BACKGROUND: Bursaphelenchus xylophilus, the pinewood nematode, kills millions of pine trees worldwide every year, and causes enormous economic and ecological losses. Despite extensive research on population variation, there is little understanding of the population-wide variation spectrum in China.RESULTS: We sequenced an inbred B. xylophilus strain using Pacbio+Illumina+Bionano+Hi-C and generated a chromosomelevel assembly (AH1) with six chromosomes of 77.1 Mb (chromosome N50: 12 Mb). The AH1 assembly shows very high continuity and completeness, and contains novel genes with potentially important functions compared with previous assemblies. Subsequently, we sequenced 181 strains from China and the USA and found ∼7.8 million single nucleotide polymorphisms (SNPs). Analysis shows that the B. xylophilus population in China can be divided into geographically bounded subpopulations with severe cross-infection and potential migrations. In addition, distribution of B. xylophilus is dominated by temperature zones while geographically associated SNPs are mainly located on adaptation related GPCR gene families, suggesting the nematode has been evolving to adapt to different temperatures. A machine-learning based epidemic tracking method has been established to predict their geographical origins, which can be applied to any other species.CONCLUSION: Our study provides the community with the first high-quality chromosome-level assembly which includes a comprehensive catalogue of genetic variations. It provides insights into population structure and effective tracking method for this invasive species, which facilitates future studies to address a variety of applied, genomic and evolutionary questions in B. xylophilus as well as related species.

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Purpose Research has shown that observing hand gestures mimicking pitch movements or rhythmic patterns can improve the learning of second language (L2) suprasegmental features. However, less is known about the effects of hand gestures on the learning of novel phonemic contrasts. This study examines (a) whether hand gestures mimicking phonetic features can boost L2 segment learning by naive learners and (b) whether a mismatch between the hand gesture form and the target phonetic feature influences the learning effect. Method Fifty Catalan native speakers undertook a short multimodal training session on two types of Mandarin Chinese consonants (plosives and affricates) in either of two conditions: Gesture and No Gesture. In the Gesture condition, a fist-to-open-hand gesture was used to mimic air burst, while the No Gesture condition included no such use of gestures. Crucially, while the hand gesture appropriately mimicked the air burst produced in plosives, this was not the case for affricates. Before and after training, participants were tested on two tasks, namely, the identification task and the imitation task. Participants' speech output was rated by five Chinese native speakers. Results The perception results showed that training with or without gestures yielded similar degrees of improvement for the identification of aspiration contrasts. By contrast, the production results showed that, while training without gestures did not help improve L2 pronunciation, training with gestures improved pronunciation, but only when the given gestures appropriately mimicked the phonetic properties they represented. Conclusions Results revealed that the efficacy of observing hand gestures on the learning of nonnative phonemes depends on the appropriateness of the form of those gestures relative to the target phonetic features. That is, hand gestures seem to be more useful when they appropriately mimic phonetic features. Supplemental Material https://doi.org/10.23641/asha.13105442

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As a commonly used Sub-Kelvin refrigeration technology, helium sorption coolers play an important role in space and ground applications. The adsorption characteristics of the porous material inside the sorption cooler at low temperature have a crucial influence on its performance. At present, the analysis and calculation of sorption coolers are mainly based on helium 4 (4He) as the working gas, and there is a lack of systematic research on the low-temperature adsorption characteristics of helium-3 (3He) and its coupling effect characteristics of temperature, pressure and mass distribution in different components. In this paper, a molecular model of activated carbon that is similar to the actual structure was constructed, the adsorption isobars and isosteric heat of 3He and 4He at 0.8-5K were comparatively studied based on the grand canonical Monte Carlo method (GCMC). Besides, the influence of adsorption characteristics of 3He and 4He on the liquefaction rate, the mass distribution after condensation equilibrium, and the self-cooling loss of the sorption cooler were analyzed. The results show that for the 3He sorption cooler, the main factor affecting the liquefaction rate is the adsorbed helium in the sorption pump, while for the 4He sorption cooler, it is the adsorbed helium and the gas in the dead volume. For both 3He and 4He sorption cooler, the liquefaction rate increases as the sorption pump temperature increases or the heat sink temperature decreases, while the self-cooling loss decreases as the heat sink temperature decreases or the operating temperature increases.