An ACO Algorithm for Effective Cluster Head Selection

This paper presents an effective algorithm for selecting cluster heads in mobile ad hoc networks using ant colony optimization. A cluster in an ad hoc network consists of a cluster head and cluster members which are at one hop away from the cluster head. The cluster head allocates the resources to its cluster members. Clustering in MANET is done to reduce the communication overhead and thereby increase the network performance. A MANET can have many clusters in it. This paper presents an algorithm which is a combination of the four main clustering schemes- the ID based clustering, connectivity based, probability based and the weighted approach. An Ant colony optimization based approach is used to minimize the number of clusters in MANET. This can also be considered as a minimum dominating set problem in graph theory. The algorithm considers various parameters like the number of nodes, the transmission range etc. Experimental results show that the proposed algorithm is an effective methodology for finding out the minimum number of cluster heads.Comment: 7 pages, 5 figures, International Journal of Advances in Information Technology (JAIT); ISSN: 1798-2340; Academy Publishers, Finlan

A role of corazonin receptor in larval-pupal transition and pupariation in the oriental fruit fly Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

Corazonin (Crz) is a neuropeptide hormone, but also a neuropeptide modulator that is internally released within the CNS, and it has a widespread distribution in insects with diverse physiological functions. Here, we identified and cloned the cDNAs of Bactrocera dorsalis that encode Crz and its receptor CrzR. Mature BdCrz has 11 residues with a unique Ser11 substitution (instead of the typical Asn) and a His in the evolutionary variable position 7. The BdCrzR cDNA encodes a putative protein of 608 amino acids with 7 putative transmembrane domains, typical for the structure of G-protein-coupled receptors. When expressed in Chinese hamster ovary (CHO) cells, the BdCrzR exhibited a high sensitivity and selectivity for Crz (EC50 approximate to 52.5 nM). With qPCR, the developmental stage and tissue-specific expression profiles in B. dorsalis demonstrated that both BdCrz and BdCrzR were highly expressed in the larval stage, and BdCrzR peaked in 2-day-old 3rd-instar larvae, suggesting that the BdCrzR may play an important role in the larval-pupal transition behavior. Immunochemical localization confirmed the production of Crz in the central nervous system (CNS), specifically by a group of three neurons in the dorso-lateral protocerebrum and eight pairs of lateral neurons in the ventral nerve cord. qPCR analysis located the BdCrzR in both the CNS and epitracheal gland, containing the Inka cells. Importantly, dsRNA-BdCrzR-mediated gene-silencing caused a delay in larval-pupal transition and pupariation, and this phenomenon agreed with a delayed expression of tyrosine hydroxylase and dopa-decarboxylase genes. We speculate that CrzR-silencing blocked dopamine synthesis, resulting in the inhibition of pupariation and cuticular melanization. Finally, injection of Crz in head-ligated larvae could rescue the effects. These findings provide a new insight into the roles of Crz signaling pathway components in B. dorsalis and support an important role of CrzR in larval-pupal transition and pupariation behavior

Half Metallicity in Hybrid BCN Nanoribbons

We report a first-principles electronic-structure calculation on C and BN hybrid zigzag nanoribbons. We find that half-metallicity can arise in the hybrid nanoribbons even though stand-alone C or BN nanoribbon possesses a finite band gap. This unexpected half-metallicity in the hybrid nanos-tructures stems from a competition between the charge and spin polarizations, as well as from the pi orbital hybridization between C and BN. Our results point out a possibility of making spintronic devices solely based on nanoribbons and a new way of designing metal-free half metals

Study on Ammonia-induced Catalyst Poisoning in the Synthesis of Dimethyl Oxalate

On an industrial plant, we observed and examined the ammonia-poisoning catalyst for the synthesis of dimethyl oxalate (DMO). We investigated the catalytic activity in response to the amount of ammonia and revealed the mechanism of such poisoning by X-ray photoelectron spectroscopy (XPS) characterization. Our results show that only 0.002% ammonia in the feed gas can significantly deactivate the Pd-based catalyst. Two main reasons were proposed: one is that the competitive adsorption of ammonia on the active component Pd hinders the carbon    monoxide (CO) coupling reaction and the redox cycle between Pd0 and Pd2+; and the other is that the high-boiling nitrogen-containing amine compounds formed by reacting with ammonia have adsorbed on the catalyst, which hinders the progress of the catalytic reaction. The deactivation caused by the latter is irreversible. The catalytic activity can be completely restored by a low-temperature liquid-phase in-situ regeneration treatment. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Morphological characterization and reconstruction of fractured heat-treated glass

Fracture morphology has insightful information related to the residual effect of fractured structural glass, which is vital in assessing the post-fracture performance of glass members. This study experimentally characterized the fracture morphology of heat-treated glass and developed a novel method of morphology reconstruction, which aims to facilitate the numerical analysis of fractured structural glass. With the development of a computer-vision-based method for transparent objects, the morphology information from fragmentation tests was extracted and systematically investigated for monolithic heat-treated glass with various thicknesses, surface compressive stresses and fracture initiation locations, which are considered as the key influencing factors of heat-treated glass fracture. The geometrical features of fragments and their spatial distribution were quantitatively analysed, identifying their correlations with glass properties. The result indicates that the distribution of fragment centroids shows greater dispersion as the tempering level increases, and the fragments tend to be smaller and more rounded. The strain energy release at fracture was also assessed by fracture patterns, showing it presents high sensitivity to the glass thickness and surface compressive stress. Subsequently, a novel approach was proposed for the stochastic reconstruction of fracture morphology, combining feature points distribution and Voronoi tessellation concept. The control parameters are determined by data from the fragmentation tests and the influence of fracture load could be properly considered. The proposed method shows satisfactory outcomes and good agreement with the experimental records, which has further potential in developing refined numerical models by considering more realistic fracture morphology of glass members

Corazonin signaling is required in the male for sperm transfer in the oriental fruit fly Bactrocera dorsalis

Corazonin (Crz) is a widely distributed neuropeptide (or neurohormone) in insects with diverse physiological functions. The present study aimed to reveal the functions of Crz and its receptor (CrzR) in the regulation of sexual behavior and fertility in male Bactrocera dorsalis. Tissue-specific expression analyses showed that the BdCrz transcript was most abundant in the central nervous system (CNS), and the BdCrzR transcript was most abundant in both the fat body and CNS. Immunochemical localization confirmed that three pairs of Crz-immunoreactive neurons are located in the dorsolateral protocerebrum region of male adult brain. Importantly, RNAi-mediated Crz knockdown lengthened mating duration in males, and knockdown of Crz or CrzR strongly decreased male fertility in the following 3 days, while the courtship behavior and mating efficiency were not affected. The reduced number of sperm in the reproductive organs of mated females indicated that Crz knockdown in males reduced sperm transfer. The findings of this study indicate that Crz contributes to the reproductive physiology of the oriental fruit fly B. dorsalis by regulating sperm transfer in male adults

Analysis of failure mechanisms of adhesive joints modified by a novel additive manufacturing-assisted method

The research presented in this paper used an innovative method to modify the configuration of adhesively bonded joints for improved mechanical performance. Additive manufacturing was employed to produce sacrificial support structures with a water-soluble filament (Polyvinyl Alcohol). The design freedom offered by additive manufacturing makes it easy to tailor fixtures to any geometry, which can be used to accurately make the desired fillet shape at the end of the adhesive bond line. In addition to the experimental tests, the finite element method (FEM) was used to study the stress distribution along the bond line for four different modified bonded joints, whilst the discrete element method (DEM) was used to estimate the joint failure load and crack path in the adhesive bond line due to its strength in describing the initiation and progression of micro-cracks. The results show that the novel manufacturing method can produce an accurate fillet at the end of the bond line, regardless of the adhesive type. The mechanical performance of the joints with the modified features increased significantly. Furthermore, the failure load and crack path obtained from the DEM model is in close agreement with experimental and finite element (FE) results. Hence, the failure mechanism of the hybrid joints is then summarised

RNA-seq analysis of gene expression changes during pupariation in Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

Background: The oriental fruit fly, Bactrocera dorsalis (Hendel) has been considered to be one of the most important agricultural pest around the world. As a holometabolous insect, larvae must go through a metamorphosis process with dramatic morphological and structural changes to complete their development. To better understand the molecular mechanisms of these changes, RNA-seq of B. dorsalis from wandering stage (WS), late wandering stage (LWS) and white puparium stage (WPS) were performed. Results: In total, 11,721 transcripts were obtained, out of which 1914 genes (578 up-regulated and 1336 down-regulated) and 2047 genes (655 up-regulated and 1392 down-regulated) were found to be differentially expressed between WS and LWS, as well as between WS and WPS, respectively. Of these DEGs, 1862 and 1996 genes were successfully annotated in various databases. The analysis of RNA-seq data together with qRT-PCR validation indicated that during this transition, the genes in the oxidative phosphorylation pathway, and genes encoding P450s, serine protease inhibitor, and cuticular proteins were down-regulated, while the serine protease genes were up-regulated. Moreover, we found some 20-hydroxyecdysone (20E) biosynthesis and signaling pathway genes had a higher expression in the WS, while the genes responsible for juvenile hormone (JH) synthesis, degradation, signaling and transporter pathways were down-regulated, suggesting these genes might be involved in the process of larval pupariation in B. dorsalis. For the chitinolytic enzymes, the genes encoding chitinases (chitinase 2, chitinase 5, chitinase 8, and chitinase 10) and chitin deacetylase might play the crucial role in the degradation of insect chitin with their expressions significantly increased during the transition. Here, we also found that chitin synthase 1A might be involved in the chitin synthesis of cuticles during the metamorphosis in B. dorsalis. Conclusions: Significant changes at transcriptional level were identified during the larval pupariation of B. dorsalis. Importantly, we also obtained a vast quantity of RNA-seq data and identified metamorphosis associated genes, which would all help us to better understand the molecular mechanism of metamorphosis process in B. dorsalis

Do mutual funds have consistency in their performance?

Using a comprehensive data set of 714 Chinese mutual funds from 2004 to 2015, the study investigates these funds’ performance persistence by using the Capital Asset Pricing model, the Fama-French three-factor model and the Carhart Four-factor model. For persistence analysis, we categorize mutual funds into eight octiles based on their one year lagged performance and then observe their performance for the subsequent 12 months. We also apply Cross-Product Ratio technique to assess the performance persistence in these Chinese funds. The study finds no significant evidence of persis- tence in the performance of the mutual funds. Winner (loser) funds do not continue to be winner (loser) funds in the subsequent time period. These findings suggest that future performance of funds cannot be predicted based on their past performance.info:eu-repo/semantics/publishedVersio