Automatic thresholding from the gradients of region boundaries

We present an approach for automatic threshold segmentation of greyscale images. The procedure is inspired by a reinterpretation of the strategy observed in human operators when adjusting thresholds manually and interactively by means of ‘slider’ controls. The approach translates into two methods. The first one is suitable for single or multiple global thresholds to be applied globally to images and consists of searching for a threshold value that generates a phase whose boundary coincides with the largest gradients in the original image. The second method is a variation, implemented to operate on the discrete connected components of the thresholded phase (i.e. the binary regions) independently. Consequently, this becomes an adaptive local threshold procedure, which operates relative to regions, rather than to local image subsets as is the case in most local thresholding methods previously published. Adding constraints for specifying certain classes of expected objects in the images can improve the output of the method over the traditional ‘segmenting first, then classify’ approach.The research reported in this paper was supported by the Engineering and Physical Sciences Research Council (EPSRC), UK through funding under grant EP/M023869/1 ‘Novel contextbased segmentation algorithms for intelligent microscopy’

Optimal Design Approach Applied to Headspace GC for the Monitoring of Diacetyl Concentration, Spectrophotometric Assessment of Phenolic Compounds and Antioxidant Potential in Different Fermentation Processes of Barley

The present study aimed to validate a control method on the gas chromatography system (GC) based on the experimental design strategy, to examine the changes and correlation between the fermentation process and the quality of alcoholic and non-alcoholic beer product, especially the formation of diacetyl. On the other hand, spectrophotometric methods were applied to the determination of polyphenols content and the potential antioxidant activity of beer during different fermentation processes. with this aim, three modes of barley fermentation were used, specifically classical fermentation, stopped fermentation and thermal process. The results showed that the different fermentation modes had a major impact on diacetyl production. The highest concentration was obtained using stopped fermentation 0.36 mg/L, the lowest concentration value 0.07 mg/L was detected using the thermal process. Monitoring the increase of oxygen concentration between fermentation, filtration, and filling of the final product (32, 107, 130 ppm, respectively) has a significant impact on the concentration of diacetyl. The obtained results of spectrophotometric analysis showed that the total antioxidant activity changed during beer fermentation process and demonstrate that the extend of the antioxidant activity was very much dependent on the total polyphenolic content with a higher value in Hopped wort (13.41%, 65 mg GAE 100 mL(-1), 28 mg CE 100 mL(-1)) for antioxidant potential, total phenolic content, and total flavonoids content, respectively, whereas the lowest values was detected in Non-alcoholic beer using thermal process (7.24%, 35 mg GAE 100 mL(-1), 10 mg CE 100 mL(-1)) for antioxidant potential, total phenolic contents, and total flavonoids contents, respectively. Based on the results achieved, we reveal the impact of the fermentation process on the nutritional value of the final product

On the secrecy performance of mixed RF/UOW communication system

In this paper, the secrecy performance of a dual-hop mixed radio-frequency/underwater optical wireless communication (RF/UOWC) system is investigated. The considered system consists of one single antenna source node (S) communicating with one destination node (D), considered as the legitimate receiver, through the help of one amplify-and-forward (AF) relay node R equipped with multiple antennas for reception. Specifically, the relay receives the incoming signal from S via an RF link, applies maximal-ratio combining (MRC) technique, amplifies the output combined signal with a fixed gain, and then forwards it to D via an UOWC link. The transmission protocol is performed under the eavesdroppers’ attempt to overhear the RF link (i.e., SR). We derive an exact closed-form expression for the secrecy intercept probability (IP) in terms of the Fox’s H-function, or in terms of the Meijer’s G-function as a particular case. The derived secrecy performance metric is evaluated in terms of various channel and system parameters, and corroborated by Monte-Carlo simulation method. Our derived analytical formulas present an efficient tool to highlight the impact of some system and channel parameters on the secrecy performance, namely the number of relay antennas, number of eavesdropping nodes, relay gain, fading severity of RF links, and water turbulence severity of the UOWC link

Profiling the Volatile and Non-Volatile Compounds along with the Antioxidant Properties of Malted Barley

In this work, the stability of antioxidant compounds in malting barley seeds before and after the production of the final products is reported. In this reflection, the findings revealed that the process of fermentation had a significant impact on antioxidant activity. In vitro, antioxidant capacities were evaluated using DPPH free radical scavenging assay. The results obtained from the spectrophotometric analysis showed that the lowest inhibition value was observed in the samples that were obtained by the classical fermentation process (ABC) and the samples of non-alcoholic beer obtained by the thermal process (NABT), with free radical inhibition capacity values of 8.50% and 5.50%, respectively. The samples of hopped wort (HW) and malted barley seeds extract (BSE) showed very high antioxidant activity with free radical inhibition capacity of 14% and 12.60%, respectively. The obtained extracts were analyzed by gas chromatography and high-performance liquid chromatography, both combined with mass spectrometry detection (GC-MS, HPLC-MS). GC-MS analysis of the SPME extraction showed the presence of 29 compounds with isopentyl alcohol in major concentration (18.19%) in the alcoholic beer; on the other hand, the HPLC-DAD-ESI/MS analysis of the ethyl acetate extract showed the presence of 13 phenolic compounds. Interestingly, the degradation of 3-Hydroxyphloretin 2'-O-glucoside in the final products of the non-alcoholic beers was found. Finally, the FTIR analysis was also employed in order to detect the type of efficient groups present in the extracts

Physical Layer Security of a Dual-Hop Regenerative Mixed RF/UOW System

Ensuring physical layer security is a crucial task in conventional and emerging communication systems, which are typically characterized by stringent quality of service and security requirements. This also accounts for wireless technologies in the context of the Internet of Things paradigm, which are expected to exhibit considerably increased computational complexity. Based on this, the present contribution investigates the secrecy outage performance of a dual-hop decode-and-forward (DF) mixed radio-frequency/underwater optical wireless communication (RF/UOWC) system. Such wireless network configurations are particularly useful in efficient and demanding scenarios, such as military communications. Therefore, our analysis considers one single-antenna source node $(S)$ communicating with one legitimate destination node $(D)$ via a DF relay node $(R)$ equipped with multiple antennas for reception. Particularly, the relay receives the incoming signal from S via an RF link, applies selection-combining (SC) technique, fully decodes it, re-encodes it and then forwards it to the destination via a UOWC link. The communication is performed under the eavesdropper's attempt to intercept the $S-R$ hop (RF side). In this context, a closed-form expression for the secrecy outage probability is derived along with a thorough asymptotic analysis in the high SNR regime, based on which the achievable diversity order is provided. The offered results provide useful insights on the impact of some key system and channel parameters on the secrecy outage performance, such as the number of eavesdroppers, the number of relay antennas, fading severity parameters of RF links, and water turbulence severity of the UOWC link. The conducted analysis shows that the secrecy outage probability is dominated only by the $R-D$ link in the high SNR regime, regardless of the $S-R$ parameters, such as the number of relay antennas and the average SNR at the relay branches. The offered analytic results are corroborated with respective results from computer simulations. Since these parameters are closely related with the computational complexity at the involved terminals, the offered insights are useful for the design and deployment of such systems.acceptedVersionPeer reviewe

Analysis of Asymmetric Dual-Hop Energy Harvesting-Based Wireless Communication Systems in Mixed Fading Environments

This work investigates the performance of a dual-hop energy harvesting-based fixed-gain amplify-and-forward relaying communication system, subject to fading impairments. We consider a source node (S) communicating with a destination node (D), either directly or through a fixed distant relay (R), which harvests energy from its received signals and uses it to amplify and forward the received signals to D. We also consider maximal-ratio combining at D to combine the signals coming from S and R. Both power-splitting and time-switching energy harvesting protocols are investigated. The S-R link is modeled by Nakagami-m fading model, while the R-D and S-D links experience α-μ fading. Closed-form expressions for the statistical properties of the total signal-to-noise ratio are derived, based on which novel closed-form expressions are then derived for the average symbol error rate as well as for the average channel capacity, considering four different adaptive transmission policies. The derived expressions are validated through Monte Carlo simulations.acceptedVersionPeer reviewe

Analysis of Asymmetric Dual-Hop Energy Harvesting-Based Wireless Communication Systems in Mixed Fading Environments

This work investigates the performance of a dual-hop energy harvesting-based fixed-gain amplify-and-forward relaying communication system, subject to fading impairments. We consider a source node (S) communicating with a destination node (D), either directly or through a fixed distant relay (R), which harvests energy from its received signals and uses it to amplify and forward the received signals to D. We also consider maximal-ratio combining at D to combine the signals coming from S and R. Both power-splitting and time-switching energy harvesting protocols are investigated. The S-R link is modeled by Nakagami-m fading model, while the R-D and S-D links experience α-μ fading. Closed-form expressions for the statistical properties of the total signal-to-noise ratio are derived, based on which novel closed-form expressions are then derived for the average symbol error rate as well as for the average channel capacity, considering four different adaptive transmission policies. The derived expressions are validated through Monte Carlo simulations.Peer reviewe

Análise de estratégia para aplicação de Sistema Eletrônico na Referência e Contrarreferência nos serviços de saúde

Objetivo: analisar estratégias para implantação do Sistema de Referência e Contrarreferência por meio eletrônico nos serviços de saúde. Métodos: dentre as estratégias estava uma maior integração entre a Atenção Primária à Saúde e os outros níveis de atenção por meio de uma melhor comunicação entre os médicos. No estudo foram envolvidas três Unidades de Saúde da Família. Uma delas funcionou como a rotina do serviço, e nas outras duas foram realizadas intervenções: estímulo e orientações aos profissionais e aos pacientes. Em uma, foi disponibilizado o sistema de referência e contrarreferência informatizado. Avaliou-se o número de referências dos pacientes aos médicos especialistas e de contrarreferências às Unidades de Saúde da Família de origem do encaminhamento. Resultados: no período do estudo a taxa de encaminhamentos foi de 8,56%. O tempo para consulta especializada variou de 1 a 90 dias, após a emissão do encaminhamento de referência, e o tempo do retorno do paciente à Unidade de Saúde de origem foi de 6 a 110 dias. O estudo demonstrou ainda que foram solicitadas e agendadas mais consultas nas Unidades de Saúde da Família Intervenção. Conclusões: o estudo confirmou falhas existentes no sistema, como: dificuldades de acesso da população aos especialistas e baixo número de retorno de pacientes referenciados às Unidades de Saúde de origem. Foi verificado, também, que orientações e estímulo aos profissionais e aos pacientes influenciam positivamente no retorno destes e de contrarreferências, e que é factível implantar o sistema de referência e contrarreferência por meio eletrônico nas Unidades de Saúde

estudo comparativo do desempenho do instrumento relacionado ao gênero

Objective: To evaluate the performance of the No-Apnea score, a simplified screening instrument for obstructive sleep apnea (OSA), by gender. Methods: This was a crosssectional study including adults undergoing full polysomnography. The No-Apnea model comprises two items (neck circumference and age) with a total score of 0 to 9. The severity of OSA was categorized, on the basis of the apnea-hypopnea index, as any (≥ 5 events/h), moderate-to-severe (≥ 15 events/h), or severe (≥ 30 events/h). The performance of the No-Apnea instrument was assessed by determining the area under the (ROC) curve (AUC) and by constructing contingency tables. Results: We evaluated a total of 6,606 adults (53.8% men). For categorizing the level of OSA severity, the NoApnea score had a sensitivity of 83.9-93.0% and a specificity of 57.3-35.2%. At all OSA severity levels, the No-Apnea score exhibited higher sensitivity and lower specificity in men than in women. The No-Apnea score proved to be an appropriate screening model for patients in general or when separated by gender or severity of OSA (AUC > 0.7 for all). The discriminatory power of the No-Apnea score to predict any, moderate-to-severe, and severe OSA was similar between genders (p = 0.109, p = 0.698, and p = 0.094, respectively). Conclusions: In a sample of adults referred to the sleep laboratory, there was no significant difference between men and women in terms of the discriminatory power of the No-Apnea instrument in for screening for OSA severity.publishersversionpublishe