| 1. |
- Correa, D. F., et al.
(författare)
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Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates
- 2023
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Ingår i: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 32:1, s. 49-69
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Tidskriftsartikel (refereegranskat)abstract
- Aim To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser-availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource-availability hypothesis). Time period Tree-inventory plots established between 1934 and 2019. Major taxa studied Trees with a diameter at breast height (DBH) >= 9.55 cm. Location Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. Methods We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree-inventory plots across terra-firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance-weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Results Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra-firme forests (excluding podzols) compared to flooded forests. Main conclusions The disperser-availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types.
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| 2. |
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| 3. |
- Klitgaard, Kent K, et al.
(författare)
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Characterization of Leg Push Forces and Their Relationship to Velocity in On-Water Sprint Kayaking.
- 2021
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 21:20
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this work was to describe the leg-muscle-generated push force characteristics in sprint kayak paddlers for females and males on water. Additionally, the relationship between leg pushing force characteristics and velocity was investigated. Twenty-eight paddlers participated in the study. The participants had five minutes of self-chosen warm-up and were asked to paddle at three different velocities, including maximal effort. Left- and right-side leg extension force were collected together with velocity. Linear regression analyses were performed with leg extension force characteristics as independent variables and velocity as the dependent variable. A second linear regression analysis investigated the effect of paddling velocity on different leg extension force characteristics with an explanatory model. The results showed that the leg pushing force elicits a sinus-like pattern, increasing and decreasing throughout the stroke cycle. Impulse over 10 s showed the highest correlation to maximum velocity (r = 0.827, p < 0.01), while a strong co-correlation was observed between the impulse per stroke cycle and mean force (r = 0.910, p < 0.01). The explanatory model results revealed that an increase in paddling velocity is, among other factors, driven by increased leg force. Maximal velocity could predict 68% of the paddlers' velocity within 1 km/h with peak leg force, impulse over 10 s, and stroke rate (p-value < 0.001, adjusted R-squared = 0.8). Sprint kayak paddlers elicit a strong positive relationship between leg pushing forces and velocity. The results confirm that sprint kayakers' cyclic leg movement is a key part of the kayaking technique.
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| 4. |
- Klitgaard, S., et al.
(författare)
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Long wavelength depolarized light scattering from silver nanoparticles
- 2007
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 443:1-3, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- We report the depolarized light scattering from heterodisperse silver nanoparticles. The profile of the wavelength dependent anisotropy of the colloidal solution of silver nanoparticles extends to the red and near-infrared (NIR) spectral region. For long wavelengths, above 600 nm, the anisotropy drops below 0.5. The presence of such a strong orthogonal component in the scattering opens new opportunities for imaging in dispersive media when polarizers can be used to suppress the background. The anisotropy profile of the scattering of heterodisperse silver nanoparticles can be satisfactorily explained by a theory based on interference between two surface plasmon resonances. (c) 2007 Elsevier B.V. All rights reserved.
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| 5. |
- Neves-Petersen, Maria Teresa, et al.
(författare)
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Flash Photolysis of Cutinase: Identification and Decay Kinetics of Transient Intermediates Formed upon UV Excitation of Aromatic Residues
- 2009
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Ingår i: Biophysical Journal. - : Elsevier BV. - 1542-0086 .- 0006-3495. ; 97:1, s. 211-226
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Tidskriftsartikel (refereegranskat)abstract
- Aromatic amino acids play an important role in ultraviolet (UV)-induced photochemical reactions in proteins. In this work, we aim at gaining insight into the photochemical reactions induced by near-UV light excitation of aromatic residues that lead to breakage of disulfide bridges in our model enzyme, Fusarium solani pisi cutinase, a lipolytic enzyme. With this purpose, we acquired transient absorption data of cutinase, with supplemental experimental data on tryptophan (Trp) and lysozyme as reference molecules. We here report formation kinetics and lifetimes of transient chemical species created upon UV excitation of aromatic residues in proteins. Two proteins, lysozyme and cutinase, as well as the free amino acid Trp, were studied under acidic, neutral, and alkaline conditions. The shortest-lived species is assigned to solvated electrons (lifetimes of a few microseconds to nanoseconds), whereas the longer-lived species are assigned to aromatic neutral and ionic radicals, Trp triplet states, and radical ionic disulphide bridges. The pH-dependent lifetimes of each species are reported. Solvated electrons ejected from the side chain of free Trp residues and aromatic residues in proteins were observed 12 ns after excitation, reaching a maximum yield after similar to 40 ns. It is interesting to note that the formation kinetics of solvated electrons is not pH-dependent and is similar in the different samples. On the other hand, a clear increase of the solvated electron lifetime is observed with increasing pH. This observation is correlated with H3O+ being an electron scavenger. Prolonged UV illumination of cutinase leads to a larger concentration of solvated electrons and to greater absorption at 410 nm (assigned to disulphide electron adduct RSSR center dot-), with concomitant faster decay kinetics and near disappearance of the Trp(center dot) radical peak at 330 nm, indicating possible additional formation of TyrO(center dot) formed upon reaction of Trp(center dot) with Tyr residues. Prolonged UV illumination of cutinase also leads to a larger concentration of free thiol groups, known to originate from the dissociation of RSSR center dot-. Additional mechanisms that may lead to the near disappearance of Trp(center dot) are discussed. Our study provides insight into one key UV-light-induced reaction in cutinase, i.e., light-induced disruption of disulphide bridges mediated by the excitation of aromatic residues. Knowledge about the nature of the formed species and their lifetimes is important for the understanding of UV-induced reactions in humans that lead to light-induced diseases, e.g., skin cancer and cataract formation.
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| 6. |
- Ståhl, Bertil, 1957-, et al.
(författare)
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Leguminosae : key to genera
- 2015
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Ingår i: Flora of Ecuador. - Göteborg : Department of Biological and Environmental Sciences, University of Gothenburg. - 0347-8742. ; :92, s. 1-116
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Tidskriftsartikel (refereegranskat)abstract
- A key to all genera of Leguminosae occurring in or expected to occur in Ecuador is presented along with short descriptions of all genera, including information on morphology, ecology, diversity and distribution. A total of 147 genera are treated, nine of which are expected but not yet recorded from Ecuador. The treatment includes 21 genera that in their entirety include species introduced to Ecuador, chiefly as ornamentals, animal forage or crop plants. The most species rich genera are Inga (75 spp.), Senna (40 spp.), Acacia (23 spp., including Senegalia and Vachellia), Lupinus (22 spp.), Mimosa (21 spp.), Desmodium (20 spp.), and Swartzia (17 spp.). Most genera recorded from Ecuador are illustrated with colour photos of selected species.
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