| 1. |
- Alalam, Hanna, et al.
(författare)
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A High-Throughput Method for Screening for Genes Controlling Bacterial Conjugation of Antibiotic Resistance.
- 2020
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Ingår i: mSystems. - 2379-5077. ; 5:6
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Tidskriftsartikel (refereegranskat)abstract
- The rapid horizontal transmission of antibiotic resistance genes on conjugative plasmids between bacterial host cells is a major cause of the accelerating antibiotic resistance crisis. There are currently no experimental platforms for fast and cost-efficient screening of genetic effects on antibiotic resistance transmission by conjugation, which prevents understanding and targeting conjugation. We introduce a novel experimental framework to screen for conjugation-based horizontal transmission of antibiotic resistance between >60,000 pairs of cell populations in parallel. Plasmid-carrying donor strains are constructed in high-throughput. We then mix the resistance plasmid-carrying donors with recipients in a design where only transconjugants can reproduce, measure growth in dense intervals, and extract transmission times as the growth lag. As proof-of-principle, we exhaustively explore chromosomal genes controlling F-plasmid donation within Escherichia coli populations, by screening the Keio deletion collection in high replication. We recover all seven known chromosomal gene mutants affecting conjugation as donors and identify many novel mutants, all of which diminish antibiotic resistance transmission. We validate nine of the novel genes' effects in liquid mating assays and complement one of the novel genes' effect on conjugation (rseA). The new framework holds great potential for exhaustive disclosing of candidate targets for helper drugs that delay resistance development in patients and societies and improve the longevity of current and future antibiotics. Further, the platform can easily be adapted to explore interspecies conjugation, plasmid-borne factors, and experimental evolution and be used for rapid construction of strains.IMPORTANCE The rapid transmission of antibiotic resistance genes on conjugative plasmids between bacterial host cells is a major cause of the accelerating antibiotic resistance crisis. There are currently no experimental platforms for fast and cost-efficient screening of genetic effects on antibiotic resistance transmission by conjugation, which prevents understanding and targeting conjugation. We introduce a novel experimental framework to screen for conjugation-based horizontal transmission of antibiotic resistance between >60,000 pairs of cell populations in parallel. As proof-of-principle, we exhaustively explore chromosomal genes controlling F-plasmid donation within E. coli populations. We recover all previously known and many novel chromosomal gene mutants that affect conjugation efficiency. The new framework holds great potential for rapid screening of compounds that decrease transmission. Further, the platform can easily be adapted to explore interspecies conjugation, plasmid-borne factors, and experimental evolution and be used for rapid construction of strains.
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| 2. |
- Thormar, Jonas, et al.
(författare)
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Eelgrass (Zostera marina) food web structure in different environmental settings.
- 2016
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- This study compares the structure of eelgrass (Zostera marina L.) meadows and associated food webs in two eelgrass habitats in Denmark, differing in exposure, connection to the open sea, nutrient enrichment and water transparency. Meadow structure strongly reflected the environmental conditions in each habitat. The eutrophicated, protected site had higher biomass of filamentous algae, lower eelgrass biomass and shoot density, longer and narrower leaves, and higher above to below ground biomass ratio compared to the less nutrient-enriched and more exposed site. The faunal community composition and food web structure also differed markedly between sites with the eutrophicated, enclosed site having higher biomass of consumers and less complex food web. These relationships resulted in a column shaped biomass distribution of the consumers at the eutrophicated site whereas the less nutrient-rich site showed a pyramidal biomass distribution of consumers coupled with a more diverse consumer community. The differences in meadow and food web structure of the two seagrass habitats, suggest how physical setting may shape ecosystem response and resilience to anthropogenic pressure. We encourage larger, replicated studies to further disentangle the effects of different environmental variables on seagrass food web structure.
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| 3. |
- Almqvist, Sara, et al.
(författare)
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Fördjupad analys av den svenska klimatomställningen 2020 : Klimat och luft i fokus
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sverige har ambitiösa klimatåtaganden där regeringen uttalat att Sverige ska bli världens första fossilfria välfärdsland. Riksdagen har antagit ambitiösa mål för att minska utsläppen av växthusgaser i Sverige för att vara med i omställningen och begränsa den globala uppvärmningen i linje med Parisavtalet. Under 2017 antog riksdagen ett klimatpolitiskt ramverk för Sverige med nya klimatmål. Det långsiktiga klimatmålet innebär att Sverige senast år 2045 inte ska ha några nettoutsläpp av växthusgaser till atmosfären, för att därefter uppnå negativa utsläpp. Det innebär att utsläppen av växthusgaser inom Sveriges gränser ska ha minskat med minst 85 procent senast år 2045 jämfört med utsläppen år 1990.Naturvårdsverket visar vägen mot klimatmålenNaturvårdsverket ansvarar för uppföljningen av Sveriges nationellt fastställda klimatmål. Årets rapport innehåller fördjupade analyser av trender i den svenska klimatomställningen för Sveriges utsläpp och nettoupptag av växthusgaser och ger en övergripande bild av hur vi befinner oss på vägen mot Sveriges klimatmål. Rapporten innehåller ett särskilt fokuskapitel som beskriver möjligheter med att integrera åtgärdsstrategier i luft- och klimatarbetet.Sveriges utsläpp av växthusgaser minskar för långsamtSveriges territoriella utsläpp av växthusgaser var 50,9 miljoner ton koldioxidekvivalenter år 2019, vilket motsvarar en minskning om 2,4 procent jämfört med 2018. För att nå det långsiktiga klimatmålet om nettonollutsläpp till 2045 krävs en genomsnittlig minskningstakt om 6–10 procent per år från 2019.Det senaste årets utsläppsminskning beror främst på minskade utsläpp inom industrisektorn och el- och fjärrvärmesektorn. Inom industrin har utsläppen framför allt minskat på grund av planerade underhållsstopp på raffinaderier och minskad produktion inom mineralindustrin. Minskade utsläpp syns i de flesta sektorerna, förutom jordbrukssektorn och arbetsmaskiner där utsläppen har ökat jämfört med föregående år.
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| 4. |
- Aquilante, Francesco, et al.
(författare)
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Cholesky decomposition techniques in electronic structure theory
- 2011
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Ingår i: Linear-Scaling Techniques in Computational Chemistry and Physics. - Dordrecht : Springer. - 9789048128525 ; , s. 301-304
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- We review recently developed methods to efficiently utilize the Cholesky decomposition technique in electronic structure calculations. The review starts with a brief introduction to the basics of the Cholesky decomposition technique. Subsequently, examples of applications of the technique to ab inito procedures are presented. The technique is demonstrated to be a special type of a resolution-of-identity or density-fitting scheme. This is followed by explicit examples of the Cholesky techniques used in orbital localization, computation of the exchange contributionto the Fock matrix, in MP2, gradient calculations, and so-called method specific Cholesky decomposition. Subsequently, examples of calibration of the method with respect to computed total energies, excitation energies, and auxiliary basis set pruning are presented. In particular, it is demonstrated that the Cholesky method is an unbiased method to derive auxiliary basis sets. Furthermore, details of the implementational considerations are put forward and examples from a parallel Cholesky decomposition scheme is presented. Finally, an outlook and perspectives are presented, followed by a summary and conclusions section. We are of the opinion that the Cholesky decomposition method is a technique that has been overlooked for too long. We have just recently started to understand how to efficiently incorporate the method in existing ab initio programs. The full potential of the Cholesky technique has not yet been fully explored.
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| 5. |
- Baden, Susanne P., 1952, et al.
(författare)
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Effects of depth and overgrowth of ephemeral macroalgae on a remote subtidal NE Atlantic eelgrass (Zostera marina) community
- 2022
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Ingår i: Marine Pollution Bulletin. - : Elsevier BV. - 0025-326X. ; 177
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Tidskriftsartikel (refereegranskat)abstract
- We conducted a short-term field sampling complemented with time integrating stable isotope analysis to ho- listically investigate status and ecological interactions in a remote NE Atlantic Zostera marina meadow. We found high nutrient water concentrations, large biomass of fast-growing, ephemeral macroalgae, low abundance, and biodiversity of epifauna and a food web with thornback ray (Raja clavata) as intermediate and cod (Gadus morhua) as top predator. We observed no variation with increasing depth (3.5–11 m) except for decreasing shoot density and biomass of Zostera and macroalgae. Our results indicate that the Finnøya Zostera ecosystem is eutrophicated. During the past three to four decades, nutrients from aquaculture have steadily increased to reach 75% of anthropogenic input while the coastal top predator cod has decreased by 50%. We conclude that bottom-up regulation is a predominant driver of change since top-down regulation is generally weak in low density and exposed Zostera ecosystems such as Finnøya.
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| 6. |
- Bengtsson Boström, Kristina, et al.
(författare)
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Polymorphism in the angiotensin converting enzyme but not in the angiotensinogen gene is associated with hypertension and type 2 diabetes: the Skaraborg Hypertension and diabetes project
- 1999
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Ingår i: Journal of Hypertension. - 1473-5598. ; 17:11, s. 1569-1575
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To study the association between polymorphisms in the angiotensin converting enzyme (ACE) gene and angiotensinogen (AGT) gene and hypertension and/or type 2 diabetes in a community population. PATIENTS AND METHODS: The insertion (I)/deletion (D) polymorphism of the ACE gene and the M235T polymorphism of the AGT gene were genotyped in 773 nondiabetic individuals with hypertension, 193 normotensive patients with type 2 diabetes, 243 patients with type 2 diabetes and hypertension, and in 820 normotensive control individuals identified in a community-based study. RESULTS: The DD genotype was associated with hypertension in individuals less than 70 years [odds ratio (OR) = 1.54, confidence interval (CI) = 1.09-2.18] and remained so when patients with type 2 diabetes were excluded from the analysis (OR = 1.45, CI = 1.01-2.09). The strongest association was with the combination of type 2 diabetes and hypertension (OR = 2.19, CI = 1.09-4.38). There was no association with type 2 diabetes without hypertension. No association was observed between the M235T variant or the 3'-microsatellite polymorphism of the AGT gene and hypertension. CONCLUSION: The D-allele of the ACE gene ID polymorphism increases susceptibility to hypertension, particularly when associated with type 2 diabetes. No association was observed between the M235T variant or 3'-microsatellite polymorphism of the AGT gene and hypertension.
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| 7. |
- Bjurshammar, N., et al.
(författare)
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The Effect of Local Phototherapy on Gingival Inflammation - A Randomized Controlled Study
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Aim: To investigate if a toothbrush with incorporated 450 nm LEDs used in daily oral care can reduce dental plaque and gingival inflammation.Materials and methods: An 8-week single blinded randomized clinical trial comparing toothbrushes with and without 450 nm blue LED light emission including 48 subjects. Clinical parameters of interest were plaque index (PI), gingival index (GI) and bleeding on probing (BOP). Analyzes were also made on Interleukin-1β (IL), IL-6, IL -8, and Tumor necrosis factor alpha.Results: A significant reduction in PI, GI and BOP was detected within the groups from baseline to follow-up visit, but no statistical differences between subjects using a toothbrush with 450 nm blue light and a toothbrush without light. Significant decreases in the levels of both MMP-8 and TIMP-1 in saliva, and IL-1b and IL-8 in GCF for the blue light toothbrush groups.Conclusion: A toothbrush with 450 nm LEDs did not yield any statistical significant adjunctive effect to tooth brushing with regard to reduction in gingival inflammation. A larger decrease in PI for the blue light toothbrush compared to control was found at a significance level of p=0.058. To get an optimal phototherapeutic effect we suggest that a wavelength of 405 nm should be used in future studies.
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| 8. |
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| 9. |
- Boström, Anders E, 1951, et al.
(författare)
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Scattering of elastic waves by a rectangular crack in an anisotropic half-space
- 2003
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Ingår i: Wave Motion. - 0165-2125. ; 38, s. 91-107
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Tidskriftsartikel (refereegranskat)abstract
- The scattering of elastic waves by a rectangular crack in a half-space of arbitrary anisotropy is considered. The application in mind is ultrasonic testing of thick-walled anisotropic components where the crack is close to a planar back surface. The orientation of the crack and the back surface may be arbitrary relative the anisotropy. The scattering problem is formulated as hypersingular integral equation for the crack-opening-displacement (COD) by means of a half-spce Green's tensor. The integral equation is solved by expanding the COD in a double series of Chebyshev functions with the correct behavior along the crack's edges. Insertion inte the integral equation and projection onto the same set of functions result in a linear system of equations for the expansion coefficients appearing in the representation of the COD. The transmitting transducer is modeled by the traction beneath it on the scanning surface and the incident field may then be calculated. An electromechanical reciprocity relation is used to model the receiving transducer. Numerical examples are included which show the influence of the anisotropy and espcially the prexence of a nearby planar back surface.
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| 10. |
- Boström, Hanna L., et al.
(författare)
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Ordered B-Site Vacancies in an ABX(3) Formate Perovskite
- 2019
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 141:45, s. 17978-17982
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Tidskriftsartikel (refereegranskat)abstract
- We report the synthesis and structural characterization of the ABX3 perovskite frameworks [C(NH2)(3)]Mn-1-x(2+)(Fe-2x/3(3+),square(x/3))(HCOO)(3) (square = B-site vacancy). For large x, the vacancies order, lowering the crystal symmetry. This system establishes B-site vacancies as a new type of defect in formate perovskites, with important chemical, structural, and functional implications. Monte Carlo simulations driven by nearest-neighbor vacancy repulsions show checkerboard vacancy order to emerge for x > 0.6, in accord with experiment.
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