The performance loss of an approximately 3 dB signal-to-noise ratio is always paid with conventional differential detection compared to the related coherent detection. A new detection scheme consisting of two steps is...The performance loss of an approximately 3 dB signal-to-noise ratio is always paid with conventional differential detection compared to the related coherent detection. A new detection scheme consisting of two steps is proposed for the differential unitary space-time modulation （DUSTM） system. In the first step, the data sequence is estimated by conventional unitary space-time demodulation （DUSTD） and differentially encoded again to produce an initial estimate of the transmitted symbol stream. In the second step, the initial estimate of the symbol stream is utilized to initialize an expectation maximization （EM）-based iterative detector. In each iteration, the most recent detected symbol stream is employed to estimate the channel, which is then used to implement coherent sequence detection to refine the symbol stream. Simulation results show that the proposed detection scheme performs much better than the conventional DUSTD after several iterations.展开更多
This paper revisits the Space-Time Gradient(STG) method which was developed for efficient analysis of unsteady flows due to rotor–stator interaction and presents the method from an alternative time-clocking perspecti...This paper revisits the Space-Time Gradient(STG) method which was developed for efficient analysis of unsteady flows due to rotor–stator interaction and presents the method from an alternative time-clocking perspective. The STG method requires reordering of blade passages according to their relative clocking positions with respect to blades of an adjacent blade row. As the space-clocking is linked to an equivalent time-clocking, the passage reordering can be performed according to the alternative time-clocking. With the time-clocking perspective, unsteady flow solutions from different passages of the same blade row are mapped to flow solutions of the same passage at different time instants or phase angles. Accordingly, the time derivative of the unsteady flow equation is discretized in time directly, which is more natural than transforming the time derivative to a spatial one as with the original STG method. To improve the solution accuracy, a ninth order difference scheme has been investigated for discretizing the time derivative. To achieve a stable solution for the high order scheme, the implicit solution method of Lower-Upper Symmetric GaussSeidel/Gauss-Seidel(LU-SGS/GS) has been employed. The NASA Stage 35 and its blade-countreduced variant are used to demonstrate the validity of the time-clocking based passage reordering and the advantages of the high order difference scheme for the STG method. Results from an existing harmonic balance flow solver are also provided to contrast the two methods in terms of solution stability and computational cost.展开更多
In this article,we establish new and more general traveling wave solutions of space-time fractional Klein–Gordon equation with quadratic nonlinearity and the space-time fractional breaking soliton equations using the...In this article,we establish new and more general traveling wave solutions of space-time fractional Klein–Gordon equation with quadratic nonlinearity and the space-time fractional breaking soliton equations using the modified simple equation method.The proposed method is so powerful and effective to solve nonlinear space-time fractional differential equations by with modified Riemann–Liouville derivative.展开更多
Differential space-time coding was proposed recently in the literature for multi-antenna systems, where neither the transmitter nor the receiver knows the fading coefficients. Among existing schemes, double differenti...Differential space-time coding was proposed recently in the literature for multi-antenna systems, where neither the transmitter nor the receiver knows the fading coefficients. Among existing schemes, double differential space-time (DDST) coding is of special interest because it is applicable to continuous fast time-varying channels. However, it is less effective in fre- quency-selective fading channels. This paper’s authors derived a novel time-frequency double differential space-time (TF-DDST) coding scheme for multi-antenna orthogonal frequency division multiplexing (OFDM) systems in a time-varying fre- quency-selective fading environment, where double differential space-time coding is introduced into both time domain and fre- quency domain. Our proposed TF-DDST-OFDM system has a low-complexity non-coherent decoding scheme and is robust for time- and frequency-selective Rayleigh fading. In this paper, we also propose the use of state-of-the-art low-density parity-check (LDPC) code in serial concatenation with our TF-DDST scheme as a channel code. Simulations revealed that the LDPC based TF-DDST OFDM system has low decoding complexity and relatively better performance.展开更多
Background: For nursing students, gathering social information is essential for understanding healthcare and social issues and developing critical thinking and decision-making skills. However, the choice of informatio...Background: For nursing students, gathering social information is essential for understanding healthcare and social issues and developing critical thinking and decision-making skills. However, the choice of information sources varies by age and individual habits. With the widespread use of the internet, there are notable differences between younger and older generations in their reliance on the internet versus traditional media sources like newspapers and television. Given the wide age range and diverse backgrounds of nursing students, understanding generational differences in information-gathering methods is important for implementing effective education. Purpose: The purpose of this study is to identify how nursing students in different age groups obtain social information and to examine media usage trends by age group. Additionally, we aim to use the findings to provide insights into effective information dissemination methods in nursing education. Results: The results showed that nursing students in their teens to forties, regardless of gender, primarily relied on the internet as their main information source, with television playing a secondary role. In contrast, students in their fifties tended to obtain information more often from newspapers and television than from the internet. This highlights an age-related difference in preferred information sources, with older students showing a greater reliance on traditional media. Conclusions: This study demonstrates that nursing students use different information-gathering methods based on their age, suggesting a need to custo-mize information dissemination strategies in nursing education. Digital media may be more effective for younger students, while traditional media or printed materials might better serve older students. Educational institutions should consider these generational differences in media usage and adopt strategies that meet the diverse needs of their student populations.展开更多
Objective:Near vision loss(NVL)is one of the leading causes of visual impairment worldwide,exerting a profound impact on individual quality of life and socio-economic development.This study aims to analyze the burden ...Objective:Near vision loss(NVL)is one of the leading causes of visual impairment worldwide,exerting a profound impact on individual quality of life and socio-economic development.This study aims to analyze the burden of NVL in China by sex and age groups from 1990 to 2021 and to project trends over the next 15 years.Methods:Using data from the Global Burden of Disease(GBD)2021 database,we conducted descriptive analyses of NVL prevalence in China,calculated age-standardized prevalence rates(ASPR)and age-standardized disability-adjusted life years rates(ASDR)to compare burden differences between sexes and age groups,and applied an autoregressive integrated moving average(ARIMA)model to predict NVL trends for the next 15 years.The model selection was based on best-fit criteria to ensure reliable projections.Results:From 1990 to 2021,China’s ASPR of NVL rose from 10096.24/100000 to 15624.54/100000,and ASDR increased from 101.75/100000 to 158.75/100000.In 2021,ASPR(16551.70/100000)and ASDR(167.69/100000)were higher among females than males(14686.21/100000 and 149.76/100000,respectively).China ranked highest globally in both NVL cases and disability-adjusted life years(DALYs),with female burden significantly exceeding male burden.Projections indicated this trend and sex gap will persist until 2036.Compared with 1990,the prevalence cases and DALYs increased by 239.20%and 238.82%,respectively in 2021,with the highest burden among females and the 55−59 age group.The ARIMA model predicted continued increases in prevalence and DALYs by 2036,with females maintaining a higher burden than males.Conclusion:This study reveals a marked increase in the NVL burden in China and predicts continued growth in the coming years.Public health policies should prioritize NVL prevention and control,with special attention to women and middle-aged populations to mitigate long-term societal and health impacts.展开更多
BACKGROUND Depression and anxiety are prevalent psychological challenges among patients with adolescent idiopathic scoliosis(AIS),affecting individuals across both sex and age groups.AIM To explore the network structu...BACKGROUND Depression and anxiety are prevalent psychological challenges among patients with adolescent idiopathic scoliosis(AIS),affecting individuals across both sex and age groups.AIM To explore the network structure of depression and anxiety symptoms,with a focus on identifying differences at the symptom level between sex and age subgroups.METHODS A total of 1955 participants diagnosed with AIS aged 10-18 years were assessed using the Patient Health Questionnaire Depression Scale(PHO-9)and the Generalized Anxiety Disorder Scale(GAD-7),and 765 patients exhibiting PHQ-9 or GAD-7 scores ≥ 5 were enrolled in our study. Network analysis and network comparison tests were utilized toconstruct and compare the depression-anxiety symptoms networks among sex and age subgroups.RESULTSThe results revealed GAD3 “Excessive worry” and PHQ2 “Sad mood” were the most significant central symptomsin all subgroups, while “Sad mood” had higher strength than “Excessive worry” in the lower age group. In thenetwork comparisons, the female network exhibited tighter connectivity, especially on GAD6 “Irritability” andGAD2 “Uncontrollable worry”, while only PHQ3 “Sleep” and PHQ9 “Suicidal ideation” had differences at thelocal level in the lower age group.CONCLUSIONSeveral interventions targeting excessive worry and sad mood could reduce the risk of depression and anxietysymptoms in the AIS population. Furthermore, specific anxiety symptoms in females, along with sleep disturbancesand suicidal ideation in the lower age group, should be addressed at an early stage to prevent significantdisruptions in mental health trajectories.展开更多
This paper proposes a new step-by-step Chebyshev space-time spectral method to analyze the force vibration of functionally graded material structures.Although traditional space-time spectral methods can reduce the acc...This paper proposes a new step-by-step Chebyshev space-time spectral method to analyze the force vibration of functionally graded material structures.Although traditional space-time spectral methods can reduce the accuracy mismatch between tem-poral low-order finite difference and spatial high-order discre tization,the ir time collocation points must increase dramatically to solve highly oscillatory solutions of structural vibration,which results in a surge in computing time and a decrease in accuracy.To address this problem,we introduced the step-by-step idea in the space-time spectral method.The Chebyshev polynomials and Lagrange's equation were applied to derive discrete spatial goverming equations,and a matrix projection method was used to map the calculation results of prev ious steps as the initial conditions of the subsequent steps.A series of numerical experiments were carried out.The results of the proposed method were compared with those obtained by traditional space-time spectral methods,which showed that higher accuracy could be achieved in a shorter computation time than the latter in highly oscillatory cases.展开更多
Experimental mice play a critical role in biomedical research.The phenotype and application of different substrains vary due to genetic differentiation and variation.To ensure validity and reliability of results,it is...Experimental mice play a critical role in biomedical research.The phenotype and application of different substrains vary due to genetic differentiation and variation.To ensure validity and reliability of results,it is imperative to adhere to standardized experiments and controls.This paper objectively reviews the origin,differentiation,and phenotypic and genetic differences between the C57BL/6 and BALB/c mouse substrains.Furthermore,an optimal selection strategy is proposed based on the genetic quality control technology to facilitate the precise application of these two mouse substrains.展开更多
Existing orthogonal space-time block coding(OSTBC)schemes for backscatter communication systems cannot achieve a full transmission code rate when the tag is equipped with more than two antennas.In this paper,we propos...Existing orthogonal space-time block coding(OSTBC)schemes for backscatter communication systems cannot achieve a full transmission code rate when the tag is equipped with more than two antennas.In this paper,we propose a quasi-orthogonal spacetime block code(QOSTBC)that can achieve a full transmission code rate for backscatter communication systems with a four-antenna tag and then extend the scheme to support tags with 2i antennas.Specifically,we first present the system model for the backscatter system.Next,we propose the QOSTBC scheme to encode the tag signals.Then,we provide the corresponding maximum likelihood detection algorithms to recover the tag signals.Finally,simulation results are provided to demonstrate that our proposed QOSTBC scheme and the detection algorithm can achieve a better transmission code rate or symbol error rate performance for backscatter communication systems compared with benchmark schemes.展开更多
Population migration data derived from location-based services has often been used to delineate population flows between cities or construct intercity relationship networks to reveal and explore the complex interactio...Population migration data derived from location-based services has often been used to delineate population flows between cities or construct intercity relationship networks to reveal and explore the complex interaction patterns underlying human activities.Nevertheless,the inherent heterogeneity in multimodal migration big data has been ignored.This study conducts an in-depth comparison and quantitative analysis through a comprehensive lens of spatial association.Initially,the intercity interactive networks in China were constructed,utilizing migration data from Baidu and AutoNavi collected during the same time period.Subsequently,the characteristics and spatial structure similarities of the two types of intercity interactive networks were quantitatively assessed and analyzed from overall(network)and local(node)perspectives.Furthermore,the precision of these networks at the local scale is corroborated by constructing an intercity network from mobile phone(MP)data.Results indicate that the intercity interactive networks in China,as delineated by Baidu and AutoNavi migration flows,exhibit a high degree of structure equivalence.The correlation coefficient between these two networks is 0.874.Both networks exhibit a pronounced spatial polarization trend and hierarchical structure.This is evident in their distinct core and peripheral structures,as well as in the varying importance and influence of different nodes within the networks.Nevertheless,there are notable differences worthy of attention.Baidu intercity interactive network exhibits pronounced cross-regional effects,and its high-level interactions are characterized by a“rich-club”phenomenon.The AutoNavi intercity interactive network presents a more significant distance attenuation effect,and the high-level interactions display a gradient distribution pattern.Notably,there exists a substantial correlation between the AutoNavi and MP networks at the local scale,evidenced by a high correlation coefficient of 0.954.Furthermore,the“spatial dislocations”phenomenon was observed within the spatial structures at different levels,extracted from the Baidu and AutoNavi intercity networks.However,the measured results of network spatial structure similarity from three dimensions,namely,node location,node size,and local structure,indicate a relatively high similarity and consistency between the two networks.展开更多
This study explores the impact of intergenerational differences on farmers' terrace abandonment in response to increasing intergenerational differentiation among rural households and the practical issue of terrace...This study explores the impact of intergenerational differences on farmers' terrace abandonment in response to increasing intergenerational differentiation among rural households and the practical issue of terrace abandonment. Logit and Tobit models are employed to conduct empirical analysis and it is found that terrace abandonment increases sequentially among the new, middle, and old generations, confirming that intergenerational differences significantly influence whether farmers abandon terraces and the terrace abandonment scale. Village characteristics and government subsidies significantly influence farmers' terrace abandonment. An increase in the number of migrant workers in the village increases terrace abandonment among new and middle generation farmers, whereas an increase in the distance from the village to the county significantly increases terrace abandonment among old generation farmers. An increase in the village's total population significantly reduces terrace abandonment among new generation farmers. An increase in government subsidies significantly reduces terrace abandonment among middle and old generation farmers. The impact of intergenerational differences on terrace abandonment is more pronounced in low-altitude areas. To reduce terrace abandonment, it is necessary to promote terrace transfer, develop characteristic agriculture, improve terrace farming subsidies, and propose targeted strategies for the different generations of farmers.展开更多
In this paper,we propose a hybrid decode-and-forward and soft information relaying(HDFSIR)strategy to mitigate error propagation in coded cooperative communications.In the HDFSIR approach,the relay operates in decode-...In this paper,we propose a hybrid decode-and-forward and soft information relaying(HDFSIR)strategy to mitigate error propagation in coded cooperative communications.In the HDFSIR approach,the relay operates in decode-and-forward(DF)mode when it successfully decodes the received message;otherwise,it switches to soft information relaying(SIR)mode.The benefits of the DF and SIR forwarding strategies are combined to achieve better performance than deploying the DF or SIR strategy alone.Closed-form expressions for the outage probability and symbol error rate(SER)are derived for coded cooperative communication with HDFSIR and energy-harvesting relays.Additionally,we introduce a novel normalized log-likelihood-ratio based soft estimation symbol(NL-SES)mapping technique,which enhances soft symbol accuracy for higher-order modulation,and propose a model characterizing the relationship between the estimated complex soft symbol and the actual high-order modulated symbol.Further-more,the hybrid DF-SIR strategy is extended to a distributed Alamouti space-time-coded cooperative network.To evaluate the~performance of the proposed HDFSIR strategy,we implement extensive Monte Carlo simulations under varying channel conditions.Results demonstrate significant improvements with the hybrid technique outperforming individual DF and SIR strategies in both conventional and distributed Alamouti space-time coded cooperative networks.Moreover,at a SER of 10^(-3),the proposed NL-SES mapping demonstrated a 3.5 dB performance gain over the conventional averaging one,highlighting its superior accuracy in estimating soft symbols for quadrature phase-shift keying modulation.展开更多
To understand career adaptability among undergraduates majoring in Primary Education in provincial normal universities,this study surveyed 257 such students and analyzed the current state and characteristics of their ...To understand career adaptability among undergraduates majoring in Primary Education in provincial normal universities,this study surveyed 257 such students and analyzed the current state and characteristics of their career adaptability.The results indicate that their overall career adaptability is moderately high.Significant differences in career adaptability were found by program type.Maternal education exerted a notable influence on overall career adaptability and on the“career confidence”dimension,whereas paternal education only showed a highly significant effect on“career confidence.”Therefore,schools should consolidate their role as the main arena for education,while families should provide supportive environments,jointly addressing the career adaptation and development needs of Primary Education undergraduates and further enhancing their career adaptability.展开更多
This article compares the cognitive differences and influencing factors of traditional Chinese medicine culture among rural residents in Guigang,Guangxi,and Jinhua,Zhejiang,providing a reference for balanced developme...This article compares the cognitive differences and influencing factors of traditional Chinese medicine culture among rural residents in Guigang,Guangxi,and Jinhua,Zhejiang,providing a reference for balanced development.A stratified sampling method was used to conduct a questionnaire survey in three townships in each region,and data were analyzed using SPSS 25.0 and chi-square test.The survey shows that residents in Guigang rely more on personal experience for their understanding,resulting in fragmented cognition,with their needs concentrated on disease treatment.On the other hand,residents in Jinhua rely on rational trust and digital communication,leading to deeper cognition,and their needs tend to focus on preventive healthcare.Occupational factors significantly affect the cognitive level in Jinhua,while in Guigang,it is closely related to trust and cultural atmosphere.The interaction of regional economy,occupational background,and cultural tradition affects cognitive differences.It is suggested that Guigang should build a community traditional Chinese medicine cultural experience matrix,develop digital content for ethnic medical resources,and strengthen the“experience-identification-dissemination”closed loop.Jinhua should deepen the construction of digital IP and promote the integration of industry and education.The two regions should jointly build a cross-regional cultural corridor,cultivate inheritors,and use new media to expand the coverage of dissemination.展开更多
In this paper, performance of space-time trellis-code (STTC), space-time block code (STBC), and space-time trellis-code concatenated with space-time block code (STTC-STBC) for multi-carrier code-division multiple-acce...In this paper, performance of space-time trellis-code (STTC), space-time block code (STBC), and space-time trellis-code concatenated with space-time block code (STTC-STBC) for multi-carrier code-division multiple-access (MC-CDMA) system are studied. These schemes are considered by employing different detection techniques with various multi input multi output (MIMO) antenna diversity for different number of states in multi-path fading channel. The corresponding bit error rate (BER) is obtained using simulation for minimum mean-square error (MMSE), maximum-ratio combining (MRC), and equal-gain combining (EGC) receivers employing Viterbi decoder. The simulation results show that the STTC-STBC MC-CDMA system perform better compared to other schemes considered in this paper using MMSE detection and it is also observed that the performance can also be enhanced by increasing diversity using more transmitter and receiver antennas. However, this improvement in performance comes at the cost of increased computational complexity, which is calculated for different transmitting and receiving antennas.展开更多
Objectives:Suicidal ideation is a strong predictor of suicide deaths,which refers to the consideration or desire to give up one's own life.Left-behind children in rural China are more vulnerable to psychological p...Objectives:Suicidal ideation is a strong predictor of suicide deaths,which refers to the consideration or desire to give up one's own life.Left-behind children in rural China are more vulnerable to psychological problems and suicidal ideation compared to their non-left-behind peers.The aim of the current study was to examine two potential protective factors,negotiable fate belief and coping self-efficacy,and to test the mediating role of coping self-efficacy in the relationship between negotiable fate belief and suicidal ideation.We also analyzed gender differences in this mediation model.Methods:Across-sectional survey was conducted in rural areas ofChina.A sample of 526 left-behind children(285 males,54.18%;241 females,45.82%;Meanage=13.29 years,SD=0.97 years)was recruited to complete the Negotiable Fate Belief Scale,Coping Self-Efficacy Scale,and the Positive and Negative Suicide Ideation Inventory-Negative Scale.We used structural equation modeling to test the mediation model and multigroup analysis to test the moderation effect of gender.Results:Negotiable fate belief is negatively correlated with suicidal ideation(r=-0.13,p<0.01).Moreover,coping self-efficacy mediates the relationship between negotiable fate belief and suicidal ideation(β=-0.06,95%confidence interval(CI)[-0.12,-0.02]),accounting for 35.29%of the total effect.Finally,the mediating effect of coping self-efficacy was found to be significant only for female left-behind children(male:95%CI[-0.09,0.07];female:95%CI[-0.16,-0.01]).For female left-behind children,the mediating effect was complete,with a coefficient of-0.06,accounting for 85.71%of the total effect.Conclusions:The relationship between negotiable fate belief and suicidal ideation among rural left-behind children is mediated by coping self-efficacy,and this mediation effect was moderated by gender.This study provides a theoretical explanation for how cultivating the belief in negotiable fate and coping self-efficacy is effective for reducing suicidal ideation of rural left-behind children.展开更多
In this paper,we mainly discuss a discrete estimation of the average differential entropy for a continuous time-stationary ergodic space-time random field.By estimating the probability value of a time-stationary rando...In this paper,we mainly discuss a discrete estimation of the average differential entropy for a continuous time-stationary ergodic space-time random field.By estimating the probability value of a time-stationary random field in a small range,we give an entropy estimation and obtain the average entropy estimation formula in a certain bounded space region.It can be proven that the estimation of the average differential entropy converges to the theoretical value with a probability of 1.In addition,we also conducted numerical experiments for different parameters to verify the convergence result obtained in the theoretical proofs.展开更多
基金The National Natural Science Foundation of China(No60572072,60496311)the National High Technology Research and Development Program of China (863Program) (No2006AA01Z264)+1 种基金the National Basic Research Program of China (973Program) (No2007CB310603)the PhD Programs Foundation of Ministry of Educa-tion of China (No20060286016)
文摘The performance loss of an approximately 3 dB signal-to-noise ratio is always paid with conventional differential detection compared to the related coherent detection. A new detection scheme consisting of two steps is proposed for the differential unitary space-time modulation （DUSTM） system. In the first step, the data sequence is estimated by conventional unitary space-time demodulation （DUSTD） and differentially encoded again to produce an initial estimate of the transmitted symbol stream. In the second step, the initial estimate of the symbol stream is utilized to initialize an expectation maximization （EM）-based iterative detector. In each iteration, the most recent detected symbol stream is employed to estimate the channel, which is then used to implement coherent sequence detection to refine the symbol stream. Simulation results show that the proposed detection scheme performs much better than the conventional DUSTD after several iterations.
基金co-supported by the National Natural Science Foundation of China(No.51976172)the National Science and Technology Major Project of China(No.2017-Ⅱ-0009-0023)。
文摘This paper revisits the Space-Time Gradient(STG) method which was developed for efficient analysis of unsteady flows due to rotor–stator interaction and presents the method from an alternative time-clocking perspective. The STG method requires reordering of blade passages according to their relative clocking positions with respect to blades of an adjacent blade row. As the space-clocking is linked to an equivalent time-clocking, the passage reordering can be performed according to the alternative time-clocking. With the time-clocking perspective, unsteady flow solutions from different passages of the same blade row are mapped to flow solutions of the same passage at different time instants or phase angles. Accordingly, the time derivative of the unsteady flow equation is discretized in time directly, which is more natural than transforming the time derivative to a spatial one as with the original STG method. To improve the solution accuracy, a ninth order difference scheme has been investigated for discretizing the time derivative. To achieve a stable solution for the high order scheme, the implicit solution method of Lower-Upper Symmetric GaussSeidel/Gauss-Seidel(LU-SGS/GS) has been employed. The NASA Stage 35 and its blade-countreduced variant are used to demonstrate the validity of the time-clocking based passage reordering and the advantages of the high order difference scheme for the STG method. Results from an existing harmonic balance flow solver are also provided to contrast the two methods in terms of solution stability and computational cost.
文摘In this article,we establish new and more general traveling wave solutions of space-time fractional Klein–Gordon equation with quadratic nonlinearity and the space-time fractional breaking soliton equations using the modified simple equation method.The proposed method is so powerful and effective to solve nonlinear space-time fractional differential equations by with modified Riemann–Liouville derivative.
基金Project supported by the Hi-Tech Research and Development Pro-gram (863) of China (No. 2003AA123310) and the National Natural Science Foundation of China (No. 60272079)
文摘Differential space-time coding was proposed recently in the literature for multi-antenna systems, where neither the transmitter nor the receiver knows the fading coefficients. Among existing schemes, double differential space-time (DDST) coding is of special interest because it is applicable to continuous fast time-varying channels. However, it is less effective in fre- quency-selective fading channels. This paper’s authors derived a novel time-frequency double differential space-time (TF-DDST) coding scheme for multi-antenna orthogonal frequency division multiplexing (OFDM) systems in a time-varying fre- quency-selective fading environment, where double differential space-time coding is introduced into both time domain and fre- quency domain. Our proposed TF-DDST-OFDM system has a low-complexity non-coherent decoding scheme and is robust for time- and frequency-selective Rayleigh fading. In this paper, we also propose the use of state-of-the-art low-density parity-check (LDPC) code in serial concatenation with our TF-DDST scheme as a channel code. Simulations revealed that the LDPC based TF-DDST OFDM system has low decoding complexity and relatively better performance.
文摘Background: For nursing students, gathering social information is essential for understanding healthcare and social issues and developing critical thinking and decision-making skills. However, the choice of information sources varies by age and individual habits. With the widespread use of the internet, there are notable differences between younger and older generations in their reliance on the internet versus traditional media sources like newspapers and television. Given the wide age range and diverse backgrounds of nursing students, understanding generational differences in information-gathering methods is important for implementing effective education. Purpose: The purpose of this study is to identify how nursing students in different age groups obtain social information and to examine media usage trends by age group. Additionally, we aim to use the findings to provide insights into effective information dissemination methods in nursing education. Results: The results showed that nursing students in their teens to forties, regardless of gender, primarily relied on the internet as their main information source, with television playing a secondary role. In contrast, students in their fifties tended to obtain information more often from newspapers and television than from the internet. This highlights an age-related difference in preferred information sources, with older students showing a greater reliance on traditional media. Conclusions: This study demonstrates that nursing students use different information-gathering methods based on their age, suggesting a need to custo-mize information dissemination strategies in nursing education. Digital media may be more effective for younger students, while traditional media or printed materials might better serve older students. Educational institutions should consider these generational differences in media usage and adopt strategies that meet the diverse needs of their student populations.
基金supported by the Natural Science Foundation of Hunan Province(2023JJ30817)Hunan Provincial Natural Science Foundation-Hengyang City Joint Fund Project(2025JJ70129)+1 种基金Changsha Natural Science Foundation(kq2403057)China。
文摘Objective:Near vision loss(NVL)is one of the leading causes of visual impairment worldwide,exerting a profound impact on individual quality of life and socio-economic development.This study aims to analyze the burden of NVL in China by sex and age groups from 1990 to 2021 and to project trends over the next 15 years.Methods:Using data from the Global Burden of Disease(GBD)2021 database,we conducted descriptive analyses of NVL prevalence in China,calculated age-standardized prevalence rates(ASPR)and age-standardized disability-adjusted life years rates(ASDR)to compare burden differences between sexes and age groups,and applied an autoregressive integrated moving average(ARIMA)model to predict NVL trends for the next 15 years.The model selection was based on best-fit criteria to ensure reliable projections.Results:From 1990 to 2021,China’s ASPR of NVL rose from 10096.24/100000 to 15624.54/100000,and ASDR increased from 101.75/100000 to 158.75/100000.In 2021,ASPR(16551.70/100000)and ASDR(167.69/100000)were higher among females than males(14686.21/100000 and 149.76/100000,respectively).China ranked highest globally in both NVL cases and disability-adjusted life years(DALYs),with female burden significantly exceeding male burden.Projections indicated this trend and sex gap will persist until 2036.Compared with 1990,the prevalence cases and DALYs increased by 239.20%and 238.82%,respectively in 2021,with the highest burden among females and the 55−59 age group.The ARIMA model predicted continued increases in prevalence and DALYs by 2036,with females maintaining a higher burden than males.Conclusion:This study reveals a marked increase in the NVL burden in China and predicts continued growth in the coming years.Public health policies should prioritize NVL prevention and control,with special attention to women and middle-aged populations to mitigate long-term societal and health impacts.
基金Supported by The Sanming Project of Medicine in Shenzhen,No.SZSM202211003Shenzhen-Hong Kong Jointly Funded Project,Shenzhen Science and Technology Program,No.SGDX20230116093645007+1 种基金Shenzhen Second People's Hospital Clinical Project,No.20243357003Shenzhen Medical Research Fund,No.B2303005.
文摘BACKGROUND Depression and anxiety are prevalent psychological challenges among patients with adolescent idiopathic scoliosis(AIS),affecting individuals across both sex and age groups.AIM To explore the network structure of depression and anxiety symptoms,with a focus on identifying differences at the symptom level between sex and age subgroups.METHODS A total of 1955 participants diagnosed with AIS aged 10-18 years were assessed using the Patient Health Questionnaire Depression Scale(PHO-9)and the Generalized Anxiety Disorder Scale(GAD-7),and 765 patients exhibiting PHQ-9 or GAD-7 scores ≥ 5 were enrolled in our study. Network analysis and network comparison tests were utilized toconstruct and compare the depression-anxiety symptoms networks among sex and age subgroups.RESULTSThe results revealed GAD3 “Excessive worry” and PHQ2 “Sad mood” were the most significant central symptomsin all subgroups, while “Sad mood” had higher strength than “Excessive worry” in the lower age group. In thenetwork comparisons, the female network exhibited tighter connectivity, especially on GAD6 “Irritability” andGAD2 “Uncontrollable worry”, while only PHQ3 “Sleep” and PHQ9 “Suicidal ideation” had differences at thelocal level in the lower age group.CONCLUSIONSeveral interventions targeting excessive worry and sad mood could reduce the risk of depression and anxietysymptoms in the AIS population. Furthermore, specific anxiety symptoms in females, along with sleep disturbancesand suicidal ideation in the lower age group, should be addressed at an early stage to prevent significantdisruptions in mental health trajectories.
基金supported by the Advance Research Project of Civil Aerospace Technology(Grant No.D020304)National Nat-ural Science Foundation of China(Grant Nos.52205257 and U22B2083).
文摘This paper proposes a new step-by-step Chebyshev space-time spectral method to analyze the force vibration of functionally graded material structures.Although traditional space-time spectral methods can reduce the accuracy mismatch between tem-poral low-order finite difference and spatial high-order discre tization,the ir time collocation points must increase dramatically to solve highly oscillatory solutions of structural vibration,which results in a surge in computing time and a decrease in accuracy.To address this problem,we introduced the step-by-step idea in the space-time spectral method.The Chebyshev polynomials and Lagrange's equation were applied to derive discrete spatial goverming equations,and a matrix projection method was used to map the calculation results of prev ious steps as the initial conditions of the subsequent steps.A series of numerical experiments were carried out.The results of the proposed method were compared with those obtained by traditional space-time spectral methods,which showed that higher accuracy could be achieved in a shorter computation time than the latter in highly oscillatory cases.
基金National Key R&D Program of China,Grant/Award Number:2021YFF0703200Key Technology Fund of the National Institutes for Food and Drug Control,Grant/Award Number:GJJS-2022-1-5。
文摘Experimental mice play a critical role in biomedical research.The phenotype and application of different substrains vary due to genetic differentiation and variation.To ensure validity and reliability of results,it is imperative to adhere to standardized experiments and controls.This paper objectively reviews the origin,differentiation,and phenotypic and genetic differences between the C57BL/6 and BALB/c mouse substrains.Furthermore,an optimal selection strategy is proposed based on the genetic quality control technology to facilitate the precise application of these two mouse substrains.
基金supported by Beijing Municipal Natural Science Foundation(L222002)the Natural Science Foundation of China(U22B2004).
文摘Existing orthogonal space-time block coding(OSTBC)schemes for backscatter communication systems cannot achieve a full transmission code rate when the tag is equipped with more than two antennas.In this paper,we propose a quasi-orthogonal spacetime block code(QOSTBC)that can achieve a full transmission code rate for backscatter communication systems with a four-antenna tag and then extend the scheme to support tags with 2i antennas.Specifically,we first present the system model for the backscatter system.Next,we propose the QOSTBC scheme to encode the tag signals.Then,we provide the corresponding maximum likelihood detection algorithms to recover the tag signals.Finally,simulation results are provided to demonstrate that our proposed QOSTBC scheme and the detection algorithm can achieve a better transmission code rate or symbol error rate performance for backscatter communication systems compared with benchmark schemes.
基金National Natural Science Foundation of China,No.42361040。
文摘Population migration data derived from location-based services has often been used to delineate population flows between cities or construct intercity relationship networks to reveal and explore the complex interaction patterns underlying human activities.Nevertheless,the inherent heterogeneity in multimodal migration big data has been ignored.This study conducts an in-depth comparison and quantitative analysis through a comprehensive lens of spatial association.Initially,the intercity interactive networks in China were constructed,utilizing migration data from Baidu and AutoNavi collected during the same time period.Subsequently,the characteristics and spatial structure similarities of the two types of intercity interactive networks were quantitatively assessed and analyzed from overall(network)and local(node)perspectives.Furthermore,the precision of these networks at the local scale is corroborated by constructing an intercity network from mobile phone(MP)data.Results indicate that the intercity interactive networks in China,as delineated by Baidu and AutoNavi migration flows,exhibit a high degree of structure equivalence.The correlation coefficient between these two networks is 0.874.Both networks exhibit a pronounced spatial polarization trend and hierarchical structure.This is evident in their distinct core and peripheral structures,as well as in the varying importance and influence of different nodes within the networks.Nevertheless,there are notable differences worthy of attention.Baidu intercity interactive network exhibits pronounced cross-regional effects,and its high-level interactions are characterized by a“rich-club”phenomenon.The AutoNavi intercity interactive network presents a more significant distance attenuation effect,and the high-level interactions display a gradient distribution pattern.Notably,there exists a substantial correlation between the AutoNavi and MP networks at the local scale,evidenced by a high correlation coefficient of 0.954.Furthermore,the“spatial dislocations”phenomenon was observed within the spatial structures at different levels,extracted from the Baidu and AutoNavi intercity networks.However,the measured results of network spatial structure similarity from three dimensions,namely,node location,node size,and local structure,indicate a relatively high similarity and consistency between the two networks.
基金Key Program of National Natural Science Foundation of China,No.41930757National Natural Science Foundation of China,No.42371285。
文摘This study explores the impact of intergenerational differences on farmers' terrace abandonment in response to increasing intergenerational differentiation among rural households and the practical issue of terrace abandonment. Logit and Tobit models are employed to conduct empirical analysis and it is found that terrace abandonment increases sequentially among the new, middle, and old generations, confirming that intergenerational differences significantly influence whether farmers abandon terraces and the terrace abandonment scale. Village characteristics and government subsidies significantly influence farmers' terrace abandonment. An increase in the number of migrant workers in the village increases terrace abandonment among new and middle generation farmers, whereas an increase in the distance from the village to the county significantly increases terrace abandonment among old generation farmers. An increase in the village's total population significantly reduces terrace abandonment among new generation farmers. An increase in government subsidies significantly reduces terrace abandonment among middle and old generation farmers. The impact of intergenerational differences on terrace abandonment is more pronounced in low-altitude areas. To reduce terrace abandonment, it is necessary to promote terrace transfer, develop characteristic agriculture, improve terrace farming subsidies, and propose targeted strategies for the different generations of farmers.
基金funded by the Deanship of Graduate Studies and Scientific Research at Jouf University under grant No.(DGSSR-2024-02-02160).
文摘In this paper,we propose a hybrid decode-and-forward and soft information relaying(HDFSIR)strategy to mitigate error propagation in coded cooperative communications.In the HDFSIR approach,the relay operates in decode-and-forward(DF)mode when it successfully decodes the received message;otherwise,it switches to soft information relaying(SIR)mode.The benefits of the DF and SIR forwarding strategies are combined to achieve better performance than deploying the DF or SIR strategy alone.Closed-form expressions for the outage probability and symbol error rate(SER)are derived for coded cooperative communication with HDFSIR and energy-harvesting relays.Additionally,we introduce a novel normalized log-likelihood-ratio based soft estimation symbol(NL-SES)mapping technique,which enhances soft symbol accuracy for higher-order modulation,and propose a model characterizing the relationship between the estimated complex soft symbol and the actual high-order modulated symbol.Further-more,the hybrid DF-SIR strategy is extended to a distributed Alamouti space-time-coded cooperative network.To evaluate the~performance of the proposed HDFSIR strategy,we implement extensive Monte Carlo simulations under varying channel conditions.Results demonstrate significant improvements with the hybrid technique outperforming individual DF and SIR strategies in both conventional and distributed Alamouti space-time coded cooperative networks.Moreover,at a SER of 10^(-3),the proposed NL-SES mapping demonstrated a 3.5 dB performance gain over the conventional averaging one,highlighting its superior accuracy in estimating soft symbols for quadrature phase-shift keying modulation.
基金supported by the School-Level Teaching Reform Research Project of Qilu Normal University(JG202304Z)the Research Project and Platform Cultivation Project for Education and Teaching Reform of Qilu Normal University(BP202416).
文摘To understand career adaptability among undergraduates majoring in Primary Education in provincial normal universities,this study surveyed 257 such students and analyzed the current state and characteristics of their career adaptability.The results indicate that their overall career adaptability is moderately high.Significant differences in career adaptability were found by program type.Maternal education exerted a notable influence on overall career adaptability and on the“career confidence”dimension,whereas paternal education only showed a highly significant effect on“career confidence.”Therefore,schools should consolidate their role as the main arena for education,while families should provide supportive environments,jointly addressing the career adaptation and development needs of Primary Education undergraduates and further enhancing their career adaptability.
文摘This article compares the cognitive differences and influencing factors of traditional Chinese medicine culture among rural residents in Guigang,Guangxi,and Jinhua,Zhejiang,providing a reference for balanced development.A stratified sampling method was used to conduct a questionnaire survey in three townships in each region,and data were analyzed using SPSS 25.0 and chi-square test.The survey shows that residents in Guigang rely more on personal experience for their understanding,resulting in fragmented cognition,with their needs concentrated on disease treatment.On the other hand,residents in Jinhua rely on rational trust and digital communication,leading to deeper cognition,and their needs tend to focus on preventive healthcare.Occupational factors significantly affect the cognitive level in Jinhua,while in Guigang,it is closely related to trust and cultural atmosphere.The interaction of regional economy,occupational background,and cultural tradition affects cognitive differences.It is suggested that Guigang should build a community traditional Chinese medicine cultural experience matrix,develop digital content for ethnic medical resources,and strengthen the“experience-identification-dissemination”closed loop.Jinhua should deepen the construction of digital IP and promote the integration of industry and education.The two regions should jointly build a cross-regional cultural corridor,cultivate inheritors,and use new media to expand the coverage of dissemination.
文摘In this paper, performance of space-time trellis-code (STTC), space-time block code (STBC), and space-time trellis-code concatenated with space-time block code (STTC-STBC) for multi-carrier code-division multiple-access (MC-CDMA) system are studied. These schemes are considered by employing different detection techniques with various multi input multi output (MIMO) antenna diversity for different number of states in multi-path fading channel. The corresponding bit error rate (BER) is obtained using simulation for minimum mean-square error (MMSE), maximum-ratio combining (MRC), and equal-gain combining (EGC) receivers employing Viterbi decoder. The simulation results show that the STTC-STBC MC-CDMA system perform better compared to other schemes considered in this paper using MMSE detection and it is also observed that the performance can also be enhanced by increasing diversity using more transmitter and receiver antennas. However, this improvement in performance comes at the cost of increased computational complexity, which is calculated for different transmitting and receiving antennas.
基金funded by the 2023Laibin City Philosophy and Social Science Research Project(No.2023LBZS035)2024Guangxi Student Innovation and Entrepreneurship Training Program Project(No.S202411546046X)2025 Research Project of Guangxi Science&Technology Normal University(No.GXKS2025YB020).
文摘Objectives:Suicidal ideation is a strong predictor of suicide deaths,which refers to the consideration or desire to give up one's own life.Left-behind children in rural China are more vulnerable to psychological problems and suicidal ideation compared to their non-left-behind peers.The aim of the current study was to examine two potential protective factors,negotiable fate belief and coping self-efficacy,and to test the mediating role of coping self-efficacy in the relationship between negotiable fate belief and suicidal ideation.We also analyzed gender differences in this mediation model.Methods:Across-sectional survey was conducted in rural areas ofChina.A sample of 526 left-behind children(285 males,54.18%;241 females,45.82%;Meanage=13.29 years,SD=0.97 years)was recruited to complete the Negotiable Fate Belief Scale,Coping Self-Efficacy Scale,and the Positive and Negative Suicide Ideation Inventory-Negative Scale.We used structural equation modeling to test the mediation model and multigroup analysis to test the moderation effect of gender.Results:Negotiable fate belief is negatively correlated with suicidal ideation(r=-0.13,p<0.01).Moreover,coping self-efficacy mediates the relationship between negotiable fate belief and suicidal ideation(β=-0.06,95%confidence interval(CI)[-0.12,-0.02]),accounting for 35.29%of the total effect.Finally,the mediating effect of coping self-efficacy was found to be significant only for female left-behind children(male:95%CI[-0.09,0.07];female:95%CI[-0.16,-0.01]).For female left-behind children,the mediating effect was complete,with a coefficient of-0.06,accounting for 85.71%of the total effect.Conclusions:The relationship between negotiable fate belief and suicidal ideation among rural left-behind children is mediated by coping self-efficacy,and this mediation effect was moderated by gender.This study provides a theoretical explanation for how cultivating the belief in negotiable fate and coping self-efficacy is effective for reducing suicidal ideation of rural left-behind children.
基金supported by the Shenzhen sustainable development project:KCXFZ 20201221173013036 and the National Natural Science Foundation of China(91746107).
文摘In this paper,we mainly discuss a discrete estimation of the average differential entropy for a continuous time-stationary ergodic space-time random field.By estimating the probability value of a time-stationary random field in a small range,we give an entropy estimation and obtain the average entropy estimation formula in a certain bounded space region.It can be proven that the estimation of the average differential entropy converges to the theoretical value with a probability of 1.In addition,we also conducted numerical experiments for different parameters to verify the convergence result obtained in the theoretical proofs.
