In this paper, the notions of Fα-categorical and Gα-categorical structures are introduced by choosing the isomorphism such that the function itself or its graph sits on the α-th level of the Ershov hierarchy, respectively. Separations obtained by natural graphs which are the disjoint unions of countably many finite graphs. Furthermore, for size-bounded graphs, an easy criterion is given to say when it is computable-categorical and when it is only G2-categorical; in the latter case it is not Fα-categorical for any recursive (...) ordinal α. (shrink)

We show that there exist downwards properly $\Sigma _{2}^{0}$ (in fact noncuppable) e-degrees that are not high. We also show that every high e-degree bounds a noncuppable e-degree.

Resumen: el arte es la encarnación de la cultura y el espíritu nacional. El canto y el baile son una de las formas más antiguas y ricas del arte humano. No es sólo el producto de la experiencia y la experiencia emocional, sino también la trascendencia de la vida cotidiana vulgar. Como la característica más distinde las películas modernas de la India, el arte de cantar y bailar herede las ideas estéticas tradicionales de la India y la filosofía religiosa en (...) el entorno audiovisual moderno se puede encontrar. Mantiene una impresión nacional distintiva en la marea de la internacionalización. Este tipo de arte es de gran importancia para la exploración de la nacionalidad del arte chino de canto y danza. (shrink)

Related Works: Part II: C. T. Chong, Yue Yang. $\Sigma_2$ Induction and Infinite Injury Priority Argument, Part II: Tame $\Sigma_2$ Coding and the Jump Operator. Ann. Pure Appl. Logic, vol. 87, no. 2, 103--116. Mathematical Reviews : MR1490049 Part III: C. T. Chong, Lei Qian, Theodore A. Slaman, Yue Yang. $\Sigma_2$ Induction and Infinite Injury Priority Argument, Part III: Prompt Sets, Minimal Paries and Shoenfield's Conjecture. Mathematical Reviews : MR1818378.

We show that there exists a properly Σ2 minimal degree b, and moreover that b can be chosen to join with 0′ to 0″ – so that b is a 0″ complement for every degree a such that 0′ ≤ a < 0″.

We show that the structure R of recursively enumerable degrees is not a Σ₁-elementary substructure of Dn, where Dn (n > 1) is the structure of n-r.e. degrees in the Ershov hierarchy.

We show that every nonzero $\Delta _{2}^{0}$ e-degree bounds a minimal pair. On the other hand, there exist $\Sigma _{2}^{0}$ e-degrees which bound no minimal pair.

Let [NB]₁ denote the ideal generated by nonbounding c.e. degrees and NCup the ideal of noncuppable c.e. degrees. We show that both [NB]₁ ∪ NCup and the ideal generated by nonbounding and noncuppable degrees are new, in the sense that they are different from M, [NB]₁ and NCup—the only three known definable ideals so far.

Lachlan observed that any nonzero d.c.e. degree bounds a nonzero c.e. degree. In this paper, we study the c.e. predecessors of d.c.e. degrees, and prove that given a nonzero d.c.e. degree , there is a c.e. degree below and a high d.c.e. degree such that bounds all the c.e. degrees below . This result gives a unified approach to some seemingly unrelated results. In particular, it has the following two known theorems as corollaries: there is a low c.e. degree isolating (...) a high d.c.e. degree [S. Ishmukhametov, G. Wu, Isolation and the high/low hierarchy, Arch. Math. Logic 41 259–266]; there is a high d.c.e. degree bounding no minimal pairs [C.T. Chong, A. Li, Y. Yang, The existence of high nonbounding degrees in the difference hierarchy, Ann. Pure Appl. Logic 138 31–51]. (shrink)

We show that there exists a properly Σ2 minimal degree b, and moreover that b can be chosen to join with 0′ to 0″ – so that b is a 0″ complement for every degree a such that 0′ ≤ a < 0″.

In [Countable thin [Formula: see text] classes, Ann. Pure Appl. Logic 59 79–139], Cenzer, Downey, Jockusch and Shore proved the density of degrees containing members of countable thin [Formula: see text] classes. In the same paper, Cenzer et al. also proved the existence of degrees containing no members of thin [Formula: see text] classes. We will prove in this paper that the c.e. degrees containing no members of thin [Formula: see text] classes are dense in the c.e. degrees. We will (...) also prove that the c.e. degrees containing members of thin [Formula: see text] classes are dense in the c.e. degrees, improving the result of Cenzer et al. mentioned above. Thus, we obtain a new natural subclass of c.e. degrees which are both dense and co-dense in the c.e. degrees, while the other such class is the class of branching c.e. degrees 113–130] for nonbranching degrees and [T. A. Slaman, The density of infima in the recursively enumerable degrees, Ann. Pure Appl. Logic 52 155–179] for branching degrees). (shrink)

We give a survey of the study of nonstandard models in recursion theory and reverse mathematics. We discuss the key notions and techniques in effective computability in nonstandard models, and their applications to problems concerning combinatorial principles in subsystems of second order arithmetic. Particular attention is given to principles related to Ramsey’s Theorem for Pairs.

We show that for every intermediate \ s-degree there exists an incomparable \ s-degree. As a consequence, for every intermediate \ Q-degree there exists an incomparable \ Q-degree. We also show how these results can be applied to provide proofs or new proofs of upper density results in local structures of s-degrees and Q-degrees.

We give a survey of the study of nonstandard models in recursion theory and reverse mathematics. We discuss the key notions and techniques in effective computability in nonstandard models. and their applications to problems concerning combinatorial principles in subsystems of second order arithmetic. Particular attention is given to principles related to Ramsey's Theorem for Pairs.

We study the jump hierarchy of d.c.e. Turing degrees and show that there exists a high d.c.e. degree d which does not bound any minimal pair of d.c.e. degrees.

We show that every nonzero Δ20, e-degree bounds a minimal pair. On the other hand, there exist Σ20, e-degrees which bound no minimal pair.

To address the need for a valid and reliable scale of youth leadership potential based on the development theory of leadership, the current study developed the Youth Leadership Potential Scale (YLPS) and investigated its factor structure and psychometric properties in a sample of 696 students (grades 7-9) in China. Exploratory structural equation modeling (ESEM) identified a five-factor solution comprising leadership information, leadership attitude, communication skills, decision-making skills, and stress management skills. ESEM within confirmatory factor analysis demonstrated an adequate fit for (...) this structure. The scale showed good composite reliability and measurement invariance across different gender and grade/age groups. The scale also showed sufficient concurrent validity with the Coping Self-Efficacy Scale, the Chinese Roets Rating Scale for Leadership, and the Leadership Skills Inventory. Furthermore, criterion-related validity was supported by the relationship between YLPS scores and the length of student leadership positions. The results suggest that the YLPS is a valid and pragmatic measure for assessing youth leadership potential. The current study is the first to develop a youth leadership potential scale based on the development theory of leadership. (shrink)

In terms of image processing, encryption plays the main role in the field of image transmission. Using one algorithm of deep learning, such as neural network backpropagation, increases the performance of encryption by learning the parameters and weights derived from the image itself. The use of more than one layer in the neural network improves the performance of the algorithm. Also, in the process of image encryption, randomness is an important component, especially when used by smart learning methods. Deep neural (...) networks are related to pixels used to manipulate position and value according to the predicted new value given from a variable neural system. It also includes messy encrypted images used via applying randomness and increasing the key space in addition to using the logistic and Henon map for complexity. The main goal of any encryption method is to increase the complexity of the encrypted image to be difficult or impossible to decrypt the image without the proposed key. One of the important measurements for image encryption is the histogram and how it can be uniformed by the proposed method. Variables of randomness are used as features for the deep learning system, with feedback during iteration. An ideal image processing encryption yields high messy images by keeping the quality. Experimental results showed the backpropagation algorithm achieved better results than other algorithms. (shrink)

In this paper, we prove that there is a Π01 class in 2ω with a unique nonrecursive member, with that member a cohesive set. This solves an open question from Cenzer. The proof uses the Δ03 method in the context of the construction of a Π01 class.

In response to the lack of research on the online social network structure of athletes, elements of research on the online social network structure of athletes were constructed based on the whole network perspective and through the study of the characteristics of the whole online social network structure of athletes, in order to provide reference for the physical and mental health development of athletes from a new perspective. Data were collected through questionnaires, and several software programs were used to preprocess (...) and analyse the collected data. Through the analysis of the online whole network structure, it was found that the network density of the online support network was generally greater than that of the online discussion network, and athletes still showed stronger practical support demands and behaved more rationally in the process of training and learning life, while from the perspective of the relationship structure, the athletes’ family and classmates’ online support is weaker than that in previous studies; in terms of the whole network, strong relationships still dominate in this population, while attention should be paid to the impact of weak relationships. (shrink)

ObjectiveThis study took users of short-form mobile videos as research participants to explore the role of their boredom proneness in mediating the relationship between the use of mobile social media and subjective well-being.MethodsA sample of 656 users was evaluated by the Problematic Mobile Social Media Usage Assessment Questionnaire, General Well-Being Schedule, and Boredom Proneness Scale.ResultsFirstly, significant interactions were found between monthly living expenses and the UMSM of the participants, which were recognized as factors affecting SWB. Secondly, the level of living (...) expenses had little effect on the high-level and low-level groups of the UMSM but imposed a significant impact on the medium-level group. Thirdly, the UMSM showed an influence that could positively predict boredom; both the UMSM and boredom demonstrated a negative predictive effect on SWB.ConclusionThe findings indicate that the inappropriate use of mobile social media negatively affects users’ subjective well-being; boredom partially mediated the relationship between the use of mobile social media and SWB. (shrink)

According to rational pedagogy models, learners take into account the way in which teachers generate evidence, and teachers take into account the way in which learners assimilate that evidence. The authors develop a framework for integrating rational pedagogy into models of active exploration, in which agents can take actions to influence the evidence they gather from the environment. The key idea is that a single agent can be both teacher and learner.

Many studies have shown that about three biological motions can be maintained in working memory. However, no study has yet analyzed the difficulties of experiment materials used, which partially affect the ecological validity of the experiment results. We use the perspective of system anatomy to decompose BM, and thoroughly explore the influencing factors of difficulties of BMs, including presentation duration, joints to execute motions, limbs to execute motions, type of articulation interference tasks, and number of joints and planes involved in (...) the BM. We apply the change detection paradigm supplemented by the articulation interference task to measure the BM working memory capacity of participants. Findings show the following: the shorter the presentation duration, the less participants remembered; the more their wrist moved, the less accurate their memory was; repeating verbs provided better results than did repeating numerals to suppress verbal encoding; the more complex the BM, the less participants remembered; and whether the action was executed by the handed limbs did not affect the WMC. These results indicate that there are many factors that can be used to adjust BM memory load. These factors can help sports psychology professionals to better evaluate the difficulty of BMs, and can also partially explain the differences in estimations of BM WMC in previous studies. (shrink)

Due to the outbreak of the Coronavirus Disease-2019 pandemic and consequent confinement measures, young people are vulnerable to mental health problems. The current study compared a group of 440 young adolescents and a group of 330 emerging adults to investigate the extent to which perceived social support and psychological capital were differentially associated with mental health problems. Participants were asked to report their current psychosocial adaptation status during the COVID-19 pandemic, and data were collected via online questionnaires during a relatively (...) severe period of COVID-19 in China. Results of the multi-group path analysis indicated that the effect of perceived social support on mental health problems was mediated by PsyCap for young adolescents, but not for emerging adults. These results were discussed with respect to the mechanism of how social support and PsyCap serve as protective mental health factors for youth in the context of the COVID-19 pandemic. (shrink)

Many scholars have investigated education management. Scholars in the education field have made significant achievements in contributing to multiple educational reform policies, while other scholars discuss teacher-related issues from the perspective of organizational behavior. The teaching innovation of high school teachers plays a critical role in students’ learning attitude and motivation, especially in the context of the COVID-19 pandemic. Teachers need to utilize more diversified teaching methods to enable students to carry out effective learning. In order to examine teachers’ teaching (...) innovation, this study explores teaching innovation intentions and performance from the perspective of individual and social factors in combination with goal-oriented behavior and social identity theory. This study conducts questionnaires with a sample of Chinese coastal high school teachers, and obtains a total of 475 responses. The research results show that innovation attitude, positive anticipated emotion, group norms and social identity positively affect teachers’ teaching innovation intention; furthermore, teachers’ teaching innovation intention also positively affects their teaching innovation performance. Based on the comprehensive research findings, this research proposes corresponding theoretical and practical implications. (shrink)

The conflict of administrative morality among civil servants at the grassroots level arises from the background of China’s long-standing traditional culture, and the current administrative system cannot keep up with the pace of economic development. In the process of grassroots management, due to the lag in the construction of administrative morality, the traditional official standard thinking, the imperfection of the current system, and the restriction of human nature, it is easy to cause the administrative moral conflict of the grassroots civil (...) servants in practice. This paper takes the interpersonal society as the research background, analyzes the influence of the interpersonal society on the environment, and studies the administrative ethics conflicts and governance issues of basic civil servants from the interpersonal background. In addition, this paper conducts a more detailed field investigation based on fuzzy cluster analysis, analyzes the manifestations and causes of the administrative moral conflict of grassroots civil servants in the context of human society from multiple perspectives and levels, and then proposes countermeasures to solve the administrative moral conflict. The administrative moral conflict and governance of grass-roots civil servants under the background of interpersonal relationship is of great positive significance for solving the administrative moral conflict and improving the service awareness and service level of grass-roots civil servants. (shrink)

Based on the stress interaction theory, this research constructed a model to study the joint moderating effects of the perception reduction of employment opportunities under the COVID-19 epidemic on the employment pressure of college students. With two moderating variables introduced, employment policy support and job-searching self-efficacy, this research studied the mechanism and boundary conditions of perception reduction of employment opportunities on employment pressure of college students from both individual and environmental aspects. The study found that during the epidemic if college (...) students perceived fewer employment opportunities, they could have greater employment pressure from themselves, schools, and families; and that under the joint moderation of employment policy support and job-searching self-efficacy, the perception reduction of employment opportunities under the COVID-19 epidemic, the employment pressure of college students, universities, and families were connected, with different adjustment mechanisms. Based on empirical data, this research can provide theoretical enlightenment and practical guidance for the government, universities, and families to alleviate the employment pressure on college students during the epidemic. (shrink)

Since the outbreak of the COVID-19 pandemic, the physical and mental health of older adults has been threatened. Promoting physical and mental health through physical activity has therefore become a strategy for healthy aging. In order to better understand the impact of the participation of older adults in physical activity, this paper selects different types of physical activity, and examines the relationship between them and subjective well-being through the analysis of the mediation effect of outdoor exercise environment and the regulating (...) effect of exercise form. In this cross-sectional study, a questionnaire survey was conducted in mainland China. The main data come from 903 older adults in five urban areas in Chengdu, Sichuan Province. The surveys were carried out using the Physical Activity Rating Scale, Newfoundland Subjective Well-Being Scale, Exercise Environment Scale, and Exercise Form Scale. SPSS was used for statistical analysis, linear regression analysis was adopted for processing data, and AMOS was used to establish a mediation model. The mediating variable is the outdoor exercise environment, and the moderating variable is exercise form; gender, age, education level, and monthly income were used as control variables. The study results showed that different physical activities were significantly, positively correlated with the subjective well-being of older adults ; among the activities, tai chi had the strongest effect on the subjective well-being of older adults. Outdoor exercise environment played a mediating role between different physical activity types and subjective well-being of older adults [tai chi: β = 0.030, 95% CI ; health qigong: β = 0.018, 95% CI ; walking and jogging: β = 0.034, 95% CI ]. Exercise form moderated the subjective well-being of older adults in different physical activities. The results of this study demonstrate that the outdoor exercise environment plays a mediating role between different physical activities and the subjective well-being of older adults, and the form of exercise can also moderate the impact of different physical activities on the subjective well-being of older adults. This study has enlightening significance for psychological intervention with older adults facing stress, anxiety and depression. (shrink)

With the emergence of the COVID-19 pandemic, virtual simulation games have provided an effective teaching method for online entrepreneurship education. By exploring the mechanisms that influence student engagement and learning outcomes from different perspectives, such as game design, team and individual perspectives, numerous scholars have demonstrated that such a teaching method can effectively improve students’ engagement and learning performance. However, the existing studies are relatively scattered, and there is a scarcity of studies in which the effects of said factors are (...) considered. Based on the learning process 3P model proposed by Biggs, students’ perceived experience of game design, teamwork and self-efficacy were taken as variables in the early learning stage in the present study, and the influence mechanism of virtual simulation game learning experience on students’ engagement and entrepreneurial skill development was explored, so as to close the gap in existing research. In the present study, 177 college students from Chinese universities were surveyed and the data were surveyed using AMOS 23.0 software. Although the empirical results show that students’ “goal and feedback” and “alternative” experience of game design did not have a significant positive impact on students’ engagement, there was a direct and significant effect the development of entrepreneurial skills. Students’ experience of teamwork and general self-efficacy could not only directly and significantly affect the development of entrepreneurial skills, but also indirectly affect the development of entrepreneurial skills through learning engagement. The research results are practically significant for teachers in the selection and development of virtual simulation games, can be effectively applied in teaching process management, and can improve students’ engagement and learning performance. (shrink)

Rapid and precise air operation mission planning is a key technology in unmanned aerial vehicles autonomous combat in battles. In this paper, an end-to-end UAV intelligent mission planning method based on deep reinforcement learning is proposed to solve the shortcomings of the traditional intelligent optimization algorithm, such as relying on simple, static, low-dimensional scenarios, and poor scalability. Specifically, the suppression of enemy air defense mission planning is described as a sequential decision-making problem and formalized as a Markov decision process. Then, (...) the SEAD intelligent planning model based on the proximal policy optimization algorithm is established and a general intelligent planning architecture is proposed. Furthermore, three policy training tricks, i.e., domain randomization, maximizing policy entropy, and underlying network parameter sharing, are introduced to improve the learning performance and generalizability of PPO. Experiments results show that the model in this work is efficient and stable, and can be adapted to the unknown continuous high-dimensional environment. It can be concluded that the UAV intelligent mission planning model based on DRL has powerful intelligent planning performance, and provides a new idea for researching UAV autonomy. (shrink)

Wearing a myoelectric prosthesis is a basic way for limb amputees to restore their lost limb functions in the activities of daily living. However, it is estimated that around 40% of amputees refuse the prosthesis. One of the primary reasons would be that the current prostheses lack appropriate sensory feedback. Currently, the amputees only depend on their visual feedback when using their arm prostheses. It would be difficult for them to accurately control the wrist position, which is vital for flexible (...) manipulation in ADLs. This manuscript designed a myoelectric arm prosthesis with wrist position feedback. To study the effect level of position feedback on prosthetic control, two tests were performed. The vibrotactile perception range test aims to analyze the perception sensitivity of the vibration in humans and obtain the optimal perception range utilized in the sensory feedback test. The sensory feedback test analyzes the effectiveness of the position feedback by comparing three feedback methods of Vis-FB, WP-FB, and a combination of Vis-FB and WP-FB. These tests were conducted by asking six able-bodied subjects to perform 20 movement combinations of five target positions. The WP-FB was transiently activated with five vibrating motors embedded in an armband to stimulate the arm stump when the prosthetic wrist rotates to the target positions. Our experimental results showed that when WP-FB was added to the prosthetic control, the absolute angular error of the prosthetic wrist declined from 4.50° to 1.08° while the success rate 3 increased from 0.34 to 0.84, respectively. This study demonstrates the importance of WP-FB to the effective control of the arm prosthesis. (shrink)

The behavior of somatic stem cells is regulated by their niche. Interaction between hematopoietic stem cells (HSCs) and their niches are a representative model to understand stem cell‐niche interplay. Here, we provide an overview of crosstalk between HSCs and their niches in bone marrow and extramedullary organs following the life journey of HSCs from emergence, development, maturation until aging. We highlight the unique differences of HSC niches in different life stages within various organs focusing on recent literature to propose new (...) speculations and hypotheses. (shrink)

The pandemic has impacted various industries, including the sports industry. However, corporate social responsibility can mitigate the adverse effects of the crisis and promote the sports industry. To analyze the effect of CSR, the study examined the impact of perceived corporate social responsibility on injury prevention expectation, injury risk perception, and health up-gradation with the mediation of sports safety measures. There are 259 sportsmen of local sports bodies provided the data through a self-administered survey. Data analysis was conducted through Smart-PLS (...) and SEM techniques. The outcome of the analysis showed that perceived corporate social responsibility leads to injury prevention expectation, injury risk perception, and health up-gradation. Also, the study found that sports safety measure mediates the relationship between perceived corporate social responsibility and injury prevention expectation, between perceived corporate social responsibility and injury risk perception, and between perceived corporate social responsibility and health up-gradation among sportsmen of local sports bodies. The theoretical implications were presented related to the significance of CSR and sports safety measure and their impact on sportsmen injury prevention expectation, health, and risk perception. The practical implications were related to the management of local sports bodies and how they can induce CSR initiatives and programs. Some limitations related to sample size, incorporating other variables, examining the model in other contexts, and using different study designs, have also been mentioned in the study. (shrink)