In this paper, we develop an analytical model to investigate the generation of instability waves triggered by the upstream acoustic forcing near the nozzle lip of a supersonic jet. This represents an important stage, i.e. the jet receptivity, of the screech feedback loop. The upstream acoustic forcing, resulting from the shock-instability interaction (SII), reaches the nozzle lip and excites new shear-layer instability waves. To obtain the newly excited instability wave, we first determine the scattered sound field due to the upstream forcing using the Wiener–Hopf technique, with the kernel function factored using asymptotic expansions and overlapping approximations. Subsequently, the unsteady Kutta condition is imposed at the nozzle lip, enabling the derivation of the dispersion relation for the newly excited instability wave. A linear transfer function between the upstream forcing and the newly excited instability wave is obtained. We calculate the amplitude and phase delay in this receptivity process and examine their variations against the frequency. The analytically obtained phase delay enables us to evaluate the phase condition for jet screech and predict the screech frequency accordingly. The results show improved agreement with the experimental data compared with classical models. It is hoped that this model may help in developing a full screech model.

This paper provides an overview of the current status of ultrafast and ultra-intense lasers with peak powers exceeding 100 TW and examines the research activities in high-energy-density physics within China. Currently, 10 high-intensity lasers with powers over 100 TW are operational, and about 10 additional lasers are being constructed at various institutes and universities. These facilities operate either independently or are combined with one another, thereby offering substantial support for both Chinese and international research and development efforts in high-energy-density physics.

The rise of online voicing and campaigns empowered by digital technologies and online social media is rejuvenating retail investor activism that has been mostly ignored in the traditional offline setting. This article argues that online activism that is initiated by retail investors will affect managerial attention intensity and attention priority on environmental issues, thus promoting green innovation. Using a Chinese-listed companies database with 13,795 firm-year observations over the period from 2011 to 2018, our results confirm that online environmental activism induces corporate green innovation. Online activism is more effective when the retail investor base holds larger shares in total and presents questions with a more intensely negative tone. Additionally, the above-mentioned moderating effects are stronger in digital firms. Our study offers insights into the online patterns of shareholder activism in the digital era and highlights the role of minority voicing in promoting corporate sustainable transformation.

Contrafreeloading (CFL) refers to animals’ tendency to prefer obtaining food through effort rather than accessing food that is freely available. Researchers have proposed various hypotheses to explain this intriguing phenomenon, but few studies have provided a comprehensive analysis of the factors influencing this behaviour. In this study, we observed the choice of alternative food containers in budgerigars (Melopsittacus undulatus) to investigate their CFL tendencies and the effects of pre-training, food deprivation, and effort required on the CFL tasks. The results showed that budgerigars did not exhibit significant difference in their first choices or the time interacting with less challenging versus more challenging food containers. Moreover, when evaluating each budgerigar’s CFL level, only half of them were identified as strong contrafreeloaders. Thus, we suggest that budgerigars exhibit an intermediate CFL level that lies somewhere between a strong tendency and the absence of such behaviour. Furthermore, we also found that food-deprived budgerigars tended to select less challenging food containers, and pre-trained budgerigars were more likely to choose highly challenging food containers than moderately challenging food containers, which means that the requirement of only a reasonable effort (access to food from moderately challenging food containers in this study) and the experience of pre-training act to enhance their CFL levels, whereas the requirement of greater effort and the experience of food deprivation act to decrease their CFL levels. Studying animal CFL can help understand why animals choose to expend effort to obtain food rather than accessing it for free, and it also has implications for setting feeding environments to enhance the animal welfare of captive and domesticated animals.

Serotonin (5-hydroxytryptamine, 5-HT) is a key monoamine neurotransmitter in insects, which regulates neural functions and influences various developmental and physiological processes by binding to its receptors. In this study, we investigate the molecular characteristics, phylogenetic relationships, and expression patterns of the 5-HT7 receptor (Cf5-HT7) in Chrysopa formosa, with a focus on its potential involvement in developmental and diapause regulation. The Cf5-HT7 gene was identified and cloned from the C. formosa transcriptome, revealing an open reading frame of 1788 bp encoding a 596 amino acid protein. Sequence analysis confirmed that Cf5-HT7 is a typical class A G protein-coupled receptor, characterised by seven transmembrane domains and several post-translational modifications, including palmitoylation and N-glycosylation sites. Phylogenetic analysis revealed that Cf5-HT7 is most closely related to the 5-HT7 receptor from Chrysoperla carnea, with high conservation of key motifs involved in ligand binding and receptor activation. Expression analysis across different developmental stages of C. formosa showed that Cf5-HT7 is highly expressed in the first instar larvae, with significant upregulation observed during the prepupal stage. Under diapause-inducing conditions, Cf5-HT7 expression is modulated in a stage-specific manner, showing a marked decrease at the onset of diapause, followed by a significant increase during the mid-to-late diapause maintenance phase. These findings suggest that it plays a pivotal role in regulating development and diapause processes in C. formosa, offering new insights into the molecular mechanisms governing insect life cycle transitions. This study lays the groundwork for future research into the functional roles of 5-HT7 receptors in insect physiology and their potential applications in manipulating diapause.

A vast amount of empirical and theoretical research on public good games indicates that the threat of punishment can curb free-riding in human groups engaged in joint enterprises. Since punishment is often costly, however, this raises an issue of second-order free-riding: indeed, the sanctioning system itself is a common good which can be exploited. Most investigations, so far, considered peer punishment: players could impose fines on those who exploited them, at a cost to themselves. Only a minority considered so-called pool punishment. In this scenario, players contribute to a punishment pool before engaging in the joint enterprise, and without knowing who the free-riders will be. Theoretical investigations (Sigmund et al., Nature 466:861–863, 2010) have shown that peer punishment is more efficient, but pool punishment more stable. Social learning, i.e., the preferential imitation of successful strategies, should lead to pool punishment if sanctions are also imposed on second-order free-riders, but to peer punishment if they are not. Here we describe an economic experiment (the Mutual Aid game) which tests this prediction. We find that pool punishment only emerges if second-order free riders are punished, but that peer punishment is more stable than expected. Basically, our experiment shows that social learning can lead to a spontaneously emerging social contract, based on a sanctioning institution to overcome the free rider problem.

Two-dimensional gaseous detonations near critical propagation state were studied numerically in a channel with stoichiometric H$_2$/air and H$_2$/O$_2$ mixtures. Detonation waves exhibit a mode-locking effect (MLE) in a single-headed mode regime. Increasing the channel width alters the strength and propagation period of the single transverse wave. This leads to MLE failure and the occurrence of the single-dual-headed critical mode, featuring the emergence of a new transverse wave. For a stoichiometric H$_2$/air mixture, generation of the new transverse wave is due to interactions between the detonation front and the local explosion wave originating from interactions between the transverse wave and unreacted gas pocket downstream. Whereas, for a stoichiometric H$_2$/O$_2$ mixture, a transverse wave interacting with the wall produces Mach reflection bifurcation, causing MLE failure and generation of the new transverse wave. Our results show that all transverse waves manifest as strong transverse wave (STW) structures, with most belonging to the second kind, and an acoustic coupling exists between the typical second kind of STW structure and the acoustic wave in the induction zone behind the Chapman–Jouguet detonation front. A high-pressure region close to the STW structure plays a crucial role in exploring the transverse dynamics of this structure. Shock polars with rational assumptions are adopted to predict flow states in this region. The roles of pivotal factors in influencing the flow states and wave structure are clarified, and characteristic pressure values derived adequately represent the STW structure’s transverse dynamic behaviours. Lastly, the relationship between the kinematics and kinds of STW structures is unveiled.

Immunological castration can be an alternative to traditional surgical castration. The active immunization against GnRH or kisspeptin has a castrating effect. To date, the fusion protein vaccine of combination with GnRH and kisspeptin have not been studied. Thus, the present study will develop a GnRH6-kisspeptin vaccine by genetic engineering method and investigate its immunocastration effect in male rats. Twenty 20-day-old male rats were randomly divided into two groups: the control group (n=10) and the immunization group (n=10). The initial immunization took place at week 0 followed by three booster doses administered intervals. The control group received an equivalent dose of white oil adjuvant. Orbital blood samples were collected at various time points following the initial immunization, at 0, 2, 4, 6, 8, 10 and 12 weeks, respectively. The entire left testis was weighed and its volume measured at week 12. Samples from the right testis were obtained for histological analysis. Serum levels of GnRH and kisspeptin antibodies, as well as testosterone levels were determined using ELISA. The results showed that the serum levels of GnRH and kisspeptin antibody titres of the immunized rats were significantly higher compared to the control group (P<0.05). Additionally, the testosterone concentration was effectively reduced following the intensified immunization. The testes of the immunized group exhibited a reduction in size and a significant decrease in the number of spermatogonia in the testicular tissue compared to the control group (P<0.05). These data indicate that the recombinant GnRH6-kisspeptin protein effectively induced immunological castration in rats.

Acoustic resonances in cascade structures may cause structural damage and instability problems in aero-engines and other industrial plants; thus, developing corresponding prediction methods is important. However, works published in the open literature mostly focus on the special case of the stationary Parker modes and provide little knowledge into the rotating resonances in annular cascades, especially in the presence of non-zero background mean flows. This paper develops a three-dimensional semi-analytic model to study the acoustic resonances in an annular cascade in the presence of axial mean flow. The model applies an unsteady cascade response based on the three-dimensional lifting surface method to construct a matrix equation. Characteristic frequencies are solved in the complex domain by numerically searching for singular points. Both the oscillation frequency and the growth rate of the three-dimensional resonance modes are theoretically calculated for the first time under non-zero mean flow conditions. The results reveal an organised distribution with varying inter-blade phase angle and show obvious change with the background flow speed. It is found that the unsteady vortex shedding from the trailing edges of the cascade is a key factor influencing the dissipation rate of the resonance modes. In addition, the important effects of acoustic scattering by the cascade during resonances are examined, which qualitatively corroborate some previous experimental observations.

Based on a 4f system, a 0° reflector and a single laser diode side-pump amplifier, a new amplifier is designed to compensate the spherical aberration of the amplified laser generated by a single laser diode side-pump amplifier and enhance the power of the amplified laser. Furthermore, the role of the 4f system in the passive spherical aberration compensation and its effect on the amplified laser are discussed in detail. The results indicate that the amplification efficiency is enhanced by incorporating a 4f system in a double-pass amplifier and placing a 0° reflector only at the focal point of the single-pass amplified laser. This method also effectively uses the heat from the gain medium (neodymium-doped yttrium aluminium garnet) of the amplifier to compensate the spherical aberration of the amplified laser.

Barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] is a dominant weed species occurring in rice fields across China. Metamifop, a common herbicide, is frequently applied to control E. crus-galli and other grassy weeds in rice fields. Herein, HS01, an E. crus-galli population suspected to be resistant (R) to metamifop, was collected from Hanshan County in Anhui Province. Whole-plant dose-response testing revealed that, compared with the susceptible (S) population FD03, HS01 had developed high-level resistance to metamifop with a resistance index (RI) of 11.76 and showed cross-resistance to cyhalofop-butyl (RI=9.33), fenoxaprop-P-ethyl (RI=5.80) and clethodim (RI=3.24). Gene sequencing revealed a Cys-2088-Arg mutation in ACCase 1,5 allele of all the R plants, while ACCase gene overexpression was not involved in the resistance. Molecular docking indicated that the less negative binding energies might be the main reason for the resistance of HS01 to ACCase-inhibiting herbicides. A derived cleaved amplified polymorphic sequence (dCAPS) method was developed for the rapid identification of the Cys-to-Arg mutation in the ACCase gene at codon position 2088 in E. crus-galli. Additionally, pretreatment with the cytochrome P450 inhibitor piperonyl butoxide or the glutathione S-transferase inhibitor 4-chloro-7-nitrobenzoxa-diazole had no significant effects (p> 0.05) on the resistance of HS01 to metamifop. To our knowledge, this is the first report of a Cys-2088-Arg mutation in E. crus-galli ACCase that confers cross-resistance to ACCase-inhibiting herbicides.

This study explored the relationship between multifaceted multilingualism and cognitive shifting through a task-switching paradigm using fMRI. Multilingualism was modeled from both convergent (i.e., integrated multilingual index) and divergent (i.e., L2 proficiency, interpreting training, language entropy) perspectives. Participants identified letters or numbers based on task cues, with Repeat trials maintaining the same task and Switch trials requiring a different task. Switch cost (Switch–Repeat) was used to reflect shifting demands. Better task-switching performance was associated with a higher integrated multilingual index and interpreting training. Neuroimaging indicated that multilinguals predominantly engaged left-hemisphere regions for switching, with extensive multilingual experience requiring fewer neural resources for switch cost (i.e., more efficient processing for cognitive control). During task switching, brain connectivity was regulated locally by L2 proficiency, and globally by interpreting training. These findings underscore the importance of considering multifaceted multilingual experience to understand its impact on cognitive function and brain activity.