Combined Application of Antisense Oligomers to Control Transcription Factors of Candida albicans Biofilm Formation

Antisense oligomers (ASOs) have been little exploited to control determinants of Candida albicans virulence. Biofilm formation is an important virulence factor of C. albicans, that is regulated by a complex network of transcription factors (such as EFG1, BRG1 and ROB1). Thus, the main goal of this work was to project ASOs, based on the 2'-OMethyl chemical modification, to target BRG1 and ROB1 mRNA and to validate its application either alone or in combination with the EFG1 mRNA target, to reduce C. albicans biofilm formation. The ability of ASOs to control gene expression was evaluate by qRT-PCR. The effect on biofilm formation was determined by the total biomass quantification, and simultaneously the carbohydrates and proteins reduction on extracellular matrix. It was verified that all the oligomers were able to reduce the levels of gene expression and the ability of C. albicans to form biofilms. Furthermore, the combined application of the cocktail of ASOs enhances the inhibition of C. albicans biofilm formation, minimizing biofilm thickness by reducing the quantity of matrix content (protein and carbohydrate). So, our work confirms that ASOs are useful tools for research and therapeutic development on the control of Candida species biofilm formation.

ITER collective Thomson scattering-Preparing to diagnose fusion-born alpha particles (invited)

The ITER Collective Thomson scattering (CTS) diagnostic will measure the dynamics of fusion-born alpha particles in the burning ITER plasma by scattering a 1 MW 60 GHz gyrotron beam off fast-ion induced fluctuations in the plasma. The diagnostic will have seven measurement volumes across the ITER cross section and will resolve the alpha particle energies in the range from 300 keV to 3.5 MeV; importantly, the CTS diagnostic is the only diagnostic capable of measuring confined alpha particles for energies below ∼1.7 MeV and will also be sensitive to the other fast-ion populations. The temporal resolution is 100 ms, allowing the capture of dynamics on that timescale, and the typical spatial resolution is 10-50 cm. The development and design of the in-vessel and primary parts of the CTS diagnostic has been completed. This marks the beginning of a new phase of preparation to maximize the scientific benefit of the diagnostic, e.g., by investigating the capability to contribute to the determination of the fuel-ion ratio and the bulk ion temperature as well as integrating data analysis with other fast-ion and bulk-ion diagnostics.

Vulvovaginal candidiasis and asymptomatic vaginal colonization in Portugal: epidemiology, risk factors and antifungal pattern

Vulvovaginal candidiasis (VVC) has been identified as a global issue of concern due to its clinical, social and economic implications. The emerging relevance of VVC makes it crucial to increase the knowledge on its epidemiological and etiological features in order to improve its prevention and treatment. Thus, this study aimed to reveal the incidence, microbiology, antifungal pattern and risk factors of VVC in Portugal. For that, high vaginal samples were collected from 470 symptomatic and asymptomatic participants; Candida spp. were identified with molecular techniques and their antifungal susceptibility was analysed with E-tests. The results revealed an incidence of VVC among women with vulvovaginitis of 74.4%. Furthermore, 63.7% of asymptomatic women were colonized with Candida spp. Importantly, women with history of recurrent vaginal infections, those who use over-the-counter antifungals, oral contraceptive pills and non-cotton underwear were found to be at significantly higher risk of developing VVC. Candida albicans was the most common species (59%), followed by Candida glabrata (27%), in a total of 8 distinct species, with similar distribution among colonized and infected participants. Of note, various isolates, especially of the most common species, showed low susceptibility towards fluconazole. In contrast, only few isolates showed low susceptibility towards caspofungin. Overall, this study suggests that the identification of species causing VVC and their antifungal susceptibility are urgently needed in clinical practice in order to improve the decision for the most adequate treatment. It also suggests that avoiding certain risk behaviours may prevent the development of VVC.

Environmental pH modulates biofilm formation and matrix composition in Candida albicans and Candida glabrata

Candida species are fungal opportunistic pathogens capable of colonizing and infecting various human anatomical sites, where they have to adapt to distinct niche-specific pH conditions. The aim of this study was to analyse the features of Candida albicans and Candida glabrata biofilms developed under neutral and vaginal acidic (pH 4) conditions. C. albicans produced thicker and more filamentous biofilms under neutral than under acidic conditions. On the other hand, the formation of biofilms by C. glabrata was potentiated by the acidic conditions suggesting the high adaptability of this species to the vaginal environment. In general, both species developed biofilms containing higher amounts of matrix components (protein and carbohydrate) under neutral than acidic conditions, although the opposite result was found for one C. glabrata strain. Overall, this study contributes to a better understanding of the modulation of C. albicans and C. glabrata virulence by specific pH conditions.

The Factor Structure of the Portuguese Version of the Personality Inventory for DSM-5 (PID-5)

Introduction

The DSM-5 Section III proposes a dimensional-categorical model of conceptualizing personality and its disorders, which includes assessment of impairments in personality functioning (criterion A) and maladaptive personality traits (criterion B). The Personality Inventory for DSM-5 (PID-5) is a self-report, composed of 220 items, organized into 25 facets nested in five domains of personality differences, and was developed to operationalize criterion B.

Objectives

This study explores the factor structure of the Portuguese adaptation of the PID-5.

Aims

The five-factor structure that has emerged in previous studies with the PID-5 (cf. Krueger & Markon) is expected to be replicated in the current study.

Methods

Exploratory factor analyses with varimax oblique rotation were conducted on a sample of Portuguese adults from the general population (n = 379, Mage = 31.49, SD = 14.16, 25.3% males, 74.7% females).

Results

A six factor structure was retained in which the first 5 factors resemble the PID-5 domains. The model showed good fit indices (KMO = 0.897). The total explained variance was 68.25%. All the facets but four had primary loadings on the expected factor.

Conclusions

The similarity of results across studies and nationalities contributes to the validation of the Portuguese translation of the PID-5 and highlights the structural resemblance among the DSM-5 model and the five factor model (FFM) and the personality psychopathology-five model (PSY-5), drawing attention to the relevance of these models for the diagnosis of Personality Disorders.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Hormones modulate Candida vaginal isolates biofilm formation and decrease their susceptibility to azoles and hydrogen peroxide

Vulvovaginal candidiasis (VVC) is an infection usually caused by Candida albicans and increasingly by Candida glabrata, which has an intrinsically high resistance to commonly used antifungals. Candida species possess virulence factors that contribute to VVC development, as the ability to form biofilms in vaginal walls and intrauterine devices. It is known that VVC is promoted by conditions that increase the hormones levels, during pregnancy, however, the effects of hormones on Candida cells are poorly studied, especially in C. glabrata. Thus, the influence of progesterone and β-estradiol, at normal cycle and pregnancy concentrations, on biofilm formation and resistance of C. albicans and C. glabrata vaginal isolates, was analyzed using acidic conditions (pH 4). Biofilms of C. albicans developed in the presence of hormones presented reduced biomass (up to 65%) and impaired cells ability to produce filamentous forms. On the other hand, C. glabrata presented high adaptation to the presence of hormones, which did not affect its biofilm formation. Additionally, hormones impaired the susceptibility of C. albicans and C. glabrata cells to azoles, with potential clinical significance in the presence of pregnancy hormone levels. A similar result was obtained for the susceptibility to hydrogen peroxide, a biological vaginal barrier against Candida growth. Overall, the results of this study suggest that hormones may act as environmental cues promoting Candida protection from vaginal defenses and harmful conditions, what may have implications in Candida vaginal pathogenicity and treatment of VVC, especially in C. glabrata infections due to its high adaptability to vaginal conditions.

La enseñanza práctica en Fonoaudiología a través de modelos tridimensionales: una alternativa prometedora

El análisis de cuestionarios respondidos por alumnos de la disciplina Sistemas Sensoriales del curso de Fonoaudiología mostró que había dificultades para entender la histología de las regiones anatómicas del oído. Se estableció que la compresión de la histología demandaba una actividad didáctica complementaria. Por ello, se decidió crear una clase teórico-práctica diferenciada (CTP) usando un modelo tridimensional (3D) del oído humano y preparaciones histológicas de sus regiones. El modelo es una réplica anatómica muy aumentada del oído humano que permite la manipulación exploratoria de modo más eficaz que con piezas anatómicas clásicas. La CTP fue implementada en los dos semestres de 2014. La evaluación de la CTP incluyó un cuestionario de opiniones, más un cuaderno de actividades. Los resultados mostraron medias finales de mejores desempeños en ese año respecto al 2013, donde no fue dada este tipo de clase teórico-práctica. Se concluye que la CTP, asociada al modelo tridimensional y las explicaciones teóricas-prácticas de las preparaciones histológicas, permitió una mejor comprensión del contenido enseñado e introdujo una metodología más eficiente para el proceso de enseñanza-aprendizaje de un tema tan complejo así como importante para la formación académica de los estudiantes de Fonoaudiología. Adicionalmente, a partir de esta experiencia teórico-práctica se ha demostrado, una vez más, la importancia de la relación personal y profesional entre el profesor, preparador estudiantil y los alumnos para la calidad del trabajo académico.

Towards large-scale in free-standing graphene and N-graphene sheets

One of the greatest challenges in the commercialization of graphene and derivatives is production of high quality material in bulk quantities at low price and in a reproducible manner. The very limited control, or even lack of, over the synthesis process is one of the main problems of conventional approaches. Herein, we present a microwave plasma-enabled scalable route for continuous, large-scale fabrication of free-standing graphene and nitrogen doped graphene sheets. The method's crucial advantage relies on harnessing unique plasma mechanisms to control the material and energy fluxes of the main building units at the atomic scale. By tailoring the high energy density plasma environment and complementarily applying in situ IR and soft UV radiation, a controllable selective synthesis of high quality graphene sheets at 2 mg/min yield with prescribed structural qualities was achieved. Raman spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy and Near Edge X-ray-absorption fine-structure spectroscopy were used to probe the morphological, chemical and microstructural features of the produced material. The method described here is scalable and show a potential for controllable, large-scale fabrication of other graphene derivatives and promotes microwave plasmas as a competitive, green, and cost-effective alternative to presently used chemical methods.

Adult women's experiences of urinary incontinence: a systematic review of qualitative evidence

BACKGROUND

Women are affected dramatically by urinary incontinence (UI). This disease is currently considered as epidemic.

OBJECTIVE

The objective of this review is to identify, through the best available evidence, how women experience UI worldwide.

INCLUSION CRITERIA TYPES OF PARTICIPANTS

The current review included studies of adult women who had experienced UI.

PHENOMENA OF INTEREST

Women with UI from various social and cultural settings were included in this review.

TYPES OF STUDIES

Qualitative data including, but not limited to, study designs such as phenomenology, grounded theory, ethnography, action research and feminist research were included in this review.

OUTCOMES

All aspects related to the experience of UI endured by women were considered.

SEARCH STRATEGY

An initial search of MEDLINE (PubMed) and CINAHL was done, followed by the exploration of all the databases and all identified studies, published in English, Spanish, French and Portuguese. The databases searched were CINAHL, PubMed, PsycINFO, Lilacs, Scielo, BVS, BVS-Psi, Scopus, Embase, Sociological Abstracts, Dissertation Abstracts International and the University of São Paulo Dissertations and Thesis bank and gray literature.

METHODOLOGICAL QUALITY

Each primary study was assessed by two independent reviewers for methodological quality. The Joanna Briggs Institute Qualitative Appraisal and Review Instrument (JBI-QARI) data extraction form for interpretive and critical research was used to appraise the methodological quality of all papers.

DATA EXTRACTION

Qualitative data were extracted using the JBI-QARI.

DATA SYNTHESIS

Qualitative research findings were synthesized using the JBI-QARI.

RESULTS

From the 28 studies were included, 189 findings were extracted and they were grouped into 25 categories and eight synthesized findings: (i) cultural and religious backgrounds and personal reluctance contribute to delays in seeking UI treatment; (ii) the inevitable and regrettable problem of UI endured silently and alone affects women's daily activities and their social roles; (iii) poor knowledge and the vague nature of the symptoms mask the fact that UI is a disease; (iv) the experiences provoked by UI and the sense of shame regarding the condition have contributed to impair women's lives; (v) UI has provoked negative effects on women's intimacy and sexual satisfaction and provoked changes in the ways they experience their sexuality and sexual function; (vi) UI is considered a consequence of pregnancy and childbirth, inherent to aging or a religious punishment; (vii) the women affected by UI adopt several strategies to improve their health status; and (viii) women have personal preferences toward care providers and treatments; they confront difficulties through UI treatment and some care needs are not met.

CONCLUSION

Personal and tailored health care should be provided, and preferences and expectations should be taken into consideration in the provision of health care to the people affected by UI.

The Effectiveness of Voriconazole in Therapy of Candida glabrata's Biofilms Oral Infections and Its Influence on the Matrix Composition and Gene Expression

Candida glabrata is one of most prevalent yeast in fungal infections, especially in immunocompromised patients. Its azole resistance results in a low therapeutic response, particularly when associated with biofilms. The main goal of this work was to study the effectiveness of voriconazole (Vcz) against C. glabrata biofilms oral pathologies, as esophageal or oropharyngeal candidiasis. Antifungal susceptibilities were determined in pre-formed 24-h-biofilms and ERG genes expression was determined by qRT-PCR. Protein quantification was performed using BCA^® Kit, carbohydrate was estimated according to the Dubois assay and β-1,3 glucans concentration were determined using Glucatell^® kit. Finally, ergosterol, Vcz, and fluconazole (Flu) concentrations within the biofilm matrices were determined by RP-HPLC. Results showed that C. glabrata biofilms were more susceptible to Vcz than to Flu and that ERG genes expression evidenced an overexpression of the three ERG genes in the presence of both azoles. The matrix content presented a remarked decrease in proteins and an increase in carbohydrates, namely β-1,3 glucans. Ergosterol was successfully detected and quantified in the biofilm matrices, with no differences in all the considered conditions. Vcz demonstrated better diffusion through the biofilms and better cell penetration capacities, than Flu, indicating that the structure of the drug molecule fully influences its dissemination through the biofilm matrices. This work showed that Vcz is notably more effective than Flu for the treatment of resistant C. glabrata oral biofilms, which demonstrates a clinical relevance in its future use for the treatment of oropharyngeal/esophageal candidiasis caused by this species.

Implementation of the new multichannel X-mode edge density profile reflectometer for the ICRF antenna on ASDEX Upgrade

A new multichannel frequency modulated continuous-wave reflectometry diagnostic has been successfully installed and commissioned on ASDEX Upgrade to measure the plasma edge electron density profile evolution in front of the Ion Cyclotron Range of Frequencies (ICRF) antenna. The design of the new three-strap ICRF antenna integrates ten pairs (sending and receiving) of microwave reflectometry antennas. The multichannel reflectometer can use three of these to measure the edge electron density profiles up to 2 × 10¹⁹ m^-3, at different poloidal locations, allowing the direct study of the local plasma layers in front of the ICRF antenna. ICRF power coupling, operational effects, and poloidal variations of the plasma density profile can be consistently studied for the first time. In this work the diagnostic hardware architecture is described and the obtained density profile measurements were used to track outer radial plasma position and plasma shape.

Candida tropicalis biofilm and human epithelium invasion is highly influenced by environmental pH

OBJECTIVE

The main goal of this study was to investigate the role of pH on Candida tropicalis virulence determinants, namely the ability to form biofilms and to colonize/invade reconstituted human vaginal epithelia.

METHODS

Biofilm formation was evaluated by enumeration of cultivable cells, total biomass quantification and structural analysis by scanning electron microscopy and confocal laser scanning microscopy. Candida tropicalis human vaginal epithelium colonization and invasiveness were examined qualitatively by epifluorescence microscopy and quantitatively by a novel quantitative real-time PCR protocol for Candida quantification in tissues.

RESULTS

The results revealed that environmental pH influences C. tropicalis biofilm formation as well as the colonization and potential to invade human epithelium with intensification at neutral and alkaline conditions compared to acidic conditions.

CONCLUSIONS

For the first time, we have demonstrated that C. tropicalis biofilm formation and invasion is highly influenced by environmental pH.

Effects of emphasising opposition and cooperation on collective movement behaviour during football small-sided games

Optimizing collective behaviour helps to increase performance in mutual tasks. In team sports settings, the small-sided games (SSG) have been used as key context tools to stress out the players' awareness about their in-game required behaviours. Research has mostly described these behaviours when confronting teams have the same number of players, disregarding the frequent situations of low and high inequality. This study compared the players' positioning dynamics when manipulating the number of opponents and teammates during professional and amateur football SSG. The participants played 4v3, 4v5 and 4v7 games, where one team was confronted with low-superiority, low- and high-inferiority situations, and their opponents with low-, medium- and high-cooperation situations. Positional data were used to calculate effective playing space and distances from each player to team centroid, opponent team centroid and nearest opponent. Outcomes suggested that increasing the number of opponents in professional teams resulted in moderate/large decrease in approximate entropy (ApEn) values to both distance to team and opponent team centroid (i.e., the variables present higher regularity/predictability pattern). In low-cooperation game scenarios, the ApEn in amateurs' tactical variables presented a moderate/large increase. The professional teams presented an increase in the distance to nearest opponent with the increase of the cooperation level. Increasing the number of opponents was effective to overemphasise the need to use local information in the positioning decision-making process from professionals. Conversely, amateur still rely on external informational feedback. Increasing the cooperation promoted more regularity in spatial organisation in amateurs and emphasise their players' local perceptions.

Vulvovaginal candidiasis: Epidemiology, microbiology and risk factors

Vulvovaginal candidiasis (VVC) is an infection caused by Candida species that affects millions of women every year. Although Candida albicans is the main cause of VVC, the identification of non-Candida albicans Candida (NCAC) species, especially Candida glabrata, as the cause of this infection, appears to be increasing. The development of VVC is usually attributed to the disturbance of the balance between Candida vaginal colonization and host environment by physiological or nonphysiological changes. Several host-related and behavioral risk factors have been proposed as predisposing factors for VVC. Host-related factors include pregnancy, hormone replacement, uncontrolled diabetes, immunosuppression, antibiotics, glucocorticoids use and genetic predispositions. Behavioral risk factors include use of oral contraceptives, intrauterine device, spermicides and condoms and some habits of hygiene, clothing and sexual practices. Despite a growing list of recognized risk factors, much remains to be elucidated as the role of host versus microorganisms, in inducing VVC and its recurrence. Thus, this review provides information about the current state of knowledge on the risk factors that predispose to VVC, also including a revision of the epidemiology and microbiology of VVC, as well as of Candida virulence factors associated with vaginal pathogenicity.

Starch characterization in seven raw, boiled and roasted chestnuts (Castanea sativa Mill.) cultivars from Portugal

Changes occurring in seven chestnut (Castanea sativa sp.) cultivars, caused by boiling and roasting, on starch content, cell and starch granules dimension were evaluated, and morphological changes were characterized by scanning electron microscopy. Three clear patterns of variation were detected after processing, namely: i) decrease of starch content with processing; ii) starch increase with the applied treatments; iii) increase of starch with boiling and decrease with roasting. Starch granules of raw chestnuts presented round, oval or elliptical form, external smooth surface and eccentric hilum, with rather ellipsoid-shaped growth rings. Processing resulted in modifications of the granules, with fusion of individual granules, and gelatinization taking place with the formation of elongated clusters. The present results indicate that boiling and roasting, besides changing the starch content of chestnut, causes important modifications in the starch granules, which can affect the sensory, rheological and chemical characteristics of chestnuts.

Women's experience of menopause: a systematic review of qualitative evidence

BACKGROUND

Evidence shows than an estimated one billion women have experienced menopause worldwide. The experience of menopause is influenced by beliefs and values prevalent in the sociocultural setting, the background of the women, and the ways in which the women approach changes in this phase of life. Independently of the circumstances involved, women experiencing menopause need to have their care needs and corresponding support identified based on their personal and contextual perspectives. Although it is essential to provide appropriate support to women experiencing menopause, no systematic reviews have so far been conducted that focus on menopause experienced by women worldwide.

OBJECTIVES

The objective of this review is to identify the best available evidence related to how women experience menopause worldwide.

INCLUSION CRITERIA

TYPES OF PARTICIPANTS

This review considered studies that included menopausal women aged between 40 and 65 years, who have lived the transition from reproductive years through menopause and beyond. This review included only studies whose participants have lived the experience of natural menopause. Women who have had induced menopause, or with premature menopause were excluded from this review. TYPES OF INTERVENTION(S)/PHENOMENA OF INTEREST: This review considered studies that investigate women's experiences of natural menopause under the scope of different social and cultural settings. TYPES OF STUDIES: This review considered studies that have a descriptive and interpretive approach, conducted using qualitative methodology. Qualitative studies that focus on program evaluation were excluded from this review. Qualitative data including, but not limited to, study designs such as phenomenology, grounded theory, ethnography, action research and feminist research were considered for inclusion in this review. TYPES OF OUTCOMES: This review considered studies that include the following outcome measures: all aspects related both directly and indirectly to the experience of menopause, as concretely lived by women and according to their own point of view.

SEARCH STRATEGY

The search strategy aimed to find both published and unpublished studies. Studies published in English, French, Portuguese and Spanish were considered for inclusion in this review, without any restriction in terms of year of publication. This decision was made to permit the inclusion of all of research related to women's lived experiences of menopause worldwide since the inception of this type of research. The databases searched included CINAHL, Medline and Pubmed, PsycINFO, Lilacs, Scielo, Scopus, Dissertation Abstracts International and the University of São Paulo Dissertations and Thesis.

METHODOLOGICAL QUALITY

Each primary study was assessed by two independent reviewers for methodological quality. The Joanna Briggs Institute Qualitative Appraisal and Review Instrument Data Extraction Form for Interpretive and Critical Research was used to appraise the methodological quality of all papers.

DATA COLLECTION

Qualitative data was extracted from papers included in the review using standardized data extraction tools developed by the Joanna Briggs Institute.

DATA SYNTHESIS

Qualitative research findings were synthesized using The Joanna Briggs Institute Qualitative Appraisal and Review Instrument.

RESULTS

From the 24 included studies, 108 findings were extracted. These findings were aggregated into 17 categories, and then into six synthesized findings. The six synthesized findings are: (i) Menopause is a natural event in a woman’s life that is closely associated with psychosocial events of midlife and the aging process; (ii) The physical and emotional changes of menopause strongly affect the women; (iii) The women perceive menopause as a time characterized by gains and losses; (iv) Resilience is improved at the time of menopause and coping strategies are adopted to enhance physical and emotional wellbeing; (v) Health issues, family and marital relations, sociocultural background and meaning attributed to the women’s sex life determine if the sexual experiences during menopause are pleasant or not; and (vi) The women should be prepared and have their needs supported according to their perspectives.

CONCLUSIONS

The systematic review shows that menopause is a stage of life experienced in different ways. The experience of menopause is characterized by personal challenges and changes in personal roles within the family and society. Hot flushes and night sweats are the strongest symptoms of those reported by women affected by the changes experienced during menopause. The positive or negative ways in which each woman approaches the changes during menopause are influenced by their personal, family and sociocultural background. Health care providers pay little attention to women´s perceptions regarding menopause. Considering menopause is a time when women feel vulnerable, personal and tailored healthcare according to individual needs, preferences and expectations should be provided. Coping strategies regarding the effects of menopause should be determined in creative and dynamic ways through the identification and consideration of the complex issues involved. These measures are essential to ensuring effective support for menopausal women.

Effect of defensive pressure on movement behaviour during an under-18 basketball game

The aim of this study was to examine the effect of defensive pressure on movement behaviour during an under-18 basketball game. 20 international male players (age: M=16.05, SD=2.09 years old; weekly practice: M=10.9, SD=1.94 h; playing experience: M=7.1, SD=1.1 years) played two 10-min basketball quarters, using man-to-man ¼-court for the first 4 min (F¼), man-to-man full court defence for the next 3 min (FULL), and man-to-man ¼-court defence for the last 3 min (S¼). The positional data were captured by the Ubisense Real Time Location System and analysed with non-linear signal processing methods (approximate entropy) and repeated measures ANOVA. There were differences in the regularity values between F¼ and FULL in distance to the basket and to the opponents' basket. A stronger in-phase attraction in both lateral and longitudinal directions was identified; however, the centroids (i. e., the mean position from all team players) were closer and revealed higher values of irregularity in lateral displacements for all defensive systems. The individual speed displacements became more coordinated with teammates, particularly in the offensive court. Overall, this study provided evidence on how changing the level of defensive pressure promotes different collective behaviours.

Optimization of artificial neural network models through genetic algorithms for surface ozone concentration forecasting

INTRODUCTION

This study proposes three methodologies to define artificial neural network models through genetic algorithms (GAs) to predict the next-day hourly average surface ozone (O(3)) concentrations. GAs were applied to define the activation function in hidden layer and the number of hidden neurons.

METHODS

Two of the methodologies define threshold models, which assume that the behaviour of the dependent variable (O(3) concentrations) changes when it enters in a different regime (two and four regimes were considered in this study). The change from one regime to another depends on a specific value (threshold value) of an explanatory variable (threshold variable), which is also defined by GAs. The predictor variables were the hourly average concentrations of carbon monoxide (CO), nitrogen oxide, nitrogen dioxide (NO(2)), and O(3) (recorded in the previous day at an urban site with traffic influence) and also meteorological data (hourly averages of temperature, solar radiation, relative humidity and wind speed). The study was performed for the period from May to August 2004.

RESULTS AND DISCUSSION

Several models were achieved and only the best model of each methodology was analysed. In threshold models, the variables selected by GAs to define the O(3) regimes were temperature, CO and NO(2) concentrations, due to their importance in O(3) chemistry in an urban atmosphere.

CONCLUSION

In the prediction of O(3) concentrations, the threshold model that considers two regimes was the one that fitted the data most efficiently.