| 1. |
- Persson, Mats, et al.
(författare)
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2014 års Ekonomipris till Jean Tirole
- 2014
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Ingår i: Ekonomisk Debatt. - Stockholm : Nationalekonomiska föreningen. - 0345-2646. ; :8, s. 5-14
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 2. |
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| 3. |
- Ravnskov, Uffe, et al.
(författare)
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Radikal förändring av WHO:s syn på fett
- 2009
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Ingår i: Dagens medicin. - Stockholm, Sverige : Dagens Medicin Sverige AB. - 1104-7488.
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 4. |
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| 5. |
- Scherstén, Tore, et al.
(författare)
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Kostråden saknar vetenskaplig grund
- 2009
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Ingår i: Dagens medicin. - Stockholm, Sverige : Dagens Medicin Sverige AB. - 1104-7488.
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 6. |
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| 7. |
- Andersson, Tommy, et al.
(författare)
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2020 års Ekonomipris till Paul Milgrom och Robert Wilson
- 2020
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Ingår i: Ekonomisk Debatt. - : Nationalekonomiska Föreningen. - 0345-2646. ; 48:8, s. 5-12
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Kungl. Vetenskapsakademien har beslutat dela ut årets Ekonomipris till Paul Milgrom och Robert Wilson, båda från Stanford University, USA, för ”förbättringar av auktionsteorin och uppfinningar av nya auktionsformat”. Årets pristagare har i sin forskning sammanfört teori och praktik, till nytta för enskilda individer, företag och samhällen världen över.
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| 8. |
- Arcini, Caroline, 1960-, et al.
(författare)
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Pestbacken
- 2006. - 1
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Bok (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Cerantola, Yannick, et al.
(författare)
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Guidelines for perioperative care after radical cystectomy for bladder cancer : enhanced Recovery After Surgery (ERAS(®)) society recommendations
- 2013
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Ingår i: Clinical Nutrition. - Edinburgh, UK : Churchill-Livingstone. - 0261-5614 .- 1532-1983. ; 32:6, s. 879-887
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Enhanced recovery after surgery (ERAS) pathways have significantly reduced complications and length of hospital stay after colorectal procedures. This multimodal concept could probably be partially applied to major urological surgery.OBJECTIVES: The primary objective was to systematically assess the evidence of ERAS single items and protocols applied to cystectomy patients. The secondary objective was to address a grade of recommendation to each item, based on the evidence and, if lacking, on consensus opinion from our ERAS Society working group.EVIDENCE ACQUISITION: A systematic literature review was performed on ERAS for cystectomy by searching EMBASE and Medline. Relevant articles were selected and quality-assessed by two independent reviewers using the GRADE approach. If no study specific to cystectomy was available for any of the 22 given items, the authors evaluated whether colorectal guidelines could be extrapolated.EVIDENCE SYNTHESIS: Overall, 804 articles were retrieved from electronic databases. Fifteen articles were included in the present systematic review and 7 of 22 ERAS items were studied. Bowel preparation did not improve outcomes. Early nasogastric tube removal reduced morbidity, bowel recovery time and length of hospital stay. Doppler-guided fluid administration allowed for reduced morbidity. A quicker bowel recovery was observed with a multimodal prevention of ileus, including gum chewing, prevention of PONV and minimally invasive surgery.CONCLUSIONS: ERAS has not yet been widely implemented in urology and evidence for individual interventions is limited or unavailable. The experience in other surgical disciplines encourages the development of an ERAS protocol for cystectomy.
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| 10. |
- Chábera, Pavel, et al.
(författare)
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A low-spin Fe(iii) complex with 100-ps ligand-to-metal charge transfer photoluminescence
- 2017
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 543:7647, s. 695-699
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Tidskriftsartikel (refereegranskat)abstract
- Transition-metal complexes are used as photosensitizers1, in light-emitting diodes, for biosensing and in photocatalysis2. A key feature in these applications is excitation from the ground state to a charge-transfer state3,4; the long charge-transfer-state lifetimes typical for complexes of ruthenium5 and other precious metals are often essential to ensure high performance. There is much interest in replacing these scarce elements with Earth-abundant metals, with iron6 and copper7 being particularly attractive owing to their low cost and non-toxicity. But despite the exploration of innovative molecular designs6,8,9,10, it remains a formidable scientific challenge11 to access Earth-abundant transition-metal complexes with long-lived charge-transfer excited states. No known iron complexes are considered12 photoluminescent at room temperature, and their rapid excited-state deactivation precludes their use as photosensitizers13,14,15. Here we present the iron complex [Fe(btz)3]3+ (where btz is 3,3′-dimethyl-1,1′-bis(p-tolyl)-4,4′-bis(1,2,3-triazol-5-ylidene)), and show that the superior σ-donor and π-acceptor electron properties of the ligand stabilize the excited state sufficiently to realize a long charge-transfer lifetime of 100 picoseconds (ps) and room-temperature photoluminescence. This species is a low-spin Fe(iii) d5 complex, and emission occurs from a long-lived doublet ligand-to-metal charge-transfer (2LMCT) state that is rarely seen for transition-metal complexes4,16,17. The absence of intersystem crossing, which often gives rise to large excited-state energy losses in transition-metal complexes, enables the observation of spin-allowed emission directly to the ground state and could be exploited as an increased driving force in photochemical reactions on surfaces. These findings suggest that appropriate design strategies can deliver new iron-based materials for use as light emitters and photosensitizers.
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| 11. |
- Danielsson, Åke, et al.
(författare)
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A controlled randomized trial of budesonide versus prednisolone retention enemas in active distal ulcerative colitis
- 1987
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 22:8, s. 987-992
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Tidskriftsartikel (refereegranskat)abstract
- Sixty-four patients with active distal ulcerative colitis participated in a multicentre, randomized, investigator-blind trial to compare the effect of budesonide enema, 2 mg/100 ml, with prednisolone disodium phosphate enema, 31.25 mg/100 ml. Budesonide is a new potent corticosteroid with a rapid first-pass elimination. The patients were treated for 4 weeks, and the efficacy of the drugs were evaluated by sigmoidoscopy, histology, and subjective symptoms after 2 and 4 weeks. After 4 weeks of treatment 16 of 31 patients (52%) receiving budesonide enema had healed endoscopically, compared with 8 of 33 (24%) (p = 0.045) receiving prednisolone enema. Budesonide was superior to prednisolone in terms of both significantly improved sigmoidoscopic and histologic scores and subjective symptoms evaluated by visual analogue scales. The patients receiving prednisolone had a significant depression of endogenous cortisol levels during the treatment period, but not the patients receiving budesonide. Budesonide enema seems to be a promising therapy for active distal ulcerative colitis and causes no adverse reactions
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| 12. |
- Dehvari, Nodi, et al.
(författare)
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Amyloid precursor protein accumulates in aggresomes in response to proteasome inhibitor
- 2012
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Ingår i: Neurochemistry International. - : Elsevier BV. - 0197-0186 .- 1872-9754. ; 60:5, s. 533-542
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Tidskriftsartikel (refereegranskat)abstract
- Aggresomes are cytoplasmic inclusions which are localized at the microtubule organizing center (MTOC) as a result of induced proteasome inhibition, stress or over-expression of certain proteins. Aggresomes are linked to the pathogenesis of many neurodegenerative diseases. Here we studied whether amyloid precursor protein (APP), a type-I transmembrane glycoprotein, is localized in aggresomes after exposure to stress condition. Using confocal microscopy we found that APP is located in aggresomes and co-localized with vimentin, gamma-tubulin, 20S and ubiquitin at the MTOC in response to proteasome dysfunction. An interaction between vimentin and APP was found after proteasome inhibition suggesting that APP is an additional protein constituent of aggresomes. Suppression of the proteasome system in APP-HEK293 cells overexpressing APP or transfected with APP Swedish mutation caused an accumulation of stable, detergent-insoluble forms of APP containing poly-ubiquitinated proteins. In addition, brain homogenates from transgenic mice expressing human APP with the Arctic mutation demonstrated an interaction between APP and the aggresomal-marker vimentin. These data suggest that malfunctioning of the proteasome system caused by mutation or overexpression of pathological or non-pathological proteins may lead to the accumulation of stable aggresomes, perhaps contributing to the neurodegeneration.
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| 13. |
- Eriksson, Daniel, 1987-, et al.
(författare)
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Laboratory measurement method for the mechanical interaction between a tactile sensor and a cartonboard package – presentation and evaluation
- 2021
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Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter. - 0283-2631 .- 2000-0669. ; 36:1, s. 91-99
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Tidskriftsartikel (refereegranskat)abstract
- The importance of sensory information in product purchasing decisions has gained increasing attention in recent years. Tactile properties of packaging are usually measured with the help of trained evaluators. An objective, fast and repeatable method that describes the mechanical interaction and does not rely on a panel would have many benefits. We propose and evaluate such a method for measuring the mechanical interaction between a deformable finger-like shaped sensor and a package. Evaluation of the method shows good repeatability, the variability in the measurement result is within a few percent in most cases. The method captures indentation differences at contact between sensor and package due to measurement position and package design.
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| 14. |
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| 15. |
- Friman, Styrbjörn, 1948, et al.
(författare)
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Adjuvant treatment with ursodeoxycholic acid reduces acute rejection after liver transplantation.
- 1992
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Ingår i: Transplant international : official journal of the European Society for Organ Transplantation. - 0934-0874. ; 5 Suppl 1
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Tidskriftsartikel (refereegranskat)abstract
- Acute rejection, occurring with a reported frequency of 50-70%, is still a dominating problem after liver transplantation. Medication with ursodeoxycholic acid (UDCA) has beneficial effects in different cholestatic conditions and has also been shown to reduce HLA class I antigen expression on hepatocytes in patients with PBC. Since August 1989 we have consecutively treated all patients with primary graft function with UDCA (n = 41). Patients transplanted in the first half of 1989 served as a control group (n = 8). All patients in this study were given sequential quadruple drug immunosuppression. The treatment group were given oral UDCA 10 mg/kg per day. During the first postoperative month, 17% of the UDCA-treated patients had an episode of acute rejection compared with 75% of the control patients (P < 0.01). Liver biochemistry tests 1 month postoperatively were significantly better in patients treated with UDCA. The results suggest that adjuvant treatment with UDCA reduces acute liver graft rejection.
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| 16. |
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| 17. |
- Jemt, Elisabeth, et al.
(författare)
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Regulation of DNA replication at the end of the mitochondrial D-loop involves the helicase TWINKLE and a conserved sequence element
- 2015
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Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 43:19, s. 9262-9275
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Tidskriftsartikel (refereegranskat)abstract
- The majority of mitochondrial DNA replication events are terminated prematurely. The nascent DNA remains stably associated with the template, forming a triple-stranded displacement loop (D-loop) structure. However, the function of the D-loop region of the mitochondrial genome remains poorly understood. Using a comparative genomics approach we here identify two closely related 15 nt sequence motifs of the D-loop, strongly conserved among vertebrates. One motif is at the D-loop 5'-end and is part of the conserved sequence block 1 (CSB1). The other motif, here denoted coreTAS, is at the D-loop 3'-end. Both these sequences may prevent transcription across the D-loop region, since light and heavy strand transcription is terminated at CSB1 and coreTAS, respectively. Interestingly, the replication of the nascent D-loop strand, occurring in a direction opposite to that of heavy strand transcription, is also terminated at coreTAS, suggesting that coreTAS is involved in termination of both transcription and replication. Finally, we demonstrate that the loading of the helicase TWINKLE at coreTAS is reversible, implying that this site is a crucial component of a switch between D-loop formation and full-length mitochondrial DNA replication.
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| 18. |
- Josephson, Peter, 1969-
(författare)
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Den akademiska frihetens gränser : Max Weber, Humboldtmodellen och den värdefria vetenskapen
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this dissertation is to contribute to an understanding of why Weber advocated a value-free science. In en essay from 1917, Weber writes that the question of whether or not one ought to make value judgments in the lecture hall is basically a question of practical university policy. Weber's statement warrants a study of previously relatively unexamined source material. Between 1908 and 1911 Weber wrote a number of articles dealing with university policy. Using these texts as a basis for my research, I discern four reasons why he calls for a value-free science. The first reason is that he wants to provide students with protection against political indoctrination. The second reason is that he wants to counteract the ideological fragmentation that threatens to arise within universities if teachers with fundamentally irreconcilable views assume the right to preach politics from the lectern. The third reason is that he wants to avoid giving the government an excuse to intervene in academic appointments in order to make sure that the faculties do not grant chairs to individuals who question the current form of government. The fourth reason, paradoxically, is that he wants to lay the foundation for an alternative political education of students. Such a political education would not force upon students certain previously determined norms and rules of action, but instead would encourage them to examine themselves and their ethical motives, thus creating autonomous individuals. Previous resarch has argued that Weber defended academic freedom at a time when powerful forces were at work to restrict it. This conclusion is partially anachronic. The right to express political opinions in the lecture hall was as a rule seen as part of academic freedom at the turn of the twentieth century. The problems Weber intends to solve with the doctrine of value-free science, including the discrimination of dissidents, is thus a direct and indirect result of academic freedom.
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| 19. |
- Kirwan, John R, et al.
(författare)
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The effect of therapeutic glucocorticoids on the adrenal response in a randomized controlled trial in patients with rheumatoid arthritis
- 2006
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Ingår i: Arthritis and Rheumatism. - : Wiley. - 0004-3591 .- 1529-0131. ; 54:5, s. 1415-1421
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To measure the effect of low-dose systemic glucocorticoid treatment on the adrenal response to adrenocorticotropic hormone (ACTH) in patients with rheumatoid arthritis (RA). METHODS: Patients with RA who took part in a randomized double-blind placebo-controlled trial of budesonide (3 mg/day and 9 mg/day) and prednisolone (7.5 mg/day) underwent a short (60-minute) test with injection of ACTH (tetracosactide hexaacetate) at baseline and the day after completing the 3-month treatment program. Plasma cortisol measurements at baseline and 3 months were compared within and between the treatment groups. Individual patients were classified as normal responders to ACTH or as abnormal responders if changes were >2 SD below the pretreatment value in the entire group of study patients. RESULTS: Short tests with ACTH injection were performed on 139 patients before beginning the study medication and on 134 patients after cessation of the medication. There were no changes in the placebo group. Mean plasma cortisol levels following treatment were reduced in all active treatment groups. In addition, mean values were significantly reduced for the 30-minute and 60-minute responses to ACTH. The maximum reduction (35%) occurred in the prednisolone group at 60 minutes. Following treatment, 34% of patients taking budesonide 9 mg and 46% of those taking prednisolone 7.5 mg failed to reach the normal maximum cortisol response to ACTH. Four patients failed to achieve the normal percentage increase in cortisol levels, but only 1 patient failed to meet both criteria. CONCLUSION: Low doses of a glucocorticoid resulted in depression of baseline and ACTH-stimulated cortisol levels after 12 weeks of therapy. Although the responsiveness of the hypothalamic-pituitary-adrenal axis in individual patients generally remained within the normal range, these changes should be investigated further.
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| 20. |
- Kjær, Kasper Skov, et al.
(författare)
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Luminescence and reactivity of a charge-transfer excited iron complex with nanosecond lifetime
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 363:6424, s. 249-253
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Tidskriftsartikel (refereegranskat)abstract
- Iron’s abundance and rich coordination chemistry are potentially appealing features for photochemical applications. However, the photoexcitable charge-transfer (CT) states of most Fe complexes are limited by picosecond or sub-picosecond deactivation through low-lying metal centered (MC) states, resulting in inefficient electron transfer reactivity and complete lack of photoluminescence. Here we show that octahedral coordination of Fe(III) by two mono-anionic facial tris-carbene ligands can suppress such deactivation dramatically. The resulting complex [Fe(phtmeimb)2]+, where phtmeimb is [phenyl(tris(3-methylimidazol-1-ylidene))borate]-, exhibits strong, visible, room temperature photoluminescence with a 2.0 ns lifetime and 2% quantum yield via spin-allowed transition from a ligand-to-metal charge-transfer (2 LMCT) state to the ground state (2 GS). Reductive and oxidative electron transfer reactions were observed for the2 LMCT state of [Fe(phtmeimb)2]+ in bimolecular quenching studies with methylviologen and diphenylamine.
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| 21. |
- Krantz, Ingela, et al.
(författare)
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Screening for postpartum depression with the Edinburgh Postnatal Depression Scale (EPDS) : An ethical analysis
- 2008
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Ingår i: Scandinavian Journal of Public Health. - London : SAGE Publications. - 1403-4948 .- 1651-1905. ; 36:2, s. 211-216
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Tidskriftsartikel (refereegranskat)abstract
- Aims: To assess the Edinburgh Postnatal Depression Scale (EPDS), a self-administered questionnaire created to screen for symptoms of postpartum depression in the community, from an epidemiological and ethical perspective. Screening, as the practice of investigating apparently healthy individuals to detect unrecognised disease or its precursors, has interpretation problems and is complicated by deliberations on probabilities for something to occur, on which the scientific community is unanimous. Methods: Our ethical analysis is made using a framework with two different dimensions, the ethical principles autonomy and beneficence and the affected persons. To balance the ethical costs and the ethical benefits of EPDS an analogy with the assessment of pharmaceutics is used. Results: In this article we argue that routine EPDS screening of Swedish postpartum women would lead to considerable ethical problems due to the weak scientific foundation of the screening instrument. Despite a multitude of published studies, the side-effects in terms of misclassifications have not been considered carefully. The EPDS does not function very well as a routine screening instrument. The dualism created is too reductive and fails to recognize the plurality of difference that exists in the social word. Conclusions: Public health authorities should not advocate screening of unproved value. Screening is not just a medical issue but also an ethical one.
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| 22. |
- Norgren, Lars, et al.
(författare)
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Immune response to collagen impregnated Dacron double velour grafts for aortic and aorto-femoral reconstructions
- 1990
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Ingår i: European Journal of Vascular Surgery. - 0950-821X. ; 4:4, s. 379-384
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Tidskriftsartikel (refereegranskat)abstract
- This study presents 20 patients, randomised to receive either a collagen-treated or an ordinary Dacron graft for aortic reconstructions, and the results of a skin-prick test, blood parameters and ELISA for anti-collagen antibodies as well as NMR pictures during a 6 week follow-up period. Forty per cent (4/11) of those receiving a collagen impregnated graft had a significantly increased titre of antibodies and NMR revealed in two out of 11 patients either a slightly increased amount of fluid or fibrosis around the graft, both collagen impregnated. No differences were found between the graft groups concerning body temperature and leucocyte or platelet counts. The skin-prick test for collagen was negative in all cases.
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| 23. |
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| 24. |
- Persson, Petter, et al.
(författare)
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Introduction
- 2012
-
Ingår i: International Journal of Quantum Chemistry. - : Wiley. - 0020-7608 .- 1097-461X. ; 112:7, s. 1759-1759
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Tidskriftsartikel (refereegranskat)
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| 25. |
- Persson, Tore, 1945-, et al.
(författare)
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En kritisk analys av företagsnätverk
- 2005
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Rapport (populärvet., debatt m.m.)abstract
- Vi har studerat samarbetet i olika företagsgrupperingar inom Västra Götalands län. I studien har vi jämfört de aktuella grupperingarna med bl.a. beskrivningar av grupperingar i industriella distrikt i norra och mellersta Italien. Dessutom har jämförelser gjorts med det nätverkssamhälle, som Castells har beskrivit, samt det samhälle – det gamla agrarsamhället - som Tönnies och Colley studerat m. a. p. sociala relationer. *För det första har vi funnit att det tar lång tid, 5 – 10 år, att skapa ett fungerande nätverk. Alla grupperingar blir inte framgångsrika nätverk. De flesta grupperingar tycks faktiskt aldrig nå fram till ett fungerande nätverk och det är kanske inte heller alltid syftet. Så t.ex.var syftet i de LRF-grupperingar vi studerat främst att få stöd till utbildningsinsatser och för det var man i stort sett tvingad att bilda ett nätverk. Vi tycker oss se att det finns skillnader i arbetssätt mellan grupperingar, som har samarbetat inbördes under en längre tid (ca 5 år) och de som är relativt nystartade (1-2 år). Även attityderna tycks vara annorlunda. Eftersom det statistiska underlaget är begränsat kan vi inte uttala oss med säkerhet i dessa frågor. Vi har dock noterat att man i de studerade grupperingarna i allmänhet ägnar för kort tid åt att bygga nätverket. De tror att grupperingen skall fungera som ett bra verktyg utan närvaro av det sociala kapitalet. *Vi kan inte se tillstymmelse till det ”nätverkssamhälle”, som Castells har beskrivit. Möjligen finns det samhället representerat i vår region, men det har ännu inte kommit till de företag och de grupperingar som denna studie omfattar. Det är troligt att ”nätverkssamhället” finns mer påtagligt i företag, som ingår i globala koncerner. Däremot finns det tecken på att IT-kunnandet och användandet ökar starkt i företagen. *Inte heller passar Tönnies och Cooleys beskrivningar av samverkan och umgänge i agrarsamhället in på de företagsgrupperingar, som vi har studerat. Däremot kan vi se att deras beskrivningar delvis passar in på byalag och utvecklingsgrupper på landsbygden. Dessa grupperingar har ett högt värde på det sociala kapitalet och den sociala väven är relativt tät. Varje byalag är dock för litet för att kunna åstadkomma den utveckling som önskas. Med intensifierad samverkan mellan olika byalagsgrupperingarna inbördes och med andra grupperingar kan resultatet förväntas bli bättre. *När vi jämför de studerade grupperingarna med industriella distrikt ser vi att det sociala kapitalet hos dessa är mycket lägre än i de industriella distrikten. Det tar åtminstone 20-30 år att formas. Traditioner, normer och värderingar skall ha hunnit att bli en del av den lokala kulturen, dvs. de bör ha gått i arv mellan två generationer.
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| 26. |
- Prakash, Om, et al.
(författare)
-
A Stable Homoleptic Organometallic Iron(IV) Complex
- 2020
-
Ingår i: Chemistry - A European Journal. - : WILEY-V C H VERLAG GMBH. - 0947-6539 .- 1521-3765. ; 26:56, s. 12728-12732
-
Tidskriftsartikel (refereegranskat)abstract
- A homoleptic organometallic Fe(IV)complex that is stable in both solution and in the solid state at ambient conditions has been synthesized and isolated as [Fe(phtmeimb)(2)](PF6)(2)(phtmeimb=[phenyl(tris(3-methylimidazolin-2-ylidene))borate](-)). This (FeN)-N-IV-heterocyclic carbene (NHC) complex was characterized by(1)H NMR, HR-MS, elemental analysis, scXRD analysis, electrochemistry, Mossbauer spectroscopy, and magnetic susceptibility. The two latter techniques unequivocally demonstrate that [Fe(phtmeimb)(2)](PF6)(2)is a triplet Fe(IV)low-spinS=1 complex in the ground state, in agreement with quantum chemical calculations. The electronic absorption spectrum of [Fe(phtmeimb)(2)](PF6)(2)in acetonitrile shows an intense absorption band in the red and near IR, due to LMCT (ligand-to-metal charge transfer) excitation. For the first time the excited state dynamics of a Fe(IV)complex was studied and revealed a approximate to 0.8 ps lifetime of the(3)LMCT excited state of [Fe(phtmeimb)(2)](PF6)(2)in acetonitrile.
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| 27. |
- Prakash, Om, et al.
(författare)
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How Rigidity and Conjugation of Bidentate Ligands Affect the Geometry and Photophysics of Iron N-Heterocyclic Complexes : A Comparative Study
- 2024
-
Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 63:10, s. 4461-4473
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Tidskriftsartikel (refereegranskat)abstract
- Two iron complexes featuring the bidentate, nonconjugated N-heterocyclic carbene (NHC) 1,1′-methylenebis(3-methylimidazol-2-ylidene) (mbmi) ligand, where the two NHC moieties are separated by a methylene bridge, have been synthesized to exploit the combined influence of geometric and electronic effects on the ground- and excited-state properties of homoleptic FeIII-hexa-NHC [Fe(mbmi)3](PF6)3 and heteroleptic FeII-tetra-NHC [Fe(mbmi)2(bpy)](PF6)2 (bpy = 2,2′-bipyridine) complexes. They are compared to the reported FeIII-hexa-NHC [Fe(btz)3](PF6)3 and FeII-tetra-NHC [Fe(btz)2(bpy)](PF6)2 complexes containing the conjugated, bidentate mesoionic NHC ligand 3,3′-dimethyl-1,1′-bis(p-tolyl)-4,4′-bis(1,2,3-triazol-5-ylidene) (btz). The observed geometries of [Fe(mbmi)3](PF6)3 and [Fe(mbmi)2(bpy)](PF6)2 are evaluated through L-Fe-L bond angles and ligand planarity and compared to those of [Fe(btz)3](PF6)3 and [Fe(btz)2(bpy)](PF6)2. The FeII/FeIII redox couples of [Fe(mbmi)3](PF6)3 (−0.38 V) and [Fe(mbmi)2(bpy)](PF6)2 (−0.057 V, both vs Fc+/0) are less reducing than [Fe(btz)3](PF6)3 and [Fe(btz)2(bpy)](PF6)2. The two complexes show intense absorption bands in the visible region: [Fe(mbmi)3](PF6)3 at 502 nm (ligand-to-metal charge transfer, 2LMCT) and [Fe(mbmi)2(bpy)](PF6)2 at 410 and 616 nm (metal-to-ligand charge transfer, 3MLCT). Lifetimes of 57.3 ps (2LMCT) for [Fe(mbmi)3](PF6)3 and 7.6 ps (3MLCT) for [Fe(mbmi)2(bpy)](PF6)2 were probed and are somewhat shorter than those for [Fe(btz)3](PF6)3 and [Fe(btz)2(bpy)](PF6)2. [Fe(mbmi)3](PF6)3 exhibits photoluminescence at 686 nm (2LMCT) in acetonitrile at room temperature with a quantum yield of (1.2 ± 0.1) × 10-4, compared to (3 ± 0.5)
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| 28. |
- Prakash, Om, et al.
(författare)
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Photophysical Integrity of the Iron(III) Scorpionate Framework in Iron(III)-NHC Complexes with Long-Lived 2LMCT Excited States
- 2022
-
Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 61:44, s. 17515-17526
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Tidskriftsartikel (refereegranskat)abstract
- Fe(III) complexes with N-heterocyclic carbene (NHC) ligands belong to the rare examples of Earth-abundant transition metal complexes with long-lived luminescent charge-transfer excited states that enable applications as photosensitizers for charge separation reactions. We report three new hexa-NHC complexes of this class: [Fe(brphtmeimb)2]PF6 (brphtmeimb = [(4-bromophenyl)tris(3-methylimidazol-2-ylidene)borate]–, [Fe(meophtmeimb)2]PF6 (meophtmeimb = [(4-methoxyphenyl)tris(3-methylimidazol-2-ylidene)borate]–, and [Fe(coohphtmeimb)2]PF6 (coohphtmeimb = [(4-carboxyphenyl)tris(3-methylimidazol-2-ylidene)borate]–. These were derived from the parent complex [Fe(phtmeimb)2]PF6 (phtmeimb = [phenyltris(3-methylimidazol-2-ylidene)borate]– by modification with electron-withdrawing and electron-donating substituents, respectively, at the 4-phenyl position of the ligand framework. All three Fe(III) hexa-NHC complexes were characterized by NMR spectroscopy, high-resolution mass spectroscopy, elemental analysis, single crystal X-ray diffraction analysis, electrochemistry, Mößbauer spectroscopy, electronic spectroscopy, magnetic susceptibility measurements, and quantum chemical calculations. Their ligand-to-metal charge-transfer (2LMCT) excited states feature nanosecond lifetimes (1.6–1.7 ns) and sizable emission quantum yields (1.7–1.9%) through spin-allowed transition to the doublet ground state (2GS), completely in line with the parent complex [Fe(phtmeimb)2]PF6 (2.0 ns and 2.1%). The integrity of the favorable excited state characteristics upon substitution of the ligand framework demonstrates the robustness of the scorpionate motif that tolerates modifications in the 4-phenyl position for applications such as the attachment in molecular or hybrid assemblies.
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| 29. |
- Prakash, Om, et al.
(författare)
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Tailoring the Photophysical Properties of a Homoleptic Iron(II) Tetra N-Heterocyclic Carbene Complex by Attaching an Imidazolium Group to the (C∧N∧C) Pincer Ligand─A Comparative Study
- 2024
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 63:6, s. 2909-2918
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Tidskriftsartikel (refereegranskat)abstract
- We here report the synthesis of the homoleptic iron(II) N-heterocyclic carbene (NHC) complex [Fe(miHpbmi)2](PF6)4 (miHpbmi = 4-((3-methyl-1H-imidazolium-1-yl)pyridine-2,6-diyl)bis(3-methylimidazol-2-ylidene)) and its electrochemical and photophysical properties. The introduction of the π-electron-withdrawing 3-methyl-1H-imidazol-3-ium-1-yl group into the NHC ligand framework resulted in stabilization of the metal-to-ligand charge transfer (MLCT) state and destabilization of the metal-centered (MC) states. This resulted in an improved excited-state lifetime of 16 ps compared to the 9 ps for the unsubstituted parent compound [Fe(pbmi)2](PF6)2 (pbmi = (pyridine-2,6-diyl)bis(3-methylimidazol-2-ylidene)) as well as a stronger MLCT absorption band extending more toward the red spectral region. However, compared to the carboxylic acid derivative [Fe(cpbmi)2](PF6)2 (cpbmi = 1,1′-(4-carboxypyridine-2,6-diyl)bis(3-methylimidazol-2-ylidene)), the excited-state lifetime of [Fe(miHpbmi)2](PF6)4 is the same, but both the extinction and the red shift are more pronounced for the former. Hence, this makes [Fe(miHpbmi)2](PF6)4 a promising pH-insensitive analogue of [Fe(cpbmi)2](PF6)2. Finally, the excited-state dynamics of the title compound [Fe(miHpbmi)2](PF6)4 was investigated in solvents with different viscosities, however, showing very little dependency of the depopulation of the excited states on the properties of the solvent used.
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| 30. |
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| 31. |
- Zhang, Fan, et al.
(författare)
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In situ investigations of Fe3+ induced complexation of adsorbed Mefp-1 protein film on iron substrate
- 2013
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Ingår i: Journal of Colloid and Interface Science. - : Academic Press. - 0021-9797 .- 1095-7103. ; 404, s. 62-71
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Tidskriftsartikel (refereegranskat)abstract
- A range of in situ analytical techniques and theoretical calculations were applied to gain insights into the formation and properties of the Mefp-I film on iron substrate, as well as the protein complexation with Fe3+ ions. Adsorption kinetics of Mefp-1 and the complexation were investigated using QCM-D. The results suggest an initially fast adsorption, with the molecules oriented preferentially parallel to the surface, followed by a structural change within the film leading to molecules extending toward solution. Exposure to a diluted FeCl3 solution results in enhanced complexation within the adsorbed protein film, leading to water removal and film compaction. In situ Peak Force Tapping AFM was employed for determining morphology and nano-mechanical properties of the surface layer. The results, in agreement with the QCM-D observations, demonstrate that addition of Fe-3 induces a transition from an extended and soft protein layer to a denser and stiffer one. Further, in situ ATR-FTIR and Confocal Raman Micro-spectroscopy (CRM) techniques were utilized to monitor compositional/structural changes in the surface layer due to addition of Fe3+ ions. The spectroscopic analyses assisted by DFT calculations provide evidence for formation of tri-Fe3+/catechol complexes in the surface film, which is enhanced by Fe3+ addition.
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