| 1. |
- Albrectsen, Benedicte Riber, 1960-, et al.
(författare)
-
Slugs, willow seedlings and nutrient fertilization: intrinsic vigor inversely affects palatability
- 2004
-
Ingår i: Oikos. - : John Wiley & Sons. - 0030-1299 .- 1600-0706. ; 105, s. 268-278
-
Tidskriftsartikel (refereegranskat)abstract
- This study evaluates how preference by a generalist slug herbivore Arion subfuscus changes inversely with seedling size across three levels of fertilization for three full‐sib families of willow seedlings. We analyzed seedlings for condensed tannin and protein concentration, and related these data to changes in palatability. In preference tests over time, leaf discs from more fertilized seedlings experienced an extended window of vulnerability compared to discs from less fertilized seedlings, which were also more tannin‐rich. In a whole seedling selection study, slugs readily attacked smaller seedlings (<5 cm) but rarely attacked taller seedlings (>10 cm). However, a general difference in risk of damage close to 50% existed when comparing shorter and taller individuals within each family and level of fertilizer. The decrease in palatability with height of the seedlings was positively correlated with an increase in condensed tannin concentration. We found no effect of seedling size on protein concentration. Akaiki index criterion model comparisons suggested that only main effects were important for explaining seedling choice by slugs as well as the ratio between proteins and condensed tannins. Seedling size, had the largest effect, followed by fertilizer level and family. Surprisingly, seedling size and fertilizer treatment had opposite effects on palatability to slugs. Size decreased probability of damage, whereas fertilization extended the window of susceptibility. Because the seedlings were even‐aged, differences in size are interpreted as differences in growth rate or vigor. The positive phenotypic correlation found between size and tannin production in the less preferred willow seedlings confirms that several plant defense traits may be selected for simultaneously, because fast growth may allow an early development of plant defenses. We discuss these results in the light of plant‐defense theories that predict a negative correlation between the allocation to growth and the production of secondary defense compounds.
|
|
| 2. |
- Albrectsen, Benedicte R., et al.
(författare)
-
The diversity and identification of eulophid parasitic wasps (Hymenoptera: Chalcidoidea: Eulophidae) on Phyllocnistis labyrinthella (Lepidoptera: Gracillariidae) from Västerbotten, Sweden.
- 2012
-
Ingår i: Entomologisk tidskrift. - 0013-886X. ; 133:3, s. 111-118
-
Tidskriftsartikel (refereegranskat)abstract
- Caterpillars of the mining micro-moth Phyllocnistis labyrinthella feed on leaves of aspen (Populus tremula) and are often parasitized by eulophid wasps. The parasitoids are a potential important cause of death for the miners. During 2009-2011 we collected mined leaves from an experimental stand of aspen trees in Västerbotten. Adults emerged from 17-35 percent of the mines and of these every second to third specimen appeared as wasps. These wasps represented seven species of eulophid parasitoids of which three were new to Västerbotten: Chrysocharis nitetis (Walker), Cirrospilus diallus (Walker) and Cirrospilus pictus (Nees). We include an identification key that may be used to identify these eulophid species.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Arkhypchuk, Anna, 1984-
(författare)
-
Novel Approaches to Phosphorus-containing Heterocycles and Cumulenes
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fast development in all areas of life and science over the last 50 years demands versatile, energy efficient and cheap materials with specific but easily tuneable properties which can be used for example in organic light emitting diodes (OLEDs), thin-film transistors, photovoltaic cells, etc. This thesis is devoted to the development of novel synthetic approaches to molecules with potential applications in the field of molecular electronics. The acquisition of a detailed mechanistic understanding of the newly developed reactions is central to the work presented in this thesis.The first chapter is dedicated to the development of a new procedure for the preparation of phospha-Wittig-Horner (pWH) reagents, i.e. a reagents that has been known to convert carbonyl compounds into compounds with P=C double bonds. Each step of the synthetic sequence, i.e. preparation of the starting P,P-dichlorophosphines, their phosphorylation using the Michaelis-Arbuzov protocol, coordination to the metal centre and final hydrolysis, are presented in detail. A possible route to uncoordinated pWH reagents is also discussed.The second chapter focuses on the reactivity of the pWH reagents with acetone under different reaction conditions. The results show how changes in the ratio of starting material vs. base as well as reaction time or structure of the pWH reagent can influence the reaction outcome and the stability of the obtained products. The possibility to prepare unusual phosphaalkenes with unsaturated P-substituents is presented.The third chapter of the thesis is dedicated to the reactivity of pWH reagents towards symmetric and asymmetric ketones which contain one or two acetylene units. The proposed mechanisms of the reactions are studied by means of in situ FTIR spectroscopy as well as theoretical calculations. Physical-chemical properties of oxaphospholes, cumulenes and bisphospholes are presented.The last chapter is dedicated to reactivity studies of pWH reagents towards ketenes, and the exploration of a reliable route to 1-phosphaallenes. Detailed mechanistic studies of the pWH reaction that are based on the isolation and crystallographic characterization of unique reaction intermediates are presented. The reactivity of phosphaallenes towards nucleophiles such as water and methanol are examined.In summary, this thesis presents synthetic routes to novel phosphorus-containing molecules, together with detailed studies of the reaction mechanisms of the observed transformations.
|
|
| 6. |
- Bengtsson, Ingemar, et al.
(författare)
-
How to mix a density matrix
- 2003
-
Ingår i: Physical Review A. - 1050-2947. ; 67, s. 012107-
-
Tidskriftsartikel (refereegranskat)
|
|
| 7. |
|
|
| 8. |
- Berg, Camilla, et al.
(författare)
-
Amorphous Calcium Magnesium Phosphate Particles for Treatment of Dentin Hypersensitivity : A Mode of Action Study
- 2020
-
Ingår i: ACS Biomaterials Science & Engineering. - : AMER CHEMICAL SOC. - 2373-9878. ; 6:6, s. 3599-3607
-
Tidskriftsartikel (refereegranskat)abstract
- Occlusion of exposed dentin tubules may eliminate or reduce dentin hypersensitivity by hindering fluid movements within the tubules. In this study, the mode of action of spherical particles of amorphous calcium magnesium phosphate (180-440 nm in diameter) was studied. A degradation study of the particles in Tris-HCl buffer showed that the particles continuously released Ca2+, Mg2+, and phosphate, and XRD analysis revealed the formation of hydroxyapatite (HA) after 1 week. The occluding effect and efficacy of the spherical particles as an occluding agent were evaluated in an in vitro study. The ACMP particles were incorporated in a gel intended for at-home use and tested on extracted human molars. Application of the particles followed by incubation in artificial saliva resulted in occlusion of exposed tubules, and examination with SEM showed that the particles could penetrate the tubules down to 100 mu m from the dentin surface. Transformation of the particles into nanocrystalline HA-structures (nanoHA) was initiated at the dentin surface within 12 h of application, and tubule penetration of the particles, accompanied by further ion release and diffusion of ions, resulted in deep intratubular occlusion in the majority of the tubules within 3 days from application. NanoHA was tightly adhered to the tubule walls, filling the entire tubule volume after 7 days. The results of this study demonstrate the mode of action of the amorphous calcium magnesium phosphate particles in occluding exposed dentin tubules. Interaction with saliva and transformation of the particles within the tubules inducing further mineralization indicate that the particles may be used as an effective treatment to reduce dentin hypersensitivity.
|
|
| 9. |
- Berg, Christina, 1963, et al.
(författare)
-
Bra liv i Gårdsten: När invånarna själva för råda
- 2018
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna rapport beskriver ett projekt som drivs av några invånare från Gårdsten och en forskargrupp från Göteborgs Universitet och Västra Götalandsregionen. Målet för projektet är att identifiera vad som gör att man kan leva ett gott och hälsosamt liv i Gårdsten samt att föreslå och initiera förändringar. Vi har vid ett antal träffar pratat om hur vardagen fungerar i Gårdsten, vad som är bra för hälsan och vad som skulle kunna förbättras. I den processen har vi använt en forskningsmetod som innebär att alla ska kunna komma till tals och påverka (GLA – Group Level Assessment). I slutet av varje träff har vi tillsammans bestämt hur vi går vidare och forskargruppen har dokumenterat och sammanställt det som hänt. Bland annat har vi haft en utställning, där vi bjöd in fler invånare och företrädare för myndigheter och organisationer i Gårdsten. Dessa aktiviteter har resulterat i förslag på konkreta insatser. Fler mötesplatser behövs och kommunikationen mellan människorna kan bli mycket bättre. Det har också framkommit att tryggheten och känslan av tillhörighet behöver stärkas. Önskemålen om bättre kommunikation, trygghet och tillhörighet har i sin tur har lett till att några jobbar vidare på att öppna ett språkkafé. En grupp har också tagit initiativ till att bjuda in representanter för hälso- och sjukvården för att prata om munhälsa respektive hälsosam mat. Detta var lätt att ordna eftersom både Folktandvården och Angereds Närsjukhus har sådant utåtriktat arbete som en del av sina uppdrag. Genom projektet tas alltså dessa resurser nu i bruk av invånarna. Slutligen kan man säga om detta projekt att det startat idéer, diskussioner och handlingar som förhoppningsvis kommer att fortsätta bidra till Gårdstens utveckling.
|
|
| 10. |
|
|
