Matching Approach Research Articles

Impact of credit use on crop productivity and gross income of smallholder farmers: a propensity score matching approach

BackgroundAgriculture is Ethiopia’s principal economic activity, employing the vast majority of the population, however, smallholder farmers in the country face long-standing challenges, including low levels of production, low income, and less credit use. This study aimed to analyze the impact of access to credit on crop productivity and income among small-scale farmers in the study area.MethodsWe conducted a cross-sectional study from January 1st to 30th, 2022. Primary data were collected from purposely selected seven (7) kebele of the district based on potential users of agricultural credit. Then the impact was investigated by applying the propensity score matching technique. A Probit regression model was used to determine factors associated with credit use. The significance of the variables was decided at a 5% level of significance.ResultsIn our study, a total sample of 347 smallholder farmers were randomly selected, out of which 42.9% were credit-users while 59.1% were non-users. Regarding sources of credit use, Vision Fund was the most commonly used source of credit with 67.8% of users, followed by the Omo Microfinance institution with 22.1%. Sex of the farmer, age of the farmer, existence collateral, farm size, attitude towards risk, extension service, membership in credit institutions, road access, and number of total livestock units in tropical livestock units (TLU) had significant effects on credit use at a 5% level of significance. Moreover, the estimates showed that utilizing credit resulted in a rise in crop productivity in current market value and total yearly income by 19,302.44 and 18,009.63 respectively.ConclusionOur study suggested that credit use had a considerable impact on crop productivity and total annual income. As a result, the study recommended that the government’s rural finance policy agenda should prioritize opening different branches near farmers, improving credit usability, and providing more training programs to smallholder farmers to improve their skills and help reduce the problems that impede their use of agricultural credit.

Greenwashing or Going Green? An Empirical Analysis of the Drivers and the Effects of Carbon Offsets and Renewable Energy Certificates on Firm Performance

Carbon offsets and renewable energy certificates (RECs) are widely used instruments that help firms mitigate their greenhouse gas emissions (GHG). This paper investigates which internal firm characteristics are associated with investments in carbon offsets or RECs and how these purchases impact firms’ performance. Based on data from publicly traded firms in North America and Europe from 2012-2022, this paper uses a propensity score matching approach to analyze the effects of these investments on firms’ environmental scores, GHG emissions, and financial performance. Additionally, this paper employs an instrumental variable approach to examine whether board gender diversity increases carbon offset or REC purchases. The findings reveal that firms that purchase carbon offsets or RECs face higher environmental scores and higher GHG emissions, suggesting corporate greenwashing behavior. This paper also demonstrates that these purchases lead to higher sales, profitability, and assets, but lower Tobin’s Q for REC buyers. Lastly, this paper finds that a greater presence of women on the board does not lead to greater purchases of carbon offsets or RECs.

Fish species authentication in commercial fish products using mass spectrometry and spectral library matching approach

Seafood fraud has become a global issue, threatening food security and safety. Adulteration, substitution, dilution, and incorrect labeling of seafood products are fraudulent practices that violate consumer safety. In this context, developing sensitive, robust, and high-throughput molecular tools for food and feed authentication is becoming crucial for regulatory purposes. Analytical approaches such as proteomics mass spectrometry have shown promise in detecting incorrectly labeled products. For the application of these tools, genome information is crucial, but currently, for many marine species of commercial importance, such information is unavailable. However, when combining proteomic analysis with spectral library matching, commercially important fish species were successfully identified, differentiated, and quantified in pure muscle samples and mixtures, even when genome information was scarce. This study further tested the previously developed spectral library matching approach to differentiate between 29 fish species from the North Sea and examined samples including individual fish, laboratory-prepared mixtures and commercial products. For authenticating libraries generated from 29 fish species, fresh muscle samples from the fish samples were matched against the reference spectral libraries. Species of the fresh fish samples were correctly authenticated using the spectral library approach. The same result was obtained when evaluating the laboratory-prepared mixtures. Furthermore, processed commercial products containing mixtures of two or three fish species were matched against these reference spectral libraries to test the accuracy and robustness of this method for authentication of fish species. The results indicated that the method is suitable for the authentication of fish species from highly processed samples such as fish cakes and burgers. The study shows that current and future challenges in food and feed authentication can efficiently be tackled by reference spectral libraries method when prospecting new resources in the Arctic.

Immediate application of frozen-thawed embryo transfer cycle in month following COVID-19 recovery does not impair ongoing pregnancy outcome.

To investigate whether immediate frozen-thawed embryo transfer (FET) in the next month following coronavirus disease 2019 (COVID-19) recovery affects ongoing pregnancy outcome. This was a retrospective cohort study carried out at a university-affiliated reproductive medicine center. The study group (post-COVID-19 group) comprised women who were affected by COVID-19 in December 2022 and immediately underwent FET in January 2023 after recovery, with transferred embryos not exposed to the infection. The control group comprised women treated during the pre-COVID-19 period (January 2019). Multivariable logistic regression analysis and a propensity score matching (PSM) approach were used to control for potential confounders and selection bias. A total of 200 women were included in the post-COVID-19 group and 641 women were enrolled in the control group. The rate of ongoing pregnancy was comparable between the study cohorts in both the unadjusted and confounder-adjusted logistic regression models. Other reproductive outcomes, including the odds of a positive pregnancy test, implantation, clinical pregnancy and early pregnancy loss, were similar between the comparison groups. PSM models further confirmed the lack of significant differences in pregnancy outcome between the post-COVID-19 group and the control group. Among patients affected by COVID-19 for whom the transferred embryos were generated prior to infection, an immediate FET cycle in the next month after recovery does not seem to compromise ongoing pregnancy outcome. Thus, women who have frozen embryos from preinfection cycles should be counseled and encouraged to undergo FET as soon as possible after COVID-19 recovery. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Physicochemical Properties, Antioxidant Activity, and High-Performance Thin-Layer Chromatography Profiling of Propolis Samples from Western Australia.

This study reports on the physicochemical and antioxidant properties of propolis samples from various regions across Western Australia and identifies some phenolic constituents using high-performance thin-layer chromatography (HPTLC). Total phenolic content (TPC) was determined using a modified Folin-Ciocalteu assay, and antioxidant activity was investigated with the Ferric Reducing Antioxidant Power (FRAP) assay and also visualised and semi-quantified by HPTLC-DPPH analysis. TPC values ranged from 9.26 to 59.3 mg gallic acid equivalent/g of raw propolis and FRAP assay data from 4.34 to 53.8 mmol Fe2+ mmol/kg of raw propolis, although some of these variations might be related to differences in extraction yields obtained with 70% ethanol. The presence of luteolin, taxifolin, naringenin, and 4-hydroxyphenylacetic acid was confirmed based on a comprehensive, validated matching approach against an HPTLC-derived database. The findings of the study highlight the importance of future research on the chemical composition and bioactivity of Western Australian propolis.

3D point cloud reconstruction using panoramic images

Panorama photogrammetry, the process of analyzing panoramic images, has gained popularity in close-range photogrammetry for 3D reconstruction over the past decade. Initially, researchers utilized cylindrical or spherical panoramic images created through specialized cameras or conventional ones with rectilinear lenses. However, these methods were hindered by the high cost of panorama equipment and the need for manual reconstruction. Consequently, there's a growing demand for automated algorithms capable of reconstructing 3D point clouds from stitched panorama images. This study aims to provide a cost-effective solution for automatic 3D point cloud reconstruction from panoramas. The study is divided into two parts; it first outlines an image acquisition strategy for capturing overlapping perspective images to facilitate accurate panorama generation. Subsequently, it introduces an automated algorithm for 3D point cloud reconstruction from panorama images. The process utilizes the KAZE feature detector for feature detection and introduces a novel feature matching approach for matching panorama images. Accuracy assessment of the reconstructed 3D point clouds was done using three methods: Line Segment Based approach, yielding RMSE errors of 34.2mm and 39mm for dataset-1 and dataset-2 respectively, No-Reference 3D Point Cloud Quality Assessment, resulting in quality scores of 8.5939 and 7.4535 for dataset-1 and dataset-2 respectively, and M3C2 distance method computed value of 0.091059 and 0.165179 respectively, indicating high quality of the generated point clouds.

Impact of urban and rural residents medical insurance on self-rated health of residents in China: a panel study from the China family panel studies national baseline survey.

This study aimed to investigate the health performance of the Urban and Rural Residents Medical Insurance (URRMI) scheme in China and to make practical recommendations and scientific references for its full implementation in China. This is a panel study that uses data from the China Family Panel Studies from 2018 to 2020, which is separated into treated and control groups each year, utilizing the key approach of propensity score matching and difference-in-difference (PSM-DID). Using 1-to-1 k-nearest neighbor matching, we proportionate the baseline data. Using difference-in-difference model, we examine the mean treatment impact of the outcome variables. Using a 500-time random sample regression model, we validate the robustness of the model estimation. The result was credible after matching, minimizing discrepancies. Good overall performance of self-rated health with an average Hukou status of, respectively, 0.8 and 0.4 in the treated and control group, primarily in rural and urban regions separately. The participation of URRMI significantly impacted self-rated health of residents, with a 0.456-unit improvement probabilities observed (p < 0.1). Additionally, the individuals are categorized into urban and rural, and those with urban hukou had a 0.311 expansion in the probability of having better health status compared to rural hukou (p < 0.05). Other factors, such as age, highest education, annual income, medical expenditure, hospital scale, clinic satisfaction, and napping, also impacted self-rated health. Moreover, elder individuals, higher education levels, and higher medical expenditure having a higher probability of improvement. The study utilized a placebo test to verify the robustness of the URRMI regression. The estimated coefficients showed that basic medical insurance did not significantly improve the health of insured residents under the URRMI scheme. The study demonstrates the crucial role of PSM-DID in determining the influence of URRMI on self-rated health status. It indicates that purchasing in URRMI has a favorable influence on the health of residents, advancing enhanced self-rated health effectiveness. It does, however, reveal geographical disparities in health, with urban dwellers faring far better than those who live in the suburb. Study suggests expanding URRMI coverage, narrowing urban-rural divide, increasing insurance subsidies, reforming laws, and developing effective advertising strategies.

Ultra-wideband absorber based on multilayer lossy frequency selective surface

In this letter, a multilayer dielectric with a lossy frequency-selective surface (FSS) absorber is proposed, which is composed of three layers of resistive film-dielectric composite layer and a metal grounded plane. Particularly, each resistive film-dielectric composite layer consists of a polyethylene terephthalate (PET), polymethacrylimide foam (PMI), and resistive film layer. An equivalent circuit model is established to further understand the performance of the absorber based on the impedance matching approach and the transmission line theory. Experimental results reveal that the metamaterial absorber (MMA) covers -10 dB bandwidth of 1.96-21.8 GHz for normal incidence. Meanwhile, the absorption rate can retain more than 80% for both TE and TM polarizations within 55° incidence angles. Furthermore, the fractional bandwidth of the MMA is 167% and its thickness is only 0.108 ?L. The MMA has the characteristics of ultra-wideband, high absorption rate, and polarization stability, making it suitable for communication systems.

Robust vision detection of pipeline solder joints

PurposeSolder joint inspection plays a critical role in various industries, with a focus on integrated chip (IC) solder joints and metal surface welds. However, the detection of tubular solder joints has received relatively less attention. This paper aims to address the challenges of detecting small targets and complex environments by proposing a robust visual detection method for pipeline solder joints. The method is characterized by its simplicity, cost-effectiveness and ease of implementation.Design/methodology/approachA robust visual detection method based on the characteristics of pipeline solder joints is proposed. With the improved hue, saturation and value (HSV) color space, the method uses a multi-level template matching approach to first segment the pipeline from the background, and then match the endpoint of the pipeline to accurately locate the solder joint. The proposed method leverages the distinctive characteristics of pipeline solder joints and employs an enhanced HSV color space. A multi-level template matching approach is utilized to segment the pipeline from the background and accurately locate the solder joint by matching the pipeline endpoint.FindingsThe experimental results demonstrate the effectiveness of the proposed solder joint detection method in practical detection tasks. The average precision of pipeline weld joint localization exceeds 95%, while the average recall is greater than 90%. These findings highlight the applicability of the method to pipeline solder joint detection tasks, specifically in the context of production lines for refrigeration equipment.Research limitations/implicationsThe precision of the method is influenced by the placement angle and lighting conditions of the test specimen, which may pose challenges and impact the algorithm's performance. Potential avenues for improvement include exploring deep learning methods, incorporating additional features and contextual information for localization, and utilizing advanced image enhancement techniques to improve image quality.Originality/valueThe proposed pipeline solder joint detection method offers a novel and practical approach. The simplicity, cost-effectiveness and ease of implementation make it an attractive choice for detecting pipeline solder joints in different industrial applications.

Evaluation of Digital Nautical Chart data for confirmation and expansion of GeoNames data

ABSTRACT This work examines how Digital Nautical Chart (DNC) data may contribute to the evolution and refinement of GeoNames data for near-shore features. GeoNames features are point data with one or more possible place names. DNC Earth Cover Text (ECRText) objects are map labels positioned nearby their real word counterpart. ECRText feature map position strikes a compromise between association with real features and cartographic readability. This work explores whether ECRText features can confirm (or expand names for) existing locations or contribute new locations through data conflation. Due to name variations and spatial position, conflating these data are nontrivial. Previous work engaged in a brief examination using the trigram string matching algorithm under coarse proximity constraints, indicating that ECRText could provide additional value to GeoNames. This work builds on that study, by engaging in a deeper examination of spatial proximity and exploring conflation agreement across an ensemble of string matching approaches. The result finds strong ensemble agreement about ECRText features which already exist in GeoNames but mixed results about which features contribute new information, as well as exploring why some of these matching techniques fail. With an eye toward automation, computational efficiency was found not to be a constraint in sustaining updates.

Long-term comparison of renal and metabolic outcomes after sodium–glucose co-transporter 2 inhibitor or glucagon-like peptide-1 receptor agonist therapy in type 2 diabetes

BackgroundRenal outcomes in patients with type 2 diabetes following treatment with sodium–glucose co-transporter-2 inhibitors (SGLT2is) or glucagon-like peptide-1 receptor agonists (GLP1RAs) have not been directly compared. This study compared the impact of SGLT2i and GLP1RA therapy on renal function and metabolic parameters.MethodsPatients with type 2 diabetes who initiated SGLT2i or GLP1RA therapy in a tertiary hospital between January 2009 and August 2023 were included to assess composite renal outcomes, such as a 40% decline in estimated glomerular filtration rate (eGFR), onset of end-stage renal disease, renal death, or new-onset macroalbuminuria. Alterations in blood pressure, glucose regulation parameters, lipid profile, and anthropometric parameters, including body fat and muscle masses, were examined over 4-years.ResultsA total of 2,112 patients were enrolled using a one-to-three propensity-score matching approach (528 patients for GLP1RAs, 1,584 patients for SGLT2i). SGLT2i treatment was favoured over GLP1RA treatment, though not significantly, for composite renal outcomes (hazard ratio [HR], 0.63; p = 0.097). SGLT2i therapy preserved renal function effectively than GLP1RAs (decrease in eGFR, ≥ 40%; HR, 0.46; p = 0.023), with improving albuminuria regression (HR, 1.72; p = 0.036). SGLT2i therapy decreased blood pressure and body weight to a greater extent. However, more patients attained HbA1c levels < 7.0% with GLP1RAs than with SGLT2is (40.6% vs 31.4%; p < 0.001). GLP1RA therapy enhanced β-cell function and decreased LDL-cholesterol levels below baseline values.ConclusionsSGLT2is were superior for preserving renal function and reducing body weight, whereas GLP1RAs were better for managing glucose dysregulation and dyslipidaemia.

Effects of unbalanced fertilizer use on system productivity and profitability under rice‐based cropping systems: Evidence from Eastern Gangetic Plain

AbstractUnbalanced nutrient supply is one of the key causes of yield gaps and low farming profitability which impact food insecurity globally. However, the effects of an unbalanced nutrient supply on rice yields and farming profitability have not been quantified for diverse rice‐based cropping systems. To explore the effects, 412 respondents (mostly smallholder farmers) were surveyed in 2019 for the rice crops in three fully rice‐based cropping systems in four agro‐ecological zones of Bangladesh. Two robust estimation approaches namely propensity score matching and endogenous switching regression approaches were used to quantify the effects of unbalanced fertilizer use. The results show that about 68% of farmers in the study areas used unbalanced (over‐doses or under‐doses) nutrient rates relative to government‐endorsed recommendations. Adoption of recommended fertilizer rates was influenced by education, amount of organic manure used, off‐farm income, crop farming‐related training, organizational membership and lack of soil testing tendency. The findings also indicate that adopters of recommended nutrient rates received almost 16% and 46% higher system rice yield and system net return, respectively, relative to non‐adopters. However, based on our research findings, formulation and implementation of effective agricultural policies like effective extension services, strengthening soil testing facilities, increasing organizational membership and targeted awareness programmes could motivate smallholder rice farmers towards adoption of recommended nutrient rates. Adoption of recommended fertilizer rates can significantly enhance crop yields and farming profitability which can boost food security and rural livelihoods in the Eastern Gangetic Plain.

Enhancing Map Matching Accuracy Using Backtracking Technique

Map matching integrates positioning data with road network information to accurately identify a vehicle exact location on a specific road. Modern location-based services heavily rely on accurate map matching techniques to match observed trajectories with road networks. This paper presents a novel map matching approach that leverages topological information and integrates the backtracking technique to enhance the accuracy and robustness of map matching. By considering the logical relationships between road segments, our method achieves excellent results in scenarios with complex road geometries and challenging urban environments. We integrate the backtracking technique to address noise and ambiguity in trajectory data, resulting in improved precision and a reduced likelihood of false matches. Extensive experimentation using real-world trajectory datasets in Beijing validates the effectiveness of our approach, highlighting its superiority over traditional methods. The algorithm accuracy achieved as high as 99.92%. The results of the evaluation demonstrate that the proposed approach exhibits superior performance compared to earlier map-matching algorithms in both simple and complex road networks. Additionally, it can be effectively implemented on GPS datasets with different time intervals. In addition to the obvious map matching applications of our technology, it has the potential to be adapted across domains, with implications in transportation, urban planning, and location-based services. This paper not only presents a substantial advancement in map matching but also opens new avenues for location-based analyses enhancing and services across various domains.

A shared ride matching approach to low-carbon and electrified ridesplitting

Ridesplitting has the potential to enhance transportation efficiency and reduce CO2 emissions from ridesourcing services by matching multiple shared rides to the same trip. However, an inappropriate matching can significantly diminish the environmental performance of ridesplitting. This study aims to propose a shared ride matching approach to low-carbon and electrified ridesplitting. Firstly, feasible ridesplitting trips within time constraints are identified and represented using a shareability network. Subsequently, the CO2 emission reduction of each feasible ridesplitting trip is calculated by comparing it with its corresponding single ride alternative. To maximize the total CO2 emission reduction from ridesplitting trips, an optimization model for shared ride matching is established and solved using a graph-theoretic algorithm. Additionally, a priority assignment policy is designed to preferentially assign available electric vehicles to feasible ridesplitting trips that have greater potential for emission reductions. Comparative experiments conducted in Chengdu, China show that the proposed approach can achieve higher levels of CO2 emission reduction without compromising service quality in ridesplitting operations. Furthermore, significant improvements in emission reductions can be achieved by implementing the priority assignment policy instead of a random assignment policy for electrified ridesplitting trips, particularly when electric vehicles are limited. Finally, the effects of maximum tolerable delay and electric vehicle penetration are further analyzed to provide valuable insights for the government and ridesourcing companies aiming to enhance both the economic and environmental benefits associated with ridesplitting.

Stabilizing regions of dominant pole placement for second order lead processes with time delay using filtered PID controllers.

In order to handle second order lead processes with time delay, this paper provides a unique dominant pole placement based filtered PID controller design approach. This method does not require any finite term approximation like Pade to obtain the quasi-polynomial characteristic polynomial, arising due to the presence of the time delay term. The continuous time second order plus time delay systems with zero (SOPTDZ) are discretized using a pole-zero matching method with specified sampling time, where the transcendental exponential delay terms are converted into a finite number of poles. The pole-zero matching discretization approach with a predetermined sampling period is also used to discretize the continuous time filtered PID controller. As a result, it is not necessary to use any approximate discretization technique, such as Euler or Tustin, to derive the corresponding discrete time PID controller from its continuous time counterpart. The analytical expressions for discrete time dominant pole placement based filtered PID controllers are obtained using the coefficient matching approach, while two distinct kinds of non-dominant poles, namely all real and all complex conjugate, have been taken into consideration. The stabilizable region in the controller and design parameter space for the chosen class of linear second order time delay systems with lead is numerically approximated using the particle swarm optimization (PSO) based random search technique. The efficacy of the proposed method has been validated on a class of SOPTDZ systems including stable, integrating, unstable processes with minimum as well as non-minimum phase zeros.

Comparative of Student Learning Outcomes: Practice Rehearsal Pairs Learning Strategy with Index Card Match

Purpose of the study: This study aims to compare the student learning outcomes between two different learning strategies: Practice Rehearsal Pairs (PRP) with Index Card Match (ICM) in the context of Digestive System material. Methodology: This study uses a quasi-experimental approach with a Nonequivalent Control Group design. The population in this study were all students of grade XI of Public High School 1 Muara Enim totaling 5 classes. Sampling was done using simple random sampling technique in two experimental classes. Data collection was done using multiple-choice tests and analyzed using descriptive and inferential statistical techniques. Main Findings: The results of the study obtained for both groups through descriptive statistical analysis are that the average biology learning outcomes using the Practice Rehearsal Pairs learning strategy are better than using the Index Card Match learning strategy. The results of the inferential data analysis show that there is a significant difference between the use of the Practice Rehearsal Pairs learning strategy and the Index Card Match learning strategy on the biology learning outcomes of class XI students. Novelty/Originality of this study: This type of research has the potential to provide insight into the relative effectiveness of two different learning approaches in facilitating student understanding and learning outcomes on a particular topic. with the Practice Rehearsal Pairs and Index Card Match approaches likely focusing on learning methods in which students pair up to practice and repeat material together.

Hand Gesture Recognition System Based on Indian Sign Language Using SVM and CNN

Hand gestures (HGs) have been extensively acknowledged as a communication standard for the deaf and dumb school system in the Indian sign language (ISL). We suggested an automated Indian sign language recognition (ISLR) method for English in this study. Initially, the hand region is segmented using the Grasshopper optimization algorithm (GOA) based on the skin color model method. The segmentation’s efficacy is further assessed using three techniques: GOA-based skin color detection algorithm (SCDA), particle swarm optimization-based SCDA (PSO-SCDA), and artificial bee colony-based SCDA (ABC-SCDA). Finally, a database for the retrieved motions representing distinct English alphabets is created. For gesture recognition, the system is trained, and a template-based matching approach is used. The classification technique employs the support vector machine (SVM) and the convolution neural network (CNN). Our suggested recognition method achieved the highest accuracy of 97.85% with GOA-SCDA, compared to 89.29% and 93.96% with PSO-SCDA and ABC-SCDA, respectively. Furthermore, CNN outperformed SVM in classification, with a high accuracy of 99.2% and precision of 81.8%.

System identification and centralised causal impedance matching control of a row of two heaving point absorber wave energy converters

Similar to offshore wind turbines, multiple point absorber wave energy converters (WECs) will be installed in an array configuration, to increase the total capacity, and to benefit from the economies of scale. Whereas wind turbines always interact destructively due to wake effects, WECs can interact constructively, since hydrodynamic interactions between the WECs occur through radiation and diffraction of waves, changing the direction of the incoming wave energy. This paper presents the dataset and results of the experimental modelling of a row of two ‘WECfarm’ heaving point absorber WECs at the wave basin of Aalborg University (AAU). Impedance matching enables maximum power transfer between two oscillatory systems, from the waves to the Power Take-Off (PTO) of the WEC. While literature covers this impedance matching approach for single, isolated WECs, the research discussed in this paper is unique by applying the experimental modelling of the impedance matching approach on a row of two WECs. Radiation system identification tests are executed to determine the intrinsic impedance of the isolated WECs, and the 2 × 2 impedance matrix of the two-WEC array. A causal impedance matching resistive and reactive controller are designed, implemented and tested for a selection of operational sea states. For centralised control, hydrodynamic interactions are taken into account by considering the complete impedance matrix, whereas for decentralised control no hydrodynamic interactions are taken into account by considering only the diagonal of the impedance matrix. The power absorption performance of the isolated WECs, the two-WEC array with decentralised control, and the two-WEC array with centralised control, are compared. Constructive interaction is identified, yielding enhanced power absorption for the array compared to the WECs isolated. Therefore, the layout of the WEC array and the control of the PTO should be optimised simultaneously, to maximise the power absorption of the array as a whole.

Evaluating the impact of extended dosing intervals on mRNA COVID-19 vaccine effectiveness in adolescents.

Extending the dosing interval of a primary series of mRNA COVID-19 vaccination has been employed to reduce myocarditis risk in adolescents, but previous evaluation of impact on vaccine effectiveness (VE) is limited to risk after second dose. Here, we quantified the impact of the dosing interval based on case notifications and vaccination uptake in Hong Kong from January to April 2022. We estimated that the hazard ratio (HR) and odds ratio (OR) of infections after the second dose for extended (28 days or more) versus regular (21-27 days) dosing intervals ranged from 0.86 to 0.99 from calendar-time proportional hazards models, and from 0.85 to 0.87 from matching approaches, respectively. Adolescents in the extended dosing groups (including those who did not receive a second dose in the study period) had a higher hazard of infection than those with a regular dosing interval during the intra-dose period (HR: 1.66; 95% CI: 1.07, 2.59; p = 0.02) after the first dose. Implementing an extended dosing interval should consider multiple factors including the degree of myocarditis risk, the degree of protection afforded by each dose, and the extra protection achievable using an extended dosing interval.

Alloimmunization and autoimmunization among multitransfused thalassemia and sickle cell disease patients

Blood transfusion is the mainstay for management of hemoglobinopathies, including thalassemia and sickle cell disease (SCD). Apart from other transfusion related adverse effects, immunization is a significant complication, particularly in multitransfused recipients. Alloimmunization rates vary widely, both in thalassemia and SCD patients. Alloimmunization complicates the management in form of hemolytic transfusion reactions, difficulty in finding compatible units, delays in transfusion and increasing costs. Exact pathogenesis and prevention modality have not been elucidated. Apart from antigenic differences, immunomodulatory effects and inflammation also play a role in pathogenesis. Ethnic heterogeneity between donors and recipients predisposes to higher alloimmunization.Transfusion management of hemoglobinopathies across the globe is fragmented, with different levels of care. Guidelines propose red cell antigen profiling, transfusion of leucoreduced red cells, preferably matched for Rh and Kell antigens, over and above ABO-D matching. For alloimmunized patients, corresponding antibody negative red cells need to be transfused. However, patients from different backgrounds are variably transfused with whole blood/red cells, which may or may not be leukoreduced. Prophylactic antigen matching reduces the risk of alloimmunization, however, has limitations. RH variants may not be picked up by phenotyping alone. Moreover, the approach of prophylactic antigen matching is expensive, labour intensive, time consuming and may cause delays in transfusions. There is limited, low quality evidence on best practices for transfusion management of SCD and thalassemia. The review analyses the magnitude of problem, factors contributing and modalities for prevention and management of immunization.