MARIA JOSE SANTAMARIA HERGUETA | International Christian University (original) (raw)
Papers by MARIA JOSE SANTAMARIA HERGUETA
Epidemic meningococcal disease has occurred in Africa for approximately 100 years and has been re... more Epidemic meningococcal disease has occurred in Africa for approximately 100 years and has been recognized as a particular problem in subSaharan Africa, “the meningitis belt,” since 1963. Despite intervention with plain polysaccharide vaccines, thousands of cases and deaths continue to occur. The circumstances that have driven these epidemics of disease remain poorly understood, but a number of factors are likely to be important, including crowded living conditions, population movements, seasonal factors, and the characteristics of the meningococci circulating at a given time. During the latter half of the 20th century, serogroup A meningococci have been responsible for most epidemic disease in Africa; however, as with other regions of the world, cases caused by serogroup B, C, Y, W135, and X meningococci have been occasionally responsible for epidemics. Some epidemic disease outbreaks have been associated with the annual Hajj pilgrimage (e.g., the spread of serogroup A meningococci ...
Development organisations have moved from reporting on 'what they do' to addressing '... more Development organisations have moved from reporting on 'what they do' to addressing 'what difference they make' in an environment that forces them to compete for resources. Thus, measuring their effectiveness has evolved from accountability reporting to results enquiries and to evaluation of the impact of interventions at the end user's level. To adapt to these changes, most development organizations and donors have adhered to results based management and use logical framework approaches for their operations. These approaches and systems have recognised usefulness in project planning, although their utility in project monitoring and organizational performance assessment is more contested. The analysis of recent experiences calls for alternative approaches to assessing performance to improve the effectiveness of development and technical organisations at the country level. This research explores the use of logframes to assess the programmatic performance in a mult...
BMJ, 2006
Objective To review the evidence for effectiveness of treatment with antibiotics before admission... more Objective To review the evidence for effectiveness of treatment with antibiotics before admission in reducing case fatality from meningococcal disease. Design Systematic review. Data sources Cochrane register of trials and systematic reviews, database of abstracts of reviews of effectiveness, health technology assessment, and national research register in England and Wales, Medline, Embase, and CAB Health. Included studies Studies describing vital outcome of at least 10 cases of meningococcal disease classified by whether or not antibiotics were given before admission to hospital. Results 14 observational studies met the review criteria. Oral antibiotic treatment given before admission was associated with reduced mortality among cases (combined risk ratio 0.17, 95% confidence interval 0.07 to 0.44). In seven studies in which all included patients were seen in primary care, the association between parenteral antibiotics before admission and outcome was inconsistent (2 for heterogeneity 11.02, P = 0.09). After adjustment for the proportion given parenteral antibiotics before admission, there was no residual heterogeneity. A higher proportion of patients given parenteral antibiotics before admission was associated with reduced mortality after such treatment and vice versa (P = 0.04). Conclusion Confounding by severity is the most likely explanation both for the beneficial effect of oral antibiotics and the harmful effect observed in some studies of parenteral antibiotics. We cannot conclude whether or not antibiotics given before admission have an effect on case fatality. The data are consistent with benefit when a substantial proportion of cases are treated.
2021 International Conference on Visual Communications and Image Processing (VCIP), 2021
For most machine learning systems, overfitting is an undesired behavior. However, overfitting a m... more For most machine learning systems, overfitting is an undesired behavior. However, overfitting a model to a test image or a video at inference time is a favorable and effective technique to improve the coding efficiency of learning-based image and video codecs. At the encoding stage, one or more neural networks that are part of the codec are finetuned using the input image or video to achieve a better coding performance. The encoder en-codes the input content into a content bitstream. If the finetuned neural network is part (also) of the decoder, the encoder signals the weight update of the finetuned model to the decoder along with the content bitstream. At the decoding stage, the decoder first updates its neural network model according to the received weight update, and then proceeds with decoding the content bitstream. Since a neural network contains a large number of parameters, compressing the weight update is critical to reducing bitrate overhead. In this paper, we propose learn...
Carbohydrate Polymers, 2021
2021 IEEE International Symposium on Multimedia (ISM), 2021
Neural Network (NN)-based coding techniques are being developed for hybrid video coding schemes, ... more Neural Network (NN)-based coding techniques are being developed for hybrid video coding schemes, such as the Versatile Video Coding (VVC) standard. In-loop filters and postprocessing filters are two types of coding tools that aim to improve the visual quality of the reconstructed content. These tools are usually trained on large video or image datasets with varying content, but they are rarely adaptive to different content types. This problem is addressed with the proposed content-adaptive Convolutional Neural Network (CNN) post-processing filter. The proposed approach is content-adaptive in two ways. Firstly, a relatively simple CNN is pre-trained on a general video dataset and then fine-tuned on the video to be coded. Since only the bias terms of the CNN are fine-tuned, the signalling overhead is reduced. Secondly, a scaling factor indicates the influence of the CNN post-processing filter on the final reconstruction. The CNN post-processing filter is evaluated on top of VVC Test Model (VTM) 11.0 with NN-based Video Coding (NNVC) 1.0 and, overall, it can save 2.37% (Y), 3.63% (U), 2.24% (V) Bjøntegaard Delta rate (BD-rate) in the Random Access (RA) configuration.
En Afrique sub-saharienne le controle des epidemies de meningite a meningocoque depend de la dete... more En Afrique sub-saharienne le controle des epidemies de meningite a meningocoque depend de la detection precoce des epidemies et de la vaccination de masse. Cependant, l'experience montre que les interventions arrivent souvent trop tard pour avoir un impact important sur l'evolution de l'epidemie. Une nouvelle recommandation redigee lors d'une reunion de consensus sur le sujet, propose deux niveaux de seuils pour detecter une epidemie de meningite : un seuil d'alerte et un seuil epidemique. Ces seuils sont definis par le nombre de cas ou par l'incidence hebdomadaire de la meningite en fonction de la taille de la population et du risque epidemique et donnent des indicateurs de hautes sensibilite et specificite pour la detection d'une epidemie emergente. Les investigations des epidemies de meningite doivent inclure une evaluation de la qualite de la surveillance epidemiologique. La nouvelle recommandation, publiee dans le Releve Epidemiologique Hebdomadaire ...
SSRN Electronic Journal, 2021
2018 IEEE Visual Communications and Image Processing (VCIP), 2018
2020 IEEE International Conference on Multimedia & Expo Workshops (ICMEW), 2020
With the increasing demand for video content at higher resolutions, it is evermore critical to fi... more With the increasing demand for video content at higher resolutions, it is evermore critical to find ways to limit the complexity of video encoding tasks in order to reduce costs, power consumption and environmental impact of video services. In the last few years, algorithms based on Neural Networks (NN) have been shown to benefit many conventional video coding modules. But while such techniques can considerably improve the compression efficiency, they usually are very computationally intensive. It is highly beneficial to simplify models learnt by NN so that meaningful insights can be exploited with the goal of deriving less complex solutions. This paper presents two ways to derive simplified intra-prediction from learnt models, and shows that these streamlined techniques can lead to efficient compression solutions.
Endocrine Abstracts, 2019
International Journal of Molecular Sciences, 2016
World health statistics quarterly. Rapport trimestriel de statistiques sanitaires mondiales, 1997
Meningococcal disease which is increasing globally is still associated with a high mortality and ... more Meningococcal disease which is increasing globally is still associated with a high mortality and persistent neurological defects, particularly among infants and young children. Sporadic meningococcal meningitis occurs throughout the world, with seasonal variations, and accounts for 10-40% of endemic bacterial meningitis. Epidemic meningitis occurs in any part of the world but the largest and most frequently recurring epidemics have been in the semi-arid area of sub-Saharan Africa where the current pandemic is associated with attack rates exceeding 500 per 100,000 population and thousands of deaths. In the Americas and Europe serogroup B is the predominant agent causing systemic disease, followed in frequency by serogroup C. Serogroup A meningococcus was historically the main cause of epidemic meningococcal disease globally and still predominates in Africa and Asia. A range of internal and external factors predispose for epidemics such as strain virulence, carriers, humoral immunity,...
Japanese Journal of Health and Human Ecology, 1990
Lecture Notes in Computer Science, 2014
The High Efficiency Video Coding standard increases in the range of [30, 40]% data compression ra... more The High Efficiency Video Coding standard increases in the range of [30, 40]% data compression ratio compared to H.264/MPEG-4 (AVC), but it requires bigger number of operations. HEVC uses a quadtree coding structure. The quadtree partitioning process is a high complexity operation since it employs an exhaustive process, called rate distortion optimisation, which involves all possible combinations of quadtree partitions. In this paper, a frame partitioning strategy is addressed using motion features. Motion features are edges extracted using Gaussian smoothing, the Sobel operators, and the Otsu's method. The strategy achieves CU partitions according to the amount of motion in content, and reduces the number of operations in the inter prediction mode.
2012 7th Colombian Computing Congress (CCC), 2012
ABSTRACT Block-matching motion estimation is an efficient algorithm for reducing the temporal red... more ABSTRACT Block-matching motion estimation is an efficient algorithm for reducing the temporal redundancy in video coding and is adopted by video coding standards. Many fast block-matching algorithms have been devised to reduce the computational complexity without degrading the estimation quality. Seven algorithms are implemented and compared – using quality of prediction and efficiency: the full-search, the three-step search, the four-step search, the diamond search, the hexagonal block search, the multi-directional gradient descent search and the fast directional gradient descent search. The aforementioned algorithms are chosen not only because of their popularity, but also because they are rather generic and they represent different ways of cutting down the computation. The most efficient algorithms are the hexagonal block search, the multi-directional gradient descent search and the fast directional gradient descent search. The hexagonal block search produces low quality of prediction, while the two others have the best quality prediction among all analysed algorithms. Also, the hexagonal block search has shown to be less affected by the variation in the block size.
Vaccine, 2007
We investigate ground-state properties of a t 2g-orbital Hubbard model on a zigzag chain relevant... more We investigate ground-state properties of a t 2g-orbital Hubbard model on a zigzag chain relevant for CaV 2 O 4 , by exploiting numerical techniques such as Lanczos diagonalization and density-matrix renormalization group. Assuming a V 3+ ion, a local spin S=1 state is formed by two electrons in the t 2g orbitals. That is, the system is a Haldane system with active t 2g-orbital degrees of freedom. We observe orbital-state transitions, yielding a distinct spin system under the orbital-ordered background. We also discuss the orbital structure induced by open edges, originating in the spatial anisotropy of the t 2g orbitals.
Acta Parasitologica, 2011
Eleven parasite taxa were found infecting 68 Atlantic chub mackerel, Scomber colias Gmelin, 1789 ... more Eleven parasite taxa were found infecting 68 Atlantic chub mackerel, Scomber colias Gmelin, 1789 from the Canary Islands, Central North Atlantic. The most abundant parasites were the gill monogenean Pseudokuhnia minor (P = 54.4%), larval anisakid nematodes (P = 11.8%) in the body cavity, a larval tetraphyllidean infecting bile ducts (P = 8.8%) and didymozoid digeneans infecting the gills (P = 7.4%). No correlation between fish length and abundance of infection with these parasites was found. Within the Atlantic, the comparison of present results with previous reports on the occurrence of parasites in this fish host, might suggest that there is more than one population unit of Atlantic chub mackerel in the Eastern Atlantic.
Emerging Infectious Diseases, 2003
Epidemic meningococcal disease has occurred in Africa for approximately 100 years and has been re... more Epidemic meningococcal disease has occurred in Africa for approximately 100 years and has been recognized as a particular problem in subSaharan Africa, “the meningitis belt,” since 1963. Despite intervention with plain polysaccharide vaccines, thousands of cases and deaths continue to occur. The circumstances that have driven these epidemics of disease remain poorly understood, but a number of factors are likely to be important, including crowded living conditions, population movements, seasonal factors, and the characteristics of the meningococci circulating at a given time. During the latter half of the 20th century, serogroup A meningococci have been responsible for most epidemic disease in Africa; however, as with other regions of the world, cases caused by serogroup B, C, Y, W135, and X meningococci have been occasionally responsible for epidemics. Some epidemic disease outbreaks have been associated with the annual Hajj pilgrimage (e.g., the spread of serogroup A meningococci ...
Development organisations have moved from reporting on 'what they do' to addressing '... more Development organisations have moved from reporting on 'what they do' to addressing 'what difference they make' in an environment that forces them to compete for resources. Thus, measuring their effectiveness has evolved from accountability reporting to results enquiries and to evaluation of the impact of interventions at the end user's level. To adapt to these changes, most development organizations and donors have adhered to results based management and use logical framework approaches for their operations. These approaches and systems have recognised usefulness in project planning, although their utility in project monitoring and organizational performance assessment is more contested. The analysis of recent experiences calls for alternative approaches to assessing performance to improve the effectiveness of development and technical organisations at the country level. This research explores the use of logframes to assess the programmatic performance in a mult...
BMJ, 2006
Objective To review the evidence for effectiveness of treatment with antibiotics before admission... more Objective To review the evidence for effectiveness of treatment with antibiotics before admission in reducing case fatality from meningococcal disease. Design Systematic review. Data sources Cochrane register of trials and systematic reviews, database of abstracts of reviews of effectiveness, health technology assessment, and national research register in England and Wales, Medline, Embase, and CAB Health. Included studies Studies describing vital outcome of at least 10 cases of meningococcal disease classified by whether or not antibiotics were given before admission to hospital. Results 14 observational studies met the review criteria. Oral antibiotic treatment given before admission was associated with reduced mortality among cases (combined risk ratio 0.17, 95% confidence interval 0.07 to 0.44). In seven studies in which all included patients were seen in primary care, the association between parenteral antibiotics before admission and outcome was inconsistent (2 for heterogeneity 11.02, P = 0.09). After adjustment for the proportion given parenteral antibiotics before admission, there was no residual heterogeneity. A higher proportion of patients given parenteral antibiotics before admission was associated with reduced mortality after such treatment and vice versa (P = 0.04). Conclusion Confounding by severity is the most likely explanation both for the beneficial effect of oral antibiotics and the harmful effect observed in some studies of parenteral antibiotics. We cannot conclude whether or not antibiotics given before admission have an effect on case fatality. The data are consistent with benefit when a substantial proportion of cases are treated.
2021 International Conference on Visual Communications and Image Processing (VCIP), 2021
For most machine learning systems, overfitting is an undesired behavior. However, overfitting a m... more For most machine learning systems, overfitting is an undesired behavior. However, overfitting a model to a test image or a video at inference time is a favorable and effective technique to improve the coding efficiency of learning-based image and video codecs. At the encoding stage, one or more neural networks that are part of the codec are finetuned using the input image or video to achieve a better coding performance. The encoder en-codes the input content into a content bitstream. If the finetuned neural network is part (also) of the decoder, the encoder signals the weight update of the finetuned model to the decoder along with the content bitstream. At the decoding stage, the decoder first updates its neural network model according to the received weight update, and then proceeds with decoding the content bitstream. Since a neural network contains a large number of parameters, compressing the weight update is critical to reducing bitrate overhead. In this paper, we propose learn...
Carbohydrate Polymers, 2021
2021 IEEE International Symposium on Multimedia (ISM), 2021
Neural Network (NN)-based coding techniques are being developed for hybrid video coding schemes, ... more Neural Network (NN)-based coding techniques are being developed for hybrid video coding schemes, such as the Versatile Video Coding (VVC) standard. In-loop filters and postprocessing filters are two types of coding tools that aim to improve the visual quality of the reconstructed content. These tools are usually trained on large video or image datasets with varying content, but they are rarely adaptive to different content types. This problem is addressed with the proposed content-adaptive Convolutional Neural Network (CNN) post-processing filter. The proposed approach is content-adaptive in two ways. Firstly, a relatively simple CNN is pre-trained on a general video dataset and then fine-tuned on the video to be coded. Since only the bias terms of the CNN are fine-tuned, the signalling overhead is reduced. Secondly, a scaling factor indicates the influence of the CNN post-processing filter on the final reconstruction. The CNN post-processing filter is evaluated on top of VVC Test Model (VTM) 11.0 with NN-based Video Coding (NNVC) 1.0 and, overall, it can save 2.37% (Y), 3.63% (U), 2.24% (V) Bjøntegaard Delta rate (BD-rate) in the Random Access (RA) configuration.
En Afrique sub-saharienne le controle des epidemies de meningite a meningocoque depend de la dete... more En Afrique sub-saharienne le controle des epidemies de meningite a meningocoque depend de la detection precoce des epidemies et de la vaccination de masse. Cependant, l'experience montre que les interventions arrivent souvent trop tard pour avoir un impact important sur l'evolution de l'epidemie. Une nouvelle recommandation redigee lors d'une reunion de consensus sur le sujet, propose deux niveaux de seuils pour detecter une epidemie de meningite : un seuil d'alerte et un seuil epidemique. Ces seuils sont definis par le nombre de cas ou par l'incidence hebdomadaire de la meningite en fonction de la taille de la population et du risque epidemique et donnent des indicateurs de hautes sensibilite et specificite pour la detection d'une epidemie emergente. Les investigations des epidemies de meningite doivent inclure une evaluation de la qualite de la surveillance epidemiologique. La nouvelle recommandation, publiee dans le Releve Epidemiologique Hebdomadaire ...
SSRN Electronic Journal, 2021
2018 IEEE Visual Communications and Image Processing (VCIP), 2018
2020 IEEE International Conference on Multimedia & Expo Workshops (ICMEW), 2020
With the increasing demand for video content at higher resolutions, it is evermore critical to fi... more With the increasing demand for video content at higher resolutions, it is evermore critical to find ways to limit the complexity of video encoding tasks in order to reduce costs, power consumption and environmental impact of video services. In the last few years, algorithms based on Neural Networks (NN) have been shown to benefit many conventional video coding modules. But while such techniques can considerably improve the compression efficiency, they usually are very computationally intensive. It is highly beneficial to simplify models learnt by NN so that meaningful insights can be exploited with the goal of deriving less complex solutions. This paper presents two ways to derive simplified intra-prediction from learnt models, and shows that these streamlined techniques can lead to efficient compression solutions.
Endocrine Abstracts, 2019
International Journal of Molecular Sciences, 2016
World health statistics quarterly. Rapport trimestriel de statistiques sanitaires mondiales, 1997
Meningococcal disease which is increasing globally is still associated with a high mortality and ... more Meningococcal disease which is increasing globally is still associated with a high mortality and persistent neurological defects, particularly among infants and young children. Sporadic meningococcal meningitis occurs throughout the world, with seasonal variations, and accounts for 10-40% of endemic bacterial meningitis. Epidemic meningitis occurs in any part of the world but the largest and most frequently recurring epidemics have been in the semi-arid area of sub-Saharan Africa where the current pandemic is associated with attack rates exceeding 500 per 100,000 population and thousands of deaths. In the Americas and Europe serogroup B is the predominant agent causing systemic disease, followed in frequency by serogroup C. Serogroup A meningococcus was historically the main cause of epidemic meningococcal disease globally and still predominates in Africa and Asia. A range of internal and external factors predispose for epidemics such as strain virulence, carriers, humoral immunity,...
Japanese Journal of Health and Human Ecology, 1990
Lecture Notes in Computer Science, 2014
The High Efficiency Video Coding standard increases in the range of [30, 40]% data compression ra... more The High Efficiency Video Coding standard increases in the range of [30, 40]% data compression ratio compared to H.264/MPEG-4 (AVC), but it requires bigger number of operations. HEVC uses a quadtree coding structure. The quadtree partitioning process is a high complexity operation since it employs an exhaustive process, called rate distortion optimisation, which involves all possible combinations of quadtree partitions. In this paper, a frame partitioning strategy is addressed using motion features. Motion features are edges extracted using Gaussian smoothing, the Sobel operators, and the Otsu's method. The strategy achieves CU partitions according to the amount of motion in content, and reduces the number of operations in the inter prediction mode.
2012 7th Colombian Computing Congress (CCC), 2012
ABSTRACT Block-matching motion estimation is an efficient algorithm for reducing the temporal red... more ABSTRACT Block-matching motion estimation is an efficient algorithm for reducing the temporal redundancy in video coding and is adopted by video coding standards. Many fast block-matching algorithms have been devised to reduce the computational complexity without degrading the estimation quality. Seven algorithms are implemented and compared – using quality of prediction and efficiency: the full-search, the three-step search, the four-step search, the diamond search, the hexagonal block search, the multi-directional gradient descent search and the fast directional gradient descent search. The aforementioned algorithms are chosen not only because of their popularity, but also because they are rather generic and they represent different ways of cutting down the computation. The most efficient algorithms are the hexagonal block search, the multi-directional gradient descent search and the fast directional gradient descent search. The hexagonal block search produces low quality of prediction, while the two others have the best quality prediction among all analysed algorithms. Also, the hexagonal block search has shown to be less affected by the variation in the block size.
Vaccine, 2007
We investigate ground-state properties of a t 2g-orbital Hubbard model on a zigzag chain relevant... more We investigate ground-state properties of a t 2g-orbital Hubbard model on a zigzag chain relevant for CaV 2 O 4 , by exploiting numerical techniques such as Lanczos diagonalization and density-matrix renormalization group. Assuming a V 3+ ion, a local spin S=1 state is formed by two electrons in the t 2g orbitals. That is, the system is a Haldane system with active t 2g-orbital degrees of freedom. We observe orbital-state transitions, yielding a distinct spin system under the orbital-ordered background. We also discuss the orbital structure induced by open edges, originating in the spatial anisotropy of the t 2g orbitals.
Acta Parasitologica, 2011
Eleven parasite taxa were found infecting 68 Atlantic chub mackerel, Scomber colias Gmelin, 1789 ... more Eleven parasite taxa were found infecting 68 Atlantic chub mackerel, Scomber colias Gmelin, 1789 from the Canary Islands, Central North Atlantic. The most abundant parasites were the gill monogenean Pseudokuhnia minor (P = 54.4%), larval anisakid nematodes (P = 11.8%) in the body cavity, a larval tetraphyllidean infecting bile ducts (P = 8.8%) and didymozoid digeneans infecting the gills (P = 7.4%). No correlation between fish length and abundance of infection with these parasites was found. Within the Atlantic, the comparison of present results with previous reports on the occurrence of parasites in this fish host, might suggest that there is more than one population unit of Atlantic chub mackerel in the Eastern Atlantic.
Emerging Infectious Diseases, 2003