4,159 research outputs found
Deep learning for melanoma classification : a study using skin lesion images
Cutaneous melanoma is considered the skin cancer with highest mortality rate
and has been gaining the attention of the medical community due to its rapidly
increasing incidence. Advancements in computational technologies have paved the
way for innovative image detection methods that can be transferable to medical ap plications, significantly enhancing the potential for early intervention in melanoma
diagnosis. To make diagnosis more accurate and to further increase survival rates,
this study employs deep learning techniques on an extensive dataset derived from
multiple sources. Utilizing Microsoft Azure Cloud as the computational infras tructure, trial and error approach was employed by hyperparameterizing several
convolutional neural networks (CNN) where the decision criteria were choosing the
one with highest Fβ Score. MAR-MELA-CNN is an innovative ensemble model in corporating six state-of-the-art pre-trained CNN architectures: Xception, VGG16,
ResNet50, NASNetMobile, MobileNetV2, and InceptionV3. The primary goal of
this research is to further understand CNN’s efficiency in the diagnosis of melanoma
and to furthermore measure its performance on a merged dataset. The proposed
algorithm achieved a Fβ score of 85%, an area under the curve (AUC) score of
93%, and an average precision (AP) score of 92%, promising diagnostic tool for
cutaneous melanoma compared to traditional methods. Further improvements lay
in the improvement of the architecture, expansion of the computational instances
as well as of the dataset. Another field of future work could be devising a strategy
for real-time implementation of this model in a hospital setting, as it could be of
vital importance to provide swift support to doctors.O melanoma cutˆaneo ´e considerado o cancro de pele com a maior taxa de mortal idade e tem vindo a ganhar a aten¸c˜ao da comunidade m´edica devido ao seu r´apido
aumento de incidˆencia. Os avan¸cos tecnol´ogicos contribu´ıram para m´etodos ino vadores de detec¸c˜ao de imagens transfer´ıveis para aplica¸c˜oes m´edicas, aumentando
significativamente o potencial de interven¸c˜ao precoce no diagn´ostico de melanoma.
Para tornar o diagn´ostico mais preciso e aumentar a taxa de sobrevivˆencia, este es tudo emprega t´ecnicas de aprendizagem profunda num conjunto alargado de dados
provenientes de v´arias fontes. Utilizando a infraestrutura computacional Microsoft
Azure Cloud, a abordagem de tentativa e erro foi utilizada ao hiperparametrizar
v´arias redes neuronais convolucionais, sendo o crit´erio de decis˜ao a escolha daquela
com a maior pontua¸c˜ao Fβ. MAR-MELA-CNN ´e um modelo ensemble que incor pora seis arquiteturas pr´e-treinadas: Xception, VGG16, ResNet50, NASNetMobile,
MobileNetV2 e InceptionV3. O objetivo principal desta investiga¸c˜ao ´e potenciar a
eficiˆencia das CNNs no diagn´ostico de melanoma e medir o seu desempenho num
conjunto de dados unificado. O algoritmo proposto alcan¸cou uma pontua¸c˜ao Fβ
de 85%, AUC de 93% e uma precis˜ao m´edia de 92%, tornando-se uma ferramenta
promissora para o diagn´ostico de melanoma em compara¸c˜ao com os m´etodos tradi cionais. Os desenvolvimentos futuros incluem a melhoria da arquitetura e a extens˜ao
das ferramentas computacionais e do conjunto de dados. Outro campo de trabalho
futuro poderia ser a cria¸c˜ao de uma estrat´egia de implementa¸c˜ao em tempo real
deste modelo num hospital, j´a que pode ser de vital importˆancia para fornecer
apoio imediato aos m´edicos
Enzymatic treatment of polyamide 6.6 fibres
Tese de Doutoramento em Engenharia Têxtil - Ramo de Conhecimento Química Têxtil.The controlled hydrolysis of polyamide fibres surfaces leads to the formation
of amino and carboxylic end groups. The presence of these groups improves
hydrophilicity and creates further starting points for covalent bonding of certain
compounds. The coupling of flame retardants, proteins and other compounds
bring extra added value to polyamide fibres. Chemical hydrolysis, tradicionally
used to modify the surface of these fibres, is an “all-or-nothing” event leading
always to yellowing and loss of fibres resistance. Given that enzymes are large
globular proteins, their catalytic action remains at the surface of the fibres,
therefore preserving their intrinsic structure. This dissertation successfully
presents the use of enzymes to functionalise the surface of polyamide 6.6 fibres.
The ability of a cutinase from Fusarium solani pisi and a protease, a Subtilisin
from Bacillus sp. to hydrolyse polyamide 6.6 fibres was evaluated. Different
methodologies were developed in order to monitor the formation of the products
resulting from enzymatic hydrolysis. The first one is based on the reaction of the
compound 2,4,6-trinitrobenzenesulfonic acid (TNBS) with the amino groups
released to the bath treatment and the other one is based on the reaction of a
specific wool reactive dye with the terminal amino groups at the surface of the
treated fabrics. In this work it was proved that the enzymatic hydrolysis with
cutinase or protease leads only to surface modifications, being the reaction
selective.
Studies were performed in order to reduce the treatment time and increase
enzyme adsorption, hence increasing hydrolysis efficiency towards polyamide 6.6
fibres, by incubating polyamide 6.6 fabrics with cutinase in the presence of organic
solvents. The organic solvents used were benzyl alcohol (BA) and
dimethylacetamide (DMA), which are commonly used in polyamide processing as
dyeing assistants. The stability of cutinase in the presence of these solvents was
evaluated. It was observed that cutinase activity is preserved for several hours in
the presence of low amounts of organic solvents (half-life time of 26 hours for
1.5% of benzyl alcohol and half-life time of 14 hours for 1.5% benzyl alcohol+10%
dimethylacetamide). In the presence of these organic solvents, the polyamide
structure became more suitable to be modified by enzymatic action. The results
obtained confirmed an increase of terminal amino groups at the surface of the
fabrics incubated with cutinase in the presence of the referred organic solvents.
Cutinase was presented as a versatile enzyme with unusual stereolytic
activity towards polyamide substrates however turnover rates were very low. The
analysis of the 3D structure of cutinase from Fusarium solani pisi, (PDB code
1CEX), showed that the external, but closed active site, was hindering the access
to the fibre substrate. In order to overcome this difficulty, the genetic modification
of native cutinase was performed. The site-directed mutagenesis was performed
by changing specific amino acid residues around the active site by alanine (L81A,
N84A, L182A, V184A and L189A) and five mutations were obtained. All mutations
were done to create more space in order to fit the large inaccessible polymer in
the active site of the cutinase. Molecular modelling studies were performed by docking the synthetic model substrate of polyamide 6.6 at the cutinase active site.
These studies predicted that L182A mutation provided the best stabilization of
polyamide model substrate which support the experimental results obtained (+19%
of amines in the bath solution treatment; 25% of protein adsorption).
Cutinase and protease were not designed by nature to interact with synthetic
substrates like polyamide 6.6, therefore the accessibility of these enzymes to the
fibre surface as well as their adsorption can be restricted by the compacted
structure of polyamide fibres. As other authors have reported, the process of
enzyme adsorption is of major importance to the enzymatic hydrolysis of synthetic
fibres. Different studies have revealed that the adsorption of proteins follows
different steps and that mechanical agitation plays an important role in all of them.
In order to study the synergism among mechanical agitation, enzyme adsorption
and enzyme activity, studies were performed using different levels of mechanical
agitation. The results obtained revealed that the surface functionalisation of
polyamide fibres with cutinases or protease should be performed using low levels
of mechanical agitation for short periods of time (4 hours using a vertical agitation
– Rotawash MKIII machine, in absence of discs).
A practical application was found for the functionalised surfaces obtained.
The amine-enriched surfaces obtained by enzymatic action of a protease from
Bacillus sp. were used to immobilise an enzyme (a laccase from Trametes
hirsuta). An immobilisation procedure was developed to immobilise laccase onto
woven polyamide 6.6 supports using glutaraldeyde as the crosslinking agent with
the inclusion of a spacer (1,6-hexanediamine) in some cases. A 24 full factorial
design was applied to study the influence of pH, spacer, enzyme and crosslinker
concentration on the efficiency of immobilisation. The factors enzyme dosage and
spacer have played a critical role in the immobilisation process. Under optimised
working conditions (29 UmL-1 of laccase, 10% of glutaraldehyde, pH=5.5, with the
presence of the spacer), the half-life time attained was about 78 h (18% higher
than that of free enzyme), the protein retention was about 34% and the
immobilisation yield was 2%. Laccase immobilisation onto polyamide 6.6 matrices
can be a promising system for bioremediation of contaminated soils, wastewater
treatment, wine and other beverage stabilisation, and even biosensor applications.
The results obtained reveal that cutinase and protease are able to modify the
surface of polyamide 6.6 fibres and that these enzymes can be used in different
steps of fibre processing. Higher added value products can be obtained by
polyamide 6.6 functionalisation with enzymes, however the process of enzymatic
hydrolysis needs to be characterized in more detail in order to be applied into an
industrial process.A hidrólise controlada da superfície das fibras de poliamida conduz à
formação de grupos terminais amina e carboxílicos. A presença destes grupos
melhora a hidrofilidade das fibras e cria possíveis locais para a ligação de certos
compostos. A ligação de agentes retardadores da chama, de proteínas e outros
compostos conduz à obtenção de fibras com maior valor acrescentado. No
entanto, a hidrólise química tradicionalmente usada para modificar a superfície
destas fibras, é um mecanismo “tudo-ou-nada” que provoca o amarelecimento e
perda de resistência das fibras. Dado que as enzimas são proteínas globulares
grandes, a sua acção catalítica reduz-se somente à superfície das fibras,
preservando assim a sua estrutura. Esta dissertação apresenta com sucesso o
uso de enzimas na funcionalização da superfície de fibras de poliamida 6.6.
Foi testada a capacidade de uma cutinase, do fungo Fusarium solani pisi, e
de uma protease, da bactéria Bacillus sp., para hidrolisar as fibras de poliamida
6.6. Foram desenvolvidas diferentes metodologias para monitorizar a formação
dos produtos resultantes da hidrólise enzimática. Uma delas é baseada na
reacção do composto 2,4,6 - ácido trinitrobenzenosulfónico (TNBS) com os
grupos amina libertados para o banho de tratamento. A outra baseia-se na
reacção de um corante reactivo específico para a lã com os grupos amina
terminais que permanecem na superfície dos tecidos tratados após hidrólise.
Neste trabalho, foi provado que a hidrólise enzimática com a cutinase ou com a
protease, conduz apenas a uma modificação superficial, sendo a reacção
selectiva.
Foram efectuados estudos para reduzir o tempo de tratamento e aumentar a
adsorção da enzima, aumentando assim a eficiência hidrolítica sobre as fibras de
poliamida 6.6. Para isso, os tecidos de poliamide 6.6 foram incubados com
cutinase na presença de solventes orgânicos. Os solventes orgânicos usados
foram o álcool benzílico e a dimetilacetamida, os quais são geralmente usados no
processamento da poliamida como auxiliares no seu tingimento. Foi também
avaliada a estabilidade da cutinase na presença destes solventes. Constatou-se
que a actividade da cutinase é preservada durante algumas horas na presença de
baixas concentrações de solventes orgânicos (tempo de meia-vida de 26 horas
para 1.5% álcool benzílico e tempo de meia-vida de 14 horas para 1.5% álcool
benzílico + 10% dimetilacetamida). Na presença destes solventes, a estrutura da
poliamida torna-se mais apta a ser modificada por acção enzimática. Os
resultados confirmam um aumento de grupos terminais à superfície da fibra nos
tecidos incubados com cutinase na presença dos referidos solventes.
A cutinase foi assim apresentada como uma enzima versátil com invulgar
actividade esteriolítica sobre substratos de poliamida, no entanto os níveis de
modificação obtidos foram muito baixos. A análise da estrutura tridimensional da
cutinase do fungo Fusarium solani pisi (PDB code 1CEX), mostrava que o centro
activo externo, mas fechado, da enzima impedia o acesso ao substrato. De modo
a ultrapassar esta dificuldade, foi efectuada a modificação genética da cutinase
nativa. A técnica de mutagénese dirigida foi usada para efectuar modificações na enzima, substituindo aminoácidos específicos perto do centro activo por alanina,
obtendo-se cinco mutações (L81A, N84A, L182A, V184A e L189A). Todas as
mutações foram feitas de modo a criar mais espaço no centro activo onde o
substrato polimérico pudesse encaixar. Os estudos de modelação molecular
foram efectuados incorporando o substrato modelo de poliamida 6.6 no centro
activo da enzima. Estes estudos mostraram que a mutação L182A apresentou os
melhores resultados de estabilização do substrato modelo, os quais são
suportados pelos resultados experimentais obtidos (+19% aminas na solução do
banho de tratamento; 25% de adsorção de proteína)
A cutinase e a protease não foram “desenhadas” pela natureza para interagir
com substratos sintéticos como a poliamida 6.6, pelo que a sua acessibilidade à
superfície das fibras assim como a sua adsorção pode ser restringida pela
estrutura compacta das fibras de poliamida. Como referido por outros autores, o
processo de adsorção enzimática é de extrema importância na hidrólise de fibras
sintéticas. Diferentes estudos revelaram que a adsorção de proteínas segue
diferentes passos e que a agitação mecânica tem um papel importante em todo o
processo. De modo a estudar o sinergismo entre a agitação mecânica, adsorção
de enzima e actividade enzimática, foram realizados estudos usando diferentes
níveis de agitação mecânica. Os resultados revelaram que a funcionalização da
superfície das fibras de poliamida com cutinases ou com a protease deve ser
efectuada usando níveis baixos de agitação mecânica durante curtos períodos de
tempo (4 horas usando agitação vertical – Rotawash MKIII, sem discos).
Foi posteriormente encontrada uma aplicação prática para os tecidos
previamente funcionalizados. As superfícies dos tecidos ricas em grupos amina,
obtidas por acção enzimática de uma protease do Bacillus sp., foram usadas para
imobilizar uma enzima (lacase de Trametes hirsuta). Foi desenvolvido um
procedimento para a imobilização da lacase nos suportes de poliamida 6.6
usando o glutaraldeído como agente bifuncional, incluindo a 1,6-hexanodiamina
em alguns casos, de forma a aumentar a distância entre a matriz e a enzima.
Neste estudo foi usado o design factorial (24) para estudar a influência do pH, da
1,6-hexanodiamina, da concentração de enzima e de glutaraldeído, na eficiência
da imobilização. A dosagem de enzima e a presença de 1,6-hexanodiamina
tiveram um papel determinante no processo de imobilização. Em condições the
trabalho optimizadas (29 UmL-1 de lacase; 10% de glutaraldeído, pH=5.5, na
presença de 1,6-hexanodiamina), o tempo de meia-vida obtido foi de cerca de
78 h (18% mais elevado do que o obtido para a enzima livre), a retenção de
proteína foi de cerca de 34% e o rendimento de imobilização foi de 2%. A
imobilização da lacase em matrizes de poliamida 6.6 pode ser um sistema
promissor na bioremediação de solos contaminados, no tratamento de águas
residuais, na estabilização de vinhos e outra bebidas e até mesmo na aplicação
de biosensores.
Os resultados obtidos demonstram que a cutinase e a protease são enzimas
capazes de modificar a superfície de fibras de poliamida 6.6 e podem ser usadas
em diferentes etapas do processamento da fibra. Através da funcionalização da
poliamida 6.6 com enzimas podem ser obtidos produtos de maior valor
acrescentado, no entanto o processo de hidrólise enzimática necessita de ser
mais detalhadamente caracterizado de forma a poder ser aplicado num processo
industrial.Biosyntex European ProjectFundação para a Ciência e a Tecnologia (FCT
Reflexões sobre a implementação da pesquisa do professor em uma proposta colaborativa
O presente artigo apresenta parte dos resultados de minha pesquisa de doutorado em que, dentre outros aspectos, enfocamos a pesquisa do professor produzida numa proposta colaborativa entre universidade e escola. Nos limites desse artigo enfocaremos, de modo breve, o trabalho de uma professora de Ciências a partir dos seus relatórios produzidos durante a sua participação nessa proposta. Através desses textos temos indícios do árduo processo metodológico de uma professora pesquisadora na prática do processo reflexivo sobre a ação. Percebe-se que todo o processo de pesquisa do professor passa, antes de tudo, por processos de apropriação daquilo que o professor julga adequado/apropriado nas suas práticas
Volatility in city tourism demand
The main objectives of this research are to identify, through a systematic literature review, the potential benefits of the use of volatility models in tourism, to study the volatility of tourism demand in cities and to compare models of volatility between different destinations and source markets. The three cities analysed in Portugal were Coimbra, Lisbon and Oporto and the source markets that were studied were the domestic market, the total overnight stays, Brazil, France, Germany, Italy, Spain, the United Kingdom and other non-specified countries.
The systematic review of the literature was carried out in order to identify, in a temporal perspective, the use of each methodology, variables used, data frequencies, temporal window, type of territories and geographic object of each study. The semantic analysis of the state of the art was also a methodology used. After a preliminary analysis of the time series, models that literature indicates as more suitable to estimate the volatility were used, namely, models of autoregressive conditional heteroscedasticity: ARCH, GARCH, EGARCH and TGARCH models.
The most suitable models for each source market, in each city, were identified, as well as the existence of asymmetries face to positive and negative shocks, their magnitude and their persistence. Different models of volatility were identified in each city for each source market, as well as, different types of persistence of volatility, in each market and city, and different magnitude in face of good news and bad news, which strengthens the need to adjust the modelling of tourism demand for each market and, within a country, at a more detailed territorial scale.
The use of volatility models is quite recent in tourism demand modelling and had not yet been applied in cities in Portugal, for which, despite the growing importance in terms of tourism, there are no studies of modelling focusing on the tourism demand.
Modelling tourism demand is essential when tourism policymakers plan tourism activities. The tourism industry may be extremely sensitive to specific events’ effects, so good models must be found that reflect volatility that varies within each city and for each source market and policies must be adapted to each of the source/destination pairs
Challenges to the Implementation of Lesson Study in the Amazon
The Japanese methodology, known in the West as Lesson Study, has been exploited in teacher education programs in various parts of the world, including the Brazilian Amazon where two pioneering studies have been carried out recently. This paper is a reflection on potential challenges to the implementation of this methodology in the Amazon. An inference that is drawn from it is that the current circumstances of the teaching culture and other cultural characteristics obtaining in this region only admit the implementation of a vague version of the Japanese Lesson Study. Keywords: Lesson Study, Teacher education, Amazon, Research. DOI: 10.7176/RHSS/10-22-04 Publication date: November 30th 202
Volatility of city tourism demand
The main objectives of this research are to identify, through a systematic literature review, the potential benefits of the use of volatility models in tourism, to study the volatility of tourism demand in cities and to compare models of volatility between different destinations and source markets. The three cities analysed in Portugal were Coimbra, Lisbon and Oporto and the source markets that were studied were the domestic market, the total overnight stays, Brazil, France, Germany, Italy, Spain, the United Kingdom and other non-specified countries.
The systematic review of the literature was carried out in order to identify, in a temporal perspective, the use of each methodology, variables used, data frequencies, temporal window, type of territories and geographic object of each study. The semantic analysis of the state of the art was also a methodology used. After a preliminary analysis of the time series, models that literature indicates as more suitable to estimate the volatility were used, namely, models of autoregressive conditional heteroscedasticity: ARCH, GARCH, EGARCH and TGARCH
models.
The most suitable models for each source market, in each city, were identified, as well as the existence of asymmetries face to positive and negative shocks, their magnitude and their persistence. Different models of volatility were identified in each city for each source market, as well as, different types of persistence of volatility, in each market and city, and different magnitude in face of good news and bad news, which strengthens the need to adjust the modelling of tourism demand for each market and, within a country, at a more detailed territorial scale.
The use of volatility models is quite recent in tourism demand modelling and had not yet been applied in cities in Portugal, for which, despite the growing importance in terms of tourism, there are no studies of modelling focusing on the tourism demand.
Modelling tourism demand is essential when tourism policymakers plan tourism activities. The tourism industry may be extremely sensitive to specific events’ effects, so good models must be found that reflect volatility that varies within each city and for each source market and policies must be adapted to each of the source/destination pairs.info:eu-repo/semantics/draf
What Factors Guide the Selection of Medicinal Plants in a Local Pharmacopoeia? A Case Study in a Rural Community from a Historically Transformed Atlantic Forest Landscape
The criteria that local people use for selecting medicinal plants have been a recurrent topic in pharmacology and ethnobotany. Two of the current hypotheses regarding this phenomenon, ecological apparency and diversification, attempt to explain the inclusion of “apparent” and “non-apparent” and native and exotic taxa, respectively, in local pharmacopoeia. This study addresses the following questions: Do “apparent” and “non-apparent” medicinal plants have the same importance in local pharmacopoeia? Do “non-apparent” plants occupy more local categories of diseases than “apparent” plants? Do native and exotic medicinal plants have the same importance? Do exotic and native plants occupy different local categories of diseases? This study was conducted with householders of a community from Northeastern Brazil. Out of the 66 plant species cited, most were herbs (39 species), followed by trees and shrubs (27). Herbaceous species also occupied more local categories of diseases (51) than tree and shrub species (28). Furthermore, most of the species cited by the informants were exotic (42). Out of the 94 therapeutic applications cited in this research, 65 were treated with exotic species and 29 with native species, distributed among 13 body systems. These results support both the hypotheses of ecological apparency and diversification
Las imágenes geológicas y geocientíficas en libros didácticos de ciencias
El objetivo central de este artículo es presentar una lectura de las imágenes geológicas y geocientíficas utilizadas en los libros didácticos de ciencias así como clasificarlas según las funciones ya citadas en la literatura. El marco teórico utilizado demuestra la importancia de la imagen para la construcción conceptual y destaca las relaciones entre la imagen y el texto. Para esta investigación se analizaron los libros más utilizados por los profesores participantes de un proyecto de formación continuada en el municipio de Campinas, Estado de Saõ Pablo (Brasil). Percibimos que la mayoría de las imágenes desempeñan una función ilustrativa en relación con el texto que las acompaña, mostrando que el potencial de la imagen para la construcción conceptual del área geológica está siendo escasamente aprovechado.The aim of this paper is to present the results of an investigation about uses of geological/geoscientific images in science textbooks. As part of the analysis, the images were classified by the use of functions described in the literature about science education. The theory shows the important role of images in promoting conceptual development and its relationship with verbal language. The textbooks analyzed have been chosen considering the preferences of a group of teachers that had participated in an in-service teachers educational project, in Campinas, Brazil. It has been noticed that most of the images identifi ed in the textbooks play an illustrative function in relation to verbal texts, which means that the images potential for developing geological concepts is being neglected
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