Numerical simulation of wave propagation in a realistic model of the human external ear

In this study, a numerical investigation is performed to evaluate the effects of high-pressure sinusoidal and blast wave's propagation around and inside of a human external ear. A series of computed tomography images are used to reconstruct a realistic three-dimensional (3D) model of a human ear canal and the auricle. The airflow field is then computed by solving the governing differential equations in the time domain using a computational fluid dynamics software. An unsteady algorithm is used to obtain the high-pressure wave propagation throughout the ear canal which is validated against the available analytical and numerical data in literature. The effects of frequency, wave shape, and the auricle on pressure distribution are then evaluated and discussed. The results clearly indicate that the frequency plays a key role on pressure distribution within the ear canal. At 4 kHz frequency, the pressure magnitude is much more amplified within the ear canal than the frequencies of 2 and 6 kHz, for the incident wave angle of 90° investigated in this study, attributable to the ‘4-kHz notch’ in patients with noise-induced hearing loss. According to the results, the pressure distribution patterns at the ear canal are very similar for both sinusoidal pressure waveform with the frequency of 2 kHz and blast wave. The ratio of the peak pressure value at the eardrum to that at the canal entrance increases from about 8% to 30% as the peak pressure value of the blast wave increases from 5 to 100 kPa for the incident wave angle of 90° investigated in this study. Furthermore, incorporation of the auricle to the ear canal model is associated with centerline pressure magnitudes of about 50% and 7% more than those of the ear canal model without the auricle throughout the ear canal for sinusoidal and blast waves, respectively, without any significant effect on pressure distribution pattern along the ear canal for the incident wave angle of 90° investigated in this study.     

The genetic architecture of human complex phenotypes is modulated by linkage disequilibrium and heterozygosity

We propose an extended Gaussian mixture model for the distribution of causal effects of common single nucleotide polymorphisms (SNPs) for human complex phenotypes that depends on linkage disequilibrium (LD) and heterozygosity (H), while also allowing for independent components for small and large effects. Using a precise methodology showing how genome-wide association studies (GWASs) summary statistics (z-scores) arise through LD with underlying causal SNPs, we applied the model to GWAS of multiple human phenotypes. Our findings indicated that causal effects are distributed with dependence on total LD and H, whereby SNPs with lower total LD and H are more likely to be causal with larger effects; this dependence is consistent with models of the influence of negative pressure from natural selection. Compared with the basic Gaussian mixture model it is built on, the extended model—primarily through quantification of selection pressure—reproduces with greater accuracy the empirical distributions of z-scores, thus providing better estimates of genetic quantities, such as polygenicity and heritability, that arise from the distribution of causal effects.     

Mating frequency of Apis mellifera jemenitica under desert conditions of Saudi Arabia

Queen mating frequency is an important reproductive trait of the western honeybee Apis mellifera. Yet, it demands more attention when investigated under extreme or confined ecosystems. Queen mating frequency of the Yemeni Honeybee A. m. jemenetica was estimated under Saudi Arabia desert conditions, Riyadh (24°71′36″N, 46°67′53″E). Mating of queens took place after 8–13 days from emergence. Duration of mating flight ranged between 26 and 39 min. Subsequently, six microsatellite loci were used to genotype queen's progeny (n = 30 workers/queen). The average number of drone alleles using workers genotypes ranged between 5.83 ± 0.31 and 6.33 ± 1.09. However, effective paternal allele number was extremely low and ranged between 3.35 ± 0.34 and 3.60 ± 0.40. This relatively low mating frequency of the Yemeni honeybee, A. m. jemenetica, might have striking effect on the overall colony survival. Providentially, this relatively low mating frequency does not impact colonial heterozygosity, shown in this study (0.66 ± 0.07–70 ± 0.04), adversely. These results may affect hive survivability and entails distinctive management practices under such conditions.     

低频神经和肌肉电刺激对产程、分娩方式、母婴结局的影响分析

目的:观察低频神经和肌肉刺激仪用于分娩镇痛对产程、分娩方式、产后出血、会阴完整度、母婴结局的影响。方法:随机选择2019年8月~2020年3月在我院分娩的足月妊娠产妇220名,根据第一产程是否应用低频神经和肌肉刺激仪分为观察组112例及对照组108例,两组均接受常规分娩护理,观察组为自愿接受低频神经和肌肉电刺激镇痛的产妇,比较两组患者产程时间、剖宫产、会阴侧切及裂伤、残留、新生儿结局、产后出血、产后血细胞计数。结果:对照组剖宫产率、部分胎膜残留发生率、分娩后白细胞计数均显著高于观察组(P<0.05),总产程和第一产程时间显著长高于观察组(P<0.05);两组侧切率、裂伤率、出血量、住院时长比较差异均无统计学意义(P>0.05)。两组新生儿1 min、5 min Apgar评分比较差异均无统计学意义(P>0.05)。两组分娩后血红蛋白、红细胞计数、血细胞比容和红细胞平均容量均较分娩前显著下降(P<0.05),组间比较差异无统计学意义(P>0.05)。结论:低频脉冲电刺激可有效缩短第一产程,降低残留率、剖宫产率及产后感染风险,加快子宫复旧;对第二产程、第三产程、产后出血量等无影响,且不影响围产儿结局,能够降低产后感染风险。     

高频振荡通气联合肺表面活性物质对NRDS患儿血流动力学、氧合功能及炎症因子水平的影响

目的:探讨高频振荡通气(HFOV)联合肺表面活性物质(PS)对新生儿呼吸窘迫综合征(NRDS)血流动力学、氧合功能及炎症因子水平的影响。方法:选取2016年6月~2019年4月期间我院接收的129例NRDS患儿,按照随机数字表法将患儿分为研究组(n=65)、对照组(n=64),均给予PS治疗,在此基础上,对照组患儿给予常频机械通气(CMV)治疗,研究组给予HFOV治疗,比较两组患儿疗效、血流动力学、氧合功能、炎症因子水平及并发症发生情况。结果:研究组治疗24h后的临床总有效率为89.23%(58/65),高于对照组的68.75%(44/64)(P<0.05)。两组患儿治疗24h后动脉血氧分压(PaO2)升高,且研究组高于对照组(P<0.05);心率(HR)、肺动脉压(PAP)、白介素-6(IL-6)、降钙素原(PCT)、超敏C反应蛋白(hs-CRP)、动脉二氧化碳分压(PaCO2)、氧合指数(OI)均下降,且研究组低于对照组(P<0.05)。两组并发症总发生率比较差异无统计学意义(P>0.05)。结论:HFOV联合PS治疗NRDS可有效改善患儿血流动力学、氧合功能及炎症因子水平,且不增加并发症发生率,临床应用价值较高。     

Disentangling the roles of frequency-vs. state-dependence in generating individual differences in behavioural plasticity

Theoretical work suggests that both negative frequency-dependent payoffs and state-dependent payoffs can lead to individual variation in behavioural plasticity. We investigated the roles of both frequency- and state-dependence on the occurrence of individual variation in behavioural plasticity in a series of experiments where we manipulated perceived predation danger for red knots (Calidris canutus islandica). We found individual variation in plasticity in a trait with negative frequency-dependent payoffs (vigilance), but not in a trait with positive frequency-dependent payoffs (escape flights). Furthermore, there was no correlation between the average level of vigilance under low predation danger and the magnitude of response to increased predation danger, as would be expected under state-dependence. Thus, our results provide support for the hypothesis that negative-frequency dependence favours individual variation in plasticity. However, negative-frequency dependence alone cannot explain why plasticity would be consistent within individuals, and future studies should address the factors that might favour individual consistency.     

A Geographic Mosaic of Plant–Pollinator Interactions in the Eastern Caribbean Islands

The interplay between generalized and specialized plant–animal interactions is a core concept in understanding the evolution of mutualisms. Within the Eastern Caribbean, Heliconia bihai is a dominant forest species in the southern island of St. Vincent where H. caribaea is virtually absent. Heliconia caribaea is most common on the northern island of St. Kitts where H. bihai is restricted to the tops of the highest peaks. Both species are abundant on the central island of Dominica. We compared flowering patterns, nectar characteristics, and visitation frequency of hummingbirds in the two heliconias on the three islands to determine the extent of geographic variations in this plant–pollinator mutualism. The peak flowering season of the two heliconias was observed to be in April–May on all three islands with little within‐ and between‐island variations. Nectar production significantly varied between species and between islands. Visitation patterns by the principal hummingbird pollinators also varied between the islands: (1) on Dominica, only females of a single species of hummingbird pollinated the flowers of H. bihai (sexual specialization), whereas both sexes of the same hummingbird pollinated the flowers of H. caribaea (species specialization); (2) on St. Vincent, both sexes of the same hummingbird pollinated the flowers of H. bihai (species specialization); and (3) on St. Kitts, only females pollinated the flowers of H. bihai (sexual specialization), whereas several species of hummingbird visited the flowers of H. caribaea (species generalization). We propose that the Heliconia–hummingbird interactions in the Eastern Caribbean represent a geographically variable coevolutionary mosaic of plant–pollinator interactions.     

The Characteristic Trajectory of a Fixing Allele: A Consequence of Fictitious Selection That Arises from Conditioning

This work is concerned with the historical progression, to fixation, of an allele in a finite population. This progression is characterized by the average frequency trajectory of alleles that achieve fixation before a given time, T. Under a diffusion analysis, the average trajectory, conditional on fixation by time T, is shown to be equivalent to the average trajectory in an unconditioned problem involving additional selection. We call this additional selection “fictitious selection”; it plays the role of a selective force in the unconditioned problem but does not exist in reality. It is a consequence of conditioning on fixation. The fictitious selection is frequency dependent and can be very large compared with any real selection that is acting. We derive an approximation for the characteristic trajectory of a fixing allele, when subject to real additive selection, from an unconditioned problem, where the total selection is a combination of real and fictitious selection. Trying to reproduce the characteristic trajectory from the action of additive selection, in an infinite population, can lead to estimates of the strength of the selection that deviate from the real selection by >1000% or have the opposite sign. Strong evolutionary forces may be invoked in problems where conditioning has been carried out, but these forces may largely be an outcome of the conditioning and hence may not have a real existence. The work presented here clarifies these issues and provides two useful tools for future analyses: the characteristic trajectory of a fixing allele and the force that primarily drives this, namely fictitious selection. These should prove useful in a number of areas of interest including coalescence with selection, experimental evolution, time series analyses of ancient DNA, game theory in finite populations, and the historical dynamics of selected alleles in wild populations.