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1.
Artigo em Inglês | MEDLINE | ID: mdl-38615257

RESUMO

BACKGROUND: Preventive Photobiomodulation Therapy (PBMT) significantly reduces oral mucositis (OM) severity in patients undergoing Radiochemotherapy (RCT) for the treatment of oral cancer, but daily applications generate cost, overload the dental team, and reduce the number of patients assisted.To evaluate the effectiveness of two PBMT protocols in preventing OM in patients undergoing RCT for oral cancer. MATERIAL AND METHODS: 16 patients diagnosed with oral cancer undergoing RCT were included, equally divided into two groups: a group treated daily with PBMT, and another group also submitted to daily treatment, however, performing the application of PBMT every three days, interspersed with a simulation of PBMT (placebo). A red laser was used (~660 nm), 0.1W power, 1J of energy applied per point, 9 points per area (labial mucosa, buccal mucosa, lateral borders of the tongue, body of the tongue, and floor of the mouth) from the beginning of RCT until the end of the oncological treatment. Daily assessments were performed regarding OM scores, the World Health Organization (WHO) pain scale, and the visual analog scale (VAS). Weight, salivary flow (SGAPP), OHIP-14, and DMFT were evaluated on the initial and final days of RT. OM incidence and clinical data were compared by Pearson's chi-square test or Fisher's exact test. Pain and other scale scores were compared using the Mann-Whitney and Friedman/Dunn tests (SPSS v20.0 p<0.05). RESULTS: In the group with PBMT on alternate days, there was an increase in the frequency of grade 2 and grade 3 oral mucositis and an increased risk of grade 2 oral mucositis, in addition to higher mean pain scores and greater reduction in salivary flow. CONCLUSIONS: The daily PBMT protocol proved more effective in controlling the frequency and severity of OM, pain, and salivary flow.

2.
Med Oral Patol Oral Cir Bucal ; 27(4): e319-e329, 2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-35717621

RESUMO

BACKGROUND: This study retrospectively analyzed the risk factors for transchemotherapy oral mucositis (OM). MATERIAL AND METHODS: Before each chemotherapy cycle, patients were routinely evaluated for the presence/severity of OM based on the Common Terminology Criteria for Adverse Events (CTCAE) v5.0 scale for adverse effects and graded as follows: However, specific conditions such as mucositis are graded on a five-point scale: 0, absence of mucositis, grade 1 (Asymptomatic or mild), 2 (Presence of pain and moderate ulceration, without interference with food intake), 3 (severe pain with interference with food intake) or 4 (Life-threatening with the need for urgent intervention). Information from 2 years of evaluations was collected and patient medical records were reviewed to obtain data on chemotherapy cycle, sex, age, body mass index, body surface area, primary tumor, chemotherapy protocol, and history of head and neck radiotherapy. The X² test and multinomial logistic regression were used for statistical analysis (SPSS 20.0, p<0.05). RESULTS: Among 19,000 total evaluations of 3,529 patients during 5.32±4.7 chemotherapy cycles (CT) the prevalence of OM was 6.3% (n=1,195). Chemotherapy duration (p<0.001), female sex (p=0.001), adjuvant intention (p=0.008) and the use of carboplatin (p=0.001), cisplatin (p=0.029), docetaxel (p<0.001) and bevacizumab (p=0.026) independently increased the risk of mucositis. In head and neck tumors, 2018 year (p=0.017), chemotherapy duration (p=0.018), BMI>30 (p=0.008), radiotherapy (p=0.037) and use of carboplatin (p=0.046) and cyclophosphamide (p=0.010) increased this prevalence. CONCLUSIONS: Cycles of chemotherapy, sex, cytotoxicity drugs, bevacizumab and head and neck radiotherapy increase the risk of OM in solid tumors.


Assuntos
Neoplasias de Cabeça e Pescoço , Mucosite , Estomatite , Bevacizumab , Carboplatina , Feminino , Neoplasias de Cabeça e Pescoço/complicações , Humanos , Mucosite/complicações , Dor , Estudos Retrospectivos , Fatores de Risco , Estomatite/induzido quimicamente , Estomatite/epidemiologia
3.
Arq. bras. med. vet. zootec. (Online) ; 73(5): 1147-1158, Sept.-Oct. 2021. tab
Artigo em Inglês | LILACS, VETINDEX | ID: biblio-1345262

RESUMO

The aim of this study was to evaluate the productive and reproductive performance of dairy goat genotypes, as well as the influence of hygienic practices by farmers on the quality of goat milk. Productive and reproductive data of 81 Anglo Nubian and Alpine crossbred goats, as well as data on total milk production of goats over 100 days of lactation and partial production up to 56 days of lactation. Also, in natura milk samples from 160 properties in the region were evaluated. At the time of collection, a questionnaire was applied to diagnose goat milk production systems. Data from productive and reproductive performance were evaluated by Tukey test and descriptive analysis using the SPSS program. The herd presented a variation of the total milk production in lactation (TMP) from 267.40kg to 468.55kg, with lactation length ranging from 157 to 247 days, and average daily production between 1.43 and 1.89kg/day. Fertility rates were satisfactory, with the lowest rate being 76% and the highest 92%, with an average of 85.24% considering the six seasons of birth. The means of the gestation periods varied between 144 and 152 days. Regarding the sanitary characterization, 73% of farmers performed a cleaning of the room before and after milking. However, 94.8% of farmers did not eliminate the first jets of milk and only 29.2% used the screened mug test to identify clinical mastitis. Only 41% of farmers performed pre and post-dipping and 30.2% applied the iodine solution. Only 8.3% of farmers used disposable paper towels. However, 92% of producers still used fabric towel. It was also observed that 99% of the properties stored milk in buckets or cans without refrigeration. In the microbiological analysis, a small amount of milk samples (5.6%) was contaminated with Staphylococcus aureus, however the total coliform count was high. Regarding the somatic cell count, it was found that 86% of the properties presented values above one million cells per mL of sample. The study demonstrated the prevalence of several factors that contribute to the vulnerability of milk contamination in various stages of production such as milking and processing. Thus, the guidance and awareness of those responsible is extremely important to improve goat milk quality in the semi-arid region of Paraíba.(AU)


O objetivo do presente estudo foi avaliar o desempenho produtivo e reprodutivo de genótipos caprinos leiteiros, assim como a influência da adoção das práticas higiênicas pelos produtores sobre a qualidade do leite caprino. A primeira parte da pesquisa foi realizada na Estação Experimental Pendência-PB. Foram analisados dados produtivos e reprodutivos de 81 cabras Anglo-Nubiana e alpinas mestiças, bem como dados de produção total de leite das cabras acima de 100 dias de lactação e produção parcial até 56 dias de lactação. Também foram avaliadas amostras de leite in natura de 160 propriedades da região. No momento da coleta, foi aplicado um questionário de diagnóstico dos sistemas de produção de leite caprino. Os dados de desempenho produtivo e reprodutivo foram avaliados pelo teste de Tukey e pela análise descritiva utilizando o programa SPSS. O rebanho apresentou uma variação da produção de leite total na lactação desde 267,40kg a 468,55kg, com durações de lactação variando de 157 e 247 dias, e produção média diária entre 1,43 e 1,89kg/dia. As taxas de fertilidade foram satisfatórias, sendo a menor taxa de 76% e a maior de 92%, com uma média de 85,24% considerando as seis estações de parição. As médias dos períodos de gestação variaram entre 144 e 152 dias. Quanto à caracterização da sanidade, 73% dos produtores realizam limpeza da sala antes e após a ordenha. No entanto, 94,8% dos produtores não eliminam os primeiros jatos de leite e somente 29,2% utilizam o teste da caneca telada para identificação de mastite clínica. Apenas 41% dos produtores realizam pré-dipping e pós-dipping e 30,2% aplicam a solução de iodo. Somente 8,3% dos produtores usam toalhas descartáveis e 92% ainda utilizam toalha de tecido. Observou-se, ainda, que 99% das propriedades armazenam o leite ordenhado em baldes ou latões, sem refrigeração. Pequenas quantidades de amostras (5,6%) estavam contaminadas por Staphylococcus aureus, porém a contagem de coliformes totais teve valor elevado. Em relação à contagem de células somáticas, verificou-se que 86% das propriedades apresentaram CCS acima de um milhão de células por mL, devendo-se ajustar corretamente os manejos alimentar, produtivo e reprodutivo. As épocas de parição, lactação e o genótipo influenciaram de forma direta os índices produtivos e reprodutivos dos animais. Obsevou-se a prevalência de vários fatores que contribuem para a vulnerabilidade de contaminação do leite em diversas etapas de produção, tais como ordenha e processamento. Portanto, a orientação adequada e a conscientização dos responsáveis são de extrema importância para melhorar a qualidade do leite de cabra na região semiárida da Paraíba.(AU)


Assuntos
Animais , Feminino , Cabras , Contaminação de Alimentos/análise , Leite/microbiologia , Leite/química , Lactação , Higiene dos Alimentos , Eficiência
4.
J Appl Microbiol ; 124(5): 1283-1293, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29356247

RESUMO

AIMS: To perform a microbiological survey regarding the presence, prevalence and characterization of Aeromonas sp. and Vibrio sp. in debilitated wrecked marine birds recovered from the centre-north coast of the state of Rio de Janeiro, Brazil. METHODS AND RESULTS: Swabs obtained from 116 alive and debilitated wrecked marine birds, comprising 19 species, from the study area were evaluated by biochemical methods. Antimicrobial susceptibility tests and pathogenicity gene screening were performed for bacterial strains of public health importance. Vibrio sp. and Aeromonas sp. were identified, as well as certain pathogenic genes and resistance to selected antimicrobials. CONCLUSIONS: This study demonstrates that the identified bacteria, mainly Vibrio sp., are fairly prevalent and widespread among several species of seabirds and highlights the importance of migratory birds in bacterial dispersion. In addition, it demonstrates the importance of the bacterial strains regarding their pathogenic potential. Therefore, seabirds can act as bacterial reservoirs, and their monitoring is of the utmost importance in a public health context. SIGNIFICANCE AND IMPACT OF THE STUDY: The study comprehensively evaluates the importance of seabirds as bacteria of public health importance reservoirs, since birds comprising several pathogenic bacterial species were evaluated.


Assuntos
Aeromonas/isolamento & purificação , Aeromonas/patogenicidade , Aves/microbiologia , Reservatórios de Doenças , Saúde Pública , Vibrio/isolamento & purificação , Vibrio/patogenicidade , Animais , Anti-Infecciosos , Brasil , Resistência a Medicamentos , Testes de Sensibilidade Microbiana , Inquéritos e Questionários , Virulência/genética
5.
Mar Pollut Bull ; 119(2): 68-73, 2017 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-28431744

RESUMO

Marine debris such as plastic fragments and fishing gears are accumulating in the ocean at alarming rates. This study assesses the incidence of debris in the gastrointestinal tracts of seabirds feeding at different depths and found stranded along the Brazilian coast in the period 2010-2013. More than half (55%) of the species analysed, corresponding to 16% of the total number of individuals, presented plastic particles in their gastrointestinal tracts. The incidence of debris was higher in birds feeding predominantly at intermediate (3-6m) and deep (20-100m) waters than those feeding at surface (<2m). These results suggest that studying the presence of debris in organisms mainly feeding at the ocean surface provides a limited view about the risks that this form of pollution has on marine life and highlight the ubiquitous and three-dimensional distribution of plastic in the oceans.


Assuntos
Aves , Monitoramento Ambiental , Plásticos/farmacocinética , Animais , Brasil , Dieta , Incidência , Oceanos e Mares , Água
6.
Zoonoses Public Health ; 63(2): 97-105, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26178302

RESUMO

The aim of this study was to investigate the phenotypic and genotypic diversity and anti-microbial resistance among staphylococci of dairy herds that originated from Paraiba State, north-eastern Brazil, a region where such studies are rare. Milk samples (n = 552) were collected from 15 dairy farms. Isolates were evaluated for anti-microbial susceptibility by Kirby-Bauer disc diffusion method. Confirmation of methicillin-resistant Staphylococcus aureus (MRSA) was performed using multiplex PCR targeting mecA and nuc genes in addition to phenotypic assay based on PBP-2a latex agglutination. Clonal relatedness of isolates was determined by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) genotyping. Staphylococci were detected in 269 (49%) of the samples. Among these, 65 (24%) were S. aureus. The remaining 204 isolates were either coagulase-negative staphylococci (n = 188; 70%) or coagulase positive other than S. aureus (n = 16; 6%). Staphylococci were cultured in seven (35%) of the 20 hand swab samples, from which five isolates were S. aureus. The isolates were most commonly resistant against penicillin (43%), ampicillin (38%) and oxacillin (27%). The gene mecA was detected in 21 S. aureus from milk and in one isolate from a milker's hand. None of the isolates were resistant to vancomycin. PFGE findings showed high clonal diversity among the isolates. Based on MLST, we identified a total of 11 different sequence types (STs 1, 5, 6, 83, 97, 126, 1583, 1622, 1623, 1624 and 1625) with four novel STs (ST1622-ST1625). The findings show that MRSA is prevalent in milk from semi-extensive dairy cows in north-eastern Brazil, and further investigation on its extent in various types of milk production systems and the farm-to-table continuum is warranted.


Assuntos
Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Leite/microbiologia , Intoxicação Alimentar Estafilocócica/veterinária , Animais , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Biodiversidade , Brasil/epidemiologia , Bovinos , Indústria de Laticínios , Farmacorresistência Bacteriana Múltipla , Feminino , Contaminação de Alimentos , Microbiologia de Alimentos , Variação Genética , Genótipo , Humanos , Staphylococcus aureus Resistente à Meticilina/classificação , Testes de Sensibilidade Microbiana , Nuclease do Micrococo/genética , Tipagem de Sequências Multilocus , Proteínas de Ligação às Penicilinas/genética , Fenótipo , Reação em Cadeia da Polimerase , Intoxicação Alimentar Estafilocócica/epidemiologia , Staphylococcus aureus/efeitos dos fármacos
7.
Genet Mol Res ; 10(4): 3731-7, 2011 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-22180075

RESUMO

There have been few studies on Magellanic penguins (Spheniscus magellanicus). In 2008, these penguins washed ashore along the Brazilian coast in unusually high numbers, some reaching as far as northeast Brazil. As Magellanic penguins show little sexual dimorphism, sex determination by morphological features is not accurate. Here, we tested a molecular procedure for sexing specimens of S. magellanicus washed ashore along the coasts of Sergipe, Rio de Janeiro and Rio Grande do Sul in 2008, comparing the sex ratio between these localities. Tissue samples were collected from 135 dead, beached specimens. We carried out total genomic DNA extraction and CHD-Z/CHD-W gene amplification by PCR using P2 and P8 primers. Amplicons were separated by 12% acrylamide gel electrophoresis. We found a greater proportion of females (70%). Sex could be determined because females have two intronic regions of CHD gene of different size in the sex chromosomes, visualized as two bands on the gel (380 and 400 bp approximately), while males have only one (400 bp). Therefore, this method proved to be effective and sensitive for sex determination of S. magellanicus individuals. Data on sex ratios are useful for understanding the dynamics and ecology of Magellanic penguin populations.


Assuntos
Ecossistema , Análise para Determinação do Sexo/métodos , Spheniscidae/genética , Animais , Brasil , Feminino , Geografia , Íntrons/genética , Masculino , Razão de Masculinidade
8.
Toxicon ; 50(7): 938-46, 2007 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-17825864

RESUMO

We isolated cDNA sequences coding for dermonecrotic/sphingomyelinases factor proteins from the brown spider Loxosceles intermedia, here named Loxtox proteins. The amino acid sequences based on cloned cDNA of several Loxtox proteins revealed at least six distinct groups of proteins expressed in the venom gland. The level of similarity among the toxins varied from 99% to 55%. The finding of several isoforms of Loxtox in the venom of this spider may reflect an evolutionary adaptation for different prey types and reinforces the idea of an efficient mutational mechanism in the venom gland of spiders.


Assuntos
Diester Fosfórico Hidrolases/química , Esfingomielina Fosfodiesterase/metabolismo , Venenos de Aranha/química , Aranhas/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Clonagem Molecular , DNA Complementar/genética , Regulação da Expressão Gênica , Dados de Sequência Molecular , Diester Fosfórico Hidrolases/metabolismo , Filogenia , RNA Mensageiro/genética , Esfingomielina Fosfodiesterase/genética , Venenos de Aranha/metabolismo
9.
Trop Med Int Health ; 11(3): 332-40, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16553913

RESUMO

OBJECTIVE: To evaluate a new method of deriving the reproductive number for vector-borne diseases from the early epidemic curves for vector-borne diseases with incubations in the vectors and in the hosts. METHOD: We applied the model to several dengue epidemics in different climatic regions of Brazil: Brasilia, Belém, Fortaleza, Boa Vista. RESULTS: The new method leads to higher estimates of the reproductive number than previous models. CONCLUSION: At present, Aedes aegypti densities, the meeting of more compatible strains of viruses and mosquitoes, may lead to re-emergence of urban yellow fever epidemics.


Assuntos
Aedes/fisiologia , Dengue/epidemiologia , Insetos Vetores/fisiologia , Reprodução/fisiologia , Animais , Brasil/epidemiologia , Clima , Dengue/transmissão , Surtos de Doenças , Humanos , Modelos Biológicos , Processos Estocásticos
10.
Toxicon ; 46(8): 927-36, 2005 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-16289643

RESUMO

Accidents caused by brown spiders (Loxosceles genus) are frequent in Brazil and are associated with dermonecrotic lesions and, eventually, systemic reactions that may be lethal. The major species implicated with human envenoming have been: L. intermedia, L. gaucho and L. laeta. In this study we characterized the venom from Loxosceles similis, a species of spider normally found inside caves. L. similis venom was characterized by two-dimensional gel electrophoresis and enzymatic activity (dermonecrosis and haemolysis). The lethal dose to mice and the capacity of commercial anti-serum to neutralize this venom were also analysed. The cross-reactivity with anti-venoms against L. intermedia, L. laeta and L. gaucho were studied. Our results showed that this venom was able to induce severe dermonecrotic lesions and showed the presence of the bacteria Clostridium septicum in association with the fangs. In addition, we have cloned the DNA coding for a dermonecrotic protein (LsD1), using the genomic DNA of L. similis. The deduced amino acid sequence showed a toxin of approximately 31.2 kDa with an estimated pI of 7.37 and sequence similar to LiD1, a protein from the dermonecrotic family of Loxosceles intermedia spider venom, a synanthropic species of medical importance.


Assuntos
Diester Fosfórico Hidrolases/isolamento & purificação , Diester Fosfórico Hidrolases/toxicidade , Pele/patologia , Venenos de Aranha/isolamento & purificação , Venenos de Aranha/toxicidade , Aranhas/química , Animais , Sequência de Bases , Western Blotting , Brasil , Clostridium/isolamento & purificação , Reações Cruzadas/imunologia , Primers do DNA , Eletroforese em Gel Bidimensional , Eletroforese em Gel de Poliacrilamida , Ensaio de Imunoadsorção Enzimática , Hemólise/efeitos dos fármacos , Soros Imunes/farmacologia , Dose Letal Mediana , Camundongos , Dados de Sequência Molecular , Necrose , Diester Fosfórico Hidrolases/genética , Análise de Sequência de DNA , Especificidade da Espécie , Venenos de Aranha/antagonistas & inibidores , Venenos de Aranha/genética , Aranhas/microbiologia
11.
IEEE Trans Image Process ; 10(4): 584-97, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-18249648

RESUMO

Hyperspectral sensors collect hundreds of narrow and contiguously spaced spectral bands of data. Such sensors provide fully registered high resolution spatial and spectral images that are invaluable in discriminating between man-made objects and natural clutter backgrounds. The price paid for this high resolution data is extremely large data sets, several hundred of Mbytes for a single scene, that make storage and transmission difficult, thus requiring fast onboard processing techniques to reduce the data being transmitted. Attempts to apply traditional maximum likelihood detection techniques for in-flight processing of these massive amounts of hyperspectral data suffer from two limitations: first, they neglect the spatial correlation of the clutter by treating it as spatially white noise; second, their computational cost renders them prohibitive without significant data reduction like by grouping the spectral bands into clusters, with a consequent loss of spectral resolution. This paper presents a maximum likelihood detector that successfully confronts both problems: rather than ignoring the spatial and spectral correlations, our detector exploits them to its advantage; and it is computationally expedient, its complexity increasing only linearly with the number of spectral bands available. Our approach is based on a Gauss-Markov random field (GMRF) modeling of the clutter, which has the advantage of providing a direct parameterization of the inverse of the clutter covariance, the quantity of interest in the test statistic. We discuss in detail two alternative GMRF detectors: one based on a binary hypothesis approach, and the other on a "single" hypothesis formulation. We analyze extensively with real hyperspectral imagery data (HYDICE and SEBASS) the performance of the detectors, comparing them to a benchmark detector, the RX-algorithm. Our results show that the GMRF "single" hypothesis detector outperforms significantly in computational cost the RX-algorithm, while delivering noticeable detection performance improvement.

12.
IEEE Trans Image Process ; 10(10): 1541-51, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-18255497

RESUMO

This paper presents the surface-based factorization method to recover three-dimensional (3-D) structure, i.e., the 3-D shape and 3-D motion, of a rigid object from a two-dimensional (2-D) video sequence. The main ingredients of our approach are as follows: 1) we describe the unknown shape of the 3-D rigid object by polynomial patches; 2) projections of these patches in the image plane move according to parametric 2-D motion models; 3) we recover the parameters describing the 3-D shape and 3-D motion from the 2-D motion parameters by factorizing a matrix that is rank 1 in a noiseless situation. Our method is simultaneously an extension and a simplification of the original factorization method of Tomasi and Kanade (1992). We track regions where the 2-D motion in the image plane is described by a single set of parameters, avoiding the need to track a large number of pointwise features, in general, a difficult task. Then our method estimates the parameters describing the 3-D structure by factoring a rank 1 matrix, not rank 3 as in Tomasi and Kanade. This allows the use of fast iterative algorithms to compute the 3-D structure that best fits the data. Experimental results with real-life video sequences illustrate the good performance of our approach.

13.
Mem Inst Oswaldo Cruz ; 95(2): 251-7, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-10733749

RESUMO

A closed colony of Lutzomyia longipalpis was established with specimens collected in the Raposa - Serra do Sol indian reservoir, one of the main foci of visceral leishmaniasis in the State of Roraima, Brazil. Biological observations were made on four generations of a L. longipalpis colony with emphasis on productivity. Aspects studied were the number of laid and retained eggs, and the number of adults (male and female) per generation. During the four generations the percentage of engorged females that laid eggs varied from 64.2% (third generation-F3) to 90.3% (second generation-F2). The mean number of eggs laid per female varied from 23.6 (F3) to 39. 9 (first generation-F1). The maximum number of eggs laid per female varied from 84 (F3) to 124 (F1). The mean number of retained eggs per female was 12.7 (parental generation-P and F1) to 22.1 (F2). The number of females exceeded the number of males in all generations. However, significant difference for male/female ratio was found only for F3. Fecundity rates were between 42.1 (F3) and 58.3 (F2). From a total of 439 blood-fed females, 355 females laid 12,257 eggs that yield 5,354 adults (2,525 males and 2,829 females) in four generations. F2 presented maximum productivity and fecundity rates.


Assuntos
Oviposição/fisiologia , Psychodidae/anatomia & histologia , Razão de Masculinidade , Animais , Feminino , Fertilidade/fisiologia , Masculino , Psychodidae/fisiologia
14.
IEEE Trans Image Process ; 8(11): 1593-607, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-18267434

RESUMO

In the physical sciences, e.g., meteorology and oceanography, combining measurements with the dynamics of the underlying models is usually referred to as data assimilation. Data assimilation improves the reconstruction of the image fields of interest. Assimilating data with algorithms like the Kalman-Bucy filter (KBf) is challenging due to their computational cost which for two-dimensional (2-D) fields is of O(I(6)) where I is the linear dimension of the domain. In this paper, we combine the block structure of the underlying dynamical models and the sparseness of the measurements (e.g., satellite scans) to develop four efficient implementations of the KBf that reduce its computational cost to O(I(5)) in the case of the block KBf and the scalar KBf, and to O(I(4)) in the case of the local block KBf (lbKBf) and the local scalar KBf (lsKBf). We illustrate the application of the IbKBf to assimilate altimetry satellite data in a Pacific equatorial basin.

15.
IEEE Trans Image Process ; 5(8): 1229-42, 1996.
Artigo em Inglês | MEDLINE | ID: mdl-18285211

RESUMO

The paper describes a lossy image codec that uses a noncausal (or bilateral) prediction model coupled with vector quantization. The noncausal prediction model is an alternative to the causal (or unilateral) model that is commonly used in differential pulse code modulation (DPCM) and other codecs with a predictive component. We show how to obtain a recursive implementation of the noncausal image model without compromising its optimality and how to apply this in coding in much the same way as a causal predictor. We report experimental compression results that demonstrate the superiority of using a noncausal model based predictor over using traditional causal predictors. The codec is shown to produce high-quality compressed images at low bit rates such as 0.375 b/pixel. This quality is contrasted with the degraded images that are produced at the same bit rates by codecs using causal predictors or standard discrete cosine transform/Joint Photographic Experts Group-based (DCT/JPEG-based) algorithms.

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