Wireless body area networks (WBANs) are an emerging technology for realizing efficient healthcare and remote medicine for the aging society of the future. In order to improve the reliability of WBAN systems and support its various applications, channel modeling and performance evaluation are important. This paper proposes a simulation-based channel modeling for evaluating the performance of WBAN cooperative transmission schemes. The time series of path losses among seven on-body nodes are generated by the finite-difference time-domain method for seven body motions. The statistical parameters of the path loss for all the motions are also obtained. The generated path loss is then applied to the evaluation of the two-hop decode-and-forward relaying scheme, yielding an improvement in transmit power. From the evaluation of body motion, useful insights are obtained such as which relay links are more robust than others. Finally, the proposed approach is validated through comparison with a measurement-based approach.
The Himalayan uplift, a tectonic event of global importance, seemingly disseminated aquatic biodiversity broadly across Asia. But surprisingly, this hypothesis has yet to be tested. We do so herein by sequencing 1,140 base-pair of mtDNA cytochrome-b for 72 tetraploid Nepalese/Bhutanese Snowtrout (Schizothorax spp.), combining those data with 67 GENBANK sequences (59 ingroup/8 outgroup), then reconstructing phylogenetic relationships using maximum likelihood/ Bayesian analyses. Results indicate Snowtrout originated in Central Asia, dispersed across the Qinghai-Tibetan Plateau (QTP), then into Bhutan via south-flowing tributaries of the east-flowing Yarlung-Tsangpo River (YLTR). The headwaters of five large Asian rivers provided dispersal corridors into southeast Asia. South of the Himalaya, the YLTR transitions into a westward-flowing Brahmaputra River that facilitated successive colonization of Himalayan drainages: First Bhutan, then Nepal, followed by far-western drainages subsequently captured by the Indus River. We found greater species-divergences across rather than within-basins, implicating vicariant evolution as a driver. The Himalaya is a component of the third-pole [largest (but rapidly shrinking) glacial reservoir outside the Arctic/Antarctic]. Its unique aquatic biodiversity must not only be recognized (as herein) but also conserved through broad, trans-national collaborations. Our results effectively contrast phylogeography with taxonomy as a necessary first step in this process.
The recurrence of similar evolutionary patterns within different habitats often reflects parallel selective pressures acting upon either standing or independently occurring genetic variation to produce a convergence of phenotypes. This interpretation (i.e. parallel divergences within adjacent streams) has been hypothesized for drainage-specific morphological ‘ecotypes’ observed in polyploid snowtrout (Cyprinidae:
Schizothorax
). However, parallel patterns of differential introgression during secondary contact are a viable alternative hypothesis. Here, we used ddRADseq (
N
= 35 319
de novo
and
N
= 10 884 transcriptome-aligned SNPs), as derived from Nepali/Bhutanese samples (
N
= 48 each), to test these competing hypotheses. We first employed genome-wide allelic depths to derive appropriate ploidy models, then a Bayesian approach to yield genotypes statistically consistent under the inferred expectations. Elevational ‘ecotypes’ were consistent in geometric morphometric space, but with phylogenetic relationships at the drainage level, sustaining a hypothesis of independent emergence. However, partitioned analyses of phylogeny and admixture identified subsets of loci under selection that retained genealogical concordance with morphology, suggesting instead that apparent patterns of morphological/phylogenetic discordance are driven by widespread genomic homogenization. Here, admixture occurring in secondary contact effectively ‘masks’ previous isolation. Our results underscore two salient factors: (i) morphological adaptations are retained despite hybridization and (ii) the degree of admixture varies across tributaries, presumably concomitant with underlying environmental or anthropogenic factors.
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