Minimal Divergence Research Articles

Species diversity in the new lamprey genus Occidentis, formerly classified as western North American ‘Lampetra’

Accurate taxonomy is fundamental to the study and conservation of biodiversity. Because of their morphological similarities, most brook and river lampreys in western North America have been placed in the genus Lampetra along with lampreys from Eurasia and eastern North America. However, molecular-based phylogenetic studies dating back several decades indicate that lampreys from Pacific drainages are genetically distinct from Atlantic Lampetra. Reviewing previous phylogenetic analysis of two mitochondrial and two nuclear genes for Northern Hemisphere lampreys, we assign these western North American brook and river lampreys to a new genus, Occidentis. To assess species diversity within Occidentis, we performed a species delimitation analysis using all publicly available cytochrome b sequences of the genus. Similar to previous studies, O. ayresii and O. richardsoni were not reciprocally monophyletic and are best categorized as life history variants of a single species. In addition to O. pacifica, O. hubbsi, and the diverse O. ayresii species complex, as many as seven undescribed candidate species from Oregon and California were identified, supporting results from previous studies with more geographically limited datasets. One specimen from Paynes Creek, California, was identified as a candidate species, although this single individual showed minimal interspecific divergence (1.34%) with O. hubbsi. Further genetic assessment along with information on morphology and phylogeography is needed to determine whether the variation observed between groups of candidate species represents distinct species or divergent lineages within a species complex. Additional sampling will inform whether there are additional species not currently represented in this dataset. Thus, the number of species formally recognized under Occidentis is subject to change with new information. Systematic assessment of the distribution and phylogenetic complexity within Occidentis will enhance our understanding of its evolutionary history and taxonomic diversity, which will guide efforts to conserve the biodiversity of lampreys.

Analytical quality-by-design guided development of a novel and robust HPTLC method for quantifying plumbagin from Plumbago species

The study utilizes an analytical quality-by-design (AQbD) approach to establish a robust and efficient HPTLC method for plumbagin quantification in plumbago species. The highest-risk critical method parameters (CMP; concentration of plumbago and composition of mobile phase) and most appropriate critical analytical attributes (CAA; Peak area and retention factor [Rf]) were employed in the AQbD methodology. These CMP were tuned for higher plumbagin recovery using the central composite design (CCD) experiment. The created approach was validated by the requirements outlined in the International Conference on Harmonization (ICH) Q2 (R2). Every plate involved in the proposed method validation has been subjected to the passing requirements of the system suitability test (SST). The low LOD (16.93 ng/mL) and LOQ (49.68 ng/mL) values and the minimal divergence in intra- and inter-day studies validate the developed method’s high precision and sensitivity. Further experiments employing the proposed method to determine the amount of plumbagin from the two distinct plant sources harvested under two different climate conditions determined the highest plumbagin content in P. indica, which is in line with the results. To summarize, the AQbD method may be used in other plant systems to optimize various factors and get a greater concentration of the desired plant metabolite.

Spatial filtering and optimal generation of high-flux soft x-ray high harmonics using a Bessel–Gauss beam

In recent years, significant advancements in high-repetition-rate, high-average-power mid-infrared laser pulses have enabled the generation of tabletop high-flux coherent soft x-ray harmonics for photon-hungry experiments. However, for practical applications, it is crucial to effectively filter out the driving beam from the high harmonics. In this study, we leverage the distinctive properties of a Bessel–Gauss (BG) beam to introduce a novel approach for spatial filtering, specifically targeting soft x-ray harmonics, releasing with a high-photon flux simultaneously. Our simulations reveal that by finely adjusting the focus geometry and gas pressure, the BG beam naturally adopts an annular shape, emitting high harmonics with minimal divergence in the far field. To achieve complete spatial separation of the driving beam and harmonic emissions, we pinpoint the optimal gas pressure and focusing geometry, particularly under overdriven laser intensities, for achieving good phase matching of harmonic emissions from short-trajectory electrons within the gas medium when the exact ionization level is higher than the “critical” value. Additionally, we establish scaling relations for sustaining optimal phase-matching conditions crucial for spatially separating the driving laser and the high-harmonic field, especially as the wavelength of the driving laser increases. Furthermore, our analysis demonstrates a substantial enhancement of harmonic yields by at least one order of magnitude compared to a truncated Gaussian annular beam. We also show that under accessible experimental conditions, soft x-ray photon flux up to 1010 photons/s at 250 eV can be achieved. The utilization of the BG beam opens up a promising pathway for the development of high-flux attosecond soft x-ray light sources, poised to serve a wide range of applications.

Influence of geographic isolation and the environment on gene flow among phenotypically diverse lizards

Lizards in the genus Anolis comprise hundreds of species that display a wide range of phenotypic variation closely related to their environment. One example is the Guadeloupean anole (Anolis marmoratus ssp.) that display extreme phenotypic variation, primarily in adult male color and pattern, with twelve described subspecies on the archipelago. Here we examine the relationship between phenotypic and genetic divergence among five subspecies on the two main islands and test the role of geographic isolation and the environment in reducing gene flow. We also examined two offshore island populations to assess the impact of complete geographic isolation on gene flow. We analyzed color phenotypes by measuring spectral reflectance and genomic diversity using SNPs. Genetic divergence was correlated with dorsolateral head and body color phenotypes, and slope and geographic distance were nearly equivalent at explaining this divergence. There was minimal genome-wide divergence at neutral loci among phenotypically disparate subspecies on the two main islands and their differentiation is consistent with a model of divergence with gene flow. Our spatial visualization of gene flow showed an impact of environmental features consistent with a hypothesis of ecologically driven divergence. Nonetheless, subspecies on the two main islands remain interconnected by substantial gene flow and their phenotypic variation is likely maintained at selection-gene flow equilibrium by divergent selection at loci associated with their color phenotypes. Greater isolation, such as inhabiting a remote island, may be required for reducing gene flow. Our findings highlight the role of the environment, adaptation, and geographic isolation on gene flow.

Marine catfishes (Ariidae-Siluriformes) from the Coastal Amazon: mitochondrial DNA barcode for a recent diversification group?

Ariidae species play a significant role as fishing resources in the Amazon region. However, the family's systematic classification is notably challenging, particularly regarding species delimitation within certain genera. This difficulty arises from pronounced morphological similarities among species, posing obstacles to accurate species recognition. Following morphological identification, mitochondrial markers (COI and Cytb) were employed to assess the diversity of Ariidae species in the Amazon. Our sampling efforts yielded 12 species, representing 92% of the coastal Amazon region's diversity. Morphological identification findings were largely corroborated by molecular data, particularly for species within the Sciades and Bagre genera. Nonetheless, despite morphological support, Cathorops agassizii and Cathorops spixii displayed minimal genetic divergence (0.010). Similarly, Notarius quadriscutis and Notarius phrygiatus formed a single clade with no genetic divergence, indicating mitochondrial introgression. For the majority of taxa examined, both COI and Cytb demonstrated efficacy as DNA barcodes, with Cytb exhibiting greater polymorphism and resolution. Consequently, the molecular tools utilized proved highly effective for species discrimination and identification.

Limited sensitivity of Antarctic GIA mass change estimates to lateral viscosity variations

The Gravity Recovery and Climate Experiment (GRACE) has revealed spatiotemporal mass changes in the Antarctic Ice Sheet. However, GRACE data must be corrected for the gravity changes due to glacial isostatic adjustment (GIA). Here we investigate the sensitivity of GIA-induced gravity changes in Antarctica to the lithospheric thickness and upper mantle viscosity using a one-dimensional (1-D) model that assumes a radially varying Earth structure. The sensitivity is assessed using several Antarctic ice-history models that have been widely used to correct GRACE data. The results indicate a trade-off between lithospheric thickness and upper mantle viscosity in evaluating the Antarctic GIA correction. This trade-off exists for all ice-history models; however, the reason for the trade-off differs among models. Furthermore, since there is a sharp contrast in the Earth structure between West and East Antarctica, the adopted ice histories are separated into West and East Antarctic components to examine their contributions to the Antarctic GIA correction. We consider 1-D Earth structures that are averaged from the seismically derived three-dimensional Earth structure for West and East Antarctica. These results indicate that the contributions of the East and West Antarctic loads do not significantly affect the GIA corrections for the West and East Antarctic regions, respectively, and that the trade-off between lithospheric thickness and upper mantle viscosity results in minimal divergence in the assessment of the Antarctic GIA correction between the averaged Earth models of West and East Antarctica. Therefore, the contrast in Earth structure beneath Antarctica may have a limited effect on the ice-mass change estimates for the entire Antarctic Ice Sheet.

Synthesis, anticancer, α-glucosidase inhibition, molecular docking and dynamics studies of hydrazone-Schiff bases bearing polyhydroquinoline scaffold: In vitro and in silico approaches

A series of hydrazone-Schiff base derivatives of polyhydroquinoline (PHQ) nucleus have been synthesized, structurally deduced by NMR (13C- and 1H-) and HR-ESI-MS spectroscopic methods and finally subjected for anti-cancer and α-glucosidase inhibitory activities. The MTT assay's results exposed that these eight compounds (2j, 2u, 2t, 2w, 2s, 2r, 2x, and 2d) presented notable activity against breast cancer MDA-MB-231 cells having IC50 in the range of 11.4 ± 0.2 to 15.1 ± 0.4 µM, while the remaining fourteen compounds displayed significant to good anti-breast cancer activity. In case of α-glucosidase inhibition, eight compounds (2n, 2j, 2e, 2o, 2w, 2q, 2v, and 2l) exhibited superior inhibition against α-glucosidase enzyme with IC50 values ranging from 8.72 ± 0.14 to 16.16 ± 0.17 µM, compare with the standard acarbose. Additionally, the remaining eighteen derivatives showed significant to least inhibitory activity. The in silico docking, and molecular dynamic displayed the minimal divergence in MM-PBSA values for 2n, 2j, 2e, and 2o which suggests a strong and stable interaction with the protein's amino acid backbone. Pharmacokinetic profiles and anti-glucosidase ability suggested them as potential drug candidates for further studies.

DIPG-61. ARGININE DEPRIVATION USING ADI-PEG20 IMPROVES SURVIVAL IN A SYNGENEIC DIFFUSE MIDLINE GLIOMA MOUSE MODEL

Abstract BACKGROUND Diffuse midline glioma (DMG-H3K27) presents a significant challenge in paediatric oncology, with a <10% two-year survival rate despite standard palliative radiotherapy. Tumour infiltration behind the blood-brain barrier hampers drug delivery, contributing to clinical trial failures. ADI-PEG20 exploits tumour metabolic vulnerabilities: lack of argininosuccinate synthetase and reliability on extracellular arginine for proliferation. This study investigates ADI-PEG20’s efficacy in a syngeneic DMG mouse model. METHODS Twenty C57BL/6J mice were intracranially injected with a DMG cell line (H1H3BK27M, DNp53, PDGFRAD642V, Acvr1G328V) and monitored via bioluminescence imaging from day 7. Weekly treatments began on day 10, comprising ADI-PEG20 (5 I.U.) alone, ADI-PEG20 with concurrent radiation (2 Gy), radiation alone, or saline (0.9%), with each group comprising n=5. Radiation was administered 24 hours post-drug treatment. Bioluminescence imaging was conducted twice weekly, with mice culled upon symptom onset. Immunohistochemistry was performed on brain tissue. RESULTS The combination and ADI-PEG20 monotherapy cohorts exhibited comparable median survival rates, both surpassing those of the radiation-only and saline groups, with the latter exhibiting the lowest median survival. A significant disparity in survival curves was observed overall (p<0.0001), confirmed by log-rank (Mantel-Cox) test. Pairwise comparisons revealed significant differences in survival curves between the combination and radiation-only (p=0.0066), ADI-PEG20 monotherapy and radiation-only (p=0.0018), and ADI-PEG20 monotherapy and saline (p=0.0062) groups. Minimal divergence in IVIS signal intensity was noted across groups. Histological examination via H&E staining demonstrated marked tumour regression in mice treated with ADI-PEG20 ± radiation, contrasting with the persistent tumour mass evident in the radiation-only and saline cohorts, alongside discernible heterogeneity in cellular phenotypes within the ADI-PEG20 ± groups. CONCLUSIONS In conclusion, ADI-PEG20 shows promise as a therapeutic strategy for DMG, offering a significant survival advantage over radiation and saline. Ongoing efforts will elucidate its mechanistic underpinnings, explore its efficacy across diverse DMG models, and assess synergistic interactions with immune-based therapies.

Seed physiological traits and environmental factors influence seedling establishment of vegetable soybean (Glycine max L.).

Edamame (Glycine max (L.) Merr.), a specialty soybean prized for its nutritional value and taste, has witnessed a surge in demand within the U.S. However, subpar seedling stands have hindered its production potential, necessitating increased inputs for farmers. This study aims to uncover potential physiological factors contributing to low seedling emergence in edamame. We conducted comprehensive assessments on thirteen prominent edamame genotypes alongside two food-grade and two grain-type soybean genotypes, focusing on germination and emergence speed in both laboratory and field settings. Additionally, we employed single electrical conductivity tests and identified and quantified seed leachate components to distinguish among soybean types. Furthermore, using a LabField™ simulation table, we examined seed emergence across a wide soil temperature range (5°C to 45°C) for edamame and other soybean types. All seeds were produced under the same environmental conditions, harvested in Fall 2020, and stored under uniform conditions to minimize quality variations. Our findings revealed minimal divergence in emergence percentages among the seventeen genotypes, with over 95% germination and emergence in laboratory conditions and over 70% emergence in the field. Nonetheless, edamame genotypes typically exhibited slower germination speeds and higher leachate exudates containing higher soluble sugars and amino acids. Seed size did not significantly impact total emergence but was negatively correlated with germination and emergence speed, although this effect could be mitigated under complex field conditions. Furthermore, this study proposed differences that distinguish edamame from other soybean types regarding ideal and base temperatures, as well as thermal time. The finds offer valuable insights into edamame establishment, potentially paving the way for supporting local edamame production in the U.S.

Rayleigh length extension in long-distance free-space optical communications based on lens group optimization

In the field of high-speed data transmission, wireless optical communications provide a paradigm shift from the conventional tethered connections, offering promising bandwidth and minimal latency. The cornerstone of such systems lies in their ability to precisely control the propagation of Gaussian beams, which are favored due to their inherent properties of minimal divergence and high spatial coherence over long distances. Efficient transmission hinges on the proper manipulation of these beams’ spatial characteristics, particularly the waist radius and the associated Rayleigh length, which together delineate the beam’s diffraction and spread. This manuscript methodically explores the theoretical and practical aspects of Gaussian beam focusing through lens systems, aiming to elucidate the pivotal relationship between the optimally adjusted focal parameters and the resultant augmentation of the Rayleigh length. Through rigorous diffraction integral simulations and a keen analysis of constraints posed by finite apertures, the study articulates strategies to considerably enhance the Gaussian beam’s propagation characteristics, thereby bolstering the reliability and efficacy of wireless optical communication systems.

An novel SDA-CNN few shot domain adaptation framework for silent speech recognition

In BCI (brain-computer interface) applications, it is difficult to obtain enough well-labeled EEG data because of the expensive annotation and time-consuming data capture procedure. Conventional classification techniques that repurpose EEG data across domains and subjects lead to significant decreases in silent speech recognition classification accuracy. This research provides a supervised domain adaptation using Convolutional Neural Network framework (SDA-CNN) to tackle this problem. The objective is to provide a solution for the distribution divergence issue in the categorization of speech recognition across domains. The suggested framework involves taking raw EEG data and deriving deep features from it and the proposed feature selection method also retrieves the statistical features from the corresponding channels. Moreover, it attempts to minimize the distribution divergence caused by variations in people and settings by aligning the correlation of both the source and destination EEG characteristic dissemination. In order to obtain minimal feature distribution divergence and discriminative classification performance, the last stage entails simultaneously optimizing the loss of classification and adaption loss. The usefulness of the suggested strategy in reducing distributed divergence among the source and target Electroencephalography (EEG) data is demonstrated by extensive experiments carried out on KaraOne datasets. The suggested method achieves an average accuracy for classification of 87.4% for single-subject classification and a noteworthy average class accuracy of 88.6% for cross-subject situations, which shows that it surpasses existing cutting-edge techniques in thinking tasks. Regarding the speaking task, the model’s median classification accuracy for single-subject categorization is 86.8%, while its average classification accuracy for cross-subject classification is 87.8%. These results underscore the innovative approach of SDA-CNN to mitigating distribution discrepancies while optimizing classification performance, offering a promising avenue to enhance accuracy and adaptability in brain-computer interface applications.

The Axes of Divergence for the Evolutionary Radiation of Notothenioid Fishes in Antarctica

Notothenioid fishes, a perciform group, radiated in the cold shelf waters around the Antarctic continent and the 110 species dominate fish diversity, abundance, and biomass at levels of ≈77%, 92%, and 91%, respectively. This occurred in a locality with frequent glaciomarine cycles that fragmented and obliterated habitats, disrupted ecosystems, and made parts of the high latitude shelves periodically uninhabitable. The notothenioid radiation encompasses three stages and 10 axes: for the habitat stage, divergence in (1) depth and (2) biotope, meaning subdivisions within the pelagic and benthic realms; for the morphology stage, divergence in (3) body size, (4) body density based on proportions of skeletal and adipose tissues, (5) body shape, (6) trophic morphology, specifically head morphology related to feeding (jaws, teeth, head size, and pharyngeal gape), and (7) neuromorphology (brain and sensory systems); and for the communication stage, divergence in (8) fecundity and egg size, (9) sexual dichromatism and dimorphism in body and fins, and (10) parental care behavior associated with nesting. There was an antecedent Eocene fossil fauna that did not include notothenioids and that has minimal taxonomic representation in the modern fauna. Liparids (snailfishes) and zoarcids (eelpouts) also diversified in Antarctic waters but with minimal divergence. Hypotheses are offered as to why these radiations played out the way they did and why notothenioids are dominant.

Factors influencing the shape, size, symmetry and scar of the nipple-areola complex after bilateral reduction mammoplasty.

Asymmetry and scar formation of the nipple-areola complex (NAC) after reduction mammoplasty with periareolar suture are common complications and can significantly affect patient satisfaction. The aim of this study was to investigate possible procedure-specific influencing factors on asymmetry and shape disturbances of the nipple-areola complex to optimize postoperative outcome and thus improve patient satisfaction. 78 patients were followed-up after a 5-year period as part of a retrospective cohort study. Objective parameters as areolar diameter, symmetry, scar patterns, dimensions of the breast, and anthropometric measurements were recorded. All patients underwent surgery according to an established treatment algorithm depending on the preoperative measurements. Follow up was 1 week, 6 week, 6 months and 3 years postoperatively. The periareolar suture-technique significantly influenced the symmetry and shape of the NAC. Compared to the intraoperative determined diameter and the postoperative diameter, the net-suture technique showed the highest NAC symmetry and minimal divergence. Patients who underwent Hall-Findlay mammoplasty showed significantly higher rates of asymmetry and deformity of the NAC with teardrop formation in comparison to Lejour mammoplasty. Scar formation was affected by periareolar ruffle formation especially after purse string suture. Regardless of what reduction mammoplasty techniques and periareolar suturing-technique are used, a tension-free suture of the NAC is crucial for shape, symmetry and scar formation. The net suture technique resulted in significantly higher symmetry of the NAC.

A Thin‐Layer, Li+ Compensation, Moisture‐Tolerant Interfacial Modification of Cu Substrate Toward the Anode‐Less, Energy/Power Dense Li Metallic Batteries

AbstractThe unregulated metallic deposition and continuous cracking of the fragile solid electrolyte interphase are considered the critical barriers that compromise the cyclability of lithium metal batteries (LMB), especially under low N/P ratio (<3) pairing modes. Herein, an ultra‐thin (5 µm), lightweight (0.25 mg cm−2), and moisture‐proof interfacial layer composed of the high‐entropy alloys (denoted as HEAs) and interweaved carbon nanotubes (CNTs) scaffold is constructed to modify the current collector, moreover, the thermally‐induced Li22Si5 alloy blended with the hydrophobic ethylene‐vinyl acetate copolymer (EVA) is infiltrated into the scaffold pores as the moisture‐proof cation reservoir. The HEA@CNT/Li22Si5@EVA interfacial layer not only maximizes the Li‐utilization degree with minimal voltage divergence in symmetric cells but also compensates for irreversible Li depletion in the pouch‐format anode‐less models. As the HEA@CNT/Li22Si5@EVA‐Cu substrate paired with the LiNi0.8Mn0.1Co0.1O2 cathode in a 200 mAh prototype, the phase evolution of oxide cathode and efficient Li utilization at the anode substrate can be real‐time monitored by the transmission‐mode operando X‐ray diffraction. This interfacial layer strategy affords multifunctionality to enable the LMB prototyping without excessive Li abuse. Consequently, cycling endurance and the balanced energy densities (420.1 Wh kg−1) are obtained on the whole cell.

Antireflective vertical-cavity surface-emitting laser for LiDAR

Multijunction vertical-cavity surface-emitting lasers (VCSELs) have gained popularity in automotive LiDARs, yet achieving a divergence of less than 16° (D86) is difficult for conventional extended cavity designs due to multiple-longitudinal-mode lasing. Our innovation, the antireflective vertical-cavity surface-emitting laser (AR-VCSEL), addresses this challenge by introducing an antireflective light reservoir, where the electric field intensity is substantially higher than the gain region. This reduces the required cavity length for minimal divergence, preserving the single-longitudinal-mode lasing. A 6-junction AR-VCSEL array showcases a halved divergence and tripled brightness compared to its conventional counterpart. Various multijunction AR-VCSEL array designs achieve a divergence range of 8° to 16° (D86). Notably, a 7 μm AR-VCSEL emitter achieves 28.4 mW in single transverse mode lasing. AR-VCSEL stands out among semiconductor lasers, offering a well-balanced power density and brightness, making it a cost-effective solution for long-distance LiDARs. The antireflective cavity concept may inspire diverse applications in photonic devices beyond LiDARs.

Wood-loving magic mushrooms from Australia are saprotrophic invaders in the Northern Hemisphere

Magic mushrooms are fungi that produce psilocybin, an entheogen with long-term cultural use and a breakthrough compound for treatment of mental health disorders. Fungal populations separated by geography are candidates for allopatric speciation, yet species connectivity typically persists because there is minimal divergence at functional parts of mating compatibility genes. We studied whether connectivity is maintained across populations of awidespread species complex of magic mushrooms that has infiltrated the Northern Hemisphere from a hypothesised centre of origin in Australasia. We analysed 89 genomes of magic mushrooms to examine erosion of species connectivity in disparate populations with support from gene flow, kinship, structure, allelic diversity, and mating compatibility. We used comparative genomics and synteny to test whether the genes that produce psilocybin are under selectionin natural populations of magic mushrooms. Despite phenotypic plasticity and intercontinental distribution, sexualcompatibility is maintained across geographically isolated populations of magic mushrooms. Psilocybin loci have high allelic diversity and evidence of balancing selection. Australasia is the centre of origin of wood-degrading magic mushrooms and geographically separated populations are fully sexuall compatible, despite minimal gene flow since differentiation from a shared ancestor. Movement of woodchips, mulch, or plants has most likely facilitated invasion of these mushrooms in the Northern Hemisphere.

A lack of genetic diversity and minimal adaptive evolutionary divergence in introduced Mysis shrimp after 50 years.

The successes of introduced populations in novel habitats often provide powerful examples of evolution and adaptation. In the 1950s, opossum shrimp (Mysis diluviana) individuals from Clearwater Lake in Minnesota, USA were transported and introduced to Twin Lakes in Colorado, USA by fisheries managers to supplement food sources for trout. Mysis were subsequently introduced from Twin Lakes into numerous lakes throughout Colorado. Because managers kept detailed records of the timing of the introductions, we had the opportunity to test for evolutionary divergence within a known time interval. Here, we used reduced representation genomic data to investigate patterns of genetic diversity, test for genetic divergence between populations, and for evidence of adaptive evolution within the introduced populations in Colorado. We found very low levels of genetic diversity across all populations, with evidence for some genetic divergence between the Minnesota source population and the introduced populations in Colorado. There was little differentiation among the Colorado populations, consistent with the known provenance of a single founding population, with the exception of the population from Gross Reservoir, Colorado. Demographic modeling suggests that at least one undocumented introduction from an unknown source population hybridized with the population in Gross Reservoir. Despite the overall low genetic diversity we observed, F ST outlier and environmental association analyses identified multiple loci exhibiting signatures of selection and adaptive variation related to elevation and lake depth. The success of introduced species is thought to be limited by genetic variation, but our results imply that populations with limited genetic variation can become established in a wide range of novel environments. From an applied perspective, the observed patterns of divergence between populations suggest that genetic analysis can be a useful forensic tool to determine likely sources of invasive species.

Diversity and composition of the bacterial communities associated with the Australian spittlebugs Bathyllus albicinctus and Philagra parva (Hemiptera: Aphrophoridae).

Spittlebugs and froghoppers (Hemiptera: Cercopoidea) are insects feeding on xylem, which potentially can cause significant economic damage worldwide by transmitting plant pathogenic bacteria such as Xylella fastidiosa. Australia and New Zealand are currently free from X. fastidiosa, but they are home to at least 45 native spittlebug species. Among these, the Australian natives Bathyllus albicinctus (Erichson, 1842) and Philagra parva (Donovan, 1805) are particularly widespread and can be found across southern and eastern Australia, with B. albicinctus also in New Zealand. The potential that both species might be capable of vectoring Xylella fastidiosa poses a substantial biosecurity risk if the bacterium were to invade these regions. In this study, we examined 87 spittlebug nymphs collected across 12 different host plant species, in five locations in Victoria, Australia. Our objective was to explore the factors influencing bacterial communities within and between these widespread spittlebug species, considering geographic location, insect phylogenetics, and host plant associations. We employed COI barcoding to assess insect genetic variation and 16S high throughput sequencing (HTS) metabarcoding to analyse bacterial microbiome diversity across various host plants. Our findings revealed minimal genetic divergence among spittlebug individuals in the same species, highlighting conspecificity despite conspicuous morphological divergences. On the other hand, we recorded significant variation in bacterial communities harboured by Bathyllus albicinctus nymphs feeding on different plants, even when these were collected within close proximity to each other. Therefore, host plant association appeared to shape the bacterial communities of spittlebugs more than insect genetic divergence or geographical location. These diverse bacterial communities could potentially facilitate transmission of plant pathogenic bacteria, underscoring the risk of widespread transmission among numerous plant hosts through insect-plant interactions. This study emphasizes the critical need to understand these complex interactions, particularly in the context of biosecurity.

An improved peridynamic approach for fatigue analysis of two dimensional functionally graded materials

This study investigates the fatigue behavior of functionally graded materials (FGMs) within an enhanced peridynamic (PD) framework that eliminates the need for surface and volume correction factors. FGMs offer mechanical advantages by varying material compositions and properties in one or more directions. The distribution of mechanical properties in FGMs is achieved by employing a power law. Comparative analysis is conducted between the PD predictions for reaction forces and outcomes obtained from the reference solutions for a quasi-static problem. Minimal divergence is observed between the PD and reference solutions, affirming the accuracy of the present PD formulation. Furthermore, the PD fatigue results for a Mode I Compact Tension (CT) specimen problem match the experimental findings. An experimental stop-hole problem is used to evaluate the accuracy of the PD fatigue code in mixed-mode circumstances. The load cycle determination is achieved via ABAQUS Computational Finite Element Method (CFEM) for the mixed mode problem. There is a good correlation between CFEM and the present PD outcomes. Furthermore, the effect of stop-hole existence on fatigue life in mixed mode is examined, revealing a significant retardation effect. Notably, this study adds a novel perspective by using the PD approach to investigate the fatigue analysis of FGMs and examine the impact of the stop hole on fatigue life- a component previously unexplored in the existing literature.

Improvement of the method of calculation of pressure of combine harvester propulsion on soil

BACKGROUND: Currently there is no simple and reliable algorithm of assessment of pressure on soil for the harvesters presented on the market. Therefore, analysis of the methods presented in active standards and used in calculation of pressure of propulsion on soil as well as development of the simplified and acceptable for manufacturing specialists method are relevant.
 AIMS: Simplification of assessment of force action to wheels and soil during the operation cycle from the beginning and until the end of combine harvester tanker filling.
 METHODS: The method of assessment of values of combine harvester wheel pressure on soil during the tanker filling operation cycle that allows exclusion of weighing of a harvester with a filled tanker is proposed.
 RESULTS: As the result of studies, the complex of sequential actions of determining of load of machinery propulsion on soil, including determining of weight and center of mass coordinates for the grain inside tanker with the following determining of wheel normal forces caused by summarized load action of grain and a harvester (with an empty tanker) considering location of their centers of mass, was justified.
 CONCLUSIONS: The new method application makes it possible to define maximal wheel pressure on soil with the filled tanker as well as the range of this indicators values from the beginning and until the end of tanker filling with grain. In this case, weighing of a harvester with a filled tanker at the special area with hard surface including the procedures of grain loading, unloading and weighing, is excluded. As a result, the ability of quick comparison of combine harvesters with the criterion of level of impact on soil in respect to tanker filling operational cycle beginning and end is ensured, which is the study subject. Thus, in order to solve the given task, it suffices to use the weighing results of harvesting machinery with an empty tanker, available in open sources, followed by calculation according to the proposed algorithm. Minimal divergence (less than 2%) of calculated and measured with use of platform scales values of maximal wheel pressure on soil is found.