| 1. |
- Aalto, Susanne, 1964
(författare)
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Molecular Clouds in Starburst Galaxies
- 1994
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Starbursts in the centres of galaxies are believed to be caused by funneling of gas towards the inner regions. Gravitational interactions between galaxies are known to cause vast rearrangements of their structure as well as induce bursts of star formation in their nuclear regions. However, radial gas-transport may also be the result of a bar- instability intrinsic to the system. This report deals with the effect of a starburst on the molecular medium of galaxies. The mm-wave, rotational transitions of interstellar molecules serve as probes of the physical conditions, kinematics and total mass of the molecular gas. Observations of the J=1-0, J=2-1 and J=3-2 transitions of 12Co, the J=1-0 and J=2-1 transitions of 13Co, the J=1-0 transitions of C180 and HCN and the J=2-1 transition of CS are used to determine the properties of the molecular gas in starbursting and normal galaxies. The mean escape probability approximation is used to solve the radiative transfer equations. The inferred properties of the molecular clouds in the centres of starburst galaxies differ from those of Galactic disk clouds. Such a deviation is likely to be induced by a central gas concentration and/or the nuclear starburst disrupting the clouds. Large 12CO/13CO J=1-0 intensity ratios (R>20) are measured towards luminous mergers implying unusual, high-pressure, molecular cloud ensembles. Model cloud ensembles for the merging system, NGC 3256, and the starburst spiral NGC 1808 suggest that the 12CO-emission is dominated by warm (Tk = 100 - 300 K), small (0.5-1 pc) and moderately dense (n = 2 - 7 x 103 cm-3) molecular clouds. Such temperatures and densities are typical of Galactic photon dominated regions (PDRs). Statistical studies of molecular line ratios towards galaxy centres indicate that the optical depth of the 12CO 1-0 emission is moderate, .tau.Ã? 1. Many starburst galaxies have large-scale excitation gradients indicating warm, dense gas in the centre, and normal cool molecular gas in their extended disks. NGC 3256, in particular, has a large R = 35 in the centre, while it is found to be only R = 10 - 15 at positions 43" off centre. The model cloud ensemble of NGC 1808 indicate that the 12CO-emitting gas may be diffuse rather than self-gravitating, this could be a common phenomenon in starburst galaxies.
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| 2. |
- Aanesen, Arthur
(författare)
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GABA and human spermatozoa : characterization and regulation of GABA transport proteins
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The present project aimed at investigating the interaction between GABA and human spermatozoa under in vitro conditions. Our initial hypothesis was that human spermatozoa had specific binding proteins for GABA and that the binding of GABA to such binding sites could affect sperm function. Studies on swim-up preparations of human spermatozoa incubated with radiolabelled GABA in the presence of unlabelled GABA, alternatively displacers of GABAA/B receptors and GABA transport proteins, indicated that GABA specific binding sites were present on the surface of human spermatozoa. The potency of the different inhibitors indicated that the binding sites possibly represented GABA transport proteins. No effect on sperm motility or AR was observed following incubation with GABA. Further studies indicated that human spermatozoa are capable of a carrier mediated GABA uptake. The uptake is dependent on the concentration of chloride and sodium in the external medium, and the kinetic properties of the carrier resembled high affinity GABA transport proteins. Uptake of radiolabelled GABA into human spermatozoa in the presence of steroids was investigated. We examined progesterone, other steroids known to increase calcium influx, and steroids known to be ineffective as stimulators of calcium influx in human sperm. The results demonstrated a twofold increase in GABA uptake following preincubation with P or steroids known to stimulate calcium influx. In contrast, an inhibition of GABA uptake following preincubation with activators of protein kinase C was observed. The results suggest a role for PKC in the regulation of GABA transport in human spermatozoa. The reduced GABA uptake following incubation with phorbol esters and diacyl glycerol (DAG) analogues, as well as the lack of effect observed following addition of inactive DAG analogues, strongly indicate such a regulatory pathway. The existence of GABA transporter m-RNA and proteins in human testis and sperm was examined using RT-PCR, immunohistochemistry and immunoblotting. Oligonucleotide primer pairs were designed from nucleotide sequences for the three cloned GABA transport proteins identified in human brain: GAT-1, GAT-3 and BGT-1. From homogenized human testis, PCR products of predicted size and with homology to respective GABA transport proteins were identified. This finding indicates the MRNA expression of all three GABA transporters in human testicular tissue. Studies on the protein expression of GABA transporters in sperm cells were performed with SDS-PAGE and immunoblotting techniques. Immunoblots using polyclonal antibodies raised against rat GAT-1, GAT-2 and GAT-3 recognized bands of approximately 65kDa, indicating cross-reactivity to GABA transporters present in human sperm cells. Pharmacological characterization of GABA uptake with specific inhibitors of GABA transport revealed a unique sequence in the relative potencies of the inhibitors tested. The results may indicate the presence of more than one GABA transporter in the plasma membrane of human spermatozoa. Immunoblots and immunohistochemistry studies indicate the presence of one or several GABA transporters in human spermatozoa and testis, these results are supported by pharmacological studies using specific inhibitors of GABA transport. These studies add new information to the present knowledge concerning GABA and human spermatozoa. They also for the first time describe specific GABA transport proteins in the male reproductive tract. Further studies are however, required to elucidate the functional role for these proteins in terms of human reproduction.
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| 3. |
- Aanestad, Øystein
(författare)
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Quantitative electromyographic studies of the perineal muscles in normal subjects and patients suffering from anal or urinary incontinence
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aims of the study were to characterize the interference pattern in perineal muscles in healthy subjects with the use of quantitative EMG techniques, to evaluate if prostatic surgery had any effect on the interference pattern and furthermore to examine the interference pattern in the perineal muscles in patients suffering from urinary or anal incontinence.The interference pattern in the perineal muscles was examined with a computerized analysis, the Turns and Amplitude (T/A) analysis, and the innervation pattern of the muscles was examined with single fiber electromyography measuring the fiber density. Reference values were collected from 30 normal subjects. The patient material consisted of 20 males subjected to transurethral prostatectomy (TUR-P), 10 males who underwent radical retropubic prostatectomy (RRP), 20 patients suffering from anal incontinence and 24 women withurinary incontinence.T/A analysis of the interference pattern in the perineal muscles in normal subjects showed a significant increase in number of turns/sec and mean amplitude correlating to increasing force but no age-related changes.TUR-P and RRP did effect the innervation of the distal urethral sphincter muscle as shown by increased fiber density indicating a peripheral nerve lesion. T/A analysis did not shown any increased activation of the distal urethral sphincter as a compensation for the loss in bladder neck sphincter function but rather signs of decreasedcentral activation.Patients with idiopathic faecal incontinence showed signs of impaired innervation of the external anal sphincter muscle. A decreased interference pattern at maximal contraction indicated a reduced central activation of perineal muscles, in particular for patients with partial rupture of the external anal sphincter muscle. The reduced central activation could play a role for the aetiology of faecal incontinence.Patients with urinary stress incontinence also showed signs of impaired innervation of the external anal sphincter muscle as well as reduced interference pattern at maximal contraction and during continuous recording of the EMG activity during cystometry. A reduced central activation of the motor units was predicted as one factor involved in the aetiology.
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| 6. |
- Aas, Wenche
(författare)
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Constitution, dynamics and structure of binary and ternary actinide complexes
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Stoichiometry, ligand exchange reactions, coordinationgeometry and stability of complexes of type UO2LpFq(H2O)3-n(p= 1–2,q= 1-3), where L is one of the bidentate ligandspicolinate, oxalate, carbonate or acetate have beeninvestigated using single crystal X-ray diffraction, an arrayof19F-,13C-,17O- and1H-NMR techniques and potentiometric titration usingboth F-and H+selective electrodes. The experiments wereperformed in a 1.00 M NaClO4medium. The equilibrium constants were determinedat 25°C while most of the kinetic experiments were done at- 5°C. The equilibrium constants for the stepwise additionof F-to UO2L and UO2L2indicates that the prior coordination of L toU(VI) has a fairly small effect on the subsequent bonding offluoride, except for a statistical effect determined by thenumber of available coordination sites. This indicates thatternary complexes might be important for the speciation andtransport of hexavalent actinides in ground and surface watersystems. A single crystal structure of UO2(picolinate)F32-has been determined showing the same pentagonalbipyramidal symmetry as in aqueous solution studied by NMR. Theexchangeable donor atoms are situated in a plane perpendicularto the linear uranyl group. The complexes show a variety ofdifferent exchange reactions depending on the ligand used. Ithas been possible to quantify external fluoride and the otherligands exchange reactions as well asintra-molecular reactions. This type of detailedinformation has not been observed in aqueous solution before.Water takes a critical part in the exchange mechanism, and whenit is eliminated from the inner coordination sphere a muchslower kinetics can be observed.19F-NMR has showed to be a powerful technique tostudy these reactions, both because of the sensitivity of thisNMR nucleus and also the possibility to observe reactions wherefluoride is not directly involved in the mechanism. TernaryTh(edta)F1-2and (UO2)2(edta)2F1-4have been investigated using1H and19F-NMR. The fluoride complexation to Cm(III) wasstudied using time resolved fluorescence spectroscopy (TRLFS)and the stability constant for the CmF2+complex was determined at 25°C in 1.0 mNaCl.Keywords. Ternary complexes, actinides,dioxouranium(VI), curium(III), thorium(IV), ligand exchange,isomers, NMR, potentiometric titrations, aqueous solution,oxalate, picolinate, acetate, EDTA.
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| 7. |
- Aasa, Annika, 1963
(författare)
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User Defined Syntax
- 1992
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes two examples of user defined syntax. The first, and most thoroughly investigated, is a new datatype construction, the conctype, the elements of which have a very flexible syntax. An embedded language can easily be introduced into a programming language using conctypes and computations are easily expressed using the concrete syntax and a special pattern matching form. The second example is user defined distfix operators which give a user possibility to extend the syntax for expressions in a programming language. We describe both a user's view and the implementation of these two examples. In both cases, context-free grammars serve as a basis for the definition of the new syntax. A problem that is investigated is how to disambiguate grammars with precedences. To see how this should be done we investigate which language a grammar together with precedence rules defines. For a sub-class of context-free grammars we give a predicate that defines the precedence correct syntax trees according to some precedence rules. We also give an algorithm that transforms such a grammar to an ordinary unambiguous context-free grammar and prove the correctness of the algorithm. We use the algorithm in our implementation of distfix operators. For more general grammars, we isolate one kind of ambiguity which is suitable to resolve with precedence rules. We define the generated language for such a grammar by an attribute grammar. This approach of resolving ambiguity is used in the implementation of conctypes.
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| 8. |
- Aastrup, Teodor
(författare)
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In situ investigations of the metal/atmophere interface
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents a new experimental setup for surfaceanalysis studies, incorporating chemical information frominfrared reflection absorption spectroscopy (IRAS) andquantitative information from quartz crystal microbalance(QCM). The integrated IRAS/QCM surface analysis system enablesin situstudies to be conducted of the metal/atmosphereinteraction on a sub-monolayer level. In combination withtopographical information from tapping mode atomic forcemicroscopy (TM-AFM), it was possible to follow the formation ofcorrosion products providing information about chemicalidentity, quantity and lateral distribution. The newlydeveloped system was used to study the influence of relativehumidity (RH) and levels of sulfur dioxide (SO2), ozone (O3)and nitrogen dioxide (NO2) down to concentrations of subparts-per-million (ppm), on the initial stages of atmosphericcorrosion of copper.Exposure to RH led to the formation of small grains ofcuprous oxide (Cu2O), with an average diameter of approximately40 nm. The grain nucleation rate increased with increasing RHdue to the increasing amount of physisorbed water on thesurface.Exposure to RH and SO2 led to the formation of coppersulfite (CuSO3•xH2O) species as well as reduction in therate of Cu2O formation. The formation of CuSO3•xH2Ooccurred through the dissolution and consecutive precipitationof surface-bound copper sulfite complexes.The roles of O3 and NO2 in the SO2-induced atmosphericcorrosion of copper was also investigated. O3 was found to havea two-fold effect, resulting in the oxidation of the coppersulfite species to copper sulfate and the enhancement of Cu2Oformation. NO2 promoted the oxidation of copper sulfitespecies, though less efficiently than O3, and reduced Cu2Oformation. In addition, copper nitrate formation wasobserved.IRAS was also used to investigate the interaction betweenSO2 and surfaces made of platinum and palladium. Sulfuric acidformation was observed on both metals, showing the importanceof the surface on the formation of the metal/atmospherereaction products.Keywords:Atmospheric corrosion, IR-spectroscopy, IRAS,QCM, AFM, SO2, O3, NO2, Cu.
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| 9. |
- Abarkan, Abdellah, 1960
(författare)
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Bebyggelsemönster i medelhavsområdet: en studie av medinan i Fes ställd i relief mot Siena|
- 1995
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is an analysis and comparative study of medieval Mediterranean urban patterns. With urban patterns is meant the arrangement of houses and public spaces with special regard to the relations between them. The thesis contains four parts. Previous research on Muslim cities is described and commented in the first part. A difference between research before and after 1960 is noted. The Medina of Fes is discussed in the second part. In an historical background sketch the foundation of the Medina and its development are presented. The spatial analysis shows that the physical structure of the Medina is based on a primary pattern unit of a square courtyard house with a closed, inward-turned physical structure. A number of these primary units are grouped around a cul de sac to form a second-level community unit; a number of these latter form a quarter. The quarters are adjacent and close to each other which means that the Medina as a whole can be regarded as a complex physical and social unit surrounded with the city walls. In a comparable approach the physical and social structure of Siena is studied. The primary units here are the casa corte, which is similar to the courtyard of the Medina, and the casa a schiera which is a filehouse without any comparative physical form in the medina. These two different primary units engendered two types of building patterns, one in the city centre where courtyard units are grouped around a central square, and the other one in the periphery of the city formed by the alignment of the filehouses along the street. An attempt to compare the physical and social units in the Medina and Siena is made in the fourth part of this thesis. The primary units, the community units, the quarters and the cities are compared. This comparative study shows that the similarities between the Medina and Siena are much more apparent on the social level and on the level of the smaller physical units, i.e. the habitat, than between the larger social and physical composition of the quarters.
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| 10. |
- Abate, Getahun
(författare)
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Drug resistance in mycobacterium tuberculosis
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Drug-resistant tuberculosis is a global public health problem. This investigation was performed to find ways of improving regimens that could be used for the treatment of drug- and multidrug-resistant TB and also to find a rapid method of diagnosis of drug resistant TB, particularly MDR-TB. Among 107 isolates of M. tuberculosis from re-treatment cases of pulmonary TB in Ethiopia (study 1), 48% were resistant at least to one of the four first-line drugs tested and 12 % were AMR. In this study, rifampicin resistance was a strong predictor of MDR-TB. The extended susceptibility of 35 polyresistant isolates including NMR isolates on ten other drugs showed that all were susceptible at least to five drugs (i.e., amikacin ciprofloxacin, clofazimine ethambutol, and ethionamide). The WHO re-treatment regimen would be effective in 86 % of cases. Moreover, the extended susceptibility pattern of MDR isolates indicated that it is possible to find a low-cost treatment regimen for patients at risk of harbouring MDR-TB by replacing very expensive drugs like amikacin and ciprofloxacin. The studies on ß-lactams showed that cefepime (study II) and amoxicillin-clavulanate (study 111) are effective on M. tuberculosis isolates including MDR-isolates. Cefepime at a concentration of 32 mg/L was active on 54 % of M. tuberculosis isolates. The minimum inhibitory concentration (MIC) of amoxicillin-clavulanate was 2 or 4 mg/L for 90 %the isolates tested. The MIC was reduced to 5 0.5 mg/L for 97 %of isolates when subinhibitory concentration of ethambutol was added. The results suggested that ß-lactams, particularly in combination with ethambutol, could be important for the treatment of MDR-TB. An assay based on 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) was standardised in both microtiter (study and tube formats (study V) for the detection of rifampicin resistance in clinical isolates of M. tuberculosis. MTT is converted to a blue formazan by live cells and the amount of formazan formation was proportional to the number of viable bacilli. In suspensions containing mixed bacterial population, the assay could detect a resistant subpopulation of I%. The evaluation of the assay with the BACTEC method using 92 clinical isolates of M. tuberculosis showed that the result obtained by the MIT assay (both on the third and sixth day) matched with the result obtained by the BACTEC method. Seventy-eight strains were identified as susceptible, 13 strains as resistant and one strain as borderline resistant. In the MIT assay, resistant and susceptible stains were identified based on the relative optical density (RODU) values and changes in OD from the third to the sixth day. AD results were interpretable by the naked eye. NM assay is rapid, reliable, safe and inexpensive assay for the detection of rifampicin resistance. Rifampicin resistance is a strong predictor of MDR-TB and the assay is appropriate for clinical application in low-income countries. Fifty isoniazid-resistant strains of M. tuberculosis (study VI) were characterised based on the catalase activity, MIC of isoniazid, growth pattern in the presence of different concentrations of isomazid, and mutations in katG gene (codons 315 and 463). The MIC of 72 % of the strains was < 4 mg/L. The results also showed that these stains could be classified into three groups based on their growth pattern. A majority (80%) of stains with high MIC (>= 16 mg/L) of isoiazid had no catalase activity. Mutations in codons 315 and 463 of katG gene were detected in 91 % of strains with MIC < 8 mg/L but only in 28 % of strains with higher MlC. This study showed that mutations in codons 315 and 463 of katG gene failed to detect 72 % of clinically most important group with high MlC of isoniazid (>= 16 mg/L). The sensitivity of molecular methods based on mutations in these codons could be increased by combining with the results from the catalase activity. The majority of strains with high MIC had no catalase activity and could be detected by a simple catalase test. The results also indicated that isoniazid-resistant strains of M. tuberculosis could be characterized based on their growth pattern.
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