sub-500 fs宽度2μm光纤激光振荡器研究进展(特邀)

2μm波段超快激光持续时间短,峰值功率高,光谱范围宽,同时处在大气窗口,多种有机、无机气体分子的吸收峰和人眼安全波段,已广泛应用于生物医疗、激光雷达和非金属材料加工等领域。利用光纤锁模激光振荡器产生2μm波段超快激光是一种最直接简单的技术方法,具有结构紧凑、光束质量高和成本低等优点。然而,目前关于sub-500 fs的2μm波段的光纤激光振荡器却鲜有报道。基于传统孤子和色散管理孤子两种孤子锁模方式,全面介绍了目前2μm波段sub-500 fs光纤振荡器的研究进展,并总结了实现sub-500 fs脉宽2μm超快激光的关键技术。针对不同的应用领域的具体需求,对2μm超快激光光纤振荡器的未来发展进行展望。

Besov Estimates for Sub-Elliptic Equations in the Heisenberg Group

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.

Hepatitis B Vaccination Coverage among University Students in Sub-Saharan Africa: Systematic Review and Meta Analysis

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.

Systematic Analysis of Factors Associated with Late Breast Cancer Screening in Women in Sub-Saharan Africa from 2014 to 2020

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.

适用于Sub-6G和Wi-Fi的小型化笔记本电脑天线设计

本文设计了一种适用于Sub-6G和5G Wi-Fi频段的宽带小型化笔记本电脑天线,所述天线设置于金属笔记本电脑的A壳净空区上,天线的基本结构为一种弯折型PIFA天线形式。通过对所述宽带天线进行仿真和实际测试,结果表明:天线可以完全覆盖(699~960)MHz、(1710~2690)MHz和(3000~5000)MHz的Sub-6G频段以及(5150~5850)MHz的5G Wi-Fi频段,并且天线整体具有70 mm×11.5 mm×0.4 mm的紧凑体积,可以满足笔记本电脑对宽频带、小型化天线的应用需求。

Evaluation of Acute and Sub-Acute Oral Toxicities of Momordica foetida Schumach. (Cucurbitaceae) Leaves Methanol Extract in Wistar Rats

Momordica foetida is a plant widely used in tropical Africa to manage gastroenteric diseases. Previous studies demonstrated interesting antibacterial activity against human pathogenic bacteria. However, the security or toxicity of methanol leaf extract has not been determined yet. The aim of this study was to evaluate the acute and sub-acute toxicity of the leaf extract of Momordica foetida. In the acute toxicity study, a single oral dose of 5000 mg/kg body weight was administered to rats which were observed for 14 days in order to identify signs of toxicity or death. In the sub-acute toxicity, the animals were treated with 250, 500 and 1000 mg/kg of the extract for 28 consecutive days. Body weights and behavior were noted throughout the experiment. Upon treatment, blood and urine were collected for hematological and biochemical analysis. Liver, lungs, heart, kidneys, testes and ovaries were analyzed for relative weights and histopathology. The acute toxicity study of M. foetida leaf extract revealed no signs of toxicity related to the treatment, indicating that the median-lethal-dose (LD50) value is greater than 5000 mg/Kg of body weight. In the sub-acute toxicity assay, the extract did not affect the general behavior of animals, meanwhile, it led to a significant increase in the levels of red blood cells, platelets, hemoglobin, granulocytes and Mid-Cells (MIDs). Biochemical parameters showed an increase in total cholesterol, HDL cholesterol, serum urea, serum and urinary glucose and a decrease in urinary proteins, serum creatinine, urinary urea levels, serum activities of AST, ALT and proteins levels, as well as increases in lung, spleen and ovaries relative weight were noticed, all compared to control animals. Histological analysis revealed a normal architecture of kidneys, liver, heart, lung, ovaries and testes. This study provides valuable data on the safety of per os administration of Momordica foetida leaf methanol extract that could be very useful for future assays.

Assessing Water Resources Access of Nouhao Sub-Basin, Burkina Faso

Water resource access in the Nouhao sub-basin, assessed based on the availability of drinking water mobilization facilities, the availability of water for uses and the quality of drinking water, revealed that in 2017 the basin was covered by 1249 modern water point, main drinking water sources. On average, the sub-basin shows a ratio of 271 users per drinking water point. Communal level shows some disparity with Bittou recording the highest number of people per drinking water point, i.e., around 537. Water that can be captured in the entire sub-basin meets only 42% of the total water needs from the three mains uses: irrigation, domestic consumption and livestock. The highest demander among these uses is Irrigation with 75% of the need, i.e., approximately 12,859,995 m3. Water in 33% drinking sources of this sub basin is of poor quality. Arsenic, one of the quality parameters studied, is found in some communes of the sub-basin. 11% of the water points in Bissiga are arsenic polluted making this commune the most arsenic contaminated location. The vulnerability maps deducted from lack of water for uses;lack of drinking water works and poor water quality shows so, the exposure level of the sub-basin’ communes to some potential risks related to low water resources access.

Diagnosis Delay and Assessment of the Quality of Life of Patients with Endometriosis Using the Endometriosis Health Profile 5 Questionnaire in a Sub-Saharan Population

Context: Endometriosis is a pathology that directly affects the daily lives of women with frequent impairment of their quality of life. In our environment, medical, socio-cultural, financial factors and factors related to the organization of the health care system greatly delay its diagnosis. The objectives of the present study were to determine the diagnosis delay and to assess the quality of life before surgery of women with endometriosis using the specific Endometriosis Health Profile 5 (EHP-5) questionnaire. Methods: We carried out a descriptive, observational, retrospective study in 8 medical centers in the City of Kinshasa, from January 2019 to October 2022. A total of 80 women with endometriosis confirmed by laparoscopy (16 diagnostic and 64 operative laparoscopies) and histopathology were interviewed. We used the revised American Society for Reproductive Medicine (rASMR) classification, the Endometriosis Fertility Index (EFI) score was calculated for infertile women and the EHP-5 questionnaire to assess quality of life. Our data was entered and analyzed using Statistical Analysis Software 16.1 (STATA 16.1). Results: Diagnosis delay of endometriosis was on average 12 ± 4.3 years. The overall mean EHP-5 score of all patients showed a severe deterioration in quality of life (604 ± 235). A negative relationship was observed between the age of the patient, the diagnostic delay, and the alteration of the quality of life in patients over 36 years old and those with about 11 years of diagnostic delay presenting the slight alteration. Patients with a high social level had very severe quality impairment. Women on hormonal treatment, those with a history of pregnancy, childbirth, miscarriage and abortion had a slight and significant deterioration in quality of life (p 0.05). Conclusion: Despite some limitations, our preliminary study highlights that in sub-Saharan Africa, the diagnosis of endometriosis is delayed and associated with a severe alteration in quality of life. Moreover, diagnosis of endometriosis seems to be restricted to women with high social levels. Therefore, further efforts are required to develop a health policy to decrease delay for diagnosis with potential benefits on symptoms, quality of life, fertility while limiting stigma and psychological effects of this debilitating pathology.

Acute and Sub-Chronic Toxicity Evaluation of the Crude Methanolic Bark Extract of Bridelia micrantha (Hochst.) Baill. (Phyllanthaceae) and Its Fraction

Bridelia micrantha, commonly known as coastal golden leaf, is a member of the family Phyllanthaceae. In preliminary studies nine fractions, named F1 - F9, were obtained by fractionating the crude methanol extract of the stem bark of Bridelia micrantha using column chromatographic techniques. The fraction F6 was the most active when tested for antibacterial activity. Thus, toxicity of this fraction was investigated for further use. The present study evaluated the acute and sub-chronic toxicity of the crude methanolic bark extract of Bridelia micrantha and its fraction. The acute toxicity was carried out according to the experimental protocol of Organization for Economic Co-operation and Development (OECD). The plant extract or the fraction F6 was administered orally to female mice at a single dose of 2000 mg/kg and the animals were observed for any behavioral changes or mortality for 14 days. In the sub-chronic toxicity study, the extract and fraction were administered orally at 200, 400 and 800 mg/kg bw/day for 28 days to healthy Wistar rats. The general behavior and body weight of the rats were recorded daily. At the end of the experimental period, hematological and biochemical analyses, changes in vital organ weight (liver, lung, heart, spleen and kidney), and histopathological examination of the liver and kidney were performed. No mortality or adverse effects were noted at the 2000 mg/kg dose during the oral acute toxicity test. In the sub-chronic study, the crude methanolic bark extract of Bridelia micrantha and the fraction F6 induced no mortality or treatment-related adverse effects on body weight, general behavior, relative organ weights, hematological and biochemical parameters. Histopathological examination of the liver and kidney showed normal architecture suggesting no morphological alterations. In conclusion, the oral administration of the crude methanolic bark extract of Bridelia micrantha and the fraction F6 for 28 days at a dosage of up to 800 mg/kg did not induce toxicological damage in rats. From acute toxicity study, the median lethal dose (LD50) of the crude methanolic bark extract of Bridelia micrantha and the fraction F6 was estimated to be more than 2000 mg/kg.

Assessment of Climate Change’s Impacts on River Flows in the Songwe Sub-Basin

River flow in the Songwe sub-basin is predicted to alter due to climate change, which would have an impact on aquatic habitats, infrastructure, and people’s way of life. Therefore, the influence of climate change should be taken into account when making decisions about the sustainable management of water resources in the sub-basin. This study looked into how river discharge would react to climate change in the future. By contrasting hydrological characteristics simulated under historical climate (1981-2010) with projected climate (2011-2040, 2041-2070, and 2071-2100) under two emission scenarios, the effects of climate change on river flow were evaluated (RCP 4.5 and RCP 8.5). The ensemble average of four CORDEX regional climate models was built to address the issue of uncertainty introduced by the climate models. The SWAT model was force-calibrated using the results from the generated ensemble average for the RCP 4.5 and RCP 8.5 emission scenarios in order to mimic the river flow during past (1981-2010) and future (2011-2100) events. The increase in river flows for the Songwe sub-basin is predicted to be largest during the rainy season by both the RCP 4.5 and RCP 8.5 scenarios. Under RCP 8.5, the abrupt decrease in river flow is anticipated to reach its maximum in March 2037, when the discharge will be 44.84 m3/sec, and in March 2027, when the discharge will be 48 m3/sec. The extreme surge in river flow will peak, according to the RCA4, in February 2023, in April 2083 under RCP 4.5, and, according to the CCLM4 and RCA4, in November 2027 and November 2046, respectively. The expected decrease and increase in river flow throughout both the dry and wet seasons may have an impact on the management of the sub-water basin’s resources, biodiversity, and hydraulic structures. The right adaptations and mitigation strategies should be adopted in order to lessen the negative consequences of climate change on precipitation, temperature, and river flow in the sub-basin.

Cardiac Resynchronization Therapy in Heart Failure in Sub-Saharan Africa Environment: Experience of the Principal Hospital of Dakar (Senegal)

Background: Heart failure is a major public health challenge in sub-Saharan Africa. In patients with chronic Heart Failure and cardiac desynchrony, studies have suggested that cardiac resynchronization, can improve cardiac function and the quality of life of patients. However, in Sub-Saharan Africa, very few studies have been done on cardiac resynchronization which is in its infancy. The aim of this study is to report the local data from our hospital. Method: It was a transversal, descriptive and analytical study conducted from November 2019 to September 2022 at the Cardiology Department of the Principal Hospital of Dakar. Results: Twelve patients were implanted for Cardiac Resynchronization Therapy (CRT). The sex ratio was 8 males/4 females. The average age was 67 ± 11 years. Ten patients had non-ischemic heart disease and the two others had ischemic one. All of them had NYHA III or IV scores before CRT. The Quality of Life (QOL) was judged as poor by all of the patients. The average duration of QRS was 156 ± 9 ms. 27.9% ± 5% was the mean Left Ventricular ejection fraction (LVEF). Complications occur in 3/12 patients (25%). It was one CS vein dissection, one micro LV lead dislodgement and one phrenic nerve stimulation. Nine patients, who were considered as responders, had an improvement of QOL and NYHA, the LVEF increased and the end-diastolic dimension, and the duration of the QRS interval all decreased. Two patients do not respond and one (1) who had permanent atrial fibrillation, was a secondary responder after an atrioventricular junction ablation. Conclusion: Cardiac resynchronization is a therapy that improves the QOL of patients, the LVEF and reduces the duration of the QRS interval. However, this procedure is not without risk of complications. In sub-Saharan Africa, the major challenge is to improve the financial accessibility of this therapy for the population.

Epidemiology and Clinical Profile of Behcet’s Disease in a Sub-Saharan Country: About Five Observations

Behçet’s disease (BD) is a multi-systemic vasculitis characterized by a triad made up of oral aphthosis, genital aphthosis and uveitis which may or may not be associated with visceral involvement. Other times described in the ancient silk road, BD is increasingly found in countries south of the Sahara with the mixing of populations. Our objective was to describe the epidemiology and clinical characteristics of BD in an African country. Methodology: This was a five-year retrospective study in the internal medicine department of Donka National Hospital. We used international criteria finding BD. Urinary dipstick was use for finding kidney disease. Result: During the period, five cases of Behçet’s disease were collected. The average age was 35 years old. The male sex was more represented with 3 out of 5 cases. The most common clinical manifestation was oral aphthosis in all patients (100%), followed by genital aphthosis in 4 cases (80%). The other clinical manifestations observed were uveitis in 3 cases (60%), joint manifestations such as arthralgia in 3 cases (60%) and neurological manifestations such as chronic headache in one case (20%). HLA-B51 was found in two cases. The pattergic test done in two patients came back positive (100%). The patients received colchicine and oral corticosteroid therapy. Two patients were lost to sight. We deplored a death probably in a neuro-Behçet table before the rebellious headaches. Conclusion: Behçet’s disease is a multi-systemic vasculitis that must be evoked and managed quickly in a tropical environment, especially since the prognosis, vital and functional prognosis can be engaged.

Sub-Differential Characterizations of Non-Smooth Lower Semi-Continuous Pseudo-Convex Functions on Real Banach Spaces

In this paper, we characterize lower semi-continuous pseudo-convex functions f : X → R ∪ {+ ∞} on convex subset of real Banach spaces K ⊂ X with respect to the pseudo-monotonicity of its Clarke-Rockafellar Sub-differential. We extend the results on the characterizations of non-smooth convex functions f : X → R ∪ {+ ∞} on convex subset of real Banach spaces K ⊂ X with respect to the monotonicity of its sub-differentials to the lower semi-continuous pseudo-convex functions on real Banach spaces.

基于UWB和SUB-GHz的双向通信定位基站的实现

在智能供电站、官网隧道、石化工厂、智慧施工、体育训练和司法监狱等室内设施复杂的应用领域,传统定位基站对复杂区域尤其是工业领域等存在三维感知需求方面存在一定的短板,不能很好地表现精细定位。因此,提出了一种基于超宽带(UWB)和SUB-GHz技术相融合的双向通信定位基站的方案,在无线通信方面主要采用DW1000和SI4438射频芯片,配套对应的定位标签和定位引擎,以实现对复杂区域的定位感知和分层分区,为客户提供智能化、精细化管理及更多智能化业务的创新。实验数据表明,基于UWB和SUB-GHz双向通信的定位基站可以很好地实现对三维的感知,达到预期效果。

国际大都市Sub-CBD建设刍议

国际大都市的Sub-CBD(副中心 )建设正在形成方兴未艾的热潮。以往比较重视CBD(中央商务区 )的系统研究 ,而忽视了Sub-CBD的理论建设。本文从分析CBD与Sub -CBD的关系入手 ,研究了Sub -CBD的形成机制 ,提出了Sub -CBD的定义和对相关问题的理论认识 ,探讨了以步行街、过街天桥系统、地下街市为主要内涵的Sub-CBD建设新趋势。最后 ,本文还提出了Sub -CBD建设中必须引起注意若干建议。

基于Sub-Nyquist采样的单通道频谱感知技术

宽带频谱感知技术在认知无线电中具有广泛的应用。基于时分的思想,将信号采集时间以固定长度的时间片进行划分,分别与不同的伪随机码信号相乘,经过低通滤波和sub-Nyquist采样,利用采样数据求出信号的频率支集。与已有的多通道频谱感知结构相比,本文用相对简单的单通道结构实现,同样能够利用低速率的采样点完成频谱感知。仿真实验结果表明,在信号的频率支集未知的情况下,该算法能够有效利用sub-Nyquist采样的数据实现频谱感知。

应用Sub-G1法和PA法分析HL-60细胞自发凋亡的周期特异性

分别用Sub G1法和PA法对人类早幼粒细胞急性白血病细胞株 (HL 6 0 )的自发凋亡进行检测 ,发现HL 6 0细胞自发凋亡时 ,在DNA直方图上 ,G1峰前出现亚G1峰 (Sub G1峰 ) ,G1期细胞增加 ,S期和G2 /M期细胞减少。同时G1期细胞发生自发凋亡 ,而S期 ,G1期细胞少有凋亡发生。

Sub-CBD产业空间组织研究——以东京都新宿区为例

全球化和信息化加速产业空间组织的演变,推动生产性服务业与商业的集聚与扩散,形成多个Sub-CBD,促进了大都市区空间结构的多中心化。本研究选取东京都新宿为案例,探讨交通规划对Sub-CBD形成与发展的重要影响,分析生产性服务业与商业空间组织的集聚与关联。本研究认为政府高起点规划,依托交通枢纽,促进产业空间集聚,强化生产性服务业与商业一体化,发展有助于Sub-CBD功能拓展。

利用字典优化方法实现sub-Nyquist采样数据的频率估计

在稀疏重构理论中,重构信号需要预先设定稀疏表示字典,针对预设字典与真实字典之间的失配对信号稀疏表示造成的不利影响,提出一种基于字典优化和稀疏贝叶斯学习(Sparse Bayesian Learning,SBL)的频率估计算法。该算法首先构造基于sub-Nyquist采样数据的信号稀疏表达式,然后利用SBL算法估计信号频率,同时根据估计结果优化字典,最后反复迭代上述步骤直至计算出的频率值和对应的幅度值趋于稳定。仿真结果校验了方法的有效性。

基于SUB-SERVQUAL模型的高校图书馆嵌入式学科服务质量评价研究

[目的/意义]随着我国高校双一流建设不断推进,传统的图书馆学科服务已无法适应师生科研的个性化服务需求,嵌入式学科服务开展质效评价的问题日益凸显,探讨图书馆嵌入式学科服务质量评价尤为迫切。[方法/过程]引入SUB-SERVQUAL模型,基于用户感知价值,构建信息特征、技术功能、服务效果、嵌入过程、用户控制的感知维度指标体系。融合乘积标度法和加权质量差距分析,借助IPA象限分析图,评价用户对各项指标实际感知与期望感知的差距。[结果/结论]以河海大学图书馆学科服务为例进行实证研究,研究结果表明构建高校图书馆学科服务质量指标体系科学合理,具有操作的可行性,能有效引导图书馆嵌入式学科服务,从而推动高校双一流学科的建设。