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It is often required to avoid a specified natural frequency band when designing a structure in order to prevent vibration resonance under external excitations. However, the total number and the orders of free vibration modes falling within the forbidden frequency band are not known a priori and constantly change during the course of optimization iterations. Moreover, the mode switching issue also makes mode tracking a difficult task. Thus, it is not always realistic to fulfill the forbidden band requirement by restricting pre-specified orders of natural frequencies to be higher or lower than the forbidden band. In this paper, we propose a new form of constraint to keep the natural frequencies from falling within a given band. This constraint has a unified expression, which facilitates the design sensitivity analysis. Though this constraint form is also applicable for other types of structural design problems with forbidden frequency band constraints, we demonstrate its efficacy in topology optimization, in which imposing such constraints otherwise becomes even more challenging due to topological evolutions of the structural configuration during the optimization process. The velocity field level set method is used for formulating and solving such dynamic topology optimization problems. The design sensitivity analysis of the constraint is derived, for the cases of both distinct and repeated eigenfrequencies. Several numerical examples in 2D and 3D design domains are presented to illustrate effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Topology optimization of transient dynamics is of great importance in engineering. However, the computational cost required by the repeated dynamic response and design sensitivity analysis during design iterations is often extremely high for large-scale problems, which significantly limits its practical application. To address this issue, we propose a new method based on successive iteration of analysis and design in conjunction with a quasi-static response-enhanced mode displacement method. The conventional mode displacement method requires an inner-loop iteration in addition to the outer-loop design updating, for finding the eigenmodes of the undamped system. In order to avoid the high computational burden caused by the nested double-loop solution, we employ the concept of successive iteration of analysis and design, which integrates approximate eigenvalue analysis and design variable updating into a single iteration loop. By this means, the eigenmodes are sequentially improved through a one-step inverse iteration in each design iteration, and simultaneous convergence of the eigenmodes and the design is sought during the optimization process. These approximate eigenmodes and the quasi-static response are used as the model reduction basis for each intermediate design, and the direct time integration of the reduced-dimensional system is then performed to calculate the structural responses of interest and their derivatives with respect to the design variables. Several numerical examples are presented to demonstrate the efficiency of the proposed method. It is shown that the method can be used to solve transient dynamic topology optimization problems up to 15 million degrees of freedom on a desktop computer at affordable time cost. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of glutamine supplementation on nutrient digestibility, immunity, digestive enzyme activity, gut bacterial community and fermentation of growth-retarded yaks. A total of 16 growth-retarded yaks were randomly allocated to two groups: negative control (GRY) and glutamine supplementation group (GLN). Another eight growth-normal yaks were used as a positive control (GNY). Compared with GRY group, the crude protein digestibility was higher in GLN and GNY animals and the neutral detergent fiber digestibility was increased in GLN yaks. The concentrations of serum IgA, IgG, IgM and IL-10, as well as butyrate concentration and cellulase activity in the rumen and cecum were higher in GLN yaks compared to those in GRY animals. Supplementation with glutamine enhanced the chymotrypsin activity and increased the relative abundances of unclassified Peptostreptococcaceae and Romboutsia while decreased the relative abundances of unclassified Chitinophagaceae and Bacteroides in the jejunum and ileum of growth-retarded yaks. In the cecum, the relative abundance of unclassified Muribaculaceae was higher in GLN group than that in GRY group. The findings in this study suggest that the improved nutrient digestibility and immunity of growth-retarded yaks with glutamine supplementation may be through its potential impact on the lower gut host and microbial functions. [ABSTRACT FROM AUTHOR]

Topology optimization has become a useful tool for designing Phononic Crystals (PnCs) to achieve desired elastic wave propagation properties. However, topological design of three-dimensional (3D) PnCs remains a significant challenge due to extremely high computational cost required for the repeated solution of the nested double-loop problem of design optimization and eigenvalue analysis to determine the band structure during the optimization iteration process. This paper presents a more efficient topology optimization method based on the concept of successive iteration of analysis and design. The method employs a sequential approximation of the eigenpairs through an inverse iteration-like procedure to avoid solving the expensive eigenvalue problems in each design iteration. To further improve the efficiency of the design iteration, the eigenmodes of the intermediate PnCs designs are first computed on a relatively coarse finite element mesh. Then they are mapped onto the fine mesh and used as the initial trial eigenmodes in the eigenpair analysis and design sensitivity analysis. The high efficiency of the proposed method, as compared with conventional nested double-loop optimization approaches, is demonstrated by 3D numerical examples with over one million degrees of freedom. It is shown that this approach can achieve simultaneous convergence of the eigenvectors along with the design evolution of the unit cell, therefore substantially reduces the computational burden for high-resolution topological design of 3D PnCs. [ABSTRACT FROM AUTHOR]

Investigation of the compositional and functional characteristics of the gastrointestinal bacterial community in beef cattle breeds can improve our understanding of the influence of gastrointestinal tract (GIT) regions and host breeds on the bacterial community. In this study, 16S ribosomal RNA (16S rRNA) gene amplicon sequencing was used to characterize the bacterial communities in the rumen, duodenum, jejunum, ileum, caecum, and colon of Xuanhan yellow cattle (XHC) and Simmental crossbred cattle (SXC). The results showed that the diversity of the bacterial population was different in GIT regions of XHC and SXC (P < 0.05). In total, ten bacterial phyla, sixteen bacterial genera, and nine metabolic pathways were identified in the core bacteria. The phyla Firmicutes, Bacteroidetes, and Proteobacteria were predominant, but their proportions were different in GIT regions (P < 0.05). The diversity, structure, and composition of the bacteria in the rumen were similar between the breeds (P > 0.05), and the indices in the intestine showed significant differences (P < 0.05). Moreover, the composition and structure of the bacterial communities in the rumen, small intestine, and large intestine were different regardless of the breed. Thus, the bacterial communities were different among the gastrointestinal regions in each breed, and the bacterial community in the rumen had more stable characteristics than that in the intestine between two breeds. Further studies may focus on the minor microbial communities and the functions of GIT bacteria to better understand gut–microbe interactions. Key points: •Differences in bacteria among gastrointestinal regions differ in cattle breeds. • Differences between the breeds in the ruminal bacteria are less pronounced than differences in the intestinal bacteria. [ABSTRACT FROM AUTHOR]

Abstract In these years, many works have been done on the combustion performance and flow structure of a trapped vortex combustor (TVC). However, to the best of our knowledge, little works have been done so far to unravel the effect of combination of various factors on cavity flow structure. In this study, a TVC has been studied to understand the effects of the angle and location of primary injection on the cavity flow structure with both experimental and numerical methods. The results indicate that the computational results match well with the experimental results. Two different flow structures have been found out with different combinations of θ and H , which are termed as "broken" and "closed". Besides, when the distance between the primary injection and the bottom wall of the cavity (H) increases and the inlet angle of the primary injection (θ) is kept constant, the flow structure will be "broken". If θ increases at this moment, the flow structure changes from "broken" to "closed". The results are helpful for providing a good deal of insight into the flow structure and flow field organization of TVC. [ABSTRACT FROM AUTHOR]

We experimentally demonstrate 6.4 Tb/s wavelength division multiplexed (WDM) direct-detection transmission based on Nyquist twin-SSB modulation over 25 km SSMF with bit error rates (BERs) below the 20% hard-decision forward error correction (HD-FEC) threshold of 1.5 × 10 −2 . The two sidebands of each channel are separately detected using Kramers–Kronig receiver without MIMO equalization. We also carry out numerical simulations to evaluate the system robustness against I/Q amplitude imbalance, I/Q phase deviation and the extinction ratio of modulator, respectively. Furthermore, we show in simulation that the requirement of steep edge optical filter can be relaxed if multi-input–multi-output (MIMO) equalization between the two sidebands is used. [ABSTRACT FROM AUTHOR]

Metabolic balance is essential for oocyte maturation and acquisition of developmental capacity. Suboptimal conditions of in vitro cultures would lead to lipid accumulation and finally result in disrupted oocyte metabolism. However, the effect and mechanism underlying lipid catabolism in oocyte development remain elusive currently. In the present study, we observed enhanced developmental capacity in Procyanidin B2 (PCB2) treated oocytes during in vitro maturation. Meanwhile, reduced oxidative stress and declined apoptosis were found in oocytes after PCB2 treatment. Further studies confirmed that oocytes treated with PCB2 preferred to lipids catabolism, leading to a notable decrease in lipid accumulation. Subsequent analyses revealed that mitochondrial uncoupling was involved in lipid catabolism, and suppression of uncoupling protein 1 (UCP1) would abrogate the elevated lipid consumption mediated by PCB2. Notably, we identified peroxisome proliferator‐activated receptor gamma (PPARγ) as a potential target of PCB2 by docking analysis. Subsequent mechanistic studies revealed that PCB2 improved oocyte development capacity and attenuated oxidative stress by activating PPARγ mediated mitochondrial uncoupling. Our findings identify that PCB2 intricately improves oocyte development capacity through targeted activation of the PPARγ/UCP1 pathway, fostering uncoupling lipid catabolism while concurrently mitigating oxidative stress. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance in the laying hen production industry has become a serious public health problem. The antimicrobial resistance and phylogenetic relationships of the common conditional pathogen Enterococcus along the laying hen production chain have not been systematically clarified. 105 Enterococcus isolates were obtained from 115 environmental samples (air, dust, feces, flies, sewage, and soil) collected along the laying hen production chain (breeding chicken, chick, young chicken, and commercial laying hen). These Enterococcus isolates exhibited resistance to some clinically relevant antibiotics, such as tetracycline (92.4%), streptomycin (92.4%), and erythromycin (91.4%), and all strains had multidrug resistance phenotypes. Whole genome sequencing characterized 29 acquired antibiotic resistance genes (ARGs) that conferred resistance to 11 classes of antibiotics in 51 pleuromutilin-resistant Enterococcus isolates, and lsa(E) , which mediates resistance to pleuromutilins, always co-occurred with lnu(B). Alignments with the Mobile Genetic Elements database identified four transposons (Tn554, Tn558, Tn6261, and Tn6674) with several ARGs (erm(A), ant(9)-la, fex(A) , and optrA) that mediated resistance to many clinically important antibiotics. Moreover, we identified two new transposons that carried ARGs in the Tn554 family designated as Tn7508 and Tn7492. A complementary approach based on conventional multi-locus sequence typing and whole genome single nucleotide polymorphism analysis showed that phylogenetically related pleuromutilin-resistant Enterococcus isolates were widely distributed in various environments on different production farms. Our results indicate that environmental contamination by antimicrobial-resistant Enterococcus requires greater attention, and they highlight the risk of pleuromutilin-resistant Enterococcus and ARGs disseminating along the laying hen production chain, thereby warranting effective disinfection. [Display omitted] [ABSTRACT FROM AUTHOR]

Large-scale natural frequency-related topology optimization problems pose a great challenge due to the high computational cost required by the iterative computation of the system eigenvalues and their sensitivities in each design iteration. This paper presents a new framework based on a multi-step relay strategy in conjunction with the idea of successive iteration of analysis and design (SIAD), to find high-quality solutions at affordable computational costs. The method starts from a relatively coarse finite element discretization, and then use gradually refined meshes to improve the design resolution. For a given level of mesh resolution, the method interleaves the eigenvalue solution routine with the optimization iterations to achieves sequential approximations of the eigenpairs along with the structural design evolution, thus avoiding the time-consuming eigenpair analysis in each optimization iteration. By sequentially solving the optimization problem and projecting intermediate designs and the corresponding approximate eigenmodes from a coarser mesh onto finer meshes, the proposed multi-step relay method can further substantially alleviate the computational burden and generate high-resolution boundaries in the final design. Numerical examples show that this method can be used to solve natural frequency maximization topology optimization problems with millions of degrees of freedom on a desktop workstation, and is much more efficient than the conventional double-loop method. [ABSTRACT FROM AUTHOR]

• We experimentally demonstrate a frequency offset and phase noise-tolerant coherent PON with simplified DSP. • We achieve 30.4-dB and 40.0-dB power budget with 100-Gb/s PAM-4 and 50-Gb/s OOK signal using only 20-ns preamble. • We use unequally-spaced PAM-4 to compensates for the modulator nonlinearity and brings 1.9-dB sensitivity improvement. Coherent optics are considered a promising solution for 100G passive optical network (PON) and beyond. Both simplified structure and efficient preamble are desired for the cost-sensitive scenario and upstream burst mode detection. In this work, we experimentally demonstrate a phase-insensitive coherent PON. An optical carrier is added by the modulator bias as an offset in signal constellation to eliminate the phase ambiguity, which can remove the carrier frequency and phase recovery stages. Signal-phase least-mean-square (SP-LMS) equalizer is used to eliminate the inter-symbol interference based on the amplitude-only constraint. By using a 20-ns preamble, 100-Gb/s 4-level pulse amplitude modulation (PAM-4) signal is successfully transmitted over 25-km standard single-mode fiber with 30.4-dB power budget. The frequency offset and phase noise-tolerant scheme is a potential candidate for future cost-effective coherent PON. [ABSTRACT FROM AUTHOR]

Background: miRNA is one of the crucial roles in the complex and dynamic network that regulates the development of skeletal muscle. The landscape of skeletal muscle miRNAs from fetus to adult in New Zealand rabbits has not been revealed yet. Results: In this study, nine RNA-seq libraries of fetus, child and adult rabbits' leg muscles were constructed. A total of 278 differentially expressed miRNAs (DEmiRNAs) were identified. In the fetus vs. child group, the main functional enrichments were involved in membrane and transport. Pathway enriched terms of up-regulated DEmiRNAs were connected with the differentiation and hypertrophy of skeletal muscle, and down-regulated ones were related to muscle structure and metabolic capacity. In the child vs. adult group, functions were associated to positioning and transportation, and pathways were relevant to ECM, muscle structure and hypertrophy. Finally, ocu-miR-185-3p and ocu-miR-370-3p, which had the most target genes, were identified as hub-miRNAs in these two groups. Conclusions: In short, we summarized the highly expressed and uniquely expressed DEmiRNAs of fetus, child and adult rabbits' leg muscles. Besides, the potential functional changes of miRNAs in two consecutive stages have been explored. Among them, the ocu-miR-185-3p and ocu-miR-370-3p with the most target genes were selected as hub-miRNAs. These data improved the understanding of the regulatory molecules of meat rabbit development, and provided a novel perspective for molecular breeding of meat rabbits. [ABSTRACT FROM AUTHOR]

The experiment was conducted to compare the growth performance, rumen fermentation, nutrient digestibility, and ruminal and fecal bacterial community between yaks and cattle-yaks. Ten male yaks (36-month-old) were used as the yak (YAK) group and 10 male cattle-yaks with similar age were selected as the cattle-yak (CAY) group. All the animals were fed same ration and the experiment lasted for 60 days. The results showed that the average daily gain and dry matter intake of CAY group were higher (P < 0.05) than those of YAK group. The ruminal concentrations of total volatile fatty acids, acetate, and butyrate were higher (P < 0.05) in CAY group than those in YAK group. However, the neutral detergent fiber and acid detergent fiber digestibility exhibited an opposite between two groups. In the rumen, the relative abundances of Prevotella 1 and Prevotellaceae UCG-001 were higher (P < 0.05) and Succiniclasticum and Butyrivibrio 2 were lower (P < 0.05) in YAK group compared to CAY group. In the feces, the unclassified Lachnospiraceae, Lachnospiraceae NK4A136 group, and Lachnospiraceae AC2044 group were significantly enriched (P < 0.05) in YAK group, whereas the Ruminococcaceae UCG-010, Ruminococcaceae UCG-013, and Succiniclasticum were significantly enriched (P < 0.05) in CAY group. Overall, under the same diet, the yaks have higher fiber utilization and cattle-yaks have higher energy utilization. [ABSTRACT FROM AUTHOR]

Previous studies of percutaneous endoscopic lumbar discectomy (PELD) to treat lumbar disc herniation (LDH) have shown good clinical results. However, limited information has been reported regarding postoperative improvement in back muscle function. We aimed to determine whether changes in neuromuscular patterns, assessed using the flexion-relaxation phenomenon (FRP), could be observed after PELD. A total of 30 patients participated in the present study. The patients' muscle functions were evaluated before and after PELD using surface electromyography and self-report measures. The evaluated action included 3 repetitions of a trunk flexion and extension movement. The association between the FRP measures and patient-reported outcomes was evaluated. At 4 weeks after PELD, the patients had significantly lower visual analog scale and Quebec Back Pain Disability Scale (QBPDS) scores and significantly increased gross range of motion. Also, we observed a reduction in erector spinae muscle activation at L3 in the maximum voluntary flexion phase. Normalized electromyographic root-mean-square values were significantly reduced in the maximum voluntary flexion phase and significantly increased in the extension phase. Postoperatively, 60% of the patients successfully achieved flexion-relaxation compared with 7% of the patients preoperatively. A significant correlation was found between the FRP measures and patient-reported outcomes, except for the Fear-Avoidance Beliefs Questionnaire scale. PELD for individuals with LDH appears to normalize paraspinal muscle activation during lumbar flexion-extension movement. The gross range of motion and disability-related limitations of physical activity also improved. [ABSTRACT FROM AUTHOR]

We fabricate a nonlinear optical device based on a fiber pigtail cross-section coated with a single-layer graphene grown by chemical vapor deposition (CVD) method. Using the fabricated graphene-assisted nonlinear optical device and employing Nyquist 16-ary quadrature amplitude modulation (16-QAM) signal, we experimentally demonstrate phase conjugated wavelength conversion by degenerate four-wave mixing (FWM) and transparent wavelength conversion by non-degenerate FWM in graphene. We study the conversion efficiency as functions of the pump power and pump wavelength and evaluate the bit-error rate (BER) performance. We also compare the time-varying symbol sequence for graphene-assisted phase conjugated and transparent wavelength conversions of Nyquist 16-QAM signal. [ABSTRACT FROM AUTHOR]