Multi-Axis Attention With Convolution Parallel Block for Organoid Segmentation

Dear Editor,This letter presents an organoid segmentation model based on multi-axis attention with convolution parallel block.MACPNet adeptly captures dynamic dependencies within bright-field microscopy images,improving global modeling beyond conventional UNet.

基于远程终端的商用车排放分析方法

针对车辆无法通过循环排放结果来判断是否满足法规要求的问题,提出可以采用功基窗口法计算车辆的排放,并实时监控车辆的排放。针对单车排放提出分布图法;针对多车排放,须结合散点图的统计方法以快速找出不满足要求的车辆。采用上述方法对采用冷EGR技术路线和纯SCR技术路线的发动机进行分析,发现少数车辆的SCR温度太低导致车辆排放有风险,须进行发动机热管理的精细标定。

Mechanism underlying treatment of ischemic stroke using acupuncture:transmission and regulation

The inflammatory response after cerebral ischemia/reperfusion is an important cause of neurological damage and repair.After cerebral ischemia/reperfusion,microglia are activated,and a large number of circulating inflammatory cells infiltrate the affected area.This leads to the secretion of inflammatory mediators and an inflammatory cascade that eventually causes secondary brain damage,including neuron necrosis,blood-brain barrier destruction,cerebral edema,and an oxidative stress response.Activation of inflammatory signaling pathways plays a key role in the pathological process of ischemic stroke.Increasing evidence suggests that acupuncture can reduce the inflammatory response after cerebral ischemia/reperfusion and promote repair of the injured nervous system.Acupuncture can not only inhibit the activation and infiltration of inflammatory cells,but can also regulate the expression of inflammation-related cytokines,balance the effects of pro-inflammatory and anti-inflammatory factors,and interfere with inflammatory signaling pathways.Therefore,it is important to study the transmission and regulatory mechanism of inflammatory signaling pathways after acupuncture treatment for cerebral ischemia/reperfusion injury to provide a theoretical basis for clinical treatment of this type of injury using acupuncture.Our review summarizes the overall conditions of inflammatory cells,mediators,and pathways after cerebral ischemia/reperfusion,and discusses the possible synergistic intervention of acupuncture in the inflammatory signaling pathway network to provide a foundation to explore the multiple molecular mechanisms by which acupuncture promotes nerve function restoration.

驻村工作队如何嵌入基层治理?——基于“访民情、惠民生、聚民心”案例的分析

【问题】驻村工作队是一种独特的中国基层治理机制,其运行机制蕴含着嵌入性治理的丰富内涵,但目前尚未从学理上对“访惠聚”驻村工作队发挥作用的内在机理与治理逻辑进行系统探讨。【方法】运用实地调查、观察访谈等方法,系统梳理了“访民情、惠民生、聚民心”驻村工作队的发展历程和运行机理,并基于嵌入性治理视角,从“结构嵌入性”和“关系嵌入性”两个维度建构了“访惠聚”驻村工作队的治理逻辑。【发现】研究表明驻村工作队的运行机制和治理逻辑在中国政府治理实践中具有独特性,是一种不同于以往工作队的新样态;“访惠聚”驻村工作队以刚性的体制和制度来构建“访惠聚”驻村工作队运行的“结构嵌入性”治理机制,以柔性的价值情感、社会生态和利益关系重构来构建“访惠聚”驻村工作队运行的“关系嵌入性”治理机制。【结论】研究为推进基层治理体系和治理能力现代化提供新的研究视角和理论维度,同时也为丰富和发展中国边疆治理实践提供理论借鉴和有益参考。

Expression of neurocan mRNA and ultrastructure of brain tissue after cerebral ischemia and reperfusion in stroke-prone renovascular hypertensive rats treated by electroacupuncture

We established a stroke-prone renovascular hypertensive rat model by bilateral constriction of the renal artery with sliver loop clips. After ten weeks, middle cerebral artery occlusion was induced for 2 hours. The rats then received electro-acupuncture at Baihui （DU 20） and Dazhui （DU 14） after onset of ischemia for 30 days. In situ hybridization study showed that electroacupuncture significantly reduced the number of neurocan mRNA-positive cells in the ischemic penumbra and hippocampal tissues of rats. Electron microscopy results demonstrated that the structure of neurons and blood vessels in the ischemic tissues were restored with electroacupuncture. Overall, these data suggest that electroacupuncture may protect neurons against ischemic reperfusion injury in stroke-prone renovascular hypertensive rats, which may be regulated by downregulation of expression of nerve inhibitory factor neurocan mRNA.

Anti-free radical,anti-oxidative ability and anti-fatigue effects of Huanshaodan An experiment of aging mice

In the theory of traditional Chinese medicine, aging is mainly thought renal deficiency caused renal failure, mainly involving decline of kidney-Yang and deficiency of kidney-essence. Huanshaodan, a Chinese traditional preparation for kidney-replenishing essence, was used to be the preparation for reinforcing renal deficiency and preventing aging for aged people. OBJECTIVE： To observe the effects of Huanshaodan on swimming durance and the abilities of catalase （CAT） in serum and monoamine oxidase-B （MAO-B） in brain tissue as well as in vitro anti-oxidative ability of aging mouse. DESIGN： A controlled animal experiment. SETTING： College of Basic Medicine, Hunan University of Traditional Chinese Medicine. MATERIALS： Fifty-four healthy NIH mice, aged 18 months old, of either gender, weighing （48.9±5.4） g, and one SD male rat, aged 16 months old, weighing 51.7 g, were provided by Animal Experimental Center, Hunan University of Traditional Chinese Medicine. Thirty NIH mice were randomly chosen for swimming test, and divided into experimental group and control group, with 15 in each; The other 24 NIH mice were used for enzyme activity assay, and also divided into experimental group and control group, with 12 in each. SD rat was used for in vitro anti-oxidative ability test, Huanshaodan water decoction was composed of Cheqianzi, Wuweizi, Huaishan, Danggui, Huangbai, Shudi, Baizhi, Niuxi, Baishen, Tusizi, Buguzhi, Roucongrong and Heshouwu 13 Chinese herbs. METHODS： This study was carried out in the Second Laboratory, Department of Biochemistry, Hunan University of Traditional Chinese Medicine in June 2006. Swimming and enzyme activity assay： Mice in the two experimental groups were intragastrically administrated with l0 μL/g Huanshaodan water decoction. Mice in the two control groups were intragastrically administrated with the same amount of normal saline. All the mice were intragastrically administrated for 5 days, and they were free to access to medicine in the other 2 days in a week. Each mouse was administrated for 8 weeks. MAIN OUTCOME MEASURES： ① Forty days after administration, mice in the experimental group and control group for swimming test were loaded at tails and allowed to swim in the water-tank. Swimming durance was recorded. ② Following the method of Chen Qi, the activities of CAT in serum and MAO-B in brain tissue as well as the inhibitory rate of each medicine on malonaldehyde （MDA） content in the in vitro rat hepatic tissue were determined; Meanwhile, the inhibitory rate of different doses of Tusizi liquid to MDA content in the rat hepatic tissue in vitro was also assayed. RESULTS： Fifty-four NIH mice and one SD rat were recruited in this experiment. Three mice died in the swimming test, and all the other animals were involved in the final analysis. ① Swimming durance of mice in the experimental group was significantly longer than that in the control group （ t =7.502, P 〈 0.01 ） . The activity of CAT in serum of mice in the experimental group was significantly higher than that in the control group （ t =13.307, P 〈 0.01 ） . ② The activity of MAO-B in brain tissue of mice in the experimental group was significantly lower than that in the control group （t =l3.27, P 〈 0.01 ） . ③The inhibitory rate of Cheqianzi, Wuweizi, Huaishan, Danggui, Huangbai, Shudi, Baizhi, Niuxi, Baishen, Tusizi, Buguzhi, Roucongrong and Heshouwu 13 Chinese herbs of Huanshaodan to MDA in the rat hepatic tissue in vitro was - 62.9, - 95.1, - 34.9, - 65.1, - 99.1, - 87.2, - 94.1, - 20.0, - 67.0, - 83.7, - 91.0, - 98.4, - 93.0, respectively. ④ The inhibitory rate of low to high dose of Tusizi liquid to MDA content in the rat hepatic tissue in vitro was - 3.41, - 18.1, - 26.6, - 83.7, respectively. CONCLUSION： Huanshaodan enhances swimming endurance, anti-oxygen free radical and anti-oxidativeabilities, and thus, it can delay aging.

The genetic architecture of growth traits in Salix matsudana under salt stress

Willow(Salix)is one of the most important ornamental tree species in landscape plants.One species,Salix matsudana,is widely used as a shade tree and border tree because of its soft branches and plump crown.Some varieties of S.matsudana were salt tolerant and could grow normally in coastal regions.However,the molecular mechanisms of salt tolerance for S.matsudana have been less clear.Here,we addressed this issue by performing a mapping experiment containing 195 intraspecific F1 progeny of S.matsudana,derived from salt-sensitive‘yanjiang’and salt-tolerant‘9901’,grown by cuttings in a 100 mM NaCl solution.Growth performance of these progeny under salt stress was investigated,displaying marked genotypic variability with the coefficients of variance of 28.64–86.11%in shoot and root growth traits.We further mapped specific QTLs contributing to these differences to the Salix genome.Of the 204 QTLs identified,a few were detected to explain a remarkably larger portion of the phenotypic variation than many others.Many detected QTLs were found to reside in the region of candidate genes of known biological function.The discovery of growth QTLs expressed under salt stress provides important information for marker-assisted breeding of salt tolerant Salix varieties and founds the basis for the application of S.matsudana in coastal afforestation.

Effect of cyclovirobuxine D on human growth-associated protein 43 and neurocan expression in ischemic brain tissue of stroke-prone renovascular hypertensive rats

BACKGROUND： Experimental data indicate that human growth-associated protein 43 mRNA expression coincides with axonal growth during nerve ganglion development; while neurocan, secreted from astrocytes, can inhibit sprouting and elongation of the axonal growth cone. OBJECTIVE： To verify regulatory effects of cyclovirobuxine D （CVB-D） extracted from Chinese box branchlet on human growth-associated protein 43 （GAP-43）, and neurocan expression in brain tissue of stroke-prone renovascular hypertensive （RHRSP） rats, at different time points after cerebral ischemia/reperfusion. DESIGN： Randomized grouping design and controlled animal study. SETTING： This study was performed at the Center of Guangdong Hospital of Traditional Chinese Medicine （a national key laboratory） from March 2003 to September 2006. MATERIALS： 100 healthy male Sprague-Dawley rats, aged 2 3 months and weighing 90-120 g, were selected for this study. CVB-D was provided by Nanjing Xiaoying Pharmaceutical Factory （Batch number： 307701）. METHODS： The initial tip of renal arteries was clamped bilaterally for 10 weeks to establish the RHRSP model. 100 RHRSP rats were randomly divided into 4 groups： naive group （n = 10）, sham surgery group （n = 10）, CVB-D group （n = 40）, and lesion group （n = 40）. Rats in the naive group did not undergo any treatment, and cervical vessels of rats in the sham surgery group were exposed, but not blocked. The right middle cerebral artery of rats in the CVB-D group and lesion group were occluded to establish cerebral ischemia. Rats in the CVB-D group were intraperitoneally injected with CVB-D （6.48 mg/kg） every day and with saline （1.5 mL/injection） twice a day. Rats in the lesion group were intraperitoneally injected with saline （2 mL/injection）. MAIN OUTCOME MEASURES： Immunohistochemistry was applied to detect GAP-43 and neurocan expression in the ischemic penumbra region of CVB-D and lesion brains at 2 hours post-cerebral ischemia and at 1, 7, 14, and 30 days post-perfusion （n = 10 at each time point）. Similarly, GAP-43 and neurocan expression was detected in the right hemisphere of naive and sham-operated animals. The results were expressed as positive cells. RESULTS： A total of 100 rats were included in the final analysis. The number of GAP-43 positive cells increased in the CVB-D group 1, 7, 14, and 30 days post-cerebral ischemia/perfusion compared to the lesion group, as indicated by a significant difference between the CVB-D and lesion group （P 〈 0.054）.01）. The number of neurocan-positive cells decreased in the CVB-D group on the first day compared to the model group; however, there was no significant difference between the two groups （P 〉 0.05）. On post-ischemia days 7, 14, and 30, the number of neurocan-positive cells in the CVB-D group was significantly less than in the lesion group （P 〈 0.05）. Both, GAP-43 and neurocan expression was not detectable in brains of naive and sham-operated animals. CONCLUSION： CVB-D treatment up-regulated GAP-43 expression and down-regulated neurocan expression in the ischemic region of RHRSP rats.

Analysis of water resource benefits due to power grid interconnections using the virtual water method

The global water demand and supply situation is becoming increasingly severe due to water shortage and uneven distribution of water resources.The highest water demand in the energy sector is attributable to power generation.With cross-country and cross-continental power grid interconnections becoming a reality,electricity trading across countries and the creation of new opportunities for re-allocation of water resources are possible.This study expands the concept of virtual water and proposes a generalized virtual water flow in an interconnected power grid system to accurately estimate water resource benefits of clean power transmission from both the production and the consumption sides.By defining the water scarcity index as a price mechanism indicator,the benefits of water resources allocation through power grid interconnections are evaluated.Taking the Africa-Asia-Europe interconnection scenario as an example,the total water saving would amount to 88.95 million m^3 by 2030 and 337.8 million m^3 by 2050.This result shows that grid interconnections could promote the development of renewable energy and expand the benefits of available water resources.

Stabilization of linear time-varying systems with state and input constraints using convex optimization

The stabilization problem of linear time-varying systems with both state and input constraints is considered. Sufficient conditions for the existence of the solution to this problem are derived and a gain-switched（gain-scheduled） state feedback control scheme is built to stabilize the constrained timevarying system. The design problem is transformed to a series of convex feasibility problems which can be solved efficiently. A design example is given to illustrate the effect of the proposed algorithm.

The Design and Implementation of a Medical Parasitology Teaching Case Database Based on the Online and Offline Hybrid Teaching Model

The purpose of this paper is to comprehensively develop high-quality medical talents with strong clinical skills and innovativeness.By constructing and applying the medical parasitology teaching case database,students can gain access to various educational tools.The goal is to assist them in their progress from passive to active learning,as well as to develop their autonomous learning ability,critical thinking skills,communication skills,teamwork,and innovation skills.Besides,the goal is also to improve the overall hygiene perspective as well as digest and integrate their knowledge and skills.

Trends in Fruit and Vegetable Intake Among the Labor Force Population—China,2010-2018

Introduction:This research investigates trends pertaining to the prevalence of low fruit and vegetable consumption among the labor force population in China.The study considered data derived from four nationally representative cross-sectional surveys.Methods:The data under review for this study was derived from the China Chronic Disease and Risk Factor Surveillance(CCDRFS)carried out in 2010,2013,2015,and 2018,correspondingly.We utilized a food frequency questionnaire to evaluate the quantity and frequency of fruit and vegetable consumption.The estimated prevalence of low fruit and vegetable consumption was calculated for each survey,while considering factors such as sex,age,location,and socioeconomic status(SES).Participants’SES was ascertained via latent class analysis,serving to identify distinct classes based on criteria such as education,occupation,and household income per capita.Logistic regression was deployed to determine the statistical significance of trends.Results:From 2010 to 2018,there was a notable increase in the average daily consumption of vegetables and fruits among the working population,rising from 418.6 g/day to 491.8 g/day(P<0.01 for trend).During the same period,the prevalence of low fruit and vegetable intake declined from 51.1%to 43.5%[P<0.001 for trend;−1.6%average annual percent change(AAPC)].This downward trend was prevalent across genders,however,certain subgroups of adults(e.g.,those living in rural areas or those of low SES)saw stable consumption levels throughout this period(P>0.05 for trend).Conclusion:Over the past nine years,there has been a notable decline in the prevalence of low fruit and vegetable consumption among the labor force population in China.Moreover,the comparatively deficient intake of fruits and vegetables evident among individuals of lower SES warrants further attention.

不同围封年限对藏北高寒草原植物群落特征的影响

围栏封育是最为常见的一种高寒草地生态近自然恢复的手段,本文以藏北地区班戈县11年长期围封、5年短期围封与正常放牧高寒草原类草地植物群落为研究对象,分析不同围封年限对高寒草原植物群落特征的影响,以期为后续生态恢复研究工作提供一个参考。研究发现:长期围封能显著提升群落平均高度(P <0.05),短期围封能显著提高群落地上生物量(P <0.05),随着围封年限增加,群落密度盖度也越来越高,但差异不显著(P> 0.05);长期围封能大幅降低草地退化指示种矮小火绒草(Heteropappus bowerii)在群落中的重要值,且能显著提高高寒草原优势种紫花针茅(Stipa purpurea)生物量(P <0.05);围封降低了群落Pielou物种均匀度指数,短期封育草地4个物种多样性指数均略高于长期围封草地(P> 0.05)。

Furstenberg family and chaos

A Furstenberg family F is a family,consisting of some subsets of the set of positive integers,which is hereditary upwards,i.e.A?B and A∈F imply B∈F.For a given system(i.e.,a pair of a complete metric space and a continuous self-map of the space)and for a Furstenberg family F,the definition of F-scrambled pairs of points in the space has been given,which brings the well-known scrambled pairs in Li-Yorke sense and the scrambled pairs in distribution sense to be F-scrambled pairs corresponding respectively to suitable Furstenberg family F.In the present paper we explore the basic properties of the set of F-scrambled pairs of a system.The generically F-chaotic system and the generically strongly F-chaotic system are defined.A criterion for a generically strongly F-chaotic system is showed.

Design of precision variable-rate spray system for unmanned aerial vehicle using automatic control method

In order to reduce the use of chemical pesticides in crop plant protection and improve the utilization efficiency of pesticides,it is necessary to study advanced application machinery and application techniques.The use of unmanned aerial vehicle(UAV)for pesticide spraying has the characteristics of less application,strong penetrability,wide applicability and flexible operation scheduling,and has gradually become one of the important development directions in the field of aviation plant protection.However,the operation process of the UAV is often affected by meteorological factors and human manipulation,resulting in poor actual operation with inaccurate spray volume and uneven application.Therefore,to improve the stability and uniformity of the application of the plant protection UAV under variable operating conditions,in this paper a real-time control method was proposed for the application flow rate,and a precision variable-rate spray system was designed based on single-chip microcomputer and micro diaphragm pump that can controls the flow rate of the pump in real time with the changes of the operating state.The response s-peed of the variable-rate spray system was tested.The average control response time of the system was 0.18 s,and the average stability time of the pump flow change was 0.75 s.The test results showed that the system has a quick response to the working state and the adjustment of the target flow of the pump can be quickly completed to realize the variable-rate spray function.The research results can provide a reference for the practical application of plant protection UAV variable-rate spray system.

High-throughput genotyping of single-nucleotide polymorphisms in ace-1 gene of mosquitoes using MALDI-TOF mass spectrometry

Acetylcholinesterase （ACHE） plays a vital role in the nervous system of insects and other animal species and serves as the target for many chemical agents such as organophosphate and carbamate insecticides. The mosquito, Culex pipiens complex, a vector of human disease, has evolved to be resistant to insecticides by a limited number of amino acid substitutions in ACHE1, which is encoded by the ace-1 gene. The aims of this study are to identify single nucleotide polymorphism （SNP） sites in the ace-1 gene of the C. pipiens complex and explore an economical high-throughput method to differentiate the genotypes of these sites in mosquitoes collected in the field. We identified 22 SNP sites in exon regions of the ace-1 gene. Four of them led to non-synonymous mutations, that is, Y163C, G247S, C677S and T682A. We used matrix-assisted laser desorption ionization - time-of-flight mass spectrometry for genotyping at these four sites and another site F416V, which was relevant to insecticide resistance, in 150 mosquitoes collected from 15 field populations. We were able to synchronize analysis of the five SNP sites in each well of a 384-well plate for each individual mosquito, thus decreasing the cost to one-fifth of the routine analysis. Heterozygous genotypes at Y163C and G247S sites were observed in one mosquito. The possible influence of the five SNP sites on the activity or function of the enzyme is discussed based on the predicted tertiary structure of the enzyme.

A New Farnesyl Diphosphate Synthase Gene from Taxus media Rehder:Cloning,Characterization and Functional Complementation

Farnesyl dlphosphate synthase （FPS; EC 2.5.1.10） catalyzes the production of 15-carbon farnesyl dlphosphate which Is a branch-point Intermediate for many terpenoids. This reaction Is considered to be a ratelimiting step In terpenold biosynthesis. Here we report for the first time the cloning of a new full-length cDNA encoding farnesyl dlphosphate synthase from a gymnosperm plant species, Taxus media Rehder, designated as TmFPS1. The full-length cDNA of TmFPS1 （GenBank accession number： AY461811） was 1 464 bp with a 1 056-bp open reading frame encoding a 351-amino acid polypeptlde with a calculated molecular weight of 40.3 kDa and a theoretical pl of 5.07. Biolnformatlc analysis revealed that TmFPS1 contained all five conserved domains of prenyltransferases, and showed homology to other FPSs of plant origin. Phylogenetlc analysis showed that farnesyl dlphosphate synthases can be divided Into two groups： one of prokaryotic origin and the other of eukaryotic origin. TmFPS1 was grouped with FPSs of plant origin. Homologybased structural modeling showed that TmFPS1 had the typical spatial structure of FPS, whose most prominent structural feature Is the arrangement of 13 core helices around a large central cavity In which the catalytic reaction takes place. Our blolnformatic analysis strongly suggests that TmFPS1 is a functional gene. Southern blot analysis revealed that TmFPS1 belongs to a small FPSgene family in T. media. Northern blot analysis indicated that TmFPS1 is expressed in all tested tissues, Including the needles, stems and roots of T. media. Subsequently, functional complementatlon with TmFPS1 in a FPS-deflclent mutant yeast demonstrated that TmFPS1 did encode farnesyl dlphosphate synthase, which rescued the yeast mutant. This study will be helpful In future Investigations aiming at understanding the detailed role of FPS In terpenold biosynthesis flux control at the molecular genetic level.

Diffusive gradients in thin films using molecularly imprinted polymer binding gels for in situ measurements of antibiotics in urban wastewaters

Urban wastewater is one of main sources for the introduction of antibiotics into the environment.Monitoring the concentrations of antibiotics in wastewater is necessary for estimating the amount of antibiotics discharged into the environment through urban wastewater treatment systems.In this study,we report a novel diffusive gradient in thin films(DGT)method based on molecularly imprinted polymers(MIPs)for in situ measurement of two typical antibiotics,fluoroquinolones(FQs)and sulfonamides(SAs)in urban wastewater.MIPs show specific adsorption toward their templates and their structural analogs,resulting in the selective uptake of the two target antibiotics during MIP-DGT deployment.The uptake performance of the MIP-DGTs was evaluated in the laboratory and was relatively independent of solution pH(4.0-9.0),ionic strength(1-750 mmol/L),and dissolved organic matter(DOM,0-20 mg/L).MIP-DGT samplers were tested in the effluent of an urban wastewater treatment plant for field trials,where three SA(sulfamethoxazole,sulfapyridine,and trimethoprim)and one FQ(ofloxacin)antibiotics were detected,with concentrations ranging from 25.50 to 117.58 ng/L,which are consistent with the results measured by grab sampling.The total removal efficiency of the antibiotics was 80.1%by the treatment plant.This study demonstrates that MIP-DGT is an effective tool for in situ monitoring of trace antibiotics in complex urban wastewaters.

Dependent sets of a family of relations of full measure on a probability space

For a probability space (X, B, μ) a subfamily F of the σ-algebra B is said to be a regular base if every B ∈ B can be arbitrarily approached by some member of F which contains B in the sense of the measure theory. Assume that {R γ } γ∈Γ is a countable family of relations of the full measure on a probability space (X, B, μ), i.e. for every γ ∈ Γ there is a positive integer s γ such that R γ ? $X^{s_\gamma } $ with $\mu ^{s_\gamma } $ (R γ ) = 1. In the present paper we show that if (X, B, μ) has a regular base, the cardinality of which is not greater than the cardinality of the continuum, then there exists a set K ? X with μ*(K) = 1 such that (x 1, …, $x_{^{s_\gamma } } $ ) ∈ R γ for any γ ∈ Γ and for any s γ distinct elements x 1, …, $x_{^{s_\gamma } } $ of K, where μ* is the outer measure induced by the measure μ. Moreover, an application of the result mentioned above is given to the dynamical systems determined by the iterates of measure-preserving transformations.

Recent Trends and Challenges with COVID-19—Africa,April 4,2020

Summary What is already known about this topic?Since the first COVID-19 confirmed case was reported,the current epidemic in Africa has rapidly increased.What is added by this report?As of April 4,2020,a total of 7,405 confirmed cases and 305 deaths had been reported from 51 countries across Africa.The cumulative number of reported COVID-19 cases varied among the five regions of Africa,of which northern Africa reported the largest number of confirmed cases.The five countries with the highest number of cases are South Africa,Algeria,Egypt,Morocco,and Tunisia.What are the implications for public health practice?