Blockchain technology has witnessed a burgeoning integration into diverse realms of economic and societal development.Nevertheless,scalability challenges,characterized by diminished broadcast efficiency,heightened com...Blockchain technology has witnessed a burgeoning integration into diverse realms of economic and societal development.Nevertheless,scalability challenges,characterized by diminished broadcast efficiency,heightened communication overhead,and escalated storage costs,have significantly constrained the broad-scale application of blockchain.This paper introduces a novel Encode-and CRT-based Scalability Scheme(ECSS),meticulously refined to enhance both block broadcasting and storage.Primarily,ECSS categorizes nodes into distinct domains,thereby reducing the network diameter and augmenting transmission efficiency.Secondly,ECSS streamlines block transmission through a compact block protocol and robust RS coding,which not only reduces the size of broadcasted blocks but also ensures transmission reliability.Finally,ECSS utilizes the Chinese remainder theorem,designating the block body as the compression target and mapping it to multiple modules to achieve efficient storage,thereby alleviating the storage burdens on nodes.To evaluate ECSS’s performance,we established an experimental platformand conducted comprehensive assessments.Empirical results demonstrate that ECSS attains superior network scalability and stability,reducing communication overhead by an impressive 72% and total storage costs by a substantial 63.6%.展开更多
In blockchain-based unmanned aerial vehicle(UAV)communication systems,the length of a block affects the performance of the blockchain.The transmission performance of blocks in the form of finite character segments is ...In blockchain-based unmanned aerial vehicle(UAV)communication systems,the length of a block affects the performance of the blockchain.The transmission performance of blocks in the form of finite character segments is also affected by the block length.Therefore,it is crucial to balance the transmission performance and blockchain performance of blockchain communication systems,especially in wireless environments involving UAVs.This paper investigates a secure transmission scheme for blocks in blockchain-based UAV communication systems to prevent the information contained in blocks from being completely eavesdropped during transmission.In our scheme,using a friendly jamming UAV to emit jamming signals diminishes the quality of the eavesdropping channel,thus enhancing the communication security performance of the source UAV.Under the constraints of maneuverability and transmission power of the UAV,the joint design of UAV trajectories,transmission power,and block length are proposed to maximize the average minimum secrecy rate(AMSR).Since the optimization problem is non-convex and difficult to solve directly,we first decompose the optimization problem into subproblems of trajectory optimization,transmission power optimization,and block length optimization.Then,based on firstorder approximation techniques,these subproblems are reformulated as convex optimization problems.Finally,we utilize an alternating iteration algorithm based on the successive convex approximation(SCA)technique to solve these subproblems iteratively.The simulation results demonstrate that our proposed scheme can achieve secure transmission for blocks while maintaining the performance of the blockchain.展开更多
Introduction: Human papillomavirus (HPV) infection is the most widespread sexually transmitted infection in the world. Today, there is growing evidence that HPV can be transmitted early in life, and one potential rout...Introduction: Human papillomavirus (HPV) infection is the most widespread sexually transmitted infection in the world. Today, there is growing evidence that HPV can be transmitted early in life, and one potential route is mother-to-child transmission. Data on this route of HPV transmission are scarce in Africa and particularly in Burkina Faso, where no data on the subject are yet available. The aim of our study was to estimate the rate of mother-to-child transmission of HPV infection and to identify circulating genotypes. Methodology: Cervico-uterine samples were collected from 100 full-term pregnant women and, buccal samples were obtained from their newborns at Hopital Saint Camille de Ouagadougou (HOSCO) by the specialist physician. HPV DNA amplification and genotyping were performed by PCR followed by hybridization using the HPV Direct Flow Chips kit, detecting 36 genotypes including 18 high-risk and 18 low-risk. Results: The prevalence of HPV in newborns was 8% (8/100). Six (6) HPV-positive neonates had HPV-positive mothers, while 2 HPV-positive neonates had HPV-negative mothers. The vertical transmission rate was 26.09% (6/23). Mother-newborn genotypes were concordant. However, the genotype profile of the newborns was more restricted than that of the mothers. Conclusion: HPV DNA was found in 8% of newborns in our study. The genotype profile of the mother-newborn pair was concordant. Asymptomatic HPV infection in a pregnant woman could constitute a risk factor for vertical transmission.展开更多
Hepatitis B virus(HBV)infection is a major public health burden.In HBV endemic regions,high prevalence is also correlated with the infections acquired in infancy through perinatal transmission or early childhood expos...Hepatitis B virus(HBV)infection is a major public health burden.In HBV endemic regions,high prevalence is also correlated with the infections acquired in infancy through perinatal transmission or early childhood exposure to HBV,the socalled mother-to-child transmission(MTCT).Children who are infected with HBV at a young age are at higher risk of developing chronic HBV infection than those infected as adults,which may lead to worse clinical outcome.To reduce the incidence of HBV MTCT,several interventions for the infants or the mothers,or both,are already carried out.This review explores the newest information and approaches available in literature regarding HBV MTCT prevalence and its challenges,especially in high HBV endemic countries.This covers HBV screening in pregnant women,prenatal intervention,infant immunoprophylaxis,and postvaccination serological testing for children.展开更多
Introduction: Acquired immunodeficiency syndrome is one of the leading causes of mortality among women of reproductive age and Mother to Child Transmission of Human immunodeficiency virus is still a challenge affectin...Introduction: Acquired immunodeficiency syndrome is one of the leading causes of mortality among women of reproductive age and Mother to Child Transmission of Human immunodeficiency virus is still a challenge affecting many countries. Globally, an estimation of 180,000 children under 15 years acquire the Human immunodeficiency virus every day, and more than 90% of those infections are due to Mother to Child Transmission. The study sought to explore the experiences of mothers on the Elimination of Mother to Child Transmission-HIV services at Mtendere Clinic, Lusaka. Materials and Methods: Qualitative interpretive phenomenology study design was employed using in-depth interviews to collect data from a sample that was selected using purposive sampling technique. Thirteen participants were recruited, and these were HIV-positive mothers at least between the ages of 15 and 49 years and enrolled in the Elimination of Mother To Child Transmission-HIV program. The in-depth interviews were audiotape recorded and transcribed verbatim. Data was analyzed using thematic method. Findings: Three main themes that emerged are;living with HIV, support system and barriers to utilization of Elimination of Mother To Child Transmission-HIV services. Most of the participants expressed having acquired knowledge from the program, and received counselling and support from spouses, family as well as health personnel at Mtendere health facility which culminated into a positive experience and enhanced their uptake of the Elimination of Mother to Child Transmission-HIV services. However, barriers to service utilization were identified and these included fear of stigma, negative attitudes from health workers, long waiting times, lack of support and lack of transport to the health facility. Conclusion: Interventions such as community awareness campaigns on Elimination of Mother To Child Transmission-HIV, male involvement and implementing mother-to-mother peer support strategies in Elimination of Mother To Child Transmission-HIV service utilization should be prioritized so as to alleviate stigma and enhancing a positive experience for these mothers thus reducing on the Mother to Child HIV Transmission burden and mortality rates.展开更多
The elimination of vertical transmission of HIV from mother to child is a major global goal. In Senegal, the transmission rate was estimated at 3.2% in 2017. To reduce or even eliminate this transmission, Senegal has ...The elimination of vertical transmission of HIV from mother to child is a major global goal. In Senegal, the transmission rate was estimated at 3.2% in 2017. To reduce or even eliminate this transmission, Senegal has implemented various strategies and programs adopted and applied nationally. Thus access to services for the prevention of mother-to-child transmission of HIV has been extended to the level of the health post (the lowest level of the country’s health pyramid) with a delegation of tasks to paramedical staff (nurse, midwife) in the diagnosis and therapeutic management. Objectives: To describe the epidemiological profile of HIV (Human Immunodeficiency Virus)-positive mothers, to assess the care of children born to HIV-positive mothers, to determine the rate of HIV transmission from mother to child. Patients and Method: We carried out a retrospective, cross-sectional and descriptive study of all live newborns of HIV-positive mothers who gave birth at the Gaspard Kamara Health Center (a level 2 health center in Dakar, Senegal) between January 1, 2015 and December 31, 2018. The data were collected from prevention of mother-to-child transmission (PMTCT) prenatal follow-up registers and files, delivery files and registers, and neonatology and pediatric follow-up files, and exploited using the Epi info 7 software. Results: There were 98 children of seropositive mothers. The epidemiological profile of the HIV-positive woman was that of a young woman aged between 16 and 43 with an average of 31.31 years, pauciparous (>65% of cases) from Dakar center (>75% of cases), housewife with a low socio-economic level (63.1% of cases), married in almost all cases, with HIV profile (in almost all cases) and diagnosed before pregnancy (51.02%). The analysis of the children’s data revealed a predominance of girls (52.04%) with a good birth weight (2964g on average) and a pregnancy carried to term in more than 95% of cases. ARV prophylaxis was almost entirely respected with triple therapy (AZT + 3TC + NVP) in a fixed combination as protocol. Protected breastfeeding (80.21%), including 6 months of exclusive protected breastfeeding, was the rule for the mode of feeding. Three children were diagnosed positive with PCR1 as with serology (3.06%). Discussion and Conclusion: the initiatives and strategies put in place in Senegal have enabled a significant reduction in mother-to-child transmission of HIV and deserve to be supported by insisting on primary prevention, programming and good follow-up of pregnancies, and a good support for HIV-positive women.展开更多
Introduction: For several years, the fight against the human immunodeficiency virus (HIV) has been a major public health issue in Africa. Since 2012, Senegal has adopted WHO option B+, consisting of systematic triple ...Introduction: For several years, the fight against the human immunodeficiency virus (HIV) has been a major public health issue in Africa. Since 2012, Senegal has adopted WHO option B+, consisting of systematic triple therapy for HIV-positive pregnant women, combined with breastfeeding and antiretroviral (ARV) prophylaxis for exposed newborns. It is in this dynamic that we set ourselves the objectives of evaluating the rate of transmission of HIV from mother to child and taking stock of the monitoring of children born to HIV-positive mothers at the Pediatric Department of the CHN of Pikine located in the Dakar suburbs. Methodology: Thus, we conducted a descriptive and analytical cross-sectional cohort follow-up study from 11/25/2014 to 03/09/2022 including all children born to HIV-positive mothers followed at the Pikine CHN since the start of care. Results: We had collected 51 children exposed to HIV and followed in our structure. They were exposed to HIV1 in 92% of cases. The HIV status of the mothers was known before pregnancy in more than half of the cases. The couples were serodiscordant in 56% of cases. The mothers were in clinical stage 1 of the disease in 69.6% of cases and were already under treatment in 47% of cases. The most used treatment regimen was ATRIPLA with Tenofovir (TDF) + Emtracitabine (FTC) + Efavirenz (EFV) in 59% of cases. Compliance was good in the majority of cases. The CD4 count during pregnancy was low in 10.6% of cases. The pregnancy was well followed in only 36.2% of cases. The mothers had given birth in our structure in 91.4% of cases. The vaginal route was found in 72.5% of cases and delivery was carried out by a midwife in 69.4% of cases. The average birth weight was 2733 ± 564. The majority of newborns had received antiretroviral (ARV) prophylaxis after birth, half of them between 12 and 24 hours. The most used therapeutic protocol was Zidovudine (AZT) + Lamivudine (3TC) + Lopinavir/Ritonavir (LPV/r). Protected breastfeeding was the option chosen in 76.8% of cases. The PCR performed at 6 weeks was negative in more than half of the cases. Retroviral serology was carried out after 14 months in 43% of cases. We noted a single positive case with a negative initial PCR, representing an overall transmission rate of 1.96%. Conclusion: Senegal’s current policy targeting EMTCT of HIV is on good momentum with a fairly low transmission rate thanks to screening of pregnant women and prophylaxis with antiretrovirals (ARV) for HIV-positive mothers during pregnancy and for life. And children exposed from birth and during breastfeeding up to 6 weeks with regular monitoring.展开更多
[ Objective] To investigate the blocking effects of spleen vaccine on vertical transmission of classical swine fever virus (CSFV) in sows. [ Method] Sows infected by CSFV were selected from three large-scale pig far...[ Objective] To investigate the blocking effects of spleen vaccine on vertical transmission of classical swine fever virus (CSFV) in sows. [ Method] Sows infected by CSFV were selected from three large-scale pig farms and they were randomly divided into group Ⅰ, group Ⅱ and control group. The sows in the group Ⅰ were vaccinated with CSF spleen vaccine at a 1.5 times normal dose per pig; those in the group Ⅱ were vaccinated with CSF spleen vaccine at a 2.0 times normal dose per pig; and those in the control group were vaccinated with cell vaccine at a 4.0 times normal- dose per pig. The CSF antigens of piglets were detected by enzyme-linked immunosorbent assay (ELISA). [ Result] The antigen positive rate of piglets in the experimental group (18.5%) was significantly lower than that in the control group (48.1% ). No significant difference was found be- tween the group Ⅰ and the group Ⅱ. [ Condmion] CSF spleen vaccine has good blocking effects on vertical transmission of CSFV in sows.展开更多
In this paper,we investigate the evolution of spatiotemporal patterns and synchronization transitions in dependence on the information transmission delay and ion channel blocking in scale-free neuronal networks.As the...In this paper,we investigate the evolution of spatiotemporal patterns and synchronization transitions in dependence on the information transmission delay and ion channel blocking in scale-free neuronal networks.As the underlying model of neuronal dynamics,we use the Hodgkin-Huxley equations incorporating channel blocking and intrinsic noise.It is shown that delays play a significant yet subtle role in shaping the dynamics of neuronal networks.In particular,regions of irregular and regular propagating excitatory fronts related to the synchronization transitions appear intermittently as the delay increases.Moreover,the fraction of working sodium and potassium ion channels can also have a significant impact on the spatiotemporal dynamics of neuronal networks.As the fraction of blocked sodium channels increases,the frequency of excitatory events decreases,which in turn manifests as an increase in the neuronal synchrony that,however,is dysfunctional due to the virtual absence of large-amplitude excitations.Expectedly,we also show that larger coupling strengths improve synchronization irrespective of the information transmission delay and channel blocking.The presented results are also robust against the variation of the network size,thus providing insights that could facilitate understanding of the joint impact of ion channel blocking and information transmission delay on the spatiotemporal dynamics of neuronal networks.展开更多
The worldwide decline over the last decade in the number of clinical cases of malaria does not mean an end to the universal problem of malaria pathogenesis in those afflicted by infection. Resistance to drugs, higher ...The worldwide decline over the last decade in the number of clinical cases of malaria does not mean an end to the universal problem of malaria pathogenesis in those afflicted by infection. Resistance to drugs, higher risk of disease relapse and failure to maintain effective memory of the pathogen in the absence of persistent exposure result in the repeated failure of anti-malarialtreatments. The artificial blocking of transmission of the Plasmodium parasite between hosts from human to Anopheles mosquito, and vice versa, is crucial to restricting the spread of disease. However, a limited knowledge of the molecular mechanisms in operation for transmission of malaria has impeded progress towards a transmission-blocking vaccine. This review highlights the role of anti-malarial immune responses to antigen-specific targets for designing effective vaccines against the sexual stages of Plasmodium that occur within the invertebrate vector. In particular, artificial induction of gametocyte and ookinete apoptosis as a novel means to prevent gamete fertilization and oocyte development, respectively, is highlighted. This and other recent insights into our understanding of the molecular regulation of transmission-blocking immunity are discussed and future prospects considered.展开更多
AIM: To determine the therapeutic effect of lamivu- dine in late pregnancy for the interruption of motherto-child transmission (MTCT) of hepatitis B virus (HBV). METHODS: Studies were identified by searching ava...AIM: To determine the therapeutic effect of lamivu- dine in late pregnancy for the interruption of motherto-child transmission (MTCT) of hepatitis B virus (HBV). METHODS: Studies were identified by searching available databases up to January 2011. Inclusive criteria were HBV-carrier mothers who had been involved in randomized controlled clinical trials (RCTs) with lamivudine treatment in late pregnancy, and newborns or infants whose serum hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg) or HBV DNA had been documented. The relative risks (RRs) for inerruption of MTCT as indicated by HBsAg, HBV DNA or HBeAg of newborns or infants were calculated with 95% confidence interval (CI) to estimate the efficacy of lamivudine treatment. RESULTS: Fifteen RCTs including 1693 HBV-carrier mothers were included in this meta-analysis. The overall RR was 0.43 (95% CI, 0.25-0.76; 8 RCTs; Phet- erogeneity= 0.04) and 0.33 (95% CI, 0.23-0.47; 6 RCTs; Pheterogeneity = 0.93) indicated by newborn HBsAg or HBV DNA. The RR was 0.33 (95% CI, 0.21-0.50; 6 RCTs; Pheterogeneity = 0.46) and 0.32 (95% CI, 0.20-0.50; 4 RCTs; Pheterogeneity = 0.33) indicated by serum HBsAg or HBV DNA of infants 6-12 mo after birth. The RR (lamivudine vs hepatitis B immunoglobulin) was 0.27 (95% CI, 0.16-0.46; 5 RCTs; Pheterogeneity = 0.94) and 0.24 (95% CI, 0.07-0.79; 3 RCTs; Pheterogeneity = 0.60) indicated by newborn HBsAg or HBV DNA, respectively. In the mothers with viral load 〈 106 copies/mL after lamivudine treatment, the efficacy (RR, 95% CI) was 0.33, 0.21-0.53 (5 RCTs; Pheterogeneity = 0.82) for the interruption of MTCT, however, this value was not significant if maternal viral load was 〉 106 copies/mL after lamivudine treatment (P = 0.45, 2 RCTs), as indicated by newborn serum HBsAg. The RR (lamivudine initiated from 28 wk of gestation vs control) was 0.34 (95% CI, 0.22-0.52; 7 RCTs; Pheterogeneity = 0.92) and 0.33 (95% CI, 0.22-0.50; 5 RCTs; Pheterogeneity = 0.86) indicated by newborn HBsAg or HBV DNA. The incidence of adverse effects of lamivudine was not higher in the mothers than in controls (P = 0.97). Only one study reported side effects of lamivudine in newborns. CONCLUSION: Lamivudine treatment in HBV carrier- mothers from 28 wk of gestation may interrupt MTCT of HBV efficiently. Lamivudine is safe and more efficient than hepatitis B immunoglobulin in interrupting MTCT. HBV MTCT might be interrupted efficiently if maternal viral load is reduced to 〈 106 copies/mL by lamivudine treatment.展开更多
In 2016, there were 17.8 million (15.4-20.3 million) women living with HIV/AIDS across the world and the prevalence of reproductive desire among this group was 26%-49%[1]. If pregnant women living with HIV/AIDS are le...In 2016, there were 17.8 million (15.4-20.3 million) women living with HIV/AIDS across the world and the prevalence of reproductive desire among this group was 26%-49%[1]. If pregnant women living with HIV/AIDS are left untreated, the rates of HIV transmission from mother-to-child would range from 14% to 48%, depending on the presence and duration of breastfeeding[2].展开更多
An analytic method is used to study the reflection and transmission coefficients of the double submerged rectangular blocks (DSRBs) in oblique waves. The scattering potentials are obtained by means of the eigenfunct...An analytic method is used to study the reflection and transmission coefficients of the double submerged rectangular blocks (DSRBs) in oblique waves. The scattering potentials are obtained by means of the eigenfunction expansion method, and expressions for the reflection and transmission coefficients are determined. The boundary element method is employed to verify the correctness of the present analytical method. The DSRBs have better performance than the single submerged rectangular block (SSRB) in certain cases. The reflection and transmission properties of the DSRBs are investigated for some specific cases, and the influences of the geometric parameters are also presented.展开更多
Mother-to-child transmission(MTCT)of syphilis remains a leading cause of stillbirth and death among neonates in many developing countries.In 2007,World Health Orgernization launched the global elimination of MTCT(EMTC...Mother-to-child transmission(MTCT)of syphilis remains a leading cause of stillbirth and death among neonates in many developing countries.In 2007,World Health Orgernization launched the global elimination of MTCT(EMTCT)of syphilis.Given the high burden of congenital syphilis,China subsequently released the specific national EMTCT policies and programs to reduce MTCT of syphilis.The congenital syphilis incidence rate per 100,000 live births in China has markedly decreased from 69.9 in 2013 to 11.9 in 2019.However,due to the global pandemic of COVID-19,the current measures for eliminating MTCT of syphilis are greatly challenged.In this article,we summarize the strategies and measures for the EMTCT of syphilis in China in the past 20 years,the remarkable achievements by the policy support under the leadership of the government.In the context of COVID-19 pandemics,strengthening emergency response to the regional outbreaks of COVID-19,adopting safe,rapid,early and high-quality clinical care for 100%of pregnant women to receive prenatal syphilis testing services,ensuring the availability of Benzathine penicillin for the treatment,and strengthening the closed-loop management of pregnant women and newborns infected with syphilis are the key measures to determine the effectiveness of MTCT for syphilis.Lessons from China may be valuable for other countries that are planning to eliminate MTCT of syphilis.展开更多
As an alternative to satellite communications,multi-hop relay networks can be deployed for maritime long-distance communications.Distinct from terrestrial environment,marine radio signals are affected by many factors,...As an alternative to satellite communications,multi-hop relay networks can be deployed for maritime long-distance communications.Distinct from terrestrial environment,marine radio signals are affected by many factors,e.g.,weather conditions,evaporation ducting,and ship rocking caused by waves.To ensure the data transmission reliability,the block Markov superposition transmission(BMST)codes,which are easily configurable and have predictable performance,are applied in this study.Meanwhile,the physical-layer network coding(PNC)scheme with spatial modulation(SM)is adopted to improve the spectrum utilization.For the BMST-SMPNC system,we propose an iterative algorithm,which utilizes the channel observations and the a priori information from BMST decoder,to compute the soft information corresponding to the XORed bits constructed by the relay node.The results indicate that the proposed scheme outperforms the convolutional coded SM-PNC over fast-fading Rician channels.Especially,the performance can be easily improved in high spatial correlation maritime channel by increasing the memory m.展开更多
In free-space optical(FSO) communications, the performance of the communication systems is severely degraded by atmospheric turbulence. Channel coding and diversity techniques are commonly used to combat channel fadin...In free-space optical(FSO) communications, the performance of the communication systems is severely degraded by atmospheric turbulence. Channel coding and diversity techniques are commonly used to combat channel fading induced by atmospheric turbulence. In this paper, we present the generalized block Markov superposition transmission(GBMST) of repetition codes to improve time diversity. In the GBMST scheme, information sub-blocks are transmitted in the block Markov superposition manner, with possibly different transmission memories. Based on analyzing an equivalent system, a lower bound on the bit-error-rate(BER) of the proposed scheme is presented. Simulation results demonstrate that, under a wide range of turbulence conditions, the proposed scheme improves diversity gain with only a slight reduction of transmission rate. In particular, with encoding memory sequence(0, 0, 8) and transmission rate 1/3, a diversity order of eleven is achieved under moderate turbulence conditions. Numerical results also show that, the GBMST systems with appropriate settings can approach the derived lower bound, implying that full diversity is achievable.展开更多
In order to improve the poor performance of Space-Time Block Coding (STBC) in a downlink correlated fading environment, a closed loop scheme is proposed. With the known channel fading statistics fed from the receiver,...In order to improve the poor performance of Space-Time Block Coding (STBC) in a downlink correlated fading environment, a closed loop scheme is proposed. With the known channel fading statistics fed from the receiver, eigenbeamforming is utilized to improve the performance of STBC at the transmitter. The new system achieves the array and diversity gain simultaneously. Because reduced dimension processing is adopted, the proposed system has a relative simple structure compared with the traditional beamforming system. The validity of the scheme is verified in several situations by simulation experiments.展开更多
The main source of HIV infection in young children is of their mothers, during pregnancy, labor and delivery, or by breastfeeding. The rate of HIV transmission from infected mothers to their newborn children varies fr...The main source of HIV infection in young children is of their mothers, during pregnancy, labor and delivery, or by breastfeeding. The rate of HIV transmission from infected mothers to their newborn children varies from 15% to 40% with one-thirds of these infections was through breastfeeding. This paper examines cross-sectional population-based survey data of HIV test results among mothers and their children in Uganda, Swaziland to estimates of mother-to- child transmission (MTCT) rate of HIV infection. The prevalence of HIV among women aged 15 - 49 who gave birth in the past 5 years in Uganda is 7.3%, and in Swaziland is 37.9%. The HIV prevalence of children who mothers were HIV positive were very similar: 10.3% in Uganda and 11.5% in Swaziland. This association represents the crude rate of MTCT in these two countries at the time of the survey. Presence of HIV antibody in early age (0 - 11 months) is due to both true infection and passive antibody from mothers. The seroconversion dropped nearly half in the second year of age which was likely that many of these children died before reaching the age of 12 - 23 months and passive antibody were gradually cleared at this point. This analysis demonstrated that cross-sectional data can be used to estimate indirectly the magnitude and dynamic of MTCT.展开更多
Objective: To determine the knowledge and awareness of Human Immunodeficiency Virus (HIV)/Acquired Immunodeficiency Syndrome (AIDS) and mother-to-child transmission (MTCT) among women attending the antenatal clinic. M...Objective: To determine the knowledge and awareness of Human Immunodeficiency Virus (HIV)/Acquired Immunodeficiency Syndrome (AIDS) and mother-to-child transmission (MTCT) among women attending the antenatal clinic. Methods and Subjects: This was primarily a descriptive cross-sectional study carried out at the antenatal clinic of Olabisi Onabanjo University Teaching Hospital (OOUTH), Sagamu, Nigeria from July 1st, 2010 to October 31st, 2010. Results: The age range of the respondents was 18 - 41 years, (mean 29 ± 5 years). One hundred and forty-nine (92.5%) were married. All the respondents interviewed were aware of HIV/AIDS and 93 (57.8%) had been aware of the disease for ≥5 years. The main sources of information were television 93 (57.8%), radio 77 (47.8%), health workers 53 (32.9%), friends, relatives and neighbors 41 (25.5%) and posters 34 (21.1%). Majority of the respondents identified sexual intercourse as a route of transmission of HIV. Sharing of sharp objects and blood transfusion were identified as routes of transmission by 99 (61.5%) and 82 (50.9%) respectively. One hundred and sixteen (72%) of the respondents knew an apparently healthy person could be living with HIV. Majority of the respondents 125 (77.6%) were aware that HIV can coexist with pregnancy and 120 (74.5%) were aware of MTCT of HIV. Vaginal delivery and breastfeeding were identified as routes of HIV transmission by 44 (27.3%) and 53 (32.9%) of respondents respectively. Delivery by caesarean section was identified as a method of prevention of MTCT by 25 (15.5%) respondents while as many as 48 (29.8%) respondents did not know any method of prevention of MTCT of HIV. Conclusion: This study demonstrates a low level of awareness of methods of prevention of MTCT of HIV among pregnant women booking for antenatal care in our center. Thus, there is the need for adequate counseling about HIV/AIDS and specific aspects of prevention of mother-to-child transmission in our antenatal clinics.展开更多
Background: The elimination of HIV transmission from mother to child is currently possible. Cote d’Ivoire, which has a 4.6% HIV prevalence among women, is one of 22 pilot countries for the elimination of mother-to-ch...Background: The elimination of HIV transmission from mother to child is currently possible. Cote d’Ivoire, which has a 4.6% HIV prevalence among women, is one of 22 pilot countries for the elimination of mother-to-child transmission of HIV. Since 2015, Cote d’Ivoire has adopted new strategies according to the WHO B+ guidelines. Objective: To identify factors associated with mother-to-child HIV transmission in children born of seropositive mothers managed at Treichville university hospital. Material and methods: A case-control study was conducted in the obstetrics department at Treichville university hospital, between January 2013 and December 2015. It involved children born to mothers infected with HIV, whose first PCR (Polymerase Chain Reaction) result was available during this period. A standardized questionnaire on data related to exposed children and their mother was used. Factors associated with mother-to-child HIV transmission were investigated using logistic regression. Results: A total of 214 HIV-exposed children were included in the study with a sex ratio of 0.9. The majority of the children were born by vaginal route (52.8%) and received post-exposure prophylaxis (88.3%) and replacement feed (51.9%). Their mothers received antiretroviral therapy during pregnancy in 45.3% of the cases. The first PCR was performed at the sixth week of life in 52.3% of cases. The prevalence of HIV infection in exposed children was 7.5% (95% CI = 4.5% - 11.8%). In multivariate analysis, the absence of antiretroviral prophylaxis in children [aOR = 4.3, 95% (1.2 to 15.6), p = 0.03], the mixed feed [aOR = 3.8, 95% (1.1 - 13.1), p < 0.03], the failure to take antiretroviral regimen during pregnancy [aOR = 8.0, 95% CI (1.9 - 32.4), p < 0.003], were associated with mother-child HIV transmission. Conclusion: The mother-to-child HIV transmission rate remains high in our practice. Strategies to reduce situations that do not comply with current recommendations should be considered to prevent mother-to-child HIV transmission.展开更多
文摘Blockchain technology has witnessed a burgeoning integration into diverse realms of economic and societal development.Nevertheless,scalability challenges,characterized by diminished broadcast efficiency,heightened communication overhead,and escalated storage costs,have significantly constrained the broad-scale application of blockchain.This paper introduces a novel Encode-and CRT-based Scalability Scheme(ECSS),meticulously refined to enhance both block broadcasting and storage.Primarily,ECSS categorizes nodes into distinct domains,thereby reducing the network diameter and augmenting transmission efficiency.Secondly,ECSS streamlines block transmission through a compact block protocol and robust RS coding,which not only reduces the size of broadcasted blocks but also ensures transmission reliability.Finally,ECSS utilizes the Chinese remainder theorem,designating the block body as the compression target and mapping it to multiple modules to achieve efficient storage,thereby alleviating the storage burdens on nodes.To evaluate ECSS’s performance,we established an experimental platformand conducted comprehensive assessments.Empirical results demonstrate that ECSS attains superior network scalability and stability,reducing communication overhead by an impressive 72% and total storage costs by a substantial 63.6%.
基金supported in part by the National Key R&D Program of China under Grant 2022YFB3104503in part by the China Postdoctoral Science Foundation under Grant 2024M750199+1 种基金in part by the National Natural Science Foundation of China under Grants 62202054,62002022 and 62472251in part by the Fundamental Research Funds for the Central Universities under Grant BLX202360.
文摘In blockchain-based unmanned aerial vehicle(UAV)communication systems,the length of a block affects the performance of the blockchain.The transmission performance of blocks in the form of finite character segments is also affected by the block length.Therefore,it is crucial to balance the transmission performance and blockchain performance of blockchain communication systems,especially in wireless environments involving UAVs.This paper investigates a secure transmission scheme for blocks in blockchain-based UAV communication systems to prevent the information contained in blocks from being completely eavesdropped during transmission.In our scheme,using a friendly jamming UAV to emit jamming signals diminishes the quality of the eavesdropping channel,thus enhancing the communication security performance of the source UAV.Under the constraints of maneuverability and transmission power of the UAV,the joint design of UAV trajectories,transmission power,and block length are proposed to maximize the average minimum secrecy rate(AMSR).Since the optimization problem is non-convex and difficult to solve directly,we first decompose the optimization problem into subproblems of trajectory optimization,transmission power optimization,and block length optimization.Then,based on firstorder approximation techniques,these subproblems are reformulated as convex optimization problems.Finally,we utilize an alternating iteration algorithm based on the successive convex approximation(SCA)technique to solve these subproblems iteratively.The simulation results demonstrate that our proposed scheme can achieve secure transmission for blocks while maintaining the performance of the blockchain.
文摘Introduction: Human papillomavirus (HPV) infection is the most widespread sexually transmitted infection in the world. Today, there is growing evidence that HPV can be transmitted early in life, and one potential route is mother-to-child transmission. Data on this route of HPV transmission are scarce in Africa and particularly in Burkina Faso, where no data on the subject are yet available. The aim of our study was to estimate the rate of mother-to-child transmission of HPV infection and to identify circulating genotypes. Methodology: Cervico-uterine samples were collected from 100 full-term pregnant women and, buccal samples were obtained from their newborns at Hopital Saint Camille de Ouagadougou (HOSCO) by the specialist physician. HPV DNA amplification and genotyping were performed by PCR followed by hybridization using the HPV Direct Flow Chips kit, detecting 36 genotypes including 18 high-risk and 18 low-risk. Results: The prevalence of HPV in newborns was 8% (8/100). Six (6) HPV-positive neonates had HPV-positive mothers, while 2 HPV-positive neonates had HPV-negative mothers. The vertical transmission rate was 26.09% (6/23). Mother-newborn genotypes were concordant. However, the genotype profile of the newborns was more restricted than that of the mothers. Conclusion: HPV DNA was found in 8% of newborns in our study. The genotype profile of the mother-newborn pair was concordant. Asymptomatic HPV infection in a pregnant woman could constitute a risk factor for vertical transmission.
基金Supported by Rumah Program 2024 of Research Organization for Health,National Research and Innovation Agency(BRIN)of Indonesia.
文摘Hepatitis B virus(HBV)infection is a major public health burden.In HBV endemic regions,high prevalence is also correlated with the infections acquired in infancy through perinatal transmission or early childhood exposure to HBV,the socalled mother-to-child transmission(MTCT).Children who are infected with HBV at a young age are at higher risk of developing chronic HBV infection than those infected as adults,which may lead to worse clinical outcome.To reduce the incidence of HBV MTCT,several interventions for the infants or the mothers,or both,are already carried out.This review explores the newest information and approaches available in literature regarding HBV MTCT prevalence and its challenges,especially in high HBV endemic countries.This covers HBV screening in pregnant women,prenatal intervention,infant immunoprophylaxis,and postvaccination serological testing for children.
文摘Introduction: Acquired immunodeficiency syndrome is one of the leading causes of mortality among women of reproductive age and Mother to Child Transmission of Human immunodeficiency virus is still a challenge affecting many countries. Globally, an estimation of 180,000 children under 15 years acquire the Human immunodeficiency virus every day, and more than 90% of those infections are due to Mother to Child Transmission. The study sought to explore the experiences of mothers on the Elimination of Mother to Child Transmission-HIV services at Mtendere Clinic, Lusaka. Materials and Methods: Qualitative interpretive phenomenology study design was employed using in-depth interviews to collect data from a sample that was selected using purposive sampling technique. Thirteen participants were recruited, and these were HIV-positive mothers at least between the ages of 15 and 49 years and enrolled in the Elimination of Mother To Child Transmission-HIV program. The in-depth interviews were audiotape recorded and transcribed verbatim. Data was analyzed using thematic method. Findings: Three main themes that emerged are;living with HIV, support system and barriers to utilization of Elimination of Mother To Child Transmission-HIV services. Most of the participants expressed having acquired knowledge from the program, and received counselling and support from spouses, family as well as health personnel at Mtendere health facility which culminated into a positive experience and enhanced their uptake of the Elimination of Mother to Child Transmission-HIV services. However, barriers to service utilization were identified and these included fear of stigma, negative attitudes from health workers, long waiting times, lack of support and lack of transport to the health facility. Conclusion: Interventions such as community awareness campaigns on Elimination of Mother To Child Transmission-HIV, male involvement and implementing mother-to-mother peer support strategies in Elimination of Mother To Child Transmission-HIV service utilization should be prioritized so as to alleviate stigma and enhancing a positive experience for these mothers thus reducing on the Mother to Child HIV Transmission burden and mortality rates.
文摘The elimination of vertical transmission of HIV from mother to child is a major global goal. In Senegal, the transmission rate was estimated at 3.2% in 2017. To reduce or even eliminate this transmission, Senegal has implemented various strategies and programs adopted and applied nationally. Thus access to services for the prevention of mother-to-child transmission of HIV has been extended to the level of the health post (the lowest level of the country’s health pyramid) with a delegation of tasks to paramedical staff (nurse, midwife) in the diagnosis and therapeutic management. Objectives: To describe the epidemiological profile of HIV (Human Immunodeficiency Virus)-positive mothers, to assess the care of children born to HIV-positive mothers, to determine the rate of HIV transmission from mother to child. Patients and Method: We carried out a retrospective, cross-sectional and descriptive study of all live newborns of HIV-positive mothers who gave birth at the Gaspard Kamara Health Center (a level 2 health center in Dakar, Senegal) between January 1, 2015 and December 31, 2018. The data were collected from prevention of mother-to-child transmission (PMTCT) prenatal follow-up registers and files, delivery files and registers, and neonatology and pediatric follow-up files, and exploited using the Epi info 7 software. Results: There were 98 children of seropositive mothers. The epidemiological profile of the HIV-positive woman was that of a young woman aged between 16 and 43 with an average of 31.31 years, pauciparous (>65% of cases) from Dakar center (>75% of cases), housewife with a low socio-economic level (63.1% of cases), married in almost all cases, with HIV profile (in almost all cases) and diagnosed before pregnancy (51.02%). The analysis of the children’s data revealed a predominance of girls (52.04%) with a good birth weight (2964g on average) and a pregnancy carried to term in more than 95% of cases. ARV prophylaxis was almost entirely respected with triple therapy (AZT + 3TC + NVP) in a fixed combination as protocol. Protected breastfeeding (80.21%), including 6 months of exclusive protected breastfeeding, was the rule for the mode of feeding. Three children were diagnosed positive with PCR1 as with serology (3.06%). Discussion and Conclusion: the initiatives and strategies put in place in Senegal have enabled a significant reduction in mother-to-child transmission of HIV and deserve to be supported by insisting on primary prevention, programming and good follow-up of pregnancies, and a good support for HIV-positive women.
文摘Introduction: For several years, the fight against the human immunodeficiency virus (HIV) has been a major public health issue in Africa. Since 2012, Senegal has adopted WHO option B+, consisting of systematic triple therapy for HIV-positive pregnant women, combined with breastfeeding and antiretroviral (ARV) prophylaxis for exposed newborns. It is in this dynamic that we set ourselves the objectives of evaluating the rate of transmission of HIV from mother to child and taking stock of the monitoring of children born to HIV-positive mothers at the Pediatric Department of the CHN of Pikine located in the Dakar suburbs. Methodology: Thus, we conducted a descriptive and analytical cross-sectional cohort follow-up study from 11/25/2014 to 03/09/2022 including all children born to HIV-positive mothers followed at the Pikine CHN since the start of care. Results: We had collected 51 children exposed to HIV and followed in our structure. They were exposed to HIV1 in 92% of cases. The HIV status of the mothers was known before pregnancy in more than half of the cases. The couples were serodiscordant in 56% of cases. The mothers were in clinical stage 1 of the disease in 69.6% of cases and were already under treatment in 47% of cases. The most used treatment regimen was ATRIPLA with Tenofovir (TDF) + Emtracitabine (FTC) + Efavirenz (EFV) in 59% of cases. Compliance was good in the majority of cases. The CD4 count during pregnancy was low in 10.6% of cases. The pregnancy was well followed in only 36.2% of cases. The mothers had given birth in our structure in 91.4% of cases. The vaginal route was found in 72.5% of cases and delivery was carried out by a midwife in 69.4% of cases. The average birth weight was 2733 ± 564. The majority of newborns had received antiretroviral (ARV) prophylaxis after birth, half of them between 12 and 24 hours. The most used therapeutic protocol was Zidovudine (AZT) + Lamivudine (3TC) + Lopinavir/Ritonavir (LPV/r). Protected breastfeeding was the option chosen in 76.8% of cases. The PCR performed at 6 weeks was negative in more than half of the cases. Retroviral serology was carried out after 14 months in 43% of cases. We noted a single positive case with a negative initial PCR, representing an overall transmission rate of 1.96%. Conclusion: Senegal’s current policy targeting EMTCT of HIV is on good momentum with a fairly low transmission rate thanks to screening of pregnant women and prophylaxis with antiretrovirals (ARV) for HIV-positive mothers during pregnancy and for life. And children exposed from birth and during breastfeeding up to 6 weeks with regular monitoring.
基金supported by the Scientific Research Project Foundation of Jiangxi Provincial Education Department(GJJ08372)
文摘[ Objective] To investigate the blocking effects of spleen vaccine on vertical transmission of classical swine fever virus (CSFV) in sows. [ Method] Sows infected by CSFV were selected from three large-scale pig farms and they were randomly divided into group Ⅰ, group Ⅱ and control group. The sows in the group Ⅰ were vaccinated with CSF spleen vaccine at a 1.5 times normal dose per pig; those in the group Ⅱ were vaccinated with CSF spleen vaccine at a 2.0 times normal dose per pig; and those in the control group were vaccinated with cell vaccine at a 4.0 times normal- dose per pig. The CSF antigens of piglets were detected by enzyme-linked immunosorbent assay (ELISA). [ Result] The antigen positive rate of piglets in the experimental group (18.5%) was significantly lower than that in the control group (48.1% ). No significant difference was found be- tween the group Ⅰ and the group Ⅱ. [ Condmion] CSF spleen vaccine has good blocking effects on vertical transmission of CSFV in sows.
基金supported by the National Natural Science Foundation of China(11172017 and 10972001)the Fujian Natural Science Foundation of China(2009J05004)a Key Project of Fujian Provincial Universities(Information Technology Research Based on Mathematics)
文摘In this paper,we investigate the evolution of spatiotemporal patterns and synchronization transitions in dependence on the information transmission delay and ion channel blocking in scale-free neuronal networks.As the underlying model of neuronal dynamics,we use the Hodgkin-Huxley equations incorporating channel blocking and intrinsic noise.It is shown that delays play a significant yet subtle role in shaping the dynamics of neuronal networks.In particular,regions of irregular and regular propagating excitatory fronts related to the synchronization transitions appear intermittently as the delay increases.Moreover,the fraction of working sodium and potassium ion channels can also have a significant impact on the spatiotemporal dynamics of neuronal networks.As the fraction of blocked sodium channels increases,the frequency of excitatory events decreases,which in turn manifests as an increase in the neuronal synchrony that,however,is dysfunctional due to the virtual absence of large-amplitude excitations.Expectedly,we also show that larger coupling strengths improve synchronization irrespective of the information transmission delay and channel blocking.The presented results are also robust against the variation of the network size,thus providing insights that could facilitate understanding of the joint impact of ion channel blocking and information transmission delay on the spatiotemporal dynamics of neuronal networks.
文摘The worldwide decline over the last decade in the number of clinical cases of malaria does not mean an end to the universal problem of malaria pathogenesis in those afflicted by infection. Resistance to drugs, higher risk of disease relapse and failure to maintain effective memory of the pathogen in the absence of persistent exposure result in the repeated failure of anti-malarialtreatments. The artificial blocking of transmission of the Plasmodium parasite between hosts from human to Anopheles mosquito, and vice versa, is crucial to restricting the spread of disease. However, a limited knowledge of the molecular mechanisms in operation for transmission of malaria has impeded progress towards a transmission-blocking vaccine. This review highlights the role of anti-malarial immune responses to antigen-specific targets for designing effective vaccines against the sexual stages of Plasmodium that occur within the invertebrate vector. In particular, artificial induction of gametocyte and ookinete apoptosis as a novel means to prevent gamete fertilization and oocyte development, respectively, is highlighted. This and other recent insights into our understanding of the molecular regulation of transmission-blocking immunity are discussed and future prospects considered.
基金Supported by National Natural Science Foundation of China,No. 81025015 and No. 30921006
文摘AIM: To determine the therapeutic effect of lamivu- dine in late pregnancy for the interruption of motherto-child transmission (MTCT) of hepatitis B virus (HBV). METHODS: Studies were identified by searching available databases up to January 2011. Inclusive criteria were HBV-carrier mothers who had been involved in randomized controlled clinical trials (RCTs) with lamivudine treatment in late pregnancy, and newborns or infants whose serum hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg) or HBV DNA had been documented. The relative risks (RRs) for inerruption of MTCT as indicated by HBsAg, HBV DNA or HBeAg of newborns or infants were calculated with 95% confidence interval (CI) to estimate the efficacy of lamivudine treatment. RESULTS: Fifteen RCTs including 1693 HBV-carrier mothers were included in this meta-analysis. The overall RR was 0.43 (95% CI, 0.25-0.76; 8 RCTs; Phet- erogeneity= 0.04) and 0.33 (95% CI, 0.23-0.47; 6 RCTs; Pheterogeneity = 0.93) indicated by newborn HBsAg or HBV DNA. The RR was 0.33 (95% CI, 0.21-0.50; 6 RCTs; Pheterogeneity = 0.46) and 0.32 (95% CI, 0.20-0.50; 4 RCTs; Pheterogeneity = 0.33) indicated by serum HBsAg or HBV DNA of infants 6-12 mo after birth. The RR (lamivudine vs hepatitis B immunoglobulin) was 0.27 (95% CI, 0.16-0.46; 5 RCTs; Pheterogeneity = 0.94) and 0.24 (95% CI, 0.07-0.79; 3 RCTs; Pheterogeneity = 0.60) indicated by newborn HBsAg or HBV DNA, respectively. In the mothers with viral load 〈 106 copies/mL after lamivudine treatment, the efficacy (RR, 95% CI) was 0.33, 0.21-0.53 (5 RCTs; Pheterogeneity = 0.82) for the interruption of MTCT, however, this value was not significant if maternal viral load was 〉 106 copies/mL after lamivudine treatment (P = 0.45, 2 RCTs), as indicated by newborn serum HBsAg. The RR (lamivudine initiated from 28 wk of gestation vs control) was 0.34 (95% CI, 0.22-0.52; 7 RCTs; Pheterogeneity = 0.92) and 0.33 (95% CI, 0.22-0.50; 5 RCTs; Pheterogeneity = 0.86) indicated by newborn HBsAg or HBV DNA. The incidence of adverse effects of lamivudine was not higher in the mothers than in controls (P = 0.97). Only one study reported side effects of lamivudine in newborns. CONCLUSION: Lamivudine treatment in HBV carrier- mothers from 28 wk of gestation may interrupt MTCT of HBV efficiently. Lamivudine is safe and more efficient than hepatitis B immunoglobulin in interrupting MTCT. HBV MTCT might be interrupted efficiently if maternal viral load is reduced to 〈 106 copies/mL by lamivudine treatment.
基金supported by National Science and Technology Major Project of the Ministry of Science and Technology of China [2015ZX10001001]
文摘In 2016, there were 17.8 million (15.4-20.3 million) women living with HIV/AIDS across the world and the prevalence of reproductive desire among this group was 26%-49%[1]. If pregnant women living with HIV/AIDS are left untreated, the rates of HIV transmission from mother-to-child would range from 14% to 48%, depending on the presence and duration of breastfeeding[2].
基金This proiect was supported by the Natural Science Foundation of Guangdong Province under contract No 04000377.
文摘An analytic method is used to study the reflection and transmission coefficients of the double submerged rectangular blocks (DSRBs) in oblique waves. The scattering potentials are obtained by means of the eigenfunction expansion method, and expressions for the reflection and transmission coefficients are determined. The boundary element method is employed to verify the correctness of the present analytical method. The DSRBs have better performance than the single submerged rectangular block (SSRB) in certain cases. The reflection and transmission properties of the DSRBs are investigated for some specific cases, and the influences of the geometric parameters are also presented.
基金National Natural Science Foundation of China(81772209 and 81601804).
文摘Mother-to-child transmission(MTCT)of syphilis remains a leading cause of stillbirth and death among neonates in many developing countries.In 2007,World Health Orgernization launched the global elimination of MTCT(EMTCT)of syphilis.Given the high burden of congenital syphilis,China subsequently released the specific national EMTCT policies and programs to reduce MTCT of syphilis.The congenital syphilis incidence rate per 100,000 live births in China has markedly decreased from 69.9 in 2013 to 11.9 in 2019.However,due to the global pandemic of COVID-19,the current measures for eliminating MTCT of syphilis are greatly challenged.In this article,we summarize the strategies and measures for the EMTCT of syphilis in China in the past 20 years,the remarkable achievements by the policy support under the leadership of the government.In the context of COVID-19 pandemics,strengthening emergency response to the regional outbreaks of COVID-19,adopting safe,rapid,early and high-quality clinical care for 100%of pregnant women to receive prenatal syphilis testing services,ensuring the availability of Benzathine penicillin for the treatment,and strengthening the closed-loop management of pregnant women and newborns infected with syphilis are the key measures to determine the effectiveness of MTCT for syphilis.Lessons from China may be valuable for other countries that are planning to eliminate MTCT of syphilis.
基金the National Key Research and Development Program of China(No.2017YFE0112600)the National Science Foundation of China[No.61971454,No.91438101&No.61771499]the National Science Foundation of Guangdong,China[No.2016A030308008].
文摘As an alternative to satellite communications,multi-hop relay networks can be deployed for maritime long-distance communications.Distinct from terrestrial environment,marine radio signals are affected by many factors,e.g.,weather conditions,evaporation ducting,and ship rocking caused by waves.To ensure the data transmission reliability,the block Markov superposition transmission(BMST)codes,which are easily configurable and have predictable performance,are applied in this study.Meanwhile,the physical-layer network coding(PNC)scheme with spatial modulation(SM)is adopted to improve the spectrum utilization.For the BMST-SMPNC system,we propose an iterative algorithm,which utilizes the channel observations and the a priori information from BMST decoder,to compute the soft information corresponding to the XORed bits constructed by the relay node.The results indicate that the proposed scheme outperforms the convolutional coded SM-PNC over fast-fading Rician channels.Especially,the performance can be easily improved in high spatial correlation maritime channel by increasing the memory m.
基金partially supported by the Basic Research Project of Guangdong Provincial Natural Science Foundation (No.2016A030308008)the National Natural Science Foundation of China (No.91438101 and No.61501206)the National Basic Research Program of China (973 Program) (No.2012CB316100)
文摘In free-space optical(FSO) communications, the performance of the communication systems is severely degraded by atmospheric turbulence. Channel coding and diversity techniques are commonly used to combat channel fading induced by atmospheric turbulence. In this paper, we present the generalized block Markov superposition transmission(GBMST) of repetition codes to improve time diversity. In the GBMST scheme, information sub-blocks are transmitted in the block Markov superposition manner, with possibly different transmission memories. Based on analyzing an equivalent system, a lower bound on the bit-error-rate(BER) of the proposed scheme is presented. Simulation results demonstrate that, under a wide range of turbulence conditions, the proposed scheme improves diversity gain with only a slight reduction of transmission rate. In particular, with encoding memory sequence(0, 0, 8) and transmission rate 1/3, a diversity order of eleven is achieved under moderate turbulence conditions. Numerical results also show that, the GBMST systems with appropriate settings can approach the derived lower bound, implying that full diversity is achievable.
文摘In order to improve the poor performance of Space-Time Block Coding (STBC) in a downlink correlated fading environment, a closed loop scheme is proposed. With the known channel fading statistics fed from the receiver, eigenbeamforming is utilized to improve the performance of STBC at the transmitter. The new system achieves the array and diversity gain simultaneously. Because reduced dimension processing is adopted, the proposed system has a relative simple structure compared with the traditional beamforming system. The validity of the scheme is verified in several situations by simulation experiments.
文摘The main source of HIV infection in young children is of their mothers, during pregnancy, labor and delivery, or by breastfeeding. The rate of HIV transmission from infected mothers to their newborn children varies from 15% to 40% with one-thirds of these infections was through breastfeeding. This paper examines cross-sectional population-based survey data of HIV test results among mothers and their children in Uganda, Swaziland to estimates of mother-to- child transmission (MTCT) rate of HIV infection. The prevalence of HIV among women aged 15 - 49 who gave birth in the past 5 years in Uganda is 7.3%, and in Swaziland is 37.9%. The HIV prevalence of children who mothers were HIV positive were very similar: 10.3% in Uganda and 11.5% in Swaziland. This association represents the crude rate of MTCT in these two countries at the time of the survey. Presence of HIV antibody in early age (0 - 11 months) is due to both true infection and passive antibody from mothers. The seroconversion dropped nearly half in the second year of age which was likely that many of these children died before reaching the age of 12 - 23 months and passive antibody were gradually cleared at this point. This analysis demonstrated that cross-sectional data can be used to estimate indirectly the magnitude and dynamic of MTCT.
文摘Objective: To determine the knowledge and awareness of Human Immunodeficiency Virus (HIV)/Acquired Immunodeficiency Syndrome (AIDS) and mother-to-child transmission (MTCT) among women attending the antenatal clinic. Methods and Subjects: This was primarily a descriptive cross-sectional study carried out at the antenatal clinic of Olabisi Onabanjo University Teaching Hospital (OOUTH), Sagamu, Nigeria from July 1st, 2010 to October 31st, 2010. Results: The age range of the respondents was 18 - 41 years, (mean 29 ± 5 years). One hundred and forty-nine (92.5%) were married. All the respondents interviewed were aware of HIV/AIDS and 93 (57.8%) had been aware of the disease for ≥5 years. The main sources of information were television 93 (57.8%), radio 77 (47.8%), health workers 53 (32.9%), friends, relatives and neighbors 41 (25.5%) and posters 34 (21.1%). Majority of the respondents identified sexual intercourse as a route of transmission of HIV. Sharing of sharp objects and blood transfusion were identified as routes of transmission by 99 (61.5%) and 82 (50.9%) respectively. One hundred and sixteen (72%) of the respondents knew an apparently healthy person could be living with HIV. Majority of the respondents 125 (77.6%) were aware that HIV can coexist with pregnancy and 120 (74.5%) were aware of MTCT of HIV. Vaginal delivery and breastfeeding were identified as routes of HIV transmission by 44 (27.3%) and 53 (32.9%) of respondents respectively. Delivery by caesarean section was identified as a method of prevention of MTCT by 25 (15.5%) respondents while as many as 48 (29.8%) respondents did not know any method of prevention of MTCT of HIV. Conclusion: This study demonstrates a low level of awareness of methods of prevention of MTCT of HIV among pregnant women booking for antenatal care in our center. Thus, there is the need for adequate counseling about HIV/AIDS and specific aspects of prevention of mother-to-child transmission in our antenatal clinics.
文摘Background: The elimination of HIV transmission from mother to child is currently possible. Cote d’Ivoire, which has a 4.6% HIV prevalence among women, is one of 22 pilot countries for the elimination of mother-to-child transmission of HIV. Since 2015, Cote d’Ivoire has adopted new strategies according to the WHO B+ guidelines. Objective: To identify factors associated with mother-to-child HIV transmission in children born of seropositive mothers managed at Treichville university hospital. Material and methods: A case-control study was conducted in the obstetrics department at Treichville university hospital, between January 2013 and December 2015. It involved children born to mothers infected with HIV, whose first PCR (Polymerase Chain Reaction) result was available during this period. A standardized questionnaire on data related to exposed children and their mother was used. Factors associated with mother-to-child HIV transmission were investigated using logistic regression. Results: A total of 214 HIV-exposed children were included in the study with a sex ratio of 0.9. The majority of the children were born by vaginal route (52.8%) and received post-exposure prophylaxis (88.3%) and replacement feed (51.9%). Their mothers received antiretroviral therapy during pregnancy in 45.3% of the cases. The first PCR was performed at the sixth week of life in 52.3% of cases. The prevalence of HIV infection in exposed children was 7.5% (95% CI = 4.5% - 11.8%). In multivariate analysis, the absence of antiretroviral prophylaxis in children [aOR = 4.3, 95% (1.2 to 15.6), p = 0.03], the mixed feed [aOR = 3.8, 95% (1.1 - 13.1), p < 0.03], the failure to take antiretroviral regimen during pregnancy [aOR = 8.0, 95% CI (1.9 - 32.4), p < 0.003], were associated with mother-child HIV transmission. Conclusion: The mother-to-child HIV transmission rate remains high in our practice. Strategies to reduce situations that do not comply with current recommendations should be considered to prevent mother-to-child HIV transmission.