| 1. |
- Holmberg, Anders
(författare)
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Contact fatigue and crack propagation studies of sintered PM steel
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gears made of PM steel are of interest for the automotive industry because from the press/sinter route, complex geometries can be produced to near net shape with only a few processing steps while keeping the material and energy usage at a minimum. However, the PM steels of today have significant performance limitations caused by the inherent porosity which impairs the mechanical properties by acting as stress raisers in the material. The teeth of automotive gears are subjected to pure rolling and sliding as well as a mixture between the two, leading to different mechanisms of wear at different parts of the gear surface. Pure rolling occurs only at the pitch line and the sliding to rolling ratio increases with distance from it. At the vicinity of the pitch line, the force acting on the gear teeth is at its maximum and the repeated cyclic loading leads to fatigue wear. For PM steels, which due to the porosity are highly sensitive to cyclic loads, this results in crack initiation at pores underneath the surface, eventually causing failure of the gear teeth as these cracks propagate to the surface. The SSF project Nanotechnology Enhanced Sintering Steel Processing aims to reduce the gap in performance between PM steels and wrought steels by using nanopowders as a compliment to the standard microsized powder to increase the performance of the material. This thesis aims to increase the knowledge of how different manufacturing parameters, such as sintering temperature, initial powder particles size distribution and addition of nanopowder affect the fatigue properties of the materials. This was done by developing new test equipment for rolling contact fatigue which simulates the contact at the pitch line in a spur gear contact. Utilizing extensive image analysis enables coupling of the different input parameters and their respective pore and microstructure to the fatigue properties. Furthermore, I have investigated how cracks propagate in PM steels using a novel setup which can propagate short cracks in the material. Extensive EBSD studies were performed on the materials after sintering, after case hardening and on cracks after testing. From the rolling contact fatigue tests and image analysis, it was found that materials manufactured using a finer powder fraction together with a higher sintering temperature results in a material well suited for handling cyclic fatigue despite the inherent porosity. Also, by adding a relatively small amount of nanopowder to the standard fraction the fatigue properties were improved considerably. The improved fatigue properties are probably attributed to the reduction of pores with a size in the range of 200 – 400 µm2. These pores are probably the cause of early crack initiation as they are large enough in size as well as in numbers. Smaller pores, although many in numbers do not appear to promote early crack initiation and larger pores, although critical in terms of size, are too few to statistically affect the outcome of the fatigue tests. From the crack propagation studies, it was found that cracks appear to propagate along prior austenite grain boundaries, which for sintered steels are highly related to the particle boundaries after sintering. A finding which helps to explain the deflective pattern of crack propagation found in the rolling contact fatigue studies.
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| 3. |
- Holmlund, Petter, 1988-, et al.
(författare)
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Posture-dependent collapse of the optic nerve subarachnoid space : A combined MRI and modeling study
- 2021
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Ingår i: Investigative Ophthalmology and Visual Science. - : Association for Research in Vision and Ophthalmology. - 0146-0404 .- 1552-5783. ; 62:4
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: We hypothesize that a collapse of the optic nerve subarachnoid space (ONSAS) in the upright posture may protect the eyes from large translamina cribrosa pressure differences (TLCPD) believed to play a role in various optic nerve diseases (e.g., glaucoma). In this study, we combined magnetic resonance imaging (MRI) and mathematical modeling to investigate this potential ONSAS collapse and its effects on the TLCPD.METHODS: First, we performed MRI on six healthy volunteers in 6° head-down tilt (HDT) and 13° head-up tilt (HUT) to assess changes in ONSAS volume (measured from the eye to the optic canal) with changes in posture. The volume change reflects optic nerve sheath (ONS) distensibility. Second, we used the MRI data and mathematical modeling to simulate ONSAS pressure and the potential ONSAS collapse in a 90° upright posture.RESULTS: The MRI showed a 33% decrease in ONSAS volume from the HDT to HUT (P < 0.001). In the upright posture, the simulations predicted an ONSAS collapse 25 mm behind lamina cribrosa, disrupting the pressure communication between the ONSAS and the intracranial subarachnoid space. The collapse reduced the simulated postural increase in TLCPD by roughly 1 mm Hg, although this reduction was highly sensitive to ONS distensibility, varying between 0 and 4.8 mm Hg when varying the distensibility by ± 1 SD.CONCLUSIONS: The ONSAS volume along the optic nerve is posture dependent. The simulations supported the hypothesized ONSAS collapse in the upright posture and showed that even small changes in ONS stiffness/distensibility may affect the TLCPD.
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| 4. |
- Vimláti, László, 1971-
(författare)
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Benefits of Spontaneous Breathing : Compared with Mechanical Ventilation
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- When spontaneous breathing (SB) is allowed during mechanical ventilation (MV), atelectatic lung areas are recruited and oxygenation improves thereby. Whether unsupported SB at its natural pattern (without PEEP and at low pressure/small tidal volume) equally recruits and improves oxygenation, and if so by which mechanism, has not been studied.A porcine lung collapse model was designed to study this question. The cardiac output dependency of the pulmonary shunt was investigated with healthy lungs and with major shunt (during one-lung ventilation) and with SB, MV and continuous positive airway pressure (CPAP). The hypoxic pulmonary vasoconstriction (HPV) was blocked with sodium nitroprusside (SNP) to see whether HPV is the only mechanism available for ventilation/perfusion (VA/Q) matching during MV and SB. In all experiments, respiratory rate and tidal volume during MV were matched to SB. Oxygenation was assessed by serial blood gas measurements, recruitment by thoracic CTs; pulmonary shunt was assessed by multiple inert gas elimination or venous admixture.SB attained better oxygenation and lower pulmonary shunt compared with MV, although it did not recruit collapsed lung. Pulmonary shunt did not correlate with cardiac output during SB, whereas a correlation was found during MV and CPAP. With blocked HPV, pulmonary shunt was considerably lower during SB than MV.In conclusion, SB improves VA/Q matching as compared with MV, even when no recruitment occurs. In contrast to MV and CPAP, cardiac output has no major effect on pulmonary shunt during SB. The improved VA/Q matching during SB despite a blocked HPV might indicate the presence of a SB-specific mechanism that improves pulmonary blood flow redistribution towards ventilated lung regions independent of or supplementary to HPV.
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| 5. |
- Wiklund, Jenny, 1975-
(författare)
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Journal - rekonstruktion av kropp och minne
- 2017
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Konstnärligt arbete (övrigt vetenskapligt/konstnärligt)abstract
- Projektet har utvecklats i interdisciplinärt samarbete mellan Jenny Wiklund och KTH, Akademiska Sjukhuset i Uppsala, Uppsala Universitet, Karolinska Institutet, Kungl. Konsthögskolan, Aarhus Arkitektskole, och curator Jan Åman.Projektet har utvecklats skulpturalt vid Kungl. Konsthögskolan. Förstudier har genomförts vid Karolinska Universitetssjukhuset. I finalstudien kombineras studier vid Uppsala Akademiska Sjukhuset, Bild- och Funktionsmedicinskt centrum/Röntgen i tredimensionell visualisering av medicinsk bild med studier i klinisk anatomi vid Uppsala Universitet, för att förenas i skulptural gestaltning och iscensättning.R1 Reaktorhallen iscensätts som ett platsspecifikt monumentalverk. Den fysiska installationen i rummet bildar en temporal kappa om utställningskapitlen i avhandlingsutställningen som handlar om kropp och hjärna. Utställningen berättar om en specifik tidpunkt, utan minne och proprioception. Här finns ingen historia och ingen framtid.Genom utställningen skapas en förståelse för sambanden mellan teoretiskt tänkande och visuell gestaltning. Det är forskning genom konstnärlig och arkitektonisk precision med referenser till konst, arkitektur, medicin och medicinsk teknik. Referenserna är från verkliga objekt i verkliga rum, specifika verk från specifika konstnärer och genom auskultering vid flertalet expertpresentationer, där människor genom närvaro förmedlat sin kunskap.Arkitektur är spatial konstruktion av identitet, här i utställningsform som temporal visuell spatial-estetisk poetik. Formen på framläggningen av avhandlingen är vald efter det huvudsakliga ämnet som utreds, minnet, och dess temporala omskapande av rummet vid varje specifik tidpunkt det framkallas. Det visuella intrycket kommer före alla andra beskrivningar, i logik med den händelse som föregick doktorandprojektets ämne, en minnesförlust, där upplevelsen av rummet kom före språket, kroppen före hjärnan, intränade minnen i form av siffror före en självbiografi.
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| 6. |
- Forssell, Jonas
(författare)
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Textens Transfigurationer
- 2015
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Konstnärligt arbete (övrigt vetenskapligt/konstnärligt)abstract
- This thesis focuses on the opera text enlightened from four different perspectives: the translator, the librettist, the composer and finally the singer, based on the author’s thirty years of professsional practice, in the spirit of Donald A. Schön’s study from 1983: The Reflective Practitioner; How professionals think in action. The method is basically hermeneutic and the esthetics inspired by Umberto Eco’s Opera Aperta (”The Open Work”) from 1962. Questions from within the perspective of the translator are: In what ways does opera translation differ from other forms of translation, and how does an opera translator work? What is the history of “opera in the ver-nacular” compared to “opera in original language” and are singable translations needed whatsoever in the modern era of subtitling? The perspective of the librettist examines the opera form’s SWOT-analysis, the differences from other “storytelling” art forms, the task of making an adaption compared to choosing to create an original plot, the matter of taste and building the form from dramaturgical principles, the shaping of aria texts, the importance of tight collaboration and cutting, cutting, cutting (“a libretto cannot be short enough” Edgar Istel, 1922). The composer’s perspective contains practical and theoretical words of advice and examples from practice, together with a so ”think aloud”-study from within a composer’s thought process while working. The final chapter, from the singer’s perspective, focuses on whether modern vocal ideals and singing “in original language”, with subtitles, together with expanding performance halls, have made opera text harder to perceive, and rendered earlier established texting techniques forgotten or obsolete. The answers to all these questions are complex. This thesis concludes that the opera form is still expanding, but not necessarily in the direction of creating a new, contemporary canon. “There are about 600 opera houses in the world, all are ‘National Galleries’, none is the Tate Modern” (Per-Erik Öhrn, 2012), but there are also opportunities. Almost all successful new opera productions in recent years have their librettos written in English, a language traditionnally regarded as “weak” in the field of opera. Opera audiences worldwide are nowadays accustomed to hearing and understanding sung English words and comprehending a dramatic context when expressed in English, thanks to 100 years of Anglo-American dominance in popular music and about 50 years of dominance in television and films.
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| 7. |
- Lomnäs, Erling, 1933-
(författare)
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Franz Berwalds Estrella de Soria : Verkhistorik. Källor. Edition av libretto och överblivna nottexter
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The first step of the creation of Estrella de Soria ended in Vienna in 1841, with the finishing of an opera entitled “Estrella di Soria”. Major parts of this opera probably had been composed already in Berlin in the years before. An Austrian dramatist, Otto Prechtler, could offer Berwald a libretto suiting him. In Vienna, after only a private rehearsal of parts of the opera, the libretto was revised – and the score just put aside! It then had to rest for nearly two decades.At the latest in 1861, Berwald was promised to have his work staged at the Stockholm Royal Theatre. He revised “Estrella di Soria”, using the new libretto of 1841/42. Massive parts of the score were refused, other sections revised, new music added.The result, Estrella de Soria, now with Spanish spelling, still proved too largescale. Berwald had to reduce the compass further before and during the performances in April 1862. The reductions ended in a “final” version of the opera.This “final” version has been published in vol. 17a-b of Franz Berwald. Sämtliche Werke / Complete Works (BwGA, Bärenreiter-Verlag, Kassel etc.) In the present dissertation all manuscripts not included in the “final” version have been accounted for and edited (partly being a pre-edition of vol. 17c of BwGA), together with an overview and discussion of the creation of the opera.
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| 8. |
- Sperling, Martina, 1969-
(författare)
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Glucks Reformopern in der Gustavianischen Epoche : Eine Repertoirestudie im Kontext europäischer Hoftheater in der zweiten Hälfte des 18.Jahrhunderts
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is to be understood as an analysis in which the first-night opera repertoires at four European court-theatres are discussed and compared during a period of approximately twenty years (from 1771 to 1792) corresponding to the rule of Gustav III of Sweden.The study focuses on Christoph Willibald Gluck's reform-operas Orfeo ed Euridice, Alceste, Iphigénie en Aulide, Iphigénie en Tauride and Armide, the same five Gluck-operas which after Gustav III had had them introduced at his newly-founded Royal Opera came to constitute an essential part of the Gustavian Opera's repertoire.Apart from the Royal Opera in Stockholm, the Imperial Court-Theatres in Vienna, the Académie Royale de Musique in Paris and the Tsarist Court-Theatres in St.Petersburg together with the Counts of Chérémétief's private theatres in Kouskovo and Ostankino are dealt with in the present study. This clearly demonstrates that each repertoire bears immanent features due to traditional, cultural and political influences granting Gluck's reform-operas acclaimed reception or not. In order to locate Gluck's status and that of his reform-works in the above mentioned theatres, it was considered essential to carry out empirical investigations elucidating the politico-cultural situation in the respective countries. Attention was explicitly directed to characterizing the individual personalities of the monarchs who, ruling as enlightened despots, to a certain extent used opera as a tool in order to influence public opinion.The appendix provides a description of the musical sources – covering the score, instrumental and vocal parts – for the first night performances of Alceste in 1781 and Iphigénie en Tauride in 1783, as well as of the stage design dating from 1809/10 – of the five relevant reform-operas at the Stockholm Royal Opera. Furthermore the descriptive records of the composition of the orchestra, chorus and ballet of the same performances are included.
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| 9. |
- Strömberg, Thomas, 1965-
(författare)
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The Regulation of Growth and Survival in Human Multiple Myeloma Cells by IGF-I Receptor Signaling
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Multiple myeloma (MM) is an incurable B-cell malignancy mainly localized to the bone marrow. Our aim was to examine the growth- and survival-promoting role of the IGF-IR and its downstream signaling components in MM cells to identify potential targets for therapy. Octreotide, a somatostatin analog that has been demonstrated to interfere with the actions of IGF-I, induced growth inhibition in both IL-6-dependent and IL-6-independent MM cell lines expressing the somatostatin receptors sst2, sst3 and sst5. Additionally, a slight pro-apoptotic effect could be observed in a few cell lines. In primary MM cells octreotide induced apoptosis, an effect that was abrogated by exogenously added IGF-I, but not by IL-6.Inhibition of IGF-I signaling in Karpas 707 cells, using either the anti-IGF-IR antibody αIR3 or the PI 3-K inhibitors LY294002 and wortmannin, increased sensitivity to apoptosis induced by dexamethasone. Exogenously added IGF-I prevented dexamethasone-induced apoptosis, an effect that could partly be mimicked by the pharmacological GSK-3β inhibitors LiCl and SB415286. Thus, we suggest the GSK-3β as an important mediator of the anti-apoptotic effects of IGF-IR signaling in MM.Using rapamycin we selectively inhibited mTOR, a phosphoprotein downstream of the IGF-IR. In MM cell lines rapamycin induced G0/G1-arrest, an effect being associated with an increase of the cyclin-dependent kinase inhibitor p27 and a decrease of the cyclins D2, D3 and E. Interestingly, in primary MM cells rapamycin induced apoptosis. Moreover, rapamycin potentiated dexamethasone-induced apoptosis, an effect that was associated with a downregulation of the anti-apoptotic protein survivin. Strikingly, the combinatorial treatment with rapamycin and dexamethasone suppressed the anti-apoptotic effects of exogenously added IGF-I and IL-6, thus suggesting this drug-combination to be active also in vivo. Two newly developed, selective IGF-I RTK inhibitors proved to be very effective in MM cell lines and in primary MM cells providing 50-90% growth inhibition within 48 h of incubation. The inhibitors induced massive apoptosis together with a prominent cell cycle arrest in the G2/M-phase. Importantly, the IGF-I RTK inhibitors downregulated the tyrosine phosphorylation of the IGF-IR β-chain but not of the insulin receptor β-chain. In conclusion, the IGF-IR potently promotes growth and survival of MM cells. Therefore, interfering with the IGF-IR signaling pathway might be a suitable strategy to improve MM treatment.
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| 10. |
- Wiklund, Anna-Lena, 1970-
(författare)
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The Syntax of Tenselessness : On Copying Constructions in Swedish
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis investigates three construction types in Swedish where two (or more) verbs display identical inflectional morphology (COPYING) and share one overt subject. The constructions are referred to as (i) T(ENSE)M(OOD)A(SPECT)-COPYING complements, of the form John started and wrote (John started writing), (ii) PARTICIPLE COPYING complements, of the form John had been-able written (John had been able to write), and (iii) PSEUDOCOORDINATIONS, of the form John sat and wrote (John was writing). (i) and (ii) differ from (iii) in alternating with infinitives. (ii) differs from (i) and (iii) in restricting copying to participial form and in being incompatible with a linking element (corresponding to 'and'). The main claim is that the construction types are three surface variants of one and the same phenomenon, involving complementation and semantically vacuous inflection on the embedded verb(s). The differences between them are argued to be derivable from independent factors. (i) and (iii) are shown to differ from (ii) w.r.t. amount of functional structure present in the embedded clause. Matrix verbs in (iii) are shown to instantiate light verb uses of otherwise lexical verbs. Copying complements are argued to instantiate subtypes of "tenseless" infinitivals (infinitivals whose tense orientation fully overlaps with that of the matrix clause), characterized by an underspecified functional domain. Copying is assumed to be a surface reflection of (Agree-type) dependencies between functional heads of the same label; features of the embedded functional heads copy values from the corresponding functional heads in the matrix clause. Arguments for treating copying complements as instantiating restructuring are presented. It is proposed that copying complements differ from non-copying infinitival complements in being subject to valuation from the matrix functional domain. This suggests that an imporant aspect of (possibility of) restructuring is alternation between unmarked (negatively specified) and unvalued varieties of the same features.
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