| 1. |
- Metcalfe, Daniel B., et al.
(författare)
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Impacts of experimentally imposed drought on leaf respiration and morphology in an Amazon rain forest
- 2010
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 24:3, s. 524-533
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Tidskriftsartikel (refereegranskat)abstract
- P>1. The Amazon region may experience increasing moisture limitation over this century. Leaf dark respiration (R) is a key component of the Amazon rain forest carbon (C) cycle, but relatively little is known about its sensitivity to drought. 2. Here, we present measurements of R standardized to 25 degrees C and leaf morphology from different canopy heights over 5 years at a rain forest subject to a large-scale through-fall reduction (TFR) experiment, and nearby, unmodified Control forest, at the Caxiuana reserve in the eastern Amazon. 3. In all five post-treatment measurement campaigns, mean R at 25 degrees C was elevated in the TFR forest compared to the Control forest experiencing normal rainfall. After 5 years of the TFR treatment, R per unit leaf area and mass had increased by 65% and 42%, respectively, relative to pre-treatment means. In contrast, leaf area index (L) in the TFR forest was consistently lower than the Control, falling by 23% compared to the pre-treatment mean, largely because of a decline in specific leaf area (S). 4. The consistent and significant effects of the TFR treatment on R, L and S suggest that severe drought events in the Amazon, of the kind that may occur more frequently in future, could cause a substantial increase in canopy carbon dioxide emissions from this ecosystem to the atmosphere.
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| 2. |
- Archetti, Joao A. G., et al.
(författare)
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Hardware-in-the-Loop Volt-Watt and Volt-VAr Control for Distribution Systems with High Penetration of Renewables
- 2023
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Ingår i: Journal of Control Automation and Electrical Systems. - : Springer Nature. - 2195-3880 .- 2195-3899. ; 34:1, s. 177-188
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Tidskriftsartikel (refereegranskat)abstract
- This work aims to validate in control hardware in the loop (CHIL) simulations new voltage profile control strategies in distribution systems with different levels of photovoltaic penetration. The proposed control is implemented through intelligent inverters with control functions that act through voltage sensitivity. The Volt-VAr (V-V) and Volt-Watt (V-W) functions act in the local voltage control being implemented in a complementary way. The simulations are performed in real time, using the real-time digital simulator. Residential load profiles, solar irradiance and temperature curves are discretized hourly over a daily period, with the intention of making the emulation more realistic. Voltage source converters were implemented in RSCAD software. The contribution of this article points to the performance of the Volt-Watt (V-W) control function in single-stage inverters, which allows the maximum generation of instantaneous active power, acting directly on the maximum power point tracking algorithm, this strategy being validated by the CHIL simulation. The results show that the Volt-VAr and Volt-Watt control functions, acting at different levels of photovoltaic penetration, were effective in preventing the voltage profiles from violating the critical level imposed by the regulatory standard. Leading to the conclusion that its implementation directly in photovoltaic inverters entails a low cost and a complementary solution for the new challenges of electrical systems.
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| 3. |
- Archetti, Joao Antonio Guedes, et al.
(författare)
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Real time validation of a control system for microgrids with distributed generation and storage resources
- 2023
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Ingår i: Electric power systems research. - : Elsevier. - 0378-7796 .- 1873-2046. ; 223
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Tidskriftsartikel (refereegranskat)abstract
- Faced with a scenario in which the increase in renewable energy generated near consumer centers can cause problems for the operation of the electrical network, the present work proposes a real-time simulation model for automation and control systems of electrical distribution networks with microgrids, distributed generation, and storage resources. The proposed model consists of a hardware-in-the-loop control with the aid of a simulation tool in conjunction with a Real-Time Digital Simulator (RTDS) and considers the dynamic behavior of switched elements and inverters. A communication platform using TCP/IP protocol between RTDS (power system) and MatLab/Simulink (optimization algorithms) allows the operation of the network in grid-connected and islanded mode, guaranteeing the computational time for experimental implementation. For the first mode, an algorithm is proposed to solve an optimal dispatch energy storage system problem. Second mode, an algorithm is proposed to solve a load shedding problem. The objective is to operate the microgrids optimally and evaluate the performance of a storage system based on real data from the state of Parana, in Brazil. Results show that the optimization algorithms are experimentally applicable, obtaining reasonable computational time to find optimal solutions and an assertive decision-making to meet the objectives. Thus, the proposed framework is a potential tool to validate algorithms for active management of microgrids in real-time simulation.
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| 4. |
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| 5. |
- Bonilla, Cesar, et al.
(författare)
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Collider signatures of vector-like fermions from a flavor symmetric model
- 2022
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2022:1
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Tidskriftsartikel (refereegranskat)abstract
- We propose a model with two Higgs doublets and several SU(2) scalar singlets with a global non-Abelian flavor symmetry Q6× Z2. This discrete group accounts for the observed pattern of fermion masses and mixing angles after spontaneous symmetry breaking. In this scenario only the third generation of fermions get their masses as in the Standard Model (SM). The masses of the remaining fermions are generated through a seesaw-like mechanism. To that end, the matter content of the model is enlarged by introducing electrically charged vector-like fermions (VLFs), right handed Majorana neutrinos and several SM scalar singlets. Here we study the processes involving VLFs that are within the reach of the Large Hadron Collider (LHC). We perform collider studies for vector-like leptons (VLLs) and vector-like quarks (VLQs), focusing on double production channels for both cases, while for VLLs single production topologies are also included. Utilizing genetic algorithms for neural network optimization, we determine the statistical significance for a hypothetical discovery at future LHC runs. In particular, we show that we can not safely exclude VLLs for masses greater than 200 GeV. For VLQ’s in our model, we show that we can probe their masses up to 3.8 TeV, if we take only into account the high-luminosity phase of the LHC. Considering Run-III luminosities, we can also exclude VLQs for masses up to 3.4 TeV. We also show how the model with predicted VLL masses accommodates the muon anomalous magnetic moment.
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| 6. |
- Bonilla, Cesar, et al.
(författare)
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Gravitational waves from a scotogenic two-loop neutrino mass model
- 2024
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Ingår i: Physical Review D. - 2470-0010. ; 109:9
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Tidskriftsartikel (refereegranskat)abstract
- We propose a framework to account for neutrino masses at the two-loop level. This mechanism introduces new scalars and Majorana fermions to the Standard Model. It assumes the existence of a global U(1)×Z2 symmetry which after partial breaking provides the stability of the dark matter candidates of the theory. The rich structure of the potential allows for the possibility of first-order phase transitions (FOPTs) in the early Universe which can lead to the generation of primordial gravitational waves. Taking into account relevant constraints from lepton flavor violation, neutrino physics, as well as the trilinear Higgs couplings at next-to-leading order accuracy, we have found a wide range of possible FOPTs which are strong enough to be probed at the proposed gravitational-wave interferometer experiments such as LISA.
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| 7. |
- Cachim, Afonso, et al.
(författare)
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Measuring adherence to inhaled control medication in patients with asthma : Comparison among an asthma app, patient self-report and physician assessment
- 2023
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Ingår i: Clinical and Translational Allergy. - : John Wiley & Sons. - 2045-7022. ; 13:2
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundPrevious studies have demonstrated the feasibility of using an asthma app to support medication management and adherence but failed to compare with other measures currently used in clinical practice. However, in a clinical setting, any additional adherence measurement must be evaluated in the context of both the patient and physician perspectives so that it can also help improve the process of shared decision making. Thus, we aimed to compare different measures of adherence to asthma control inhalers in clinical practice, namely through an app, patient self-report and physician assessment.MethodsThis study is a secondary analysis of three prospective multicentre observational studies with patients (≥13 years old) with persistent asthma recruited from 61 primary and secondary care centres in Portugal. Patients were invited to use the InspirerMundi app and register their inhaled medication. Adherence was measured by the app as the number of doses taken divided by the number of doses scheduled each day and two time points were considered for analysis: 1-week and 1-month. At baseline, patients and physicians independently assessed adherence to asthma control inhalers during the previous week using a Visual Analogue Scale (VAS 0–100).ResultsA total of 193 patients (72% female; median [P25–P75] age 28 [19–41] years old) were included in the analysis. Adherence measured by the app was lower (1 week: 31 [0–71]%; 1 month: 18 [0–48]%) than patient self-report (80 [60–95]) and physician assessment (82 [51–94]) (p < 0.001). A negligible non-significant correlation was found between the app and subjective measurements (ρ 0.118–0.156, p > 0.05). There was a moderate correlation between patient self-report and physician assessment (ρ = 0.596, p < 0.001).ConclusionsAdherence measured by the app was lower than that reported by the patient or the physician. This was expected as objective measurements are commonly lower than subjective evaluations, which tend to overestimate adherence. Nevertheless, the low adherence measured by the app may also be influenced by the use of the app itself and this needs to be considered in future studies.
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| 8. |
- Chari, Arpita, 1986, et al.
(författare)
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Dynamic capabilities for circular manufacturing supply chains-Exploring the role of Industry 4.0 and resilience
- 2022
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Ingår i: Business Strategy and the Environment. - : Wiley. - 1099-0836 .- 0964-4733. ; 31:5, s. 2500-2517
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Tidskriftsartikel (refereegranskat)abstract
- An organisation's sustainability performance is influenced by its capabilities (skills, resources and competences) which in turn affects the performance of its entire supply chain. However, recent research has not sufficiently explored the convergence of dynamic capabilities, circular economy, resilience and Industry 4.0 concepts for manufacturing supply chains. Therefore, this study aims to identify how dynamic capabilities theory can enable circular and resilient supply chains. A qualitative research process was deployed in three stages: literature review, European project and nine expert interviews. Key investigative variables were used to identify capabilities used in manufacturing, and five research propositions were developed to address the gaps found in literature. The empirical data helped reveal challenges to circular economy implementation and validate the literature findings. The main contributions include a dynamic capabilities model, a causal relationship model and five research propositions for circular economy implementation.
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| 9. |
- Correia, Carlos M., et al.
(författare)
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Ultraviolet-B radiation and nitrogen affect nutrient concentrations and the amount of nutrients acquired by above-ground organs of maize
- 2012
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Ingår i: The Scientific World Journal. - : Hindawi Limited. - 2356-6140 .- 1537-744X. ; 2012
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Tidskriftsartikel (refereegranskat)abstract
- UV-B radiation effects on nutrient concentrations in above-ground organs of maize were investigated at silking and maturity at different levels of applied nitrogen under field conditions. The experiment simulated a 20% stratospheric ozone depletion over Portugal. At silking, UV-B increased N, K, Ca, and Zn concentrations, whereas at maturity Ca,Mg, Zn, and Cu increased and N, P and Mn decreased in some plant organs. Generally, at maturity, N, Ca, Cu, and Mn were lower, while P, K, and Zn concentrations in stems and nitrogen-use efficiency (NUE) were higher in N-starved plants. UV-B and N effects on shoot dry biomass were more pronounced than on nutrient concentrations. Nutrient uptake decreased under high UV-B and increased with increasing N application, mainly at maturity harvest. Significant interactions UV-B x N were observed for NUE and for concentration and mass of some elements. For instance, under enhanced UV-B, N, Cu, Zn, and Mn concentrations decreased in leaves, except on Nstressed plants, whereas they were less affected by N nutrition. In order to minimize nutritional, economical, and environmental negative consequences, fertiliser recommendations based on element concentration or yield goals may need to be adjusted.
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| 10. |
- Costa, Fabiano, et al.
(författare)
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Acetic acid-induced pain elicits stress-, and camouflage-related responses in zebrafish: Modulatory effects of opioidergic drugs on neurobehavioral phenotypes
- 2023
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Ingår i: Comparative Biochemistry and Physiology - Part C: Toxicology & Pharmacology. - 1532-0456. ; 270
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Tidskriftsartikel (refereegranskat)abstract
- While pain results from the activation of nociceptors following noxious stimuli, mounting evidence links pain- and stress-related responses in mammals. In zebrafish, the activation of hypothalamic-pituitary-interrenal (HPI) axis may also regulate body pigmentation (the camouflage response). Here, we aimed to investigate a putative relationship between pain-, stress-, and camouflage-related parameters in adult zebrafish. To answer this question, we assessed whether intraperitoneal acetic acid injection can activate the HPI axis, measuring whole-body cortisol and the camouflage response as physiological endpoints in the presence or absence of morphine or naloxone, an opioid antagonist. Acetic acid induced a stereotypic circling behavior in the top of the tank, accompanied by abdominal writhing-like response, a specific phenotype that reflects local nociceptive effect. Both whole-body cortisol levels and camouflage response increased in the acetic acid group, while morphine prevented these responses, and naloxone antagonized morphine-induced effects. Moreover, we observed positive correlations between representative behavioral, physiological and skin coloration endpoints, and a “pain index” was proposed to summarize phenotypic profile of zebrafish under different pharmacological manipulations. Collectively, these findings suggest a coordinated activation of pain, camouflage- and stress-related pathways following acetic acid injection in zebrafish. Our data also support that camouflage response represents a novel and relevant biomarker for future probing pain and stress neurobiology, with a robust sensitivity to opioidergic drugs.
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