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1.
Malar J ; 22(1): 224, 2023 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-37533014

RESUMEN

BACKGROUND: Global efforts to reduce malaria burden include distribution of insecticide-treated mosquito nets through mass campaigns and routine channels. Ghana's National Malaria Elimination Programme (NMEP) distributes insecticide-treated bed nets (ITNs) through various channels, including to pregnant women at antenatal care (ANC) visits and children at vaccination visits through child welfare clinics (CWC). This study assessed historical ITN distribution throughout ANCs and CWCs across Ghana and the characteristics of high performing facilities. METHODS: Monthly data on routine ITN distribution was provided from Ghana's national health information management system for the years 2016-2021. Analyses were conducted to assess the performance of ITN distribution at ANC and CWC across time, ecological zone, regions, districts, facility ownership, and facility type. Univariate and multivariate logistic regressions were performed to predict the odds of ANC and CWC issuing rates greater or equal to 80% for a given facility type or ownership. RESULTS: In 2021, 93% of women who attended their first antenatal care visit and 92% of children under five who received their second dose of the measles-rubella vaccine (MR2) had received an ITN. At the regional level, 94% of regions (n = 15/16) maintained the NSP target issuing rate of 80% throughout 2020 and 2021. While there were no clear differences in issuing rates between ecological zones, district-level differences were present across the six years. All health facility types performed at or above 80% in 2021 for both ANC and CWC. Odds ratios demonstrated differences in the likelihood of meeting the 80% issuing rate goal among different facility types as well as private versus public ownership when comparing ANC and CWC. CONCLUSION: By 2021, Ghana had improved its ITN issuing rates since the initial year of analysis, surpassing the 80% target by issuing nets to over 90% of pregnant women and young children attending ANC and CWC. Future work can explore the reasons for national and subnational differences in issuing rates as well as help understand additional characteristics of high performing facilities. Additionally, it is necessary to identify and expand on the drivers for improved performance over the time period.


Asunto(s)
Mosquiteros Tratados con Insecticida , Malaria , Niño , Humanos , Femenino , Embarazo , Preescolar , Ghana , Malaria/prevención & control , Propiedad , Atención Prenatal , Instituciones de Salud , Control de Mosquitos
2.
Malar J ; 22(1): 222, 2023 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-37533064

RESUMEN

BACKGROUND: Continuous distribution channels are effective methods to deliver malaria interventions such as insecticide treated nets (ITNs) to pregnant women attending antenatal care clinics and children under five attending immunization visits. Facility-based and provider-based checklists were used during supportive supervision visits to measure the quality of facility-based services and interventions. This study looks at ITN distributions at health facilities in Ghana, with the aim of providing insights on how quality can be measured and monitored. METHODS: Various quality improvement approaches for malaria services occur in Ghana. Selected indicators were analysed to highlight the similarities and differences of how the approaches measured how well the channel was doing. Generally, the approaches assessed (1) service data management, (2) logistics data management, and (3) observation of service provision (ITN issuance, malaria education, ITN use and care education). Two approaches used a binary (Yes/No) scale, and one used a Likert scale. RESULTS: Results showed that most data reported to the national HMIS is accurate. Logistics data management remained an issue at health facilities, as results showed scores below average across facility stores, antenatal care, and immunization. Though the supervision approaches differed, overall results indicated that almost all eligible clients received ITNs, data were recorded accurately and reported on-time, and logistics was the largest challenge to optimal distribution through health facilities. CONCLUSION: The supervision approaches provided valuable insights into the quality of facility-based ITN distribution. Ghana should continue to implement supportive supervision in their malaria agenda, with additional steps needed to improve reporting of collected data and increase the number of facilities visited for supportive supervision and the frequency. There were various supervision approaches used with no clear guidance on how to measure quality of facility-based ITN distribution, so there is also need for the global community to agree on standardized indicators and approaches to measuring quality of facility-based ITN distribution. Additionally, future studies can review the effect of multiple rounds of supervision visits on the quality of ITN distribution as well as understand the facilitators and barriers to scaling up supervision of facility-based ITN distribution.


Asunto(s)
Mosquiteros Tratados con Insecticida , Insecticidas , Malaria , Niño , Humanos , Femenino , Embarazo , Ghana , Malaria/prevención & control , Mujeres Embarazadas , Encuestas y Cuestionarios
3.
Entropy (Basel) ; 25(4)2023 Apr 04.
Artículo en Inglés | MEDLINE | ID: mdl-37190400

RESUMEN

We present an empirical estimator for the squared Hellinger distance between two continuous distributions, which almost surely converges. We show that the divergence estimation problem can be solved directly using the empirical CDF and does not need the intermediate step of estimating the densities. We illustrate the proposed estimator on several one-dimensional probability distributions. Finally, we extend the estimator to a family of estimators for the family of α-divergences, which almost surely converge as well, and discuss the uniqueness of this result. We demonstrate applications of the proposed Hellinger affinity estimators to approximately bounding the Neyman-Pearson regions.

4.
Am J Transplant ; 22(12): 2971-2980, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-35870119

RESUMEN

Efforts are underway to transition the current lung allocation system to a continuous distribution framework whereby multiple factors are simultaneously combined into a Composite Allocation Score (CAS) to prioritize candidates for lung transplant. The purpose of this study was to compare discrete CAS scenarios with the current concentric circle-based allocation system to assess their potential effects on the US lung transplantation system using the Scientific Registry of Transplant Recipients' thoracic simulated allocation model. Six alternative CAS scenarios were compared over 10 simulation runs using data from individuals on the lung transplant waiting list from January 1, 2018, through December 31, 2019. Outcome measures were transplant rate, count, waitlist deaths, posttransplant deaths within 2 years, donor-to-recipient distance, and percentage of organs predicted to have flown. Across scenarios, waitlist deaths decreased by 36% to 47%, with larger decreases in deaths at lower placement efficiency weight and higher weighting of the waitlist outcomes. When waitlist outcomes were equally weighted to posttransplant outcomes, more transplants occurred in individuals with the highest expected posttransplant survival. All CAS scenarios led to improved overall measures of equity compared with the current Lung Allocation Score system, including reduced waitlist deaths, and resulted in similar posttransplant survival.


Asunto(s)
Trasplante de Pulmón , Obtención de Tejidos y Órganos , Humanos , Listas de Espera , Donantes de Tejidos , Pulmón
5.
Malar J ; 21(1): 366, 2022 Dec 03.
Artículo en Inglés | MEDLINE | ID: mdl-36461005

RESUMEN

BACKGROUND: Routine continuous distribution (CD) of insecticide-treated nets (ITNs) has been an important part of an overall ITN strategy to complement mass campaigns since the early 2000s. The backbone of CD implementation for many sub-Saharan African countries is distribution through antenatal care (ANC) and Expanded Programme for Immunizations (EPI) channels. Performance of these channels is often not monitored closely at the national level, nor is it reviewed globally, unlike the oversight provided to mass campaigns. The question as to why every eligible pregnant woman and child attending these services does not get an ITN remains important and yet, unanswered. METHODS: ANC and EPI issuing rates from seven countries were reviewed with the aim of conducting a blinded multi-country analysis. Monthly data from January to December 2021 was extracted from each country's health management information system and analysed jointly with a National Malaria Control Programme (NMCP) focal point. VectorLink CD assessment reports were also reviewed to glean key findings. RESULTS: ITN issuing rates varied across countries at ANC (31% to 93%) and EPI (39% to 92%). Across the seven countries, the median ITN issuing rate was 64% at ANC and 78% at EPI. Results varied greatly across months per country at both ANC and EPI. NMCP focal points are aware that mass campaigns often negatively affect implementation of ITN distribution through ANC and EPI, even though global and national guidelines emphasize sustaining CD during campaigns. Concerns were also raised about the standard ITN issuing rate indicator at ANC and even more so at EPI due to the denominator. Findings from CD assessments were similar across countries: ITN stock was inconsistent and sometimes inadequate, and updated guidelines on ITN distribution and utilization and funding for social behaviour change activities were lacking at the facility level. CONCLUSION: The importance of optimizing ANC and EPI routine channels cannot be underscored enough. They are at the frontline to protect the most biologically vulnerable populations, i.e., pregnant women and unborn and young children. Although there are encouraging signs of improvement in issuing rates with some countries reaching optimal rates, further improvements are needed to ensure that every pregnant woman and young child receives the ITN to which they are entitled.


Asunto(s)
Programas de Inmunización , Atención Prenatal , Embarazo , Niño , Humanos , Femenino , Preescolar , Concienciación , Clorfentermina
6.
Proc Natl Acad Sci U S A ; 116(10): 4058-4063, 2019 03 05.
Artículo en Inglés | MEDLINE | ID: mdl-30782822

RESUMEN

The phase diagram of water harbors controversial views on underlying structural properties of its constituting molecular moieties, its fluctuating hydrogen-bonding network, as well as pair-correlation functions. In this work, long energy-range detection of the X-ray absorption allows us to unambiguously calibrate the spectra for water gas, liquid, and ice by the experimental atomic ionization cross-section. In liquid water, we extract the mean value of 1.74 ± 2.1% donated and accepted hydrogen bonds per molecule, pointing to a continuous-distribution model. In addition, resonant inelastic X-ray scattering with unprecedented energy resolution also supports continuous distribution of molecular neighborhoods within liquid water, as do X-ray emission spectra once the femtosecond scattering duration and proton dynamics in resonant X-ray-matter interaction are taken into account. Thus, X-ray spectra of liquid water in ambient conditions can be understood without a two-structure model, whereas the occurrence of nanoscale-length correlations within the continuous distribution remains open.

7.
Malar J ; 19(1): 158, 2020 Apr 17.
Artículo en Inglés | MEDLINE | ID: mdl-32303240

RESUMEN

Most malaria-endemic countries have struggled in the past decade to establish effective national-scale continuous distribution mechanisms for long-lasting insecticidal nets (LLINs). Since the implementation of the Tanzania National Voucher Scheme in 2004 and mass-distribution campaigns in 2009-2011 and 2015-2016, Tanzania has been committed to finding new and innovative ways of achieving and maintaining universal bed net coverage. Planning for the School Net Programme (SNP) began in 2011 and in 2013, the country piloted a SNP in three regions. Nets were distributed annually to children attending schools in selected primary and secondary grades. Intra-family re-distribution was assumed, and hence the family as a whole, rather than just the children themselves, were the targeted beneficiaries. The programme has since expanded to 14 regions and has seen six rounds of annual distribution. In its fifth year, 3 million nets were distributed at a cost of USD 3.64 per net and USD 0.60 per person-year of protection (including the net). ITN access and use were maintained at a high level (~ 50-75%) over the first 4 years of distribution within selected evaluation areas, even in the absence of a mass distribution event. Net distribution through primary schools has proven to be a feasible and effective strategy for maintaining consistently high coverage in Tanzania.


Asunto(s)
Mosquiteros Tratados con Insecticida/estadística & datos numéricos , Malaria/prevención & control , Control de Mosquitos/instrumentación , Control de Mosquitos/estadística & datos numéricos , Propiedad , Instituciones Académicas , Tanzanía
8.
Malar J ; 19(1): 105, 2020 Mar 04.
Artículo en Inglés | MEDLINE | ID: mdl-32131834

RESUMEN

BACKGROUND: Insecticide-treated nets (ITNs) are one of the most cost-effective measures for preventing malaria. The World Health Organization recommends both large-scale mass distribution campaigns and continuous distributions (CD) as part of a multifaceted strategy to achieve and sustain universal access to ITNs. A combination of these strategies has been effective for scaling up ITN access. For policy makers to make informed decisions on how to efficiently implement CD or combined strategies, information on the costs and cost-effectiveness of these delivery systems is necessary, but relatively few published studies of the cost continuous distribution systems exist. METHODS: To address the gap in continuous distribution cost data, four types of delivery systems-CD through antenatal care services (ANC) and the expanded programme on immunization (EPI) (Ghana, Mali, and mainland Tanzania), CD through schools (Ghana and mainland Tanzania), and a combined community/health facility-based distribution (Zanzibar, Tanzania), as well as mass distributions (Mali)-were costed. Data on costs were collected retrospectively from financial and operational records, stakeholder interviews, and resource use surveys. RESULTS: Overall, from a full provider perspective, mass distributions and continuous systems delivered ITNs at overlapping economic costs per net distributed (mass distributions: 4.37-4.61 USD, CD channels: 3.56-9.90 USD), with two of the school-based systems and the mass distributions at the lower end of this range. From the perspective of international donors, the costs of the CD systems were, for the most part, less costly than the mass distributions (mass distributions: 4.34-4.55 USD, Ghana and Tanzania 2017 school-based: 3.30-3.69 USD, health facility-based: 3.90-4.55 USD, combined community/health facility 4.55 USD). The 2015 school-based distribution (7.30 USD) and 2016 health facility-based distribution (6.52 USD) programmes in Tanzania were an exception. Mass distributions were more heavily financed by donors, while CD relied more extensively on domestic resource contributions. CONCLUSIONS: These results suggest that CD strategies can continue to deliver nets at a comparable cost to mass distributions, especially from the perspective of the donor.


Asunto(s)
Atención a la Salud/economía , Mosquiteros Tratados con Insecticida/economía , Malaria/prevención & control , Control de Mosquitos/economía , África del Sur del Sahara , Análisis Costo-Beneficio , Atención a la Salud/métodos , Femenino , Humanos , Mosquiteros Tratados con Insecticida/provisión & distribución , Control de Mosquitos/instrumentación , Embarazo , Mujeres Embarazadas , Salud Pública/economía , Estudios Retrospectivos , Encuestas y Cuestionarios
9.
Entropy (Basel) ; 22(11)2020 Oct 31.
Artículo en Inglés | MEDLINE | ID: mdl-33287008

RESUMEN

We discuss the motion of substance in a channel containing nodes of a network. Each node of the channel can exchange substance with: (i) neighboring nodes of the channel, (ii) network nodes which do not belong to the channel, and (iii) environment of the network. The new point in this study is that we assume possibility for exchange of substance among flows of substance between nodes of the channel and: (i) nodes that belong to the network but do not belong to the channel and (ii) environment of the network. This leads to an extension of the model of motion of substance and the extended model contains previous models as particular cases. We use a discrete-time model of motion of substance and consider a stationary regime of motion of substance in a channel containing a finite number of nodes. As results of the study, we obtain a class of probability distributions connected to the amount of substance in nodes of the channel. We prove that the obtained class of distributions contains all truncated discrete probability distributions of discrete random variable ω which can take values 0,1,⋯,N. Theory for the case of a channel containing infinite number of nodes is presented in Appendix A. The continuous version of the discussed discrete probability distributions is described in Appendix B. The discussed extended model and obtained results can be used for the study of phenomena that can be modeled by flows in networks: motion of resources, traffic flows, motion of migrants, etc.

10.
Malar J ; 17(1): 124, 2018 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-29566678

RESUMEN

BACKGROUND: Insecticide-treated nets are a key intervention for malaria prevention. While mass distribution can rapidly scale up ITN coverage, multiple channels may be needed to sustain high levels of ITN access and ownership. In Ghana's Eastern Region, a continuous ITN distribution pilot, started in October 2012, 18-24 months after a mass campaign. The pilot distributed ITNs through antenatal care services (ANC), child welfare clinic services (CWC) through the Expanded Programme on Immunization, and to students in two classes of primary schools. METHODS: ITN ownership and access were evaluated through two cross-sectional surveys, conducted at baseline in April 2012, 11-15 months after the mass campaign, and at endline in December 2013, after 1 year of continuous distribution. A representative sample was obtained using a multi-stage cluster sampling design. Household heads were interviewed using a structured questionnaire. RESULTS: Household ownership of at least one ITN was 91.3% (95% CI 88.8-93.9) at baseline and was not statistically significant at endline 18 months later at 88.3% (95% CI 84.9-91.0) (p = 0.10). Ownership of at least 1 ITN per two people significantly decreased from 51.3% (95% CI 47.1-55.4) to 40.2% (95% CI 36.4-44.6) (p < 0.01). Population access to an ITN within the household also significantly decreased from 74.5% (95% CI 71.2-77.7) at baseline to 66.4% (95% CI 62.9-69.9) at endline (p < 0.01). The concentration index score for any CD channel was slightly positive (0.10; 95% CI 0.04-0.15). CONCLUSION: Thirty-one months after the mass campaign, the 15 months of continuous distribution activities had maintained levels of household ownership at least one ITN, but household ownership of one ITN for every two people and population access to ITN had declined. Ownership and access were higher with the CD programme than without. However, the number of ITNs delivered via ANC, CWC and two primary school classes were insufficient to sustain coverage targets. Future programmes should implement continuous distribution strategies fully within 1 year after a campaign or widen eligibility criteria (such as increase the number of classes) during the first year of implementation to make up for programme delays.


Asunto(s)
Mosquiteros Tratados con Insecticida , Malaria/prevención & control , Preescolar , Femenino , Ghana/epidemiología , Humanos , Malaria/epidemiología , Masculino , Persona de Mediana Edad , Propiedad , Proyectos Piloto , Embarazo , Estaciones del Año
11.
Malar J ; 16(1): 255, 2017 06 15.
Artículo en Inglés | MEDLINE | ID: mdl-28619076

RESUMEN

BACKGROUND: The Tanzania National Voucher Scheme (TNVS) was a public private partnership managed by the Ministry of Health that provided pregnant women and infants with highly subsidized (long-lasting) insecticide-treated nets between 2004 and 2014. It was implemented in the context of the National Insecticide Treated Nets (NATNETS) Programme and was the main keep up strategy for vulnerable populations. CASE DESCRIPTION: The programme design was adjusted considerably over time to incorporate new evidence, shifting public health policies, and changing donor priorities. Three TNVS models can be distinguished: (1) the fixed discount; (2) the fixed top-up; (3) the hybrid voucher model. The changes improved equity and effectiveness, but also had a profound effect on how the programme was managed and implemented. RESULTS: The TNVS reached the majority of beneficiaries with vouchers, and significantly increased household ownership and use of LLINs. While two mass distribution campaigns implemented between 2009 and 2011 achieved universal coverage and equity, the TNVS ensured continuous protection of the vulnerable populations before, during and after the campaigns. The TNVS stimulated and maintained a large national retail network which managed the LLIN supply chain. DISCUSSION AND LESSONS LEARNED: The effectiveness of the TNVS was a function of several interdependent factors, including the supply chain of vouchers through the public health system; the supply chain of nets in the commercial sector; the demand for nets from voucher recipients; management and risk mitigation measures; and the influence of global and donor objectives. CONCLUSION: The TNVS was a highly innovative and globally influential programme, which stimulated the thinking around effectively and equitably distributing ITNs, and contributed directly to the evolution of global policy. It was a fundamental component of the NATNETS programme which protected a malaria-vulnerable population for over a decade.


Asunto(s)
Mosquiteros Tratados con Insecticida/estadística & datos numéricos , Malaria/prevención & control , Comercialización de los Servicios de Salud/métodos , Comercialización de los Servicios de Salud/normas , Complicaciones Parasitarias del Embarazo/prevención & control , Preescolar , Composición Familiar , Femenino , Humanos , Lactante , Mosquiteros Tratados con Insecticida/economía , Mosquiteros Tratados con Insecticida/normas , Mosquiteros Tratados con Insecticida/provisión & distribución , Comercialización de los Servicios de Salud/economía , Propiedad/estadística & datos numéricos , Embarazo , Tanzanía
12.
Clin Chest Med ; 44(1): 59-68, 2023 03.
Artículo en Inglés | MEDLINE | ID: mdl-36774168

RESUMEN

The first official donor lung allocation system in the United States was initiated by the United Network of Organ Sharing in 1990. The initial policy for lung allocation was simple with donor lungs allocated based on ABO match and the amount of time the candidates accrued on the waiting list. Donor offers were first given to candidates' donor service area. In March 2005, the implementation of the lung allocation score (LAS) was the major change in organ allocation. International adoption of the LAS-based allocation system can be seen worldwide.


Asunto(s)
Trasplante de Pulmón , Obtención de Tejidos y Órganos , Humanos , Estados Unidos , Donantes de Tejidos , Listas de Espera , Pulmón
13.
J Heart Lung Transplant ; 41(7): 866-873, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35341678

RESUMEN

BACKGROUND: The lung allocation score prioritizes candidates for a lung transplant in the United States. As the country adopts the continuous distribution framework for organ allocation, we must reevaluate lung allocation score assumptions to maximize transplant benefit. METHODS: We used Scientific Registry of Transplant Recipients data to study the impact of these changes: (1) updating cohorts; (2) transitioning from 1- to 5-year posttransplant survival; (3) using time-varying effects for non-proportional hazards; and (4) weighting waitlist and posttransplant area under the curve differently. Models were compared using Spearman correlations and C-statistics. The thoracic simulation allocation model characterized transplant rates and proportions of recipient subgroups under the current and new systems. RESULTS: Posttransplant areas under the curve models were estimated with recipients aged ≥12 from January 1, 2014, to December 31, 2018. All models had similar C-statistics and Spearman correlations, indicating similar predictive performance and posttransplant area under the curve rankings. Five-year posttransplant area under the curve across age and diagnosis groups varied more than 1-year groups. Using the thoracic simulation allocation model, 1- and 5-year posttransplant model under the curve models showed similar transplant rates and recipient characteristics under the current system, but under continuous distribution, 5-year posttransplant area under the curve resulted in increased transplant rates with more recipients younger and in diagnosis groups B and C. CONCLUSION: Incorporating equally weighted waitlist and posttransplant models using 5-year posttransplant survival detected the largest variability in survival under the continuous distribution system, which could improve long-term survival in the United States.


Asunto(s)
Trasplante de Pulmón , Obtención de Tejidos y Órganos , Humanos , Sistema de Registros , Tasa de Supervivencia , Receptores de Trasplantes , Estados Unidos/epidemiología , Listas de Espera
14.
Health Policy Plan ; 37(2): 243-254, 2022 Feb 08.
Artículo en Inglés | MEDLINE | ID: mdl-34918055

RESUMEN

Universal coverage with effective vector control remains the mainstay of malaria vector control in sub-Saharan Africa. Tanzania has utilized a number of mechanisms for the maintenance of long-lasting insecticidal net (LLIN) coverage over time. Schools have been identified as one potential channel for continuous distribution of LLIN. This research aims to evaluate an annual school-based LLIN distribution programme in Tanzania that began in 2013, called the School Net Programme (SNP). Following each of the first four rounds of SNP distribution, a household survey was conducted in intervention and comparison districts in Southern and Lake zones of Tanzania (N = 5083 households). Measures of ownership, access and use were compared between intervention and comparison districts. Determinants of reach were assessed in intervention districts. Population access to an LLIN increased from 63.1% (95% CI: 58.8, 67.5) to 76.5% (95% CI: 72.9, 80.0) in the intervention districts between the first and last surveys. Access also rose in the comparison districts from 51.4% (95% CI: 46.9, 55.9) to 79.8% (95% CI: 77.3, 82.0) following mass distribution and implementation of school-based distribution during the study period. LLIN use increased in intervention districts from 44.9% (95% CI: 40.5, 49.3) to 65.6% (95% CI: 59.4, 71.8) and from 57.2% (95% CI: 49.7, 64.7) to 77.4% (95% CI: 69.3, 85.5) specifically amongst primary school-aged children. Households reached by the SNP were wealthier households with children enrolled in school. The SNP in Tanzania was able to maintain population level LLIN ownership, use and access in the absence of mass distribution. The SNP successfully reached households that housed school-aged children. Alternative delivery strategies may need to be considered to reach households without children enrolled in schools that experienced fewer benefits from the programme.


Asunto(s)
Anopheles , Mosquiteros Tratados con Insecticida , Insecticidas , Malaria , Animales , Niño , Estudios Transversales , Humanos , Malaria/prevención & control , Control de Mosquitos , Mosquitos Vectores , Instituciones Académicas , Tanzanía
15.
Water Environ Res ; 93(10): 1934-1943, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-33249668

RESUMEN

Microcystins (MCs), the algal toxins produced by cyanobacteria, raised a worldwide concern in recent decades. Limited monitoring stations for MCs make it hard to map the MC spatial distribution in certain areas. To tackle such problems, we selected Liangxi River as our research area and developed an integrated model to get spatial continuous MC data without too many sampling sites, which integrates a hydro-environment model and an artificial neural network algorithm (ANN). The ANN algorithm can estimate concentration MCs via environmental factors. In this paper, we selected chl-a, TN, TP, NO 2 - , NO 3 - , NH3 -N, and PO 4 3 - as stressors. The ANN model we established showed good performances both in train (R2  = 0.8407) and test set (R2  = 0.7543). In the hydro-environment model, by inputting river geometry and model boundary data, the spatial continuous water quality data could be simulated. The water quality data returned from the hydro-environmental model were used as input variables of the well-trained ANN model; the continuous MC data were derived. To evaluate this model on geo-mapping the MC distribution in Liangxi River, we compared the performance of this model and spatial interpolation on the test set, it turns out the integrated model showed a better performance. © 2020 Water Environment Federation PRACTITIONER POINTS: The cost of microcystin (MC) detection is too high for routine monitoring. We integrated regression method and hydro-environment model to predict MCs. Results derived from spatial interpolation are not robust in unmonitored area. The new integration model can minimize the drawback of spatial interpolation.


Asunto(s)
Lagos , Microcistinas , China , Monitoreo del Ambiente , Microcistinas/análisis , Ríos
16.
Bio Protoc ; 11(20): e4195, 2021 Oct 20.
Artículo en Inglés | MEDLINE | ID: mdl-34761067

RESUMEN

Diffusion is a fundamental process in biological systems that governs the molecular collisions driving biochemical reactions and membrane and transport. Measurement of the diffusion coefficient and application of the Stokes-Einstein equation produces the hydrodynamic radius, which is a commonly used gauge of particle size. Additionally, measurement of the diffusion coefficient and the sedimentation coefficient, and application of the Svedberg equation, yields the molecular weight, which is particularly useful in the characterization of very large macromolecules. Dynamic light scattering (DLS) is the most common method to measure the diffusion coefficient of macromolecules. We describe a procedure to perform DLS measurements on monomeric bovine serum albumin (BSA) purified by size-exclusion chromatography using the Zetasizer Nano S particle size analyzer. We compare several analytical methods in existing software programs to estimate the diffusion coefficient of BSA (extrapolated to water at 20°C at infinite dilution, D 20 , w 0 ) and describe a statistical method to obtain 95% confidence limits of the precision of the estimates. We compare D 20 , w 0 estimates to literature values obtained by diffusiometry, sedimentation velocity analytical ultracentrifugation, and other DLS instruments. The method of cumulant analysis in the program SEDFIT (www.analyticalultracentrifugation.com) produced the most precise estimate, D 20 , w 0 6.06 ± 0.07 F (1 F = 10-7 cm2 s-1), which was within the range of estimates obtained by diffusiometry or sedimentation velocity. This protocol is useful for DLS method validation and quality control.

17.
Adv Chronic Kidney Dis ; 28(6): 511-516, 2021 11.
Artículo en Inglés | MEDLINE | ID: mdl-35367019

RESUMEN

Despite an increase in the number of kidney transplants performed annually, there remain more than 90,000 individuals awaiting transplantation in the United States. As kidney transplantation has evolved, so has kidney allocation policies. The Kidney Allocation System, which was introduced in 2014, made significant strides to improve utility and equity, but regional and geographic disparities remain. Further modifications eliminating donor service areas have been introduced. Moving forward, systems involving continuous distribution and artificial intelligence may provide further advancement toward an ideal allocation system.


Asunto(s)
Inteligencia Artificial , Obtención de Tejidos y Órganos , Humanos , Riñón , Políticas , Estados Unidos , Listas de Espera
18.
J Appl Stat ; 47(13-15): 2479-2491, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-35707434

RESUMEN

Dispersion indexes with respect to the Poisson and binomial distributions are widely used to assess the conformity of the underlying distribution from an observed sample of the count with one or the other of these theoretical distributions. Recently, the exponential variation index has been proposed as an extension to nonnegative continuous data. This paper aims to gather to study the unified definition of these indexes with respect to the relative variability of a nonnegative natural exponential family of distributions through its variance function. We establish the strong consistency of the plug-in estimators of the indexes as well as their asymptotic normalities. Since the exact distributions of the estimators are not available in closed form, we consider the test of hypothesis relying on these estimators as test statistics with their asymptotic distributions. Simulation studies globally suggest good behaviours of these tests of hypothesis procedures. Applicable examples are analysed, including the lesser-known references such as negative binomial and inverse Gaussian, and improving the very usual case of the Poisson dispersion index. Concluding remarks are made with suggestions of possible extensions.

19.
Health Policy Plan ; 32(4): 467-475, 2017 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-28334799

RESUMEN

BACKGROUND: The continuous distribution of long-lasting insecticidal nets (LLINs) for malaria prevention, through the antenatal care (ANC) and the Expanded Programme on Immunizations (EPI), is recommended by the WHO to improve and maintain LLIN coverage. Despite these recommendations, little is known about the relative strengths and weaknesses of the ANC and EPI-based LLIN distribution. This study aimed to explore and compare the roles of the ANC and EPI for LLIN distribution in four African countries. METHODS: In a qualitative evaluation of continuous distribution through the ANC and EPI, semi-structured, individual and group interviews were conducted in Kenya, Malawi, Mali, and Rwanda. Respondents included national, sub-national, and facility-level health staff, and were selected to capture a range of roles related to malaria, ANC and EPI programmes. Policies, guidelines, and data collection tools were reviewed as a means of triangulation to assess the structure of LLIN distribution, and the methods of data collection and reporting for malaria, ANC and EPI programmes. RESULTS: In the four countries visited, distribution of LLINs was more effectively integrated through ANC than through EPI because of a) stronger linkages and involvement between malaria and reproductive health programmes, as compared to malaria and EPI, and b) more complete programme monitoring for ANC-based distribution, compared to EPI-based distribution. CONCLUSIONS: Opportunities for improving the distribution of LLINs through these channels exist, especially in the case of EPI. For both ANC and EPI, integrated distribution of LLINs has the potential to act as an incentive, improving the already strong coverage of both these essential services. The collection and reporting of data on LLINs distributed through the ANC and EPI can provide insight into the performance of LLIN distribution within these programmes. Greater attention to data collection and use, by both the global malaria community, and the integrated programmes, can improve this distribution channel strength and effectiveness.


Asunto(s)
Recolección de Datos , Programas de Inmunización/estadística & datos numéricos , Mosquiteros Tratados con Insecticida/estadística & datos numéricos , Atención Prenatal/métodos , África , Femenino , Política de Salud , Humanos , Malaria/prevención & control , Control de Mosquitos/métodos , Embarazo , Investigación Cualitativa
20.
Health Policy Plan ; 32(7): 980-989, 2017 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-28444184

RESUMEN

Many sub-Saharan African countries have achieved substantial gains in insecticide treated bednet coverage since 2005. The Tanzania National Malaria Control Programme identified school-based net distribution as one potential 'keep-up' strategy for the purpose of maintaining long-lasting insecticidal net (LLIN) coverage after a nationwide mass campaign in 2011. The School Net Programme (SNP) was implemented in three regions of southern Tanzania and distributed one LLIN to each enrolled child attending schools in primary grades (standards) 1, 3, 5 and 7, and secondary grades (forms) 2 and 4 in 2013 and again with slightly modified eligibility criteria in 2014 and 2015. Household surveys in the programme area as well as in a control area were conducted after each of the SNP distributions to measure ownership and use of long-lasting insecticide treated nets. Ownership of at least one LLIN after the first distribution was 76.1% (95% CI 70.8-80.7) in the intervention area and 78.6% (95% CI 74.4-82.3) in the control area. After the second distribution, ownership of at least one LLIN had dropped significantly in the control area to 65.4% (95% CI 59.5-71.0) in 2015 (P < 0.001), while coverage in the intervention area was maintained at 79.3% (95% CI 75.4 × 82.6). Ownership of at least one LLIN in intervention area remained stable following the second round of net distribution. During the same period LLIN ownership, especially of enough nets to ensure all household member access, fell significantly in the control area. These results demonstrate that the SNP may be sufficient to maintain stable LLIN coverage following a mass distribution of LLINs.


Asunto(s)
Mosquiteros Tratados con Insecticida/estadística & datos numéricos , Malaria/prevención & control , Instituciones Académicas , Adolescente , Niño , Femenino , Humanos , Masculino , Control de Mosquitos/métodos , Propiedad/estadística & datos numéricos , Evaluación de Programas y Proyectos de Salud , Estudiantes , Encuestas y Cuestionarios , Tanzanía
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