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| 2. |
- Poyatos, R., et al.
(författare)
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Global transpiration data from sap flow measurements: the SAPFLUXNET database
- 2021
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Ingår i: Earth System Science Data. - : Copernicus GmbH. - 1866-3508 .- 1866-3516. ; 13:6, s. 2607-2649
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Tidskriftsartikel (refereegranskat)abstract
- Plant transpiration links physiological responses of vegetation to water supply and demand with hydrological, energy, and carbon budgets at the land-atmosphere interface. However, despite being the main land evaporative flux at the global scale, transpiration and its response to environmental drivers are currently not well constrained by observations. Here we introduce the first global compilation of whole-plant transpiration data from sap flow measurements (SAPFLUXNET, https://sapfluxnet.creaf.cat/, last access: 8 June 2021). We harmonized and quality-controlled individual datasets supplied by contributors worldwide in a semi-automatic data workflow implemented in the R programming language. Datasets include sub-daily time series of sap flow and hydrometeorological drivers for one or more growing seasons, as well as metadata on the stand characteristics, plant attributes, and technical details of the measurements. SAPFLUXNET contains 202 globally distributed datasets with sap flow time series for 2714 plants, mostly trees, of 174 species. SAPFLUXNET has a broad bioclimatic coverage, with woodland/shrubland and temperate forest biomes especially well represented (80 % of the datasets). The measurements cover a wide variety of stand structural characteristics and plant sizes. The datasets encompass the period between 1995 and 2018, with 50 % of the datasets being at least 3 years long. Accompanying radiation and vapour pressure deficit data are available for most of the datasets, while on-site soil water content is available for 56 % of the datasets. Many datasets contain data for species that make up 90 % or more of the total stand basal area, allowing the estimation of stand transpiration in diverse ecological settings. SAPFLUXNET adds to existing plant trait datasets, ecosystem flux networks, and remote sensing products to help increase our understanding of plant water use, plant responses to drought, and ecohydrological processes. SAPFLUXNET version 0.1.5 is freely available from the Zenodo repository (https://doi.org/10.5281/zenodo.3971689; Poyatos et al., 2020a). The "sapfluxnetr" R package - designed to access, visualize, and process SAPFLUXNET data - is available from CRAN.
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| 3. |
- Kattge, Jens, et al.
(författare)
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TRY plant trait database - enhanced coverage and open access
- 2020
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Ingår i: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
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Tidskriftsartikel (refereegranskat)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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| 4. |
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| 5. |
- Stojanovic, M. G., et al.
(författare)
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Localized modes in linear and nonlinear octagonal-diamond lattices with two flat bands
- 2020
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : AMER PHYSICAL SOC. - 2469-9926 .- 2469-9934. ; 102:2
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Tidskriftsartikel (refereegranskat)abstract
- We consider a two-dimensional octagonal-diamond network with a fine-tuned diagonal coupling inside the diamond-shaped unit cell. Its linear spectrum exhibits coexistence of two dispersive bands (DBs) and two flat bands (FBs), touching one of the DBs embedded between them. Analogous to the kagome lattice, one of the FBs will constitute the ground state of the system for a proper sign choice of the Hamiltonian. The system is characterized by two different flat-band fundamental octagonal compactons, originating from the destructive interference of fully geometric nature. In the presence of a nonlinear amplitude (on-site) perturbation, the singleoctagon linear modes continue into one-parameter families of nonlinear compact modes with the same amplitude and phase structure. However, numerical stability analysis indicates that all strictly compact nonlinear modes are unstable, either purely exponentially or with oscillatory instabilities, for weak and intermediate nonlinearities and sufficiently large system sizes. Stabilization may appear in certain ranges for finite systems and, for the compacton originating from the band at the spectral edge, also in a regime of very large focusing nonlinearities. In contrast to the kagome lattice, the latter compacton family will become unstable already for arbitrarily weak defocusing nonlinearity for large enough systems. We show analytically the existence of a critical system size consisting of 12 octagon rings, such that the ground state for weak defocusing nonlinearity is a stable single compacton for smaller systems, and a continuation of a nontrivial, noncompact linear combination of single compacton modes for larger systems. Investigating generally the different nonlinear localized (noncompact) mode families in the semi-infinite gap bounded by this FB, we find that, for increasing (defocusing) nonlinearity the stable ground state will continuously develop into an exponentially localized mode with two main peaks in antiphase. At a critical nonlinearity strength a symmetry-breaking pitchfork bifurcation appears, so that the stable ground state is single peaked for larger defocusing nonlinearities. We also investigate numerically the mobility of localized modes in this regime and find that the considered modes are generally immobile both with respect to axial and diagonal phase-gradient perturbations.
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| 6. |
- Dhiman, Vinit, et al.
(författare)
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Multiband optical variability of the TeV blazar PG 1553+113 in 2019
- 2022
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 519:2, s. 2796-2811
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Tidskriftsartikel (refereegranskat)abstract
- We report the flux and spectral variability of PG 1553 + 113 on intra-night (IDV) to short-term time-scales using BVRI data collected over 91 nights from 28 February to 8 November 2019 employing 10 optical telescopes: three in Bulgaria, two each in India and Serbia, and one each in Greece, Georgia, and Latvia. We monitored the blazar quasi-simultaneously for 16 nights in the V and R bands and 8 nights in the V, R, I bands and examined the light curves (LCs) for intra-day flux and colour variations using two powerful tests: the power-enhanced F-test and the nested ANOVA test. The source was found to be significantly (>99 per cent) variable in 4 nights out of 27 in R-band, 1 out of 16 in V-band, and 1 out of 6 nights in I-band. No temporal variations in the colours were observed on IDV time-scale. During the course of these observations the total variation in R-band was 0.89 mag observed. We also investigated the spectral energy distribution (SED) using B-, V-, R-, and I-band data. We found optical spectral indices in the range of 0.878 +/- 0.029 to 1.106 +/- 0.065 by fitting a power law (F-nu proportional to nu(-alpha)) to these SEDs of PG 1553 + 113. We found that the source follows a bluer-when-brighter trend on IDV time-scales. We discuss possible physical causes of the observed spectral variability.
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| 7. |
- Simic, M., et al.
(författare)
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Parameter Estimation of the Single-Dispersion Fractional Cole-Impedance Model With the Embedded Hardware
- 2023
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Ingår i: IEEE Sensors Journal. - : Institute of Electrical and Electronics Engineers (IEEE). - 1530-437X .- 1558-1748. ; 23:12, s. 12978-12987
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Tidskriftsartikel (refereegranskat)abstract
- Bioimpedance modeling with equivalent electrical circuits has an important role in various biomedical applications, as it facilitates understanding of underlying physical and electrochemical processes in applications such as body composition measurements and assessment of clinical conditions. However, the estimation of model parameter values is not a straightforward task, especially when complex circuits with fractional-order components [e.g., constant phase elements (CPEs)] are used. In this article, we propose a low-complexity method for parameter estimation of the Cole-impedance model suitable for low-cost embedded hardware (e.g., 8-bit microcontrollers). Our approach uses only the measured real and imaginary impedance, without any specific software package/toolbox, or initial values provided by the user. The proposed method was validated with synthetic (noiseless and noisy) data and experimental right-side, hand-to-foot bioimpedance data from a healthy adult participant. Moreover, the proposed method was compared in terms of accuracy with the recently published relevant work and commercial Electrical Impedance Spectroscopy software (Bioimp 2.3.4). The performance evaluation in terms of complexity (suitable for deployment for the microcontroller-based platform with 256 kB of RAM and 16 MHz clock speed), execution time (18 s for the dataset with 256 points), and cost (< 25) confirms the proposed method in regards to reliable bioimpedance processing using embedded hardware.
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| 8. |
- Stojanovic, A, et al.
(författare)
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The Influence of Menopause and Inflammation on Redox Status and Bone Mineral Density in Patients with Rheumatoid Arthritis
- 2021
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Ingår i: Oxidative medicine and cellular longevity. - : Hindawi Limited. - 1942-0994 .- 1942-0900. ; 2021, s. 9458587-
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Tidskriftsartikel (refereegranskat)abstract
- Although oxidative stress is considered to be one of the key pathogenic factors in rheumatoid arthritis (RA), there is insufficient knowledge regarding the impact of menopause on redox status in this population. Thus, this study is aimed at assessing the influence of menopause within healthy women and within RA patients as well as the impact of RA in premenopausal and postmenopausal women on redox status, with special reference to bone mineral density (BMD). A total of 90 women were included in the study, 42 with RA and 48 age-matched healthy controls. They were divided into subgroups according to the presence of menopause. Following oxidative stress parameters were measured spectrophotometrically: index of lipid peroxidation (measured as TBARS), nitrites (NO2-), superoxide anion radical (O2-), hydrogen peroxide (H2O2), superoxide dismutase (SOD), catalase (CAT), and reduced glutathione (GSH). BMD was assessed by using a dual-energy X-ray absorptiometry scanner. Comorbidities and drug history were recorded. The levels of H2O2 and TBARS were elevated in patients with RA, while NO2- and O2- increased in healthy women, both in premenopausal and postmenopausal groups. SOD activity decreased in postmenopausal RA patients. BMD was reduced in postmenopausal RA women. There was a correlation between NO2- and O2- with Health Assessment Questionnaire (HAQ) index in RA patients. Given that postmenopausal state was associated with elevated oxidative stress within healthy women and that menopausal state did not affect redox homeostasis within RA patients, but the redox homeostasis was altered in both RA groups compared to healthy women, it can be presumed that impaired redox status in RA occurred due to presence of the disease, irrespective of age. Moreover, menopause attenuates BMD reduction in women with RA. These results may indicate the need for therapeutic use of antioxidants in the form of supplements in women with RA, regardless of age.
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| 9. |
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| 10. |
- Opratko, Benjamin, et al.
(författare)
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Cultures of rejection in the Covid-19 crisis
- 2021
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Ingår i: Ethnic and Racial Studies. - : ROUTLEDGE JOURNALS, TAYLOR & FRANCIS LTD. - 0141-9870 .- 1466-4356. ; 44:5, s. 893-905
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Tidskriftsartikel (refereegranskat)abstract
- This article offers a collectively developed analysis of the Covid-19 crisis as it relates to contemporary cultures of rejection, i.e. the socio-cultural conditions in which authoritarian and right-wing populist politics thrive, in Europe. We explore how the pandemic and its management reinforces, transforms and/or overrides existing antagonisms and institutes new ones in Serbia, Croatia, Austria, Germany and Sweden. We discuss how the Covid-19 crisis affects the rise of new statisms; gendered patterns of social reproduction; mobility and migration; digital infrastructures; and new political mobilizations.
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