| 26. |
- Figueiredo, Sonia, et al.
(författare)
-
Temporal and spatial evolution of discrete auroral arcs as seen by Cluster
- 2005
-
Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 23:7, s. 2531-2557
-
Tidskriftsartikel (refereegranskat)abstract
- Two event studies are presented in this paper where intense convergent electric fields, with mapped intensities up to 1350 mV/m, are measured in the auroral upward current region by the Cluster spacecraft, at altitudes between 3 and 5 Earth radii. Both events are from May 2003, Southern Hemisphere, with equatorward crossings by the Cluster spacecraft of the pre-midnight auroral oval. Event 1 occurs during the end of the recovery phase of a strong substorm. A system of auroral arcs associated with convergent electric field structures, with a maximum perpendicular potential drop of about similar to 10 kV, and upflowing field-aligned currents with densities of 3 mu A/m(2) (mapped to the ionosphere), was detected at the boundary between the Plasma Sheet Boundary Layer (PSBL) and the Plasma Sheet (PS). The auroral arc structures evolve in shape and in magnitude on a timescale of tens of minutes, merging, broadening and intensifying, until finally fading away after about 50 min. Throughout this time, both the PS region and the auroral arc structure in its poleward part remain relatively fixed in space, reflecting the rather quiet auroral conditions during the end of the substorm. The auroral upward acceleration region is shown for this event to extend beyond 3.9 Earth radii altitude. Event 2 occurs during a more active period associated with the expansion phase of a moderate substorm. Images from the Defense Meteorological Satellite Program (DMSP) F13 spacecraft show that the Cluster spacecraft crossed the horn region of a surge-type aurora. Conjugated with the Cluster spacecraft crossing above the surge horn, the South Pole All Sky Imager recorded the motion and the temporal evolution of an east-west aligned auroral arc, 30 to 50 km wide. Intense electric field variations are measured by the Cluster spacecraft when crossing above the auroral arc structure, collocated with the density gradient at the PS poleward boundary, and coupled to intense upflowing field-aligned currents with mapped densities of up to 20 mu A/m(2). The surge horn consists of multiple arc structures which later merge into one structure and intensify at the PS poleward boundary. The surge horn and the associated PS region moved poleward with a velocity at the ionospheric level of 0.5 km/s, following the large-scale poleward expansion of the auroral oval associated with the substorm expansion phase.
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| 27. |
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| 28. |
- Herlitz, Johan, 1949, et al.
(författare)
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Factors of importance for patients' decision time in acute coronary syndrome
- 2009
-
Ingår i: International Journal of Cardiology. - 1874-1754. ; 141:3, s. 236-242
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Not much is known about the patients' decision time in acute coronary syndrome (ACS). The aim of the survey was therefore to describe patients' decision time and factors associated with this parameter in ACS. METHODS: We conducted a national survey comprising intensive cardiac care units at 11 hospitals in Sweden in which patients with ACS diagnosis and symptoms onset outside hospital participated. Main outcome measures were patients' decision time and factors associated with patients' decision time. RESULTS: In all, 1939 patients took part in the survey. The major factors associated with a shorter patient decision time were: 1) ST-elevation ACS, 2) associated symptoms such as vertigo or near syncope, 3) interpreting the symptoms as cardiac in origin, 4) pain appearing suddenly and reaching a maximum within minutes, 5) having knowledge of the importance of quickly seeking medical care and 6) experiencing the symptoms as frightening. The following aspects of the disease were associated with a longer decision time: 1) pain was localised in the back and 2) symptom onset at home when alone. CONCLUSION: A number of factors, including the type of ACS, the type and localisation of symptoms, the place where symptoms occurred, patients' interpretation of symptoms and knowledge were all associated with patients' decision time in connection with ACS.
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| 29. |
- Hollenberg, Jacob, et al.
(författare)
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Difference in survival after out-of-hospital cardiac arrest between the two largest cities in Sweden: a matter of time?
- 2005
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Ingår i: J Intern Med. - : Wiley. - 0954-6820 .- 1365-2796. ; 257:3, s. 247-54
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Dramatic differences in survival after out-of-hospital cardiac arrests (OHCA) reported from different geographical locations require analysis. We therefore compared patients with OHCA in the two largest cities in Sweden with regard to various factors at resuscitation and outcome. SETTING: All patients suffering an OHCA in Stockholm and Goteborg between 1 January 2000 and 30 June 2001, in whom cardiopulmonary resuscitation (CPR) was attempted were included in this retrospective analysis. RESULTS: All together, 969 OHCA in Stockholm and 398 in Goteborg were registered during the 18-month study period. There were no differences in terms of age, gender, and percentage of witnessed cases or percentage of patients who had received bystander CPR. However, the percentage of patients with ventricular fibrillation (VF) at arrival of the ambulance crew was 18% in Stockholm versus 31% in Goteborg (P <0.0001). The percentage of patients who were alive 1 month after cardiac arrest was 2.5% in Stockholm versus 6.8% in Goteborg (P=0.0008). Various time intervals such as cardiac arrest to calling for an ambulance, cardiac arrest to the start of CPR and calling for an ambulance to its arrival were all significantly longer in Stockholm than in Goteborg. CONCLUSION: Survival was almost three times higher in Goteborg than in Stockholm amongst patients suffering an OHCA. This is primarily explained by a higher occurrence of VF at the time of arrival of the ambulance crew, which in turn probably is explained by shorter delays in Goteborg. The reason for the difference in time intervals is most likely multifactorial, with a significantly higher ambulance density in Goteborg as one possible explanation.
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| 30. |
- Hollenberg, Jacob, et al.
(författare)
-
Improved survival after out-of-hospital cardiac arrest is associated with an increase in proportion of emergency crew--witnessed cases and bystander cardiopulmonary resuscitation.
- 2008
-
Ingår i: Circulation. - : Lippincott Williams & Wilkins. - 1524-4539 .- 0009-7322. ; 118:4, s. 389-96
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Out-of-hospital cardiac arrest (OHCA) is a major public health problem. We sought to describe changes in 1-month survival after OHCA in patients given cardiopulmonary resuscitation (CPR) during the last 14 years in Sweden. METHODS AND RESULTS: All patients experiencing OHCA in whom CPR was attempted between 1992 and 2005 and who were reported to the Swedish Cardiac Arrest Register were included in the study. In all, 38,646 patients were included in this survey. The proportion of patients who were admitted alive to a hospital increased from 15.3% in 1992 to 21.7% in 2005 (P for trend <0.0001). The corresponding values for patients being alive after 1 month were 4.8% and 7.3%, respectively (P for trend <0.0001). The increase in 1-month survival was particularly evident among patients found with a shockable rhythm (increase from 12.7% in 1992 to 22.3% in 2005; P for trend <0.0001). The corresponding figures for patients found with a nonshockable rhythm were 1.2% in 1992 and 2.3% in 2005 (P for trend=0.044). Factors that potentially contributed to the improved survival rate were an increase in emergency medical crew-witnessed cases from 9% in 1992 to 15% in 2005 (P for trend <0.0001) and, to a lesser degree, an increase in bystander CPR from 31% in 1992 to 50% in 2005 (P for trend <0.0001). After adjustment for potential risk factors, the increase in survival remained significant. CONCLUSIONS: We found a significant increase in survival after OHCA in Sweden over the last 14 years. The increase was particularly marked among patients found with a shockable rhythm and was associated with an increase in the proportion of crew-witnessed cases and, to a lesser degree, an increase in the performance of bystander CPR.
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| 31. |
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| 32. |
- Kuna, P., et al.
(författare)
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Once-daily dosing with budesonide/formoterol compared with twice-daily budesonide/formoterol and once-daily budesonide in adults with mild to moderate asthma
- 2006
-
Ingår i: Respiratory Medicine. - : Elsevier BV. - 1532-3064 .- 0954-6111. ; 100:12, s. 2151-2159
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Tidskriftsartikel (refereegranskat)abstract
- Adherence to maintenance therapy is often poor in patients with asthma. Simplifying dosing regimens has the potential to improve both adherence and asthma-retated morbidity. In this 12-week, randomized, double-blind, double-dummy, parattel-group study, 617 patients with mild to moderate persistent asthma (mean forced expiratory volume in 1 s [FEV,] 78.5% predicted) who were not optimally controlled on inhaled corticosteroids (200-500pg/day) were randomized to once-daily budesonide/formoterot (80/4.5 tg, 2 inhalations in the evening), twice-daity budesonide/formoterol (80/4.5 pg, 1 inhalation), or a corresponding dose of budesonide once-daily (200pg, 1 inhalation in the evening). AR patients received budesonide (100pg twice daily) during a 2-week run-in. Changes in mean morning peak expiratory flow (PEF) were similar for od budesonide/formoterol (23.4 l/min) and twice-daily budesonide/formoterot (24.1 l/min), and both were greater than with budesonide (5.5 Unnin; both P < 0.001). Evening PEF, symptom-free days, reliever-free days, and asthma control days were improved with budesonide/ formoterol therapy vs. budesonide (P < 0.05 vs. budesonide for all variables). All treatments were well tolerated. Budesonide/formoterot administered once daily in the evening is a convenient treatment regimen that is as effective in improving asthma control as twice-daily dosing in patients with mild to moderate persistent asthma. (c) 2006 Elsevier Ltd. All rights reserved.
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| 33. |
- Levin, Max, 1969, et al.
(författare)
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ATP depletion and cell death in the neonatal lamb ductus arteriosus
- 2005
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Ingår i: Pediatr Res. - 0031-3998. ; 57:6, s. 801-805
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Tidskriftsartikel (refereegranskat)abstract
- Postnatal constriction of the full-term ductus arteriosus produces cell death and remodeling of the ductus wall. Using a bioluminescence imaging technique, we found that after birth, the lamb ductus develops ATP, glucose, and glycogen depletion in addition to hypoxia. In vitro studies showed that cell death correlates best with ATP depletion and is most marked when both glucose and oxygen are severely depleted; in addition, the degree of ATP depletion found in vivo is sufficient to account for the extensive degree of cell death that occurs after birth. Under hypoxic conditions, the immature ductus is more capable of preserving its ATP supply than the mature ductus as a result of increased glucose availability, glycogen stores, and glucose utilization. However, the immature ductus is just as susceptible as the mature ductus to ATP depletion when glucose supplies are restricted. The extensive degree of cell death that occurs in the newborn ductus after birth is associated primarily with ATP depletion. The increased glycolytic capacity of the immature ductus may enable it to tolerate episodes of hypoxia and nutrient shortage, making it more resistant to developing postnatal cell death and permanent closure.
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| 34. |
- Lindqvist, Anna-Karin, et al.
(författare)
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Influence on spontaneous tissue inflammation by the major histocompatibility complex region in the nonobese diabetic mouse.
- 2005
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Ingår i: Scandinavian Journal of Immunology. - : Wiley. - 1365-3083 .- 0300-9475. ; 61:2, s. 119-127
-
Tidskriftsartikel (refereegranskat)abstract
- We investigated the role of the major histocompatibility complex (MHC) region in the specificity of autoimmunity by analysing specifically the development of sialadenitis, but also insulitis, nephritis and autoantibody production in autoimmune-prone nonobese diabetic (NOD) mice where the MHC H2g7 haplotype had been exchanged for the H2q (NOD.Q) or H2p (NOD.P) haplotype. The exchange of H2 haplotype did not affect the frequency of sialadenitis because the H2q and H2p congenic NOD strains developed sialadenitis with the same incidence as NOD. However, the severity of sialadenitis varied among the strains, as NOD.Q > NOD > NOD.P. At 11–13 weeks of age, the NOD.Q (H2q) female mice developed more severe sialadenitis compared to NOD.P (H2p) (P = 0.038). At 20 weeks, the NOD (H2g7) female mice showed more severe sialadenitis than NOD.P (P = 0.049). This is in contrast to the development of insulitis in the present strains, because the incidence of insulitis was almost completely inhibited by the replacement of the H2g7 haplotype of NOD. The incidence of insulitis in NOD.Q was 11–22%, compared to 75% in NOD, which correlated well with lower titres of anti-glutamic acid decarboxylase (anti-GAD) antibodies in NOD.Q compared to NOD (P = 0.009). However, the introduction of the H2q haplotype into the NOD strain instead directed the autoimmune response towards the production of lupus types of autoantibodies, because the incidence of antinuclear antibodies (ANA) in NOD.Q was 89% compared with 11% in NOD.P and 12% in NOD mice, which in turn correlated with a high incidence of nephritis in NOD.Q compared to NOD. Consequently, we show that different haplotypes of MHC are instrumental in directing the specificity of the spontaneous autoimmune inflammation. This article is cited by:
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| 35. |
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| 36. |
- Lindqvist, Charlotte, et al.
(författare)
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The Laptev Sea walrus Odobenus rosmarus laptevi: an enigma revisited
- 2009
-
Ingår i: Zoologica Scripta. - : Wiley. - 0300-3256 .- 1463-6409. ; 38:2, s. 113-127
-
Tidskriftsartikel (refereegranskat)abstract
- The walrus (Odobenus rosmarus) is in some current systematic schemes divided into three subspecies: O. r. rosmarus in the North Atlantic, O. r. divergens in the North Pacific and O. r. laptevi in the Laptev Sea. These three subspecies have been described as differing in body size, but the taxonomic status of O. r. laptevi is disputed. The current study applies molecular and morphometric methods to assess the taxonomic status of O. r. laptevi and to analyse the systematic and phylogeographic relationships between the three purported walrus subspecies. Tusk length and tusk circumference were measured from the few skulls available of O. r. laptevi, and the obtained values were within the ranges reported for Pacific walruses. Thus, morphologically, subspecies status for O. r. laptevi is not supported according to the Amadon Mayr '75% rule'. Phylogenetic analyses and haplotype networks based on mitochondrial nucleotide sequence data of NADH dehydrogenase 1, 16S rRNA, cytochrome oxidase I and the D-loop of the control region of the historic O. r. laptevi bone material and contemporary O. r. rosmarus and O. r. divergens showed that the Laptev Sea walrus groups with individuals from the North Pacific. Thus, the mitochondrial sequence data do not support the recognition of three walrus subspecies as reciprocally monophyletic evolutionary units with independent evolutionary histories. Only O. r. rosmarus and O. r. divergens meet this criterion with the present sampling. Accordingly, we recommend that Odobenus r. laptevi be abandoned and the Laptev walrus instead be recognized as the westernmost population of the Pacific walrus, Odobenus r. divergens. However, further research is recommended to assess whether the Laptev walrus could be considered as a significant unit in terms of conservation and management, since it is unique in several ecological parameters.
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| 37. |
- Lindqvist, Judit, 1965-
(författare)
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Hot spur or tranquil? : The adaptation of psychometric anger assessment instruments and their evaluation and application on violent and nonviolent samples in Sweden
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Anger is a negatively toned emotion and biopsychosocially functional alarm, which automatically activates a colorful arsenal of affective, cognitive, physiological, and behavioral action impulses in the face of experienced irritations and provocations. Anger, on the other hand, is a mixed blessing and a subject of admiration and condemnation since the days of Plato, Aristotle and Thomas Aquinas. This usual and passionate human emotion has also been closely associated with phenomena of human psychopathology: mental and personality disorders, aggression, interpersonal difficulties, and violence. Until the recent past, conceptual confusion and scientific neglect have complicated the research on anger.Following a theoretical review of multiple, classical philosophical and contemporary, scientific approaches to anger, this thesis describes the work towards its principal aim: to develop the first Swedish adaptations of the psychometric anger assessment instruments Novaco Anger Scale (NAS, version 1998), Provocation Inventory (PI), and State-Trait Anger Expression Inventory-2 (STAXI-2). These psychometric anger assessment instruments focus on various theoretical dimensions of the anger concept; NAS assesses the cognitive mediation, physiological arousal, and behavioral action impulses and control efforts that compose anger. PI assesses the intensity of anger reaction as a function of various provocations. Finally, STAXI-2 assesses the various state and trait experience, expression, and control of anger. The adaptations of the instruments were developed through the co-operation of the authors of the three studies included in this thesis, with a native back-translator, and also with the authors of the original instruments. The adaptations, labeled NAS-1998-S, PI-S, and STAXI-2-S, were investigated on the basis of their factor structures, internal reliability, scale correlations, and predictive capacity of group membership of participants, in male samples of violent prisoners (N = 95; Mage = 33.2, SDage = 10.6) and nonviolent university students (N = 100; Mage = 33.2, SDage = 12.5) in Sweden. Furthermore, the level of anger reported by the violent criminal and nonviolent university student samples in Sweden was compared, as were those in turn with published norm values of American standardization samples of the original instruments. According to the results presented in the thesis, NAS-1998-S, PI-S, and STAXI-2-S have appropriate psychometric qualities. More specifically, NAS-1998-S and PI-S (but not STAXI-2-S) demonstrated factor structures that were interpreted as corresponding to the findings of previous studies on the original instruments. The parts that compose NAS-1998-S, PI-S, STAXI-2-S (i.e., subscales, scales, and total scale scores) were in good correspondence with what could be expected on the basis of previous findings on the original instruments. The scales had an appropriate pattern of correlations with concurrent scales of related and distinct theoretical constructs. The adapted assessment instruments demonstrated good capacities to discriminate the prisoners and university students from each other. The results were interpreted in terms of appropriate construct and cross-cultural validity. As expected, the violent prisoners scored higher on the various cognitive, physiological, behavioral, trait, and expressed dimensions of anger, and lower on anger control, compared with nonviolent university students and persons in the American standardization samples. An unexpected, but culturally explainable result was the relatively high levels of anger suppression by both Swedish samples. In particular, the scores of violent prisoners on cognitive inclination and general disposition to anger approached clinically high levels. The high levels of anger in the violent prisoners were interpreted as supportive of previous research indicating the high prevalence of psychopathology in the offender population. Anger being an important antecedent of aggressive behavior and a vital correlate of clinical disorders, the systematic assessment of this emotion has not yet earned a high priority in the research and clinical work with offenders in Sweden. The work described in this thesis is an effort to remedy this condition.
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| 38. |
- Lindqvist, Judit, et al.
(författare)
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Internal reliability and construct validity of the Novaco Anger Scale-1998-S in a sample of violent prison inmates in Sweden
- 2005
-
Ingår i: Psychology, Crime and Law. - : Informa UK Limited. - 1068-316X .- 1477-2744. ; 11:2, s. 223-237
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, the internal reliability and construct validity of the recently adapted Swedish version of the Novaco Anger Scale (NAS-1998-S; Lindqvist, Dderman, & Hellstrm, Social Behavior and Personality, 8, 773-788, 2003), as well as its scale correlations with demographic and criminality variables, were investigated. Construct validity was established by assessing the correlation pattern of the scales of NAS-1998-S with concurrent scales of similar and distinct constructs. Ninety-five male violent prisoners, ranging in age from 18 to 67 years, participated. The results demonstrated good internal reliability, consistent intrascale relationships, and appropriate construct validity of NAS-1998-S. The number of previous convictions had a moderate negative relationship with the capacity of control. Age and education correlated negatively with the NAS-1998-S scales, except Regulation. In addition to psychometric issues, the results were discussed from a clinical perspective on the offender population.
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| 39. |
- Lindqvist, Madelene, 1982, et al.
(författare)
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Local cytokine and inflammatory responses to candidate vaginal adjuvants in mice.
- 2009
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Ingår i: Vaccine. - : Elsevier BV. - 1873-2518 .- 0264-410X. ; 28:1, s. 270-8
-
Tidskriftsartikel (refereegranskat)abstract
- The current study was undertaken to explore the correlation of adjuvanticity and local inflammatory response elicited in the murine vagina and the draining lymph nodes following local administration of two candidate vaginal adjuvants, Toll like receptor (TLR) 9 agonist CpG ODN, and a non-TLR targeting molecule alpha-galactosylceramide (alpha-GalCer). Using real-time PCR array analysis, we could show that a group of 13 common cytokine genes are activated in the vagina within 24h after vaginal administration of these adjuvants, including Ccl2, Ccl7, Ccl12, Ccl19, Ccl20, Ccl22, Cxcl1, Cxcl5, Il10 and the Th1-inducing molecules Ifng, Cxcl9, Cxcl10 and Cxcl11. A high degree of inflammation in and damage to the epithelium was exclusively observed in the vagina of the CpG ODN treated mice, which was reversed within 48h. These results indicate that there is a group of common genes that correlate with the adjuvanticity of CpG ODN and alpha-GalCer in the vagina, and that alpha-GalCer induces less of local inflammatory reactions in the murine vagina compared to CpG ODN.
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| 40. |
- Lindqvist, Michael, 1960, et al.
(författare)
-
MERLIN observations of OH/IR stars
- 2008
-
Ingår i: Proceedings of the 9th European VLBI Network Symposium on The role of VLBI in the Golden Age for Radio Astronomy and EVN Users Meeting.. ; , s. 81-83
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 41. |
- Lindqvist, Michael, 1960, et al.
(författare)
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MERLIN observations of OH/IR stars
- 2008
-
Ingår i: Proceedings of Science. - 1824-8039. ; 72
-
Konferensbidrag (refereegranskat)abstract
- We present MERLIN OH 1612 MHz observations towards 3 OH/IR stars, OH15.7+0.8, OH38.3+1.9 and IRAS 19319+2214. The main objective of the project is to investigate if their complicated OH 1612 MHz spectral properties can be related to the phenomenon of highly time-variable mass loss found towards a handful of carbon stars, where detached shells with an overall spherical symmetry are present. Despite extensive searches, no oxygen-rich star with such a shell has been found in any molecular emission. Based on the MERLIN data however, we find that the circumstellar structure of the three OH/IR stars appears to be more complicated than that of detached shells. Signs of bipolarity in the outflows of OH38.3+1.9 and IRAS 19319+2214 could indicate that these are early post-AGB objects.
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| 42. |
- Lindqvist, Madelene, 1982, et al.
(författare)
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The mucosal adjuvant effect of alpha-galactosylceramide for induction of protective immunity to sexually transmitted viral infection.
- 2009
-
Ingår i: Journal of immunology (Baltimore, Md. : 1950). - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 182:10, s. 6435-43
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Tidskriftsartikel (refereegranskat)abstract
- Development of mucosal adjuvants to generate immunity in the female genital tract may have important implications for the development of vaccines to counter sexually transmitted infections. alpha-Galactosylceramide (alpha-GalCer) is presented by CD1d molecule on APCs to invariant Valpha14(+) NKT (iNKT) cells, which upon activation rapidly produce large amounts of immunomodulatory cytokines, leading to activation of a variety of innate and adaptive immune cells. Here, we assessed whether alpha-GalCer could act as a mucosal adjuvant for induction of protective immunity against genital herpes. We found that intranasal immunization with HSV-2 glycoprotein D (gD) in combination with alpha-GalCer elicits strong systemic gD-specific IgG Ab response as well as lymphoproliferative response with a mixed Th1/Th2 cytokine profile in the spleen, mediastinal lymph nodes, and genital lymph nodes. Importantly, such an immunization scheme conferred complete protection against an otherwise lethal vaginal HSV-2 challenge. We could also show that intravaginal immunization with gD plus alpha-GalCer generates potent gD-specific lymphoproliferative and IFN-gamma responses in the genital lymph nodes and spleen. Furthermore, the vaginally immunized mice developed a strong systemic and mucosal IgG Ab response and protection against vaginal HSV-2 challenge. The mucosal adjuvant effect of alpha-GalCer was found to be mediated via CD1d molecule and appeared to be independent of the usage of the adaptor molecule MyD88. To our knowledge, this is the first report on the mucosal adjuvant effect of alpha-GalCer for induction of protective immunity against a sexually transmitted pathogen.
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| 43. |
- Lindqvist, Per-Arne, et al.
(författare)
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EFW data in the Cluster Active Archive
- 2006
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Ingår i: European Space Agency, (Special Publication) ESA SP. - 929092909X ; , s. 495-499
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Konferensbidrag (refereegranskat)abstract
- The Cluster Active Archive is being assembled with the aim to hold high-quality, high-resolution Cluster instrument data for scientific use in both the near and the distant future. In this paper, the contributions to the archive from the Electric Field and Waves instrument are described. The archived data quantities are listed and explained, together with information on how they are computed and measures taken to ensure high scientific quality. Calibrating dc electric field data is a tedious process which involves both comparison with other data sets and theoretical as well as empirical modelling.
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| 44. |
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| 45. |
- Ngoma, Athuman M. K.
(författare)
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Characterisation and Consolidation of Historical Lime Mortars in Cultural Heritage Buildings and Associated Structures in East Africa
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- For the period of several centuries, the influence of several distinct cultures produced rich and diverse cultural heritage that we see today in East Africa countries. The most tangible remains of these heritages are stone built buildings and structures including, palaces, mosques, residential houses and tombs. At present, these heritages are in different physical state, some are in relatively good condition while many are in an appalling condition. The presence of these historical monuments has benefited these countries economically and culturally therefore, it is essential to ensure that these monuments continue to exist. Material characterisation of the historical buildings and associated structures was used to develop a suitable method of intervention that is sympathetic to the original materials. Mortar is the most damaged material therefore, historical mortar from Stone Town historical buildings and associated structures has been characterised by visual examination, optical microscopy, x-ray diffraction and hydrostatic weighing and the results have been compared. The historical mortar is mainly comprised of calcite, quartz and feldspar. The mortar condition has been divided into hard mortar, soft mortar and, soft and friable mortar. The deteriorated mortar that required consolidation is soft mortar and, soft and friable mortar with a porosity of approximately 27%. Calcium hydroxide solution (limewater) has been selected as consolidant and the consolidation procedure involves two steps. Firstly a limewater impregnation procedure has been developed and secondly, the effect of limewater treatment has been determined. For the application procedure it has been observed that, when limewater comes into contact with calcium carbonate a precipitation reaction occurs and that is the cause of poor penetration ability of calcium hydroxide solution. Major influencing factors on the penetration ability of calcium hydroxide solution have been established as, application method and absorption capacity of the treated material during the impregnation process. Optimization of the penetration ability of calcium hydroxide solution has been achieved by impregnating from the middle of the impregnated specimen. Sugar has been used to study the influence of additive on enhancing calcium hydroxide solubility. It has been verified that solubility of calcium hydroxide in a solution of sugar is proportional to the amount of sugar in the solution. Porosity and strength tests have been used to study the effectiveness of calcium hydroxide treatment. Under the conditions studied no appreciable change of porosity has been detected. It is postulated that the calcium hydroxide was deposited at the binder/aggregate interface and at the secondary pores. In terms of strength, evidence has been found to suggest the strength increment varies quantitively with the amount of calcite crystals deposited.
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| 46. |
- Nilsson, Mats E., et al.
(författare)
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Ljudkvalitet i parker och grönområden i Stockholm
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Guideline values for traffic-noise exposure in urban outdoor spaces are missing, mainly due to the lack of knowledge on the effect of noise on perceived soundscape quality. For this reason, a questionnaire study was conducted in 16 city parks and green open spaces in Stockholm. In total, 1116 respondents answered questions on, inter alia, perceived soundscape quality and road traffic noise annoyance. The areas included a wide range of soundscapes, from highly traffic noise exposed city parks to quiet suburban open spaces. Consistent relationships were found between, on the one hand, measured overall sound levels and, on the other hand, perceived soundscape quality and road traffic noise annoyance. As expected, soundscape quality was negatively related to presence of technological sounds (e.g., road traffic noise) and positively related to presence of nature sounds. These relationships remained also after controlling for overall measured sound level. Taken together, the results suggest, as a rule of thumb, that good soundscape quality in urban open spaces would require day time traffic noise exposure below 50 dBA (Lday). In situations with exposures between 50 and 55 dBA, soundscape design that promotes positive sounds from nature may be efficient in improving soundscape. At higher levels, soundscape design has to be complemented with traditional noise abatement methods in order to achieve good soundscape quality.
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| 47. |
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| 48. |
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| 49. |
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| 50. |
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