Browsing by Issue Date, starting with "2023-01"
Now showing 1 - 10 of 28
Results Per Page
Sort Options
- Quantitative evaluation of outdoor artificial light emissions using low Earth orbit radiometersPublication . Bará, Salvador; Bao-Varela, Carmen; Lima, Raul CerveiraLow Earth orbit radiometers allow monitoring nighttime anthropogenic light emissions in wide areas of the planet. In this work we describe a simple model for assessing significant outdoor lighting changes at the municipality level using on-orbit measurements complemented with ground-truth information. We apply it to evaluate the transformation effected in the municipality of Ribeira (42°33'23"N, 8°59' 32" W) in Galicia, which in 2015 reduced the amount of installed lumen in its publicly-owned outdoor lighting system from 93.2 to 28.7 Mlm. This significant cutback, with the help of additional controls, allowed to reduce from 0.768 to 0.208 Mlm/km2 the lumen emission density averaged across the territory. In combination with the VIIRS-DNB annual composite readings these data allow to estimate that the relative weight of the emissions of the public treetlight system with respect to the total emissions of light in the municipality changed from an initial value of 74.86% to 44.68% after the transformation. The effects of the sources’ spectral shift and the photon calibration factor on the radiance reported by the VIIRS-DNB are also evaluated.
- Modification of [18F]-FDG PET/CT imaging protocols in obese oncology patients: A nationwide surveyPublication . Oliveira, R.; Figueiredo, L.; Costa, P.The use of medical imaging for diagnosis, staging and follow-up in Oncology context is incredibly important, being the use of [18F]-FDG PET/CT particularly advantageous in specific contexts like the case of obese patients. However, imaging the latter can be challenging sometimes, since their own body size may affect overall image quality and adds technical difficulties for the operator(s) performing the examination. This research project was developed with the aim of analysing the current personal practices of Portuguese Nuclear Medicine Technologists (NMTs) in the adaptation of 18F-FDG PET/CT oncological protocols for obese patients and comparing the results with parameters referenced in literature. A non-experimental research study was conducted using a survey delivered online to NMTs through social media platforms (Facebook® and LinkedIn®) and by sending the link directly to contacts within the research team professional and personal networks. Answers from a total of 26 participants were obtained, with 88.5% of participants admitting modifying technical protocols in examinations for obese patients. Changes in PET protocols included an increase in the administered activity (60.9%), an increase in scan time per individual bed position (69.6%) and the use of Time-of-Flight (TOF) technology whenever available. Protocol changes in CT included increasing the mA (82.6%), raising the KVp (47.8%), the application of iterative reconstruction (69.6%) and the use of automatic exposure control (AEC) (52.2%). The remaining parameters (pitch, algorithm, slice thickness, display FOV, gantry rotation time and energy acceptance window) were claimed not to be modified by around 90% of professionals. Portuguese NMTs tend to change the [18F]-FDG PET/CT protocols for obese patients. However, while some of the parameters appear to be contradictory or redundant, others require further optimisation, especially in the CT component.
- O MicrotonalismoPublication . Vieira, Filipe Carlos Ribeiro DiasEste trabalho teórico insere-se no âmbito dos termos e efeitos previstos no Decreto-Lei n.º 206/2009, de 31 de agosto, alterado pelo Decreto-Lei n.º 27/2021 de 16 de abril, e no Despacho n.º 14093/2011, DR n.º 200, 2ª Série, de 18 de outubro, que confere a atribuição do Título de Especialista na área de Música, 212 Artes do Espetáculo, variante de composição. O tema escolhido para esta “apresentação, (…) de um trabalho de natureza profissional no âmbito da área em que são prestadas as provas, preferencialmente sobre um trabalho ou obra constante do seu currículo profissional;” (alínea b) do Art.º 6º do Despacho n.º 14093/2011 de 18 de outubro), é o Microtonalismo. A razão principal da escolha deste tema é porque trespassa toda a minha vida como compositor e é realmente a minha temática de investigação. O interesse por este tema começou logo desde muito cedo, quando no Conservatório de Música do Porto, onde estudava Flauta Transversal, ouvi o Prof. Luís Meireles tocar uma obra microtonal, chamada Beaut-Faul do compositor Cândido Lima. Fiquei automaticamente “paralisado”. Esta obra era muito diferente de todas as outras referências musicais que conhecia. Remetia para um “novo mundo sonoro”. Constatei de imediato que me sentia muito próximo desta estética e desta linguagem muito mais do que de qualquer outra, tanto a nível cognitivo, como sensorial. Surgiu de imediato um enorme desejo de conhecer mais sobre esta “nova música” que me foi apresentada de forma tão intensa e catalisadora. [...]
- The role of radiographers in nuclear medicine; the link between patient and technologyPublication . Baun, Christina ; Garcia, Rodrigo ; Costa, Pedro; Champendal, Mélanie ; Borg‑Grima, Karen ; Murphy, Shauna ; Geäo, AnaRecently, Slart and de Geus‑Oei published an editorial entitled: A new colleague in nuclear medicine, the clinical technologist: quo vadis? [1]. The authors describe how the new healthcare profession, clinical technologists, contributes to the field of nuclear medicine with a position between the physicist and the physician in the healthcare sector in the Netherlands. Furthermore, the editorial emphasizes how the clinical technologist plays a role in developing molecular imaging, dosimetry, and radionuclide therapy in a multidisciplinary environment.
- Tribological performance under different environments of Ti—C—N composite films for marine wear-resistant partsPublication . Ju, Hongbo; Zhou, Rui; Luan, Jing; Kumar, Ch Sateesh; Yu, Lihua; Xu, Junhua; Yang, Junfeng; Zhang, Bowei; Fernandes, FilipeThe need for reducing the wear in mechanical parts used in the industry makes self-lubricant films one of the sustainable solutions to achieve long-term protection under different environmental conditions. The purpose of this work is to study the influence of C additions on the tribological behavior of a magnetron-sputtered TiN film in air, water, and seawater. The results show that the addition of C into the TiN binary film induced a new amorphous phase, and the films exhibited a dual phase of fcc (face-centered cubic)-TiN and amorphous carbon. The antifriction and wear-resistance properties were enhanced in air and water by adding 19.1at% C. However, a further increase in the C concentration improved anti-frictional properties but also led to higher wear rates. Although the amorphous phase induced microbatteries and accelerated the corrosion of TiN phases in seawater, the negative abrasion state was detected for all Ti–C–N films due to the adhesion of the tribocorrosion debris on the wear track.
- MIRAU-Net :An Improved Neural Network Based on U-Net for Gliomas SegmentationPublication . Aboelenein, Nagwa M.; Songhao, Piao; Noor, Alam; Ahmad, Pir NomanGliomas are the largest prevalent and destructive of brain tumors and have crucial parts for the diagnosing and treating of MRI brain tumors during segmentation using computerized methods. Recently, U-Net architecture has achieved impressive brain tumor segmentation, but this role remains challenging due to the differing severity and appearance of gliomas. Therefore, we proposed a novel encoder-decoder architecture called Multi Inception Residual Attention U-Net (MIRAU-Net) in this work. It integrates residual, inception modules with attention gates into U-Net to further enhance brain tumor segmentation performance. Encoderdecoder is connected in this architecture through Inception Residual pathways to decrease the distance between their maps of features. We use the weight crossentropy and generalized Dice (GDL) with focal Tversky loss functions to resolve the class imbalance problem. The evaluation performance of MIRAU-Net checked with Brats 2019 and obtained mean dice similarities of 0.885 for the whole tumor, 0.879 for the core area, and 0.818 for the enhancement tumor. Experiment results reveal that the suggested MIRAU-Net beats its baselines and provides better efficiency than recent techniques for brain tumor segmentation.
- Enterococcus spp. from chicken meat collected 20 years apart overcome multiple stresses occurring in the poultry production chain: Antibiotics, copper and acidsPublication . Rebelo, Andreia; Duarte, Bárbara; Ferreira, Carolina; Mourão, Joana; Ribeiro, Sofia; Freitas, Ana R.; Coque, Teresa M.; Willems, Rob; Corander, Jukka; Peixe, Luísa; Antunes, Patrícia; Novais, CarlaPoultry meat has been a vehicle of antibiotic resistant bacteria and genes. Yet, the diversity of selective pressures associated with their maintenance in the poultry-production chain remains poorly explored. We evaluated the susceptibility of Enterococcus spp. from chicken meat collected 20 years apart to antibiotics, metals, acidic pH and peracetic acid-PAA. Contemporary chicken-meat samples (n = 53 batches, each including a pool of neck skin from 10 single carcasses) were collected in a slaughterhouse facility using PAA as disinfectant (March–August 2018, North of Portugal). Broilers were raised in intensive farms (n = 29) using CuSO4 and organic acids as feed additives. Data were compared with that of 67 samples recovered in the same region during 1999–2001. All 2018 samples had multidrug resistant-MDR isolates, with >45 % carrying Enterococcus faecalis, Enterococcus faecium or Enterococcus gallinarum resistant to tetracycline, erythromycin, ampicillin, quinupristin-dalfopristin, ciprofloxacin, chloramphenicol or aminoglycosides. Resistance rates were similar (P > 0.05) to those of 1999–2001 samples for all but five antibiotics. The decrease of samples carrying vancomycin-resistant isolates from 46 % to 0 % between 1999-2001 and 2018 was the most striking difference. Isolates from both periods were similarly susceptible to acid pH [minimum-growth pH (4.5-5.0), minimum-survival pH (3.0-4.0)] and to PAA (MIC90 = 100–120 mg/L/MBC90 = 140–160 mg/L; below concentrations used in slaughterhouse). Copper tolerance genes (tcrB and/or cueO) were respectively detected in 21 % and 4 % of 2018 and 1999-2001 samples. The tcrB gene was only detected in E. faecalis (MICCuSO4 > 12 mM), and their genomes were compared with other international ones of chicken origin (PATRIC database), revealing a polyclonal population and a plasmid or chromosomal location for tcrB. The tcrB plasmids shared diverse genetic modules, including multiple antimicrobial resistance genes (e.g. to tetracyclines, chloramphenicol, macrolide-lincosamide-streptogramin B-MLSB, aminoglycosides, bacitracin, coccidiostats). When in chromosome, the tcrB gene was co-located closely to merA (mercury) genes. Chicken meat remains an important vehicle of MDR Enterococcus spp. able to survive under diverse stresses (e.g. copper, acid) potentially contributing to these bacteria maintenance and flux among animal-environment-humans.
- Potential pathogenic and opportunistic oral bacteria in early life: the role of maternal factors in a portuguese populationPublication . Fernandes, Mariana; Azevedo, Maria João; Campos, Carla; Ferreira, Ana Filipa; Azevedo, Álvaro; Falcão-Pires, Inês; Zaura, Egija; Ramalho, Carla; Campos, Joana; Sampaio-Maia, BeneditaIn early life, maternal factors are of the utmost relevance for oral microbiome acquisition and maturation. Therefore, our study explored the impact of maternal factors, such as saliva and breastmilk colonization, cardiovascular risk factors (CRF), type of delivery, oral health, and caregiving habits on the prevalence of potential pathogenic and opportunistic oral bacteria in early life. A total of 26 healthy mothers, 23 mothers with CRF, and their 50 children were included and samples (child’s oral swabs, mother’s saliva, and breastmilk) were collected 4 to 12 weeks after delivery and inoculated in selective and differential media for detection of non-fastidious Gram-negative and Gram-positive bacteria to isolate potential pathogenic and opportunistic bacteria identified by MALDI-TOF MS (414 isolates). Within mother–child dyads, the same species were identified in 86% of the pairs and potential pathogenic microorganisms from the Staphylococcaceae and Enterobacteriaceae families were found to be statistically significantly concordant between mother–child samples, particularly in the healthy group. Staphylococcus saprophyticus and Stenotrophomonas maltophilia oral colonization in mother–child pairs were associated with the presence of CRF. Breastfeeding was related to the early life oral colonization of Staphylococcus epidermidis in children from healthy mothers and C-section was associated with higher diversity of pathogens, independent of cardiovascular status (p = 0.05). This study reveals the presence of potential oral opportunistic and pathogenic bacteria in early life and highlights the importance of maternal factors in its acquisition.
- The Influence of H Content on the Properties of a-C(W):H CoatingsPublication . Evaristo, Manuel; Fernandes, Filipe; Jeynes, Chris; Cavaleiro, AlbanoDiamond-like-carbon “DLC” coatings can be deposited in many different ways, giving a large range of material properties suitable for many different types of applications. Hydrogen content significantly influences the mechanical properties and the tribological behavior of DLC coatings, but its determination requires techniques that are not available in many research centers. Thus, it is important to find alternative indirect techniques, such as Raman spectroscopy or nanoindentation (hardness measurements), which can give comparative and indicative values of the H contents in the coatings, particularly when depositions with a reactive gas flow are being studied. In this work, “DLC” composite coatings with varying H content were deposited via Physical Vapor Deposition (PVD) magnetron sputtering in a reactive atmosphere (Ar + CH4). An Ion Beam Analysis was used to determine the elemental depth profile across the coating thickness (giving both average C:W:H ratios and film density when combined with profilometer measurements of film thickness). The hardness was evaluated with nanoindentation, and a decrease from 16 to 6 GPa (and a decrease in the film density by a factor of two) with an increasing CH4 flow was observed. Then, the hardness and Raman results were correlated with the H content in the coatings, showing that these indirect methods can be used to find if there are variations in the H content with the increase in the CH4 flow. Finally, the adhesion and tribological performance of the coatings were evaluated. No significant differences were found in the adhesion as a function of the H content. The tribological properties presented a slight improving trend with the increase in the H content with a decrease in the wear rate and friction.
- First approach to assess the effects of nanoplastics on the soil species Folsomia candida: A mixture design with bisphenol A and diphenhydraminePublication . Barreto, Ângela; Santos, Joana; Almeida, Lara; Tavares, Vítor; Pinto, Edgar; Celeiro, Maria; Garcia-Jares, Carmen; Maria, Vera L.The terrestrial environment is one of the main recipients of plastic waste. However, limited research has been performed on soil contamination by plastics and even less assessing the effects of nanoplastics (NPls). Behind the potential toxicity caused per se, NPls are recognized vectors of other environmental harmful contaminants. Therefore, the main aim of the present study is to understand whether the toxicity of an industrial chemical (bisphenol A – BPA) and a pharmaceutical (diphenhydramine – DPH) changes in the presence of polystyrene NPls to the terrestrial invertebrate Folsomia candida. Assessed endpoints encompassed organismal (reproduction, survival and behavior) and biochemical (neurotransmission and oxidative stress) levels. BPA or DPH, 28 d single exposures (1 to 2000 mg/kg), induce no effect on organisms' survival. In terms of reproduction, the calculated EC50 (concentration that causes 50% of the effect) and determined LOEC (lowest observed effect concentration) were higher than the environmental concentrations, showing that BPA or DPH single exposure may pose no threat to the terrestrial invertebrates. Survival and reproduction effects of BPA or DPH were independent on the presence of NPls. However, for avoidance behavior (48 h exposure), the effects of the tested mixtures (BPA + NPls and DPH + NPls) were dependent on the NPls concentration (at 0.015 mg/kg – interaction: no avoidance; at 600 mg/kg – no interaction: avoidance). Glutathione S-transferase activity increased after 28 d exposure to 100 mg/kg DPH + 0.015 mg/kg NPls (synergism). The increase of lipid peroxidation levels found after the exposure to 0.015 mg/kg NPls (a predicted environmental concentration) was not detected in the mixtures (antagonism). The results showed that the effects of the binary mixtures were dependent on the assessed endpoint and the tested concentrations. The findings of the present study show the ability of NPls to alter the effects of compounds with different natures and mechanisms of toxicity towards soil organisms, showing the importance of environmental risk assessment considering mixtures of contaminants.
- «
- 1 (current)
- 2
- 3
- »