In this paper,we propose a sub-6GHz channel assisted hybrid beamforming(HBF)for mmWave system under both line-of-sight(LOS)and non-line-of-sight(NLOS)scenarios without mmWave channel estimation.Meanwhile,we resort to ...In this paper,we propose a sub-6GHz channel assisted hybrid beamforming(HBF)for mmWave system under both line-of-sight(LOS)and non-line-of-sight(NLOS)scenarios without mmWave channel estimation.Meanwhile,we resort to the selfsupervised approach to eliminate the need for labels,thus avoiding the accompanied high cost of data collection and annotation.We first construct the dense connection network(DCnet)with three modules:the feature extraction module for extracting channel characteristic from a large amount of channel data,the feature fusion module for combining multidimensional features,and the prediction module for generating the HBF matrices.Next,we establish a lightweight network architecture,named as LDnet,to reduce the number of model parameters and computational complexity.The proposed sub-6GHz assisted approach eliminates mmWave pilot resources compared to the method using mmWave channel information directly.The simulation results indicate that the proposed DCnet and LDnet can achieve the spectral efficiency that is superior to the traditional orthogonal matching pursuit(OMP)algorithm by 13.66% and 10.44% under LOS scenarios and by 32.35% and 27.75% under NLOS scenarios,respectively.Moreover,the LDnet achieves 98.52% reduction in the number of model parameters and 22.93% reduction in computational complexity compared to DCnet.展开更多
This work aimed to study the efficiency of the reverse micelle(RM)preparation route in the syntheses of sub-5 nm Fe-doped CeO_(2)nanocrystals for boosting the visible-light-driven photocatalytic hydrogen production fr...This work aimed to study the efficiency of the reverse micelle(RM)preparation route in the syntheses of sub-5 nm Fe-doped CeO_(2)nanocrystals for boosting the visible-light-driven photocatalytic hydrogen production from methanol aqueous solutions.The effectiveness of confining precipitation reactions within micellar cages was evaluated through extensive physicochemical cha racterization.In particula r,the nominal composition(0-5 mol%Fe)was preserved as ascertained by ICP-MS analysis,and the absence of separate iron-containing crystalline phases was supported by X-ray diffraction.The effective aliovalent doping and modulation of the optical properties were investigated using UV-Vis,Raman,and photoluminescence spectroscopies.2.5 mol%iron was found to be an optimal content to achieve a significant decrease in the band gap,enhance the concentration of oxygen vacancy defects,and increase the charge carrier lifetime.The photocatalytic activity of Fe-doped CeO_(2)prepared at different Fe contents with RM preparation was studied and compared with undoped CeO_(2).The optimal iron load was identified to be2.5 mol%,achieving the highest hydrogen production(7566μmol L-1after 240 min under visible light).Moreover,for comparison,the conventional precipitation(P)method was adopted to prepare iron containing CeO_(2)at the optimal content(2.5 mol%Fe).The Fe-doped CeO_(2)catalyst prepared by RM showed a significantly higher hydrogen production than that obtained with the sample prepared by the P method.The optimal Fe-doped CeO_(2),prepared by the RM method,was stable for six reuse cycles.Moreover,the role of water in the mechanism of photocatalytic hydrogen evolution under visible light was studied through the test in the presence of D2O.The obtained results evidenced that hydrogen was produced from the reduction of H^(+)by the electrons promoted in the conduction band,while methanol was preferentially oxidized by the photogenerated positive holes.展开更多
Magnetic tunnel junction(MTJ) based spin transfer torque magnetic random access memory(STT-MRAM) has been gaining tremendous momentum in high performance microcontroller(MCU) applications. As e Flash-replacement type ...Magnetic tunnel junction(MTJ) based spin transfer torque magnetic random access memory(STT-MRAM) has been gaining tremendous momentum in high performance microcontroller(MCU) applications. As e Flash-replacement type MRAM approaches mass production, there is an increasing demand for non-volatile RAM(nv RAM) technologies that offer fast write speed and high endurance. In this work, we demonstrate highly reliable 4 Mb nv RAM type MRAM suitable for industry and auto grade-1 applications. This nv RAM features retention over 10 years at 125 ℃, endurance of 1 × 10^(12)cycles with 20 ns write speed, making it ideal for applications requiring both high speed and broad temperature ranges. By employing innovative MTJ materials, process engineering, and a co-optimization of process and design, reliable read and write performance across the full temperature range between -40 to 125 ℃, and array yield that meets sub-1 ppm error rate was significantly improved from 0 to above 95%, a concrete step toward applications.展开更多
Background: Unsafe abortion (USA) is defined as the termination of a non-desired pregnancy, performed by an unqualified person or in an environment without minimum medical standards, or both. It can impact negatively ...Background: Unsafe abortion (USA) is defined as the termination of a non-desired pregnancy, performed by an unqualified person or in an environment without minimum medical standards, or both. It can impact negatively the fertility in the future by tubo-peritoneal lesions. The current study aimed to highlight the infertility factors associated with USA. Material and Methods: From January 1st 2000 to December 31st 2021, a total of 3876 patients that sought care for infertility in the University Clinic of Kinshasa and the Edith Medical Center were enrolled. The socio-demographic, clinical and paraclinical variables were recorded and analyzed in relation to USA history. Results: The patients’ average age was 33.4 ± 5.7 years. Half of them were housewives;about sixty percent of the patients were nulliparous (59.31%). Seventy percent had a secondary infertility with 43.33% having a history of unsafe abortion. The main diagnosis was genital infections and uterus myoma. The chronic endometritis, bilateral tubal occlusion and Uterine synechiae were more associated with USA group. The spermogram anomalies and other partners’ lesions seemed of infectious origin. Conclusion: The USA remains a more frequent phenomenon in our setting. The chronic endometritis, bilateral tubal occlusion, uterine synechiae and indirectly uterus myoma were the infertility factors related to USA. The genital infection of any origin seems to be the main denominator underlying the female and the male infertility in our setting.展开更多
In this article, we deal with weak solutions to non-degenerate sub-elliptic equations in the Heisenberg group, and study the regularities of solutions. We establish horizontal Calderón-Zygmund type estimate in Be...In this article, we deal with weak solutions to non-degenerate sub-elliptic equations in the Heisenberg group, and study the regularities of solutions. We establish horizontal Calderón-Zygmund type estimate in Besov spaces with more general assumptions on coefficients for both homogeneous equations and non-homogeneous equations. This study of regularity estimates expands the Calderón-Zygmund theory in the Heisenberg group.展开更多
Introduction: Hepatitis B is an infectious disease that remains a real public health problem in Africa. Students represent a group at risk for this disease. The objective of this study was to estimate the hepatitis B ...Introduction: Hepatitis B is an infectious disease that remains a real public health problem in Africa. Students represent a group at risk for this disease. The objective of this study was to estimate the hepatitis B vaccination coverage rate among students in sub-Saharan Africa. Methods: A systematic search of databases (PubMed, AJOL) and a manual search of Google Scholar was conducted to retrieve all published studies reporting hepatitis B vaccination coverage among students in sub-Saharan Africa. The pooled coverage rate was estimated with a 95% confidence interval (CI) in a random-effects meta-analysis. Results: A total of 35 studies were included and included 20,520 students. The mean age was 22.1 ± 5.1 years with a predominance of female sex (sex ratio F/M = 1.05). The vaccination coverage rate was 28.8% [95% CI: 22.9% - 34.7%]. Disaggregation allowed to estimate coverage rates of 29.8% [95% CI: 22.9% - 36.7%], 23.4% [95% CI: 9.4% - 37.4%] and 17.0% [95% CI: 14.4% - 19.5%] respectively in West Africa, East Africa and Central Africa. Conclusion: Less than a third of students in sub-Saharan Africa are protected against hepatitis B. However, the majority of this target group is at risk of infection. It would be relevant to screen and, if necessary, vaccinate all new students.展开更多
Research background: Breast cancer remains a major public health problem, with a high number of new cases and deaths each year. However, despite advances in research to improve this disease, there is a high rate of la...Research background: Breast cancer remains a major public health problem, with a high number of new cases and deaths each year. However, despite advances in research to improve this disease, there is a high rate of late detection, leading to diagnosis at an advanced stage and a reduced chance of survival. Objective: The aim of this study is to identify the factors associated with late detection of breast cancer in women in Sub-Saharan Africa from 2014 to 2020.Setting: This systematic review focuses on sub-Saharan Africa. Methods: We searched for articles in four databases (PubMed, Embase, Global-Health and CINAHL) between 2014 and 2020 and performed a narrative synthesis to organize and group the different factors associated with late breast cancer detection. Result: After reviewing 583 publications, 6 studies were selected, highlighting factors such as lack of awareness, knowledge gaps, difficulties in accessing health services and financial constraints associated with late breast cancer screening. The participants, who ranged in number from 20 to 1776, were mainly aged between 18 and 25, with a mean age of 25 years and 6 months. Conclusion: The analysis enabled us to identify various factors associated with late breast cancer screening. Collaboration between health professionals, community organizations and policy-makers is essential to foster an environment conducive to the prevention and early detection of breast cancer.展开更多
Background: Evidence-based practice (EBP) is vital for high-quality patient care, yet its implementation among physiotherapists in sub-Saharan Africa (SSA) faces significant challenges. This scoping review explores th...Background: Evidence-based practice (EBP) is vital for high-quality patient care, yet its implementation among physiotherapists in sub-Saharan Africa (SSA) faces significant challenges. This scoping review explores the barriers and facilitators of EBP in this region. Objectives: To identify barriers and facilitators of EBP at individual, organisational, and extra organisational levels among physiotherapists in SSA. Methods: A comprehensive literature search was conducted across PubMed, Sabinet, BioMed Central, and Google Scholar. Seven studies from Ghana, Nigeria, Cameroon, Benin, Kenya, Zimbabwe and South Africa met the inclusion criteria. Results: Key barriers at the practitioner level included lack of time, insufficient knowledge of EBP, limited access to information resources, and inadequate research skills. Facilitators comprised positive attitudes toward EBP and a desire for further knowledge. At the organisational level, resource unavailability emerged as a major barrier. Notably, no studies addressed extra organisational factors. Conclusion: This review highlights critical barriers and facilitators of EBP among SSA physiotherapists and emphasises the need for further research on extra organisational influences. Addressing systemic challenges is essential for enhancing physiotherapist engagement in EBP, ultimately improving patient care and outcomes in sub-Saharan Africa.展开更多
A novel low-cost sub-50nm poly-Si gate patterning technology is proposed and experimentally demonstrated.The technology is resolution-independent,ie.,it does not contain any critical photolithographic steps.The nano-s...A novel low-cost sub-50nm poly-Si gate patterning technology is proposed and experimentally demonstrated.The technology is resolution-independent,ie.,it does not contain any critical photolithographic steps.The nano-scale masking pattern for gate formation is formed according to the image transfer of an edge-defined spacer.Experimental results reveal that the resultant gate length,about 75 to 85 percent of the thickness,is determined by the thickness of the film to form the spacer.From SEM photograph,the cross-section of the poly-Si gate is seen to be an inverted-trapezoid,which is useful to reduce the gate resistance.展开更多
基金supported in part by the National Natural Science Foundation of China under Grants 62325107,62341107,62261160650,and U23A20272in part by the Beijing Natural Science Foundation under Grant L222002.
文摘In this paper,we propose a sub-6GHz channel assisted hybrid beamforming(HBF)for mmWave system under both line-of-sight(LOS)and non-line-of-sight(NLOS)scenarios without mmWave channel estimation.Meanwhile,we resort to the selfsupervised approach to eliminate the need for labels,thus avoiding the accompanied high cost of data collection and annotation.We first construct the dense connection network(DCnet)with three modules:the feature extraction module for extracting channel characteristic from a large amount of channel data,the feature fusion module for combining multidimensional features,and the prediction module for generating the HBF matrices.Next,we establish a lightweight network architecture,named as LDnet,to reduce the number of model parameters and computational complexity.The proposed sub-6GHz assisted approach eliminates mmWave pilot resources compared to the method using mmWave channel information directly.The simulation results indicate that the proposed DCnet and LDnet can achieve the spectral efficiency that is superior to the traditional orthogonal matching pursuit(OMP)algorithm by 13.66% and 10.44% under LOS scenarios and by 32.35% and 27.75% under NLOS scenarios,respectively.Moreover,the LDnet achieves 98.52% reduction in the number of model parameters and 22.93% reduction in computational complexity compared to DCnet.
基金funding from the"Ministero dell'Universitàe della Ricerca(MUR)"(Italy)under the"Dipartimento di Eccellenza 2018-2022"program.
文摘This work aimed to study the efficiency of the reverse micelle(RM)preparation route in the syntheses of sub-5 nm Fe-doped CeO_(2)nanocrystals for boosting the visible-light-driven photocatalytic hydrogen production from methanol aqueous solutions.The effectiveness of confining precipitation reactions within micellar cages was evaluated through extensive physicochemical cha racterization.In particula r,the nominal composition(0-5 mol%Fe)was preserved as ascertained by ICP-MS analysis,and the absence of separate iron-containing crystalline phases was supported by X-ray diffraction.The effective aliovalent doping and modulation of the optical properties were investigated using UV-Vis,Raman,and photoluminescence spectroscopies.2.5 mol%iron was found to be an optimal content to achieve a significant decrease in the band gap,enhance the concentration of oxygen vacancy defects,and increase the charge carrier lifetime.The photocatalytic activity of Fe-doped CeO_(2)prepared at different Fe contents with RM preparation was studied and compared with undoped CeO_(2).The optimal iron load was identified to be2.5 mol%,achieving the highest hydrogen production(7566μmol L-1after 240 min under visible light).Moreover,for comparison,the conventional precipitation(P)method was adopted to prepare iron containing CeO_(2)at the optimal content(2.5 mol%Fe).The Fe-doped CeO_(2)catalyst prepared by RM showed a significantly higher hydrogen production than that obtained with the sample prepared by the P method.The optimal Fe-doped CeO_(2),prepared by the RM method,was stable for six reuse cycles.Moreover,the role of water in the mechanism of photocatalytic hydrogen evolution under visible light was studied through the test in the presence of D2O.The obtained results evidenced that hydrogen was produced from the reduction of H^(+)by the electrons promoted in the conduction band,while methanol was preferentially oxidized by the photogenerated positive holes.
基金supported by National Science and Technology Major Project (2020AAA0109003)the support from Hangzhou Innovation Team Program (TD2022018)。
文摘Magnetic tunnel junction(MTJ) based spin transfer torque magnetic random access memory(STT-MRAM) has been gaining tremendous momentum in high performance microcontroller(MCU) applications. As e Flash-replacement type MRAM approaches mass production, there is an increasing demand for non-volatile RAM(nv RAM) technologies that offer fast write speed and high endurance. In this work, we demonstrate highly reliable 4 Mb nv RAM type MRAM suitable for industry and auto grade-1 applications. This nv RAM features retention over 10 years at 125 ℃, endurance of 1 × 10^(12)cycles with 20 ns write speed, making it ideal for applications requiring both high speed and broad temperature ranges. By employing innovative MTJ materials, process engineering, and a co-optimization of process and design, reliable read and write performance across the full temperature range between -40 to 125 ℃, and array yield that meets sub-1 ppm error rate was significantly improved from 0 to above 95%, a concrete step toward applications.
文摘Background: Unsafe abortion (USA) is defined as the termination of a non-desired pregnancy, performed by an unqualified person or in an environment without minimum medical standards, or both. It can impact negatively the fertility in the future by tubo-peritoneal lesions. The current study aimed to highlight the infertility factors associated with USA. Material and Methods: From January 1st 2000 to December 31st 2021, a total of 3876 patients that sought care for infertility in the University Clinic of Kinshasa and the Edith Medical Center were enrolled. The socio-demographic, clinical and paraclinical variables were recorded and analyzed in relation to USA history. Results: The patients’ average age was 33.4 ± 5.7 years. Half of them were housewives;about sixty percent of the patients were nulliparous (59.31%). Seventy percent had a secondary infertility with 43.33% having a history of unsafe abortion. The main diagnosis was genital infections and uterus myoma. The chronic endometritis, bilateral tubal occlusion and Uterine synechiae were more associated with USA group. The spermogram anomalies and other partners’ lesions seemed of infectious origin. Conclusion: The USA remains a more frequent phenomenon in our setting. The chronic endometritis, bilateral tubal occlusion, uterine synechiae and indirectly uterus myoma were the infertility factors related to USA. The genital infection of any origin seems to be the main denominator underlying the female and the male infertility in our setting.
文摘In this article, we deal with weak solutions to non-degenerate sub-elliptic equations in the Heisenberg group, and study the regularities of solutions. We establish horizontal Calderón-Zygmund type estimate in Besov spaces with more general assumptions on coefficients for both homogeneous equations and non-homogeneous equations. This study of regularity estimates expands the Calderón-Zygmund theory in the Heisenberg group.
文摘Introduction: Hepatitis B is an infectious disease that remains a real public health problem in Africa. Students represent a group at risk for this disease. The objective of this study was to estimate the hepatitis B vaccination coverage rate among students in sub-Saharan Africa. Methods: A systematic search of databases (PubMed, AJOL) and a manual search of Google Scholar was conducted to retrieve all published studies reporting hepatitis B vaccination coverage among students in sub-Saharan Africa. The pooled coverage rate was estimated with a 95% confidence interval (CI) in a random-effects meta-analysis. Results: A total of 35 studies were included and included 20,520 students. The mean age was 22.1 ± 5.1 years with a predominance of female sex (sex ratio F/M = 1.05). The vaccination coverage rate was 28.8% [95% CI: 22.9% - 34.7%]. Disaggregation allowed to estimate coverage rates of 29.8% [95% CI: 22.9% - 36.7%], 23.4% [95% CI: 9.4% - 37.4%] and 17.0% [95% CI: 14.4% - 19.5%] respectively in West Africa, East Africa and Central Africa. Conclusion: Less than a third of students in sub-Saharan Africa are protected against hepatitis B. However, the majority of this target group is at risk of infection. It would be relevant to screen and, if necessary, vaccinate all new students.
文摘Research background: Breast cancer remains a major public health problem, with a high number of new cases and deaths each year. However, despite advances in research to improve this disease, there is a high rate of late detection, leading to diagnosis at an advanced stage and a reduced chance of survival. Objective: The aim of this study is to identify the factors associated with late detection of breast cancer in women in Sub-Saharan Africa from 2014 to 2020.Setting: This systematic review focuses on sub-Saharan Africa. Methods: We searched for articles in four databases (PubMed, Embase, Global-Health and CINAHL) between 2014 and 2020 and performed a narrative synthesis to organize and group the different factors associated with late breast cancer detection. Result: After reviewing 583 publications, 6 studies were selected, highlighting factors such as lack of awareness, knowledge gaps, difficulties in accessing health services and financial constraints associated with late breast cancer screening. The participants, who ranged in number from 20 to 1776, were mainly aged between 18 and 25, with a mean age of 25 years and 6 months. Conclusion: The analysis enabled us to identify various factors associated with late breast cancer screening. Collaboration between health professionals, community organizations and policy-makers is essential to foster an environment conducive to the prevention and early detection of breast cancer.
文摘Background: Evidence-based practice (EBP) is vital for high-quality patient care, yet its implementation among physiotherapists in sub-Saharan Africa (SSA) faces significant challenges. This scoping review explores the barriers and facilitators of EBP in this region. Objectives: To identify barriers and facilitators of EBP at individual, organisational, and extra organisational levels among physiotherapists in SSA. Methods: A comprehensive literature search was conducted across PubMed, Sabinet, BioMed Central, and Google Scholar. Seven studies from Ghana, Nigeria, Cameroon, Benin, Kenya, Zimbabwe and South Africa met the inclusion criteria. Results: Key barriers at the practitioner level included lack of time, insufficient knowledge of EBP, limited access to information resources, and inadequate research skills. Facilitators comprised positive attitudes toward EBP and a desire for further knowledge. At the organisational level, resource unavailability emerged as a major barrier. Notably, no studies addressed extra organisational factors. Conclusion: This review highlights critical barriers and facilitators of EBP among SSA physiotherapists and emphasises the need for further research on extra organisational influences. Addressing systemic challenges is essential for enhancing physiotherapist engagement in EBP, ultimately improving patient care and outcomes in sub-Saharan Africa.
文摘A novel low-cost sub-50nm poly-Si gate patterning technology is proposed and experimentally demonstrated.The technology is resolution-independent,ie.,it does not contain any critical photolithographic steps.The nano-scale masking pattern for gate formation is formed according to the image transfer of an edge-defined spacer.Experimental results reveal that the resultant gate length,about 75 to 85 percent of the thickness,is determined by the thickness of the film to form the spacer.From SEM photograph,the cross-section of the poly-Si gate is seen to be an inverted-trapezoid,which is useful to reduce the gate resistance.
