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2.
Vaccimonitor (La Habana, Print) ; 30(2)mayo.-ago. 2021. tab, graf
Artigo em Espanhol | LILACS, CUMED | ID: biblio-1252325

RESUMO

El uso de anticuerpos monoclonales en la lucha contra el cáncer se convierte cada día más en la terapia de elección. Para la introducción de anticuerpos monoclonales en mercados internacionales de alta demanda y con elevados requerimientos de calidad se requiere su producción a gran escala. El incremento de la presencia de dímeros en el producto final afecta su calidad y, por tanto, la eficiencia y eficacia del proceso. El objetivo del presente trabajo fue obtener un modelo matemático que permita relacionar el porcentaje de dímeros con las variables de operación de mayor influencia. Se realizó el ajuste de un modelo de regresión lineal múltiple usando el programa Statgraphics Centurion XVII versión 17.2.00. El modelo se validó con lotes de producción, logrando errores relativos inferiores al 20 por ciento. Las variables significativas obtenidas fueron: masa de IgG en el sobrenadante; masa de IgG en el producto de salida del paso de captura de proteína A; pH en el producto de salida del paso de captura de proteína A; pH del producto ajustado y conductividad de salida en la membrana de intercambio aniónico. El modelo permitió encontrar un intervalo de trabajo de las variables de mayor influencia en la formación de dímeros para reducirlos hasta valores inferiores al 3 por ciento(AU)


The use of monoclonal antibodies in the fight against cancer is becoming more and more the selected therapy. The introduction of monoclonal antibodies highly demanded in international markets, with high quality requirements needs the production of monoclonal antibodies on a large scale. The increase of dimers in the final product affects its quality, therefore, the efficiency and effectiveness of the process. The objective of this work was to obtain a mathematical model to relate the percentage of dimers with the most influential operating variables. A multiple linear regression model was obtained using Statgraphics Centurion XVII version 17.2.00 software. The model was validated with new production data with a mean error of validation below 20 percent. The significant variables were: supernatant IgG mass; IgG mass in the effluent from Protein A capture column; pH of the effluent from Protein A capture column; pH of the adjusted product and conductivity of the effluent from anionic exchange membrane. A working interval for each of the influential variables were established, in order to reduce dimers below 3 percent(AU)


Assuntos
Humanos , Computação Matemática , Análise de Dados , Anticorpos Monoclonais/imunologia , Neoplasias/mortalidade , Cuba
3.
Res Vet Sci ; 137: 281-286, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34058399

RESUMO

Investigators use Bland-Altman plot (Limits of Agreement plot) to compare two methods measuring the same continuous variable to determine interchangeability or agreement of the methods. The method has evolved to deal with heteroscedastic data and fixed or proportional biases (or both). Although an ordinary Bland-Altman plot can be readily made with various software applications, there is no free, open-source application that is dedicated to producing Bland-Altman plots and constructing limits of agreement for data that do not meet the assumptions of a simple comparison. To fill this gap, we created BA-plotteR, a web-based, open-source, freeware tool created in Shiny/R that is dedicated to creating Bland-Altman plots. We validated the tool using 20 datasets with various data distributions by comparing the output from the tool against manually derived results. The webtool handles data that requires a more complex analysis than is commonly available through commercial statistical programs. Moreover, the automated analysis of the data distribution will guide users and help them to correctly plot and analyse their data. The tool agreed perfectly with manually constructed plots. The Bland-Altman graphing tool provides clinical researchers with a tool that correctly analyzes and graphs studies involved in method comparisons. The tool can be accessed here: https://huygens.science.uva.nl/BA-plotteR.


Assuntos
Internet , Computação Matemática , Software
4.
Brief Bioinform ; 22(5)2021 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-33822893

RESUMO

A major task in the analysis of microbiome data is to identify microbes associated with differing biological conditions. Before conducting analysis, raw data must first be adjusted so that counts from different samples are comparable. A typical approach is to estimate normalization factors by which all counts in a sample are multiplied or divided. However, the inherent variation associated with estimation of normalization factors are often not accounted for in subsequent analysis, leading to a loss of precision. Rank normalization is a nonparametric alternative to the estimation of normalization factors in which each count for a microbial feature is replaced by its intrasample rank. Although rank normalization has been successfully applied to microarray analysis in the past, it has yet to be explored for microbiome data, which is characterized by high frequencies of 0s, strongly correlated features and compositionality. We propose to use rank normalization as an alternative to the estimation of normalization factors and examine its performance when paired with a two-sample t-test. On a rigorous 3rd-party benchmarking simulation, it is shown to offer strong control over the false discovery rate, and at sample sizes greater than 50 per treatment group, to offer an improvement in performance over commonly used normalization factors paired with t-tests, Wilcoxon rank-sum tests and methodologies implemented by R packages. On two real datasets, it yielded valid and reproducible results that were strongly in agreement with the original findings and the existing literature, further demonstrating its robustness and future potential. Availability: The data underlying this article are available online along with R code and supplementary materials at https://github.com/matthewlouisdavisBioStat/Rank-Normalization-Empowers-a-T-Test.


Assuntos
Bactérias/genética , Infecções Bacterianas/diagnóstico , Bioestatística/métodos , Neoplasias Colorretais/microbiologia , Doença de Crohn/microbiologia , Microbioma Gastrointestinal/genética , Metagenoma , Infecções Bacterianas/microbiologia , Benchmarking , Estudos de Casos e Controles , Criança , Estudos de Coortes , Simulação por Computador , Feminino , Humanos , Masculino , Computação Matemática , Metagenômica/métodos , RNA Ribossômico 16S/genética , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Estatísticas não Paramétricas
5.
PLoS One ; 16(3): e0243763, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33705431

RESUMO

What makes a literate person? What leads to literacy gains and losses within and between individuals and countries? This paper provides new evidence that helps answer these questions. The present comparative analysis of literacy is based on large representative samples from the Survey of Adult Skills conducted in 33 countries, with 25-65 year old participants. We provide, for the first time, estimates of relative importance for a comprehensive set of experiential factors, motivations, incentives, parental influence, demands of workplace, and other predictors of influence. We sketch a configuration of factors that predicts an "ideal" reader, i.e., the optimal literacy performance. Moreover, we discover a pivotal role of the age effect in predicting variability between countries. Countries with the highest literacy scores are the ones where literacy decreases with age the most strongly. We discuss this finding against current accounts of aging effects, cohort effects and others. Finally, we provide methodological recommendations for experimental studies of aging in cognitive tasks like reading.


Assuntos
Alfabetização , Adulto , Idoso , Bases de Dados Factuais , Humanos , Computação Matemática , Pessoa de Meia-Idade , Leitura
6.
Medicina (Kaunas) ; 57(2)2021 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-33567770

RESUMO

Background and objectives: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread to more than 200 countries. In light of this situation, the Japanese Government declared a state of emergency in seven regions of Japan on 7 April 2020 under the provisions of the law. The medical care delivery system has been under pressure. Although various surgical societies have published guidelines on which to base their surgical decisions, it is not clear how general anesthesia has been performed and will be performed in Japan. Materials and Methods: One of the services provided by the social network service Twitter is a voting function-Twitter Polls-through which anonymous surveys were conducted. We analyzed the results of a series of surveys 17 times over 22 weeks on Twitter on the status of operating restrictions using quadratic programming to solve the mathematical optimizing problem, and public data provided by the Japanese Government were used to estimate the current changes in the number of general anesthesia performed in Japan. Results: The minimum number of general anesthesia cases per week was estimated at 67.1% compared to 2015 on 27 April 2020. The timeseries trend was compatible with the results reported by the Japanese Society of Anesthesiologists (correlation coefficient r = 0.69, p < 0.001). Conclusions: The number of general anesthesia was reduced up to two-thirds during the pandemic of COVID-19 in Japan and was successfully quantitatively estimated using a quick questionnaire on Twitter.


Assuntos
Anestesia Geral/estatística & dados numéricos , Anestesiologia/estatística & dados numéricos , COVID-19 , Utilização de Instalações e Serviços/estatística & dados numéricos , Mídias Sociais/estatística & dados numéricos , Humanos , Japão , Computação Matemática , Projetos de Pesquisa , SARS-CoV-2 , Sociedades Médicas/estatística & dados numéricos , Inquéritos e Questionários
7.
Biochem Mol Biol Educ ; 49(3): 333-345, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33096589

RESUMO

Ionization of amino acids (AA) is very important concept in biochemistry. We integrate the mathematical concept of probability with biochemically relevant process of AA ionization. We visualize the ionization process with Mathematica software discussing intramolecular interactions between weakly acidic/basic functional groups and charge-pH variation of amino acids in water solution. The visualizations rely on the notion of probability of ionization of functional groups and demonstrate how the extent of ionization and charge varies with pH of the solution. The examples described include amino acids and weak diprotic acids and bases. The aim is to help students better appreciate the importance and consequences of AA ionization and correct some misconceptions.


Assuntos
Ácidos/química , Aminoácidos/análise , Aminoácidos/química , Bioquímica/métodos , Computação Matemática , Estudantes/estatística & dados numéricos , Humanos , Concentração de Íons de Hidrogênio
8.
Sci Rep ; 10(1): 18948, 2020 11 03.
Artigo em Inglês | MEDLINE | ID: mdl-33144594

RESUMO

The mechanisms underlying the emergence of leadership in multi-agent systems are under investigation in many areas of research where group coordination is involved. Nonverbal leadership has been mostly investigated in the case of animal groups, and only a few works address the problem in human ensembles, e.g. pedestrian walking, group dance. In this paper we study the emergence of leadership in the specific scenario of a small walking group. Our aim is to propose a rigorous mathematical methodology capable of unveiling the mechanisms of leadership emergence in a human group when leader or follower roles are not designated a priori. Two groups of participants were asked to walk together and turn or change speed at self-selected times. Data were analysed using time-dependent cross correlation to infer leader-follower interactions between each pair of group members. The results indicate that leadership emergence is due both to contextual factors, such as an individual's position in the group, and to personal factors, such as an individual's characteristic locomotor behaviour. Our approach can easily be extended to larger groups and other scenarios such as team sports and emergency evacuations.


Assuntos
Comportamento Social , Caminhada , Animais , Humanos , Liderança , Computação Matemática
9.
Network ; 31(1-4): 142-165, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33148086

RESUMO

The motivation of this investigation is to develop a single-layer Chebyshev Neural Network (ChNN) model to handle singular fractional (arbitrary)-order Lane-Emden type equations. These equations are well-known application problems of astrophysics and quantum mechanics. Fractional Lane-Emden equations are singular so it is very difficult to solve analytically. Thus, an efficient method is required to handle the above equations. Here, our main aim is to use a single-layer ChNN model for solving fractional Lane-Emden equations. ChNN model is one kind of Functional Link Neural Network (FLNN) in which the hidden layer is replaced by a functional expansion block of the input pattern using orthogonalshifted Chebyshev polynomials (SChP). Thus, the network parameters of ChNN are less than the Multi-Layer Artificial Neural Network (MLANN). We have considered factional-order singular nonlinear problems of astrophysics to show the computational effort of the proposed method. Back Propagation algorithm of the unsupervised version has been considered for minimizing the error function and updating the weights of the ChNN model. Computed results are displayed in terms of tables and graphs.


Assuntos
Algoritmos , Fenômenos Astronômicos , Computação Matemática , Redes Neurais de Computação , Humanos
10.
Math Biosci ; 329: 108442, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32777227

RESUMO

On February 5 the Japanese government ordered the passengers and crew on the Diamond Princess to start a two week quarantine after a former passenger tested positive for COVID-19. During the quarantine the virus spread rapidly throughout the ship. By February 20, there were 651 cases. We model this quarantine with a SEIR model including asymptomatic infections with differentiated shipboard roles for crew and passengers. The study includes the derivation of the basic reproduction number and simulation studies showing the effect of quarantine with COVID-19 or influenza on the total infection numbers. We show that quarantine on a ship with COVID-19 will lead to significant disease spread if asymptomatic infections are not identified. However, if the majority of the crew and passengers are immune or vaccinated to COVID-19, then quarantine would slow the spread. We also show that a disease similar to influenza, even with a ship with a fully susceptible crew and passengers, could be contained through quarantine measures.


Assuntos
Infecções Assintomáticas , Betacoronavirus , Infecções por Coronavirus/prevenção & controle , Infecções por Coronavirus/transmissão , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Pneumonia Viral/transmissão , Quarentena , Navios , Viagem , Número Básico de Reprodução/estatística & dados numéricos , COVID-19 , Teste para COVID-19 , Técnicas de Laboratório Clínico , Doenças Transmissíveis Importadas/prevenção & controle , Doenças Transmissíveis Importadas/transmissão , Simulação por Computador , Infecções por Coronavirus/diagnóstico , Infecções por Coronavirus/epidemiologia , Humanos , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , Influenza Humana/transmissão , Japão/epidemiologia , Computação Matemática , Modelos Biológicos , Pneumonia Viral/epidemiologia , Quarentena/métodos , SARS-CoV-2 , Medicina de Viagem , Doença Relacionada a Viagens
12.
Epidemiol Health ; 42: e2020028, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32512670

RESUMO

Coronavirus disease 2019 (COVID-19), which causes severe respiratory illness, has become a pandemic. The World Health Organization has declared it a public health crisis of international concern. We developed a susceptible, exposed, infected, recovered (SEIR) model for COVID-19 to show the importance of estimating the reproduction number (R0). This work is focused on predicting the COVID-19 outbreak in its early stage in India based on an estimation of R0. The developed model will help policymakers to take active measures prior to the further spread of COVID-19. Data on daily newly infected cases in India from March 2, 2020 to April 2, 2020 were to estimate R0 using the earlyR package. The maximum-likelihood approach was used to analyze the distribution of R0 values, and the bootstrap strategy was applied for resampling to identify the most likely R0 value. We estimated the median value of R0 to be 1.471 (95% confidence interval [CI], 1.351 to 1.592) and predicted that the new case count may reach 39,382 (95% CI, 34,300 to 47,351) in 30 days.


Assuntos
Número Básico de Reprodução/estatística & dados numéricos , Infecções por Coronavirus/epidemiologia , Surtos de Doenças , Pneumonia Viral/epidemiologia , COVID-19 , Previsões , Humanos , Índia/epidemiologia , Computação Matemática , Pandemias
13.
Sci Rep ; 10(1): 9716, 2020 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-32546713

RESUMO

Flow Cytometry is an analytical technology to simultaneously measure multiple markers per single cell. Ten thousands to millions of single cells can be measured per sample and each sample may contain a different number of cells. All samples may be bundled together, leading to a 'multi-set' structure. Many multivariate methods have been developed for Flow Cytometry data but none of them considers this structure in their quantitative handling of the data. The standard pre-processing used by existing multivariate methods provides models mainly influenced by the samples with more cells, while such a model should provide a balanced view of the biomedical information within all measurements. We propose an alternative 'multi-set' preprocessing that corrects for the difference in number of cells measured, balancing the relative importance of each multi-cell sample in the data while using all data collected from these expensive analyses. Moreover, one case example shows how multi-set pre-processing may benefit removal of undesired measurement-to-measurement variability and another where class-based multi-set pre-processing enhances the studied response upon comparison to the control reference samples. Our results show that adjusting data analysis algorithms to consider this multi-set structure may greatly benefit immunological insight and classification performance of Flow Cytometry data.


Assuntos
Processamento Eletrônico de Dados/métodos , Citometria de Fluxo/métodos , Análise Multivariada , Algoritmos , Biomarcadores , Análise de Dados , Humanos , Computação Matemática , Projetos de Pesquisa
14.
BMC Bioinformatics ; 21(1): 173, 2020 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-32366221

RESUMO

BACKGROUND: In shotgun proteomics, database searching of tandem mass spectra results in a great number of peptide-spectrum matches (PSMs), many of which are false positives. Quality control of PSMs is a multiple hypothesis testing problem, and the false discovery rate (FDR) or the posterior error probability (PEP) is the commonly used statistical confidence measure. PEP, also called local FDR, can evaluate the confidence of individual PSMs and thus is more desirable than FDR, which evaluates the global confidence of a collection of PSMs. Estimation of PEP can be achieved by decomposing the null and alternative distributions of PSM scores as long as the given data is sufficient. However, in many proteomic studies, only a group (subset) of PSMs, e.g. those with specific post-translational modifications, are of interest. The group can be very small, making the direct PEP estimation by the group data inaccurate, especially for the high-score area where the score threshold is taken. Using the whole set of PSMs to estimate the group PEP is inappropriate either, because the null and/or alternative distributions of the group can be very different from those of combined scores. RESULTS: The transfer PEP algorithm is proposed to more accurately estimate the PEPs of peptide identifications in small groups. Transfer PEP derives the group null distribution through its empirical relationship with the combined null distribution, and estimates the group alternative distribution, as well as the null proportion, using an iterative semi-parametric method. Validated on both simulated data and real proteomic data, transfer PEP showed remarkably higher accuracy than the direct combined and separate PEP estimation methods. CONCLUSIONS: We presented a novel approach to group PEP estimation for small groups and implemented it for the peptide identification problem in proteomics. The methodology of the approach is in principle applicable to the small-group PEP estimation problems in other fields.


Assuntos
Computação Matemática , Peptídeos/química , Algoritmos , Probabilidade , Processamento de Proteína Pós-Traducional , Proteômica , Espectrometria de Massas em Tandem
15.
Curr Med Imaging ; 16(4): 296-306, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32410533

RESUMO

BACKGROUND: Considering the increasing volume of text document information on Internet pages, dealing with such a tremendous amount of knowledge becomes totally complex due to its large size. Text clustering is a common optimization problem used to manage a large amount of text information into a subset of comparable and coherent clusters. AIMS: This paper presents a novel local clustering technique, namely, ß-hill climbing, to solve the problem of the text document clustering through modeling the ß-hill climbing technique for partitioning the similar documents into the same cluster. METHODS: The ß parameter is the primary innovation in ß-hill climbing technique. It has been introduced in order to perform a balance between local and global search. Local search methods are successfully applied to solve the problem of the text document clustering such as; k-medoid and kmean techniques. RESULTS: Experiments were conducted on eight benchmark standard text datasets with different characteristics taken from the Laboratory of Computational Intelligence (LABIC). The results proved that the proposed ß-hill climbing achieved better results in comparison with the original hill climbing technique in solving the text clustering problem. CONCLUSION: The performance of the text clustering is useful by adding the ß operator to the hill climbing.


Assuntos
Inteligência Artificial , Mineração de Dados/métodos , Computação Matemática , Algoritmos , Análise por Conglomerados , Conjuntos de Dados como Assunto , Humanos
16.
Med Decis Making ; 40(3): 348-363, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32428428

RESUMO

Metamodels can be used to reduce the computational burden associated with computationally demanding analyses of simulation models, although applications within health economics are still scarce. Besides a lack of awareness of their potential within health economics, the absence of guidance on the conceivably complex and time-consuming process of developing and validating metamodels may contribute to their limited uptake. To address these issues, this article introduces metamodeling to the wider health economic audience and presents a process for applying metamodeling in this context, including suitable methods and directions for their selection and use. General (i.e., non-health economic specific) metamodeling literature, clinical prediction modeling literature, and a previously published literature review were exploited to consolidate a process and to identify candidate metamodeling methods. Methods were considered applicable to health economics if they are able to account for mixed (i.e., continuous and discrete) input parameters and continuous outcomes. Six steps were identified as relevant for applying metamodeling methods within health economics: 1) the identification of a suitable metamodeling technique, 2) simulation of data sets according to a design of experiments, 3) fitting of the metamodel, 4) assessment of metamodel performance, 5) conducting the required analysis using the metamodel, and 6) verification of the results. Different methods are discussed to support each step, including their characteristics, directions for use, key references, and relevant R and Python packages. To address challenges regarding metamodeling methods selection, a first guide was developed toward using metamodels to reduce the computational burden of analyses of health economic models. This guidance may increase applications of metamodeling in health economics, enabling increased use of state-of-the-art analyses (e.g., value of information analysis) with computationally burdensome simulation models.


Assuntos
Simulação por Computador/normas , Economia Médica/normas , Computação Matemática , Técnicas de Apoio para a Decisão , Humanos
18.
mBio ; 11(2)2020 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-32209678

RESUMO

Many HIV prevention strategies are currently under consideration where it is highly informative to know the study participants' times of infection. These can be estimated using viral sequence data sampled early in infection. However, there are several scenarios that, if not addressed, can skew timing estimates. These include multiple transmitted/founder (TF) viruses, APOBEC (apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like)-mediated mutational enrichment, and recombination. Here, we suggest a pipeline to identify these problems and resolve the biases that they introduce. We then compare two modeling strategies to obtain timing estimates from sequence data. The first, Poisson Fitter (PF), is based on a Poisson model of random accumulation of mutations relative to the TF virus (or viruses) that established the infection. The second uses a coalescence-based phylogenetic strategy as implemented in BEAST. The comparison is based on timing predictions using plasma viral RNA (cDNA) sequence data from 28 simian-human immunodeficiency virus (SHIV)-infected animals for which the exact day of infection is known. In this particular setting, based on nucleotide sequences from samples obtained in early infection, the Poisson method yielded more accurate, more precise, and unbiased estimates for the time of infection than did the explored implementations of BEAST.IMPORTANCE The inference of the time of infection is a critical parameter in testing the efficacy of clinical interventions in protecting against HIV-1 infection. For example, in clinical trials evaluating the efficacy of passively delivered antibodies (Abs) for preventing infections, accurate time of infection data are essential for discerning levels of the Abs required to confer protection, given the natural Ab decay rate in the human body. In such trials, genetic sequences from early in the infection are regularly sampled from study participants, generally prior to immune selection, when the viral population is still expanding and genetic diversity is low. In this particular setting of early viral growth, the Poisson method is superior to the alternative approach based on coalescent methods. This approach can also be applied in human vaccine trials, where accurate estimates of infection times help ascertain if vaccine-elicited immune protection wanes over time.


Assuntos
Infecções por HIV/virologia , Filogenia , RNA Viral/sangue , Síndrome de Imunodeficiência Adquirida dos Símios/virologia , Animais , Infecções por HIV/sangue , HIV-1/genética , HIV-1/fisiologia , Macaca mulatta/virologia , Computação Matemática , Modelos Estatísticos , Distribuição de Poisson , Síndrome de Imunodeficiência Adquirida dos Símios/sangue , Vírus da Imunodeficiência Símia/genética , Vírus da Imunodeficiência Símia/fisiologia , Fatores de Tempo
19.
FASEB J ; 34(4): 5552-5562, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32103543

RESUMO

The optics of the eye is the key to a functioning visual system. The exact nature of the correlation between ocular optics and eye development is not known because of the paucity of knowledge about the growth of a key optical element, the eye lens. The sophisticated optics of the lens and its gradient of refractive index provide the superior optical quality that the eye needs and which, it is thought, has a major influence on the development of proper visual function. The nature of a gradient refractive index lens, however, renders accurate measurements of its development difficult to make and has been the reason why the influence of lens growth on visual function remains largely unknown. Novel imaging techniques have made it possible to investigate growth of the eye lens in the zebrafish. This study shows measurements using X-ray Talbot interferometry of three-dimensional gradient index profiles in eye lenses of zebrafish from late larval to adult stages. The zebrafish lens shows evidence of a gradient of refractive index from the earliest stages measured and its growth suggests an apparent coincidence between periods of rapid increase in refractive index in the lens nucleus and increased expression of a particular crystallin protein group.


Assuntos
Córnea/citologia , Córnea/fisiologia , Cristalino/citologia , Cristalino/fisiologia , Óptica e Fotônica , Animais , Computação Matemática , Refratometria , Peixe-Zebra
20.
PLoS One ; 15(1): e0227745, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31935260

RESUMO

Approximate computing is an emerging design paradigm that offers trade-offs between output accuracy and computation efforts by exploiting some applications' intrinsic error resiliency. Computation of error metrics is of paramount importance in approximate circuits to measure the degree of approximation. Most of the existing techniques for evaluating error metrics apply simulations which may not be effective for evaluation of large complex designs because of an immense increase in simulation runtime and a decrease in accuracy. To address these deficiencies, we present a novel methodology that employs SAT (Boolean satisfiability) solvers for fast and accurate determination of error metrics specifically for the calculation of an average-case error and the maximum error rate in functionally approximated circuits. The proposed approach identifies the set of all errors producing assignments to gauge the quality of approximate circuits for real-life applications. Additionally, the proposed approach provides a test generation method to facilitate design choices, and acts as an important guide to debug the approximate circuits to discover and locate the errors. The effectiveness of the approach is demonstrated by evaluating the error metrics of several benchmark-approximated adders of different sizes. Experimental results on benchmark circuits show that the proposed SAT-based methodology accurately determines the maximum error rate and an average-case error within acceptable CPU execution time in one go, and further provides a log of error-generating input assignments.


Assuntos
Algoritmos , Computação Matemática , Simulação por Computador , Projetos de Pesquisa
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