this growing overlap, which is advanced further by space and cost constraints, the vehicular community is pursuing a vision of unified vehicular communications and radar sensing that represents a major paradigm shift for next-generation connected and self-driving cars. This article outlines a path to materialize this decisive transformation. We begin by reviewing the latest developments in hybrid vehicular communications and radar systems, and then propose a concept of unified channel access over millimeter-wave and higher frequencies. Our supporting system-level performance characterization relies upon real-life measurements and extensive ray-based modeling to confirm the significant improvements brought by our proposal to mitigating the interference and deafness effects. Since our results aim to open the door to unified vehicular communications and radar sensing, we conclude by outlining the potential research directions in this rapidly developing field.
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| 4. |
- Petrov, Vitaly, et al.
(författare)
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When IoT Keeps People in the Loop : A Path Towards a New Global Utility
- 2019
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Ingår i: IEEE Communications Magazine. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0163-6804 .- 1558-1896. ; 57:1, s. 114-121
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Tidskriftsartikel (refereegranskat)abstract
- While the IoT has made significant progress supporting individual machine-type applications, it is only recently that the importance of people as an integral component of the overall IoT infrastructure has started to be fully recognized. Several powerful concepts have emerged to facilitate this vision, whether involving the human context whenever required or directly impacting user behavior and decisions. As these become the stepping stones to develop the IoT into a novel people-centric utility, this article outlines a path to realize this decisive transformation. We begin by reviewing the latest progress in human-aware wireless networking, then classify the attractive human-machine applications and summarize the enabling IoT radio technologies. We continue with a unique system-level performance characterization of a representative urban IoT scenario and quantify the benefits of keeping people in the loop on various levels. Our comprehensive numerical results confirm the significant gains that have been made available with tighter user involvement, and also corroborate the development of efficient incentivization mechanisms, thereby opening the door to future commoditization of the global people-centric IoT utility.
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