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Uppsala universitet Nationalekonomi
This thesis consists of four self-contained essays. Essay 1: Mixed-aged classes (MA-classes) are a common phenomenon around the world. In Sweden, these types of classes increased rapidly during the 1980:s and 1990:s, despite the fact that existing empirical support for MA-classes is weak. In this paper, we estimate the effect of attending an MA-class during grades 4-6 on students’ cognitive skills. Using a unique survey with information on students, parents and teachers, we are able to control for many factors that could otherwise bias the results. We find a negative effect on short-run cognitive skills, as measured by grade 6 cognitive tests, and this effect is robust to a rigorous sensitivity analysis. Essay 2: We examine whether the impact of pre-school interventions on cognitive skills differs by immigrant background. The analysis is based on Swedish data containing information on childcare attendance, rich family background information, the performance on cognitive tests at age 13, and long-run educational attainment for cohorts born between 1967 and 1982. We find that childcare attendance reduces the gap in language skills between children from immigrant backgrounds relative to native-born children. We find no differential effects on inductive skills, however. Nor does childcare appear to affect the distribution of long-run educational attainment. Essay 3: This paper estimates the effect of child gender on mothers’ and fathers’ parental leave. The focus on Sweden, a highly gender equal society, yields additional knowledge on the prevalence of gender biases in industrialized countries. The results show that a first born son increases fathers’ parental leave with 0.6 days (1.5 percent) and decreases mothers’ leave by a similar amount, leaving the total leave unchanged. Both the sign and size of this effect is in line with previous research. However, there are interesting differences between groups that departs from previous studies. Non-traditional families, with high maternal relative earnings and/or educational levels, show even larger gender biases, indicating that it may be mothers, rather than fathers, that are the driving force behind this child gender bias. Essay 4: This paper investigates the effect of parental leave – both own and spousal – on subsequent earnings using different sources of variation. Using fixed-effects models, and in line with previous results, parental leave is found to decrease each parent’s future earnings. Also spousal leave is important, but only for mothers. In fact, each month the father stays on parental leave has a larger positive effect on maternal earnings than a similar reduction in the mother’s own leave. Using two reforms of the parental leave system as exogenous sources of variation yields only imprecisely estimated effects, even though the reforms had a strong effect on parental leave usage. However, the point estimates tentatively suggest effects in the same range or larger than the fixed-effects model found.
978-91-85519-28-6 / Link / Johansson , Elly-Ann / 2009

N/A / Link / Ekstrand , Åsa /

Although dietary vitamin A is required for normal growth and development, long-term or high-dose administration of vitamin A derivatives (retinoids) may produce a variety of skeletal side-effects in man. In this study we investigated the early effects of oral isotretinoin therapy on bone turnover and calcium homeostasis in eleven consecutive patients with nodulocystic acne. The effects on bone metabolism were correlated to radiological and bone mineral density measurements following drug therapy for six months. Markers of bone turnover, i.e. serum osteocalcin, the carboxyterminal propeptide of type I collagen, bone specific alkaline phosphatase, the carboxyterminal telopeptide of type I collagen, and urine levels of calcium and hydroxyproline decreased significantly within five days of treatment (p < 0.05). There was also a statistically significant decrease in serum calcium, with a minimum on day five, and a marked increase in serum parathyroid hormone (p < 0.05). With continued treatment, however, the abnormal levels of these markers returned to baseline values within 14 days. No significant roentgenological changes or effects on bone mineral density were found in response to the drug. The observed inhibitory effects of isotretinoin on bone turnover, despite elevated parathyroid hormone levels, indicates that the drug exerts a direct effect on bone tissue.
N/A / Link / Kindmark , Andreas / 1998

Modern array systems allow for excitation of separate elements using arbitrary wave forms. This is utilized in pulse compression and coded excitation techniques to improve the imaging performance. Such techniques are however somewhat inflexible since they use predefined excitation schemes. This paper presents a more flexible method for optimizing the input signals to an ultrasonic array in such a way that the scattering strengths at arbitrarily chosen control points in the insonified object can be estimated with as small an error as possible, measured with a mean squared error criteria. The statistically motivated method is based on a linear model of the array imaging system and the method takes into account both prior information regarding the scattering strengths and measurement errors. The input signals are found by using genetic optimization and are constrained to have finite duration and bounds on the maximum amplitudes. Different constellations of control points, and different signal-to-noise ratios, yield different excitation schemes. The design approach finds multiple selective focal laws when choosing relatively well separated control points and when the control points are closely spaced, the resulting excitations result in more diffuse fields. Because of the flexibility in choosing the control points, the design method will be useful when developing transmission schemes aiming at fast imaging of large image areas using few transmissions.
N/A / Link / Lingvall , Fredrik / 2008

Epigenetic modifications are critical for regulating many different aspects of normal cell biology and tumourigenesis. Gene expression may be epigenetically silenced by DNA-methylation and histone modifications, resulting in remodelling of chromatin into a repressed state. We performed DNA-methylation analysis of the ICSBP/IRF8 gene, a member of the IRF family of transcriptional regulators expressed in monocytic and lymphocytic cells, in human monoblastic U-937 cells. We found complete methylation of all 39 CpG positions located in a 308 bp sequence encompassing the proximal promoter and transcriptional start site of the ICSBP/IRF8 gene. However, strikingly, the ICSBP/IRF8 gene is still expressed. Chromatin Immuno-precipitation (ChIP) showed that RNA-Polymerase II was present at the major transcriptional start site. Investigating the histone modifications across the ICSBP/IRF8 gene we found the positive historic marks H3K9ac and H3K4me3 to be enriched at the promoter, whereas the level of H3K9me3 was low. This suggests that an active chromatin structure, indicated by histone H3 modifications and enrichment for RNA Pol II, can over-ride the silencing effect of DNA-methylation at the promoter, thereby permitting transcription of the ICSBP/ IRF8 gene.
N/A / Link / Tshuikina , Marina / 2008

The endangered brown bear populations (Ursus arctos) in Iberia have been suggested to be the last fragments of the brown bear population that served as recolonization stock for large parts of Europe during the Pleistocene. Conservation efforts are intense, and results are closely monitored. However, the efforts are based on the assumption that the Iberian bears are a unique unit that has evolved locally for an extended period. We have sequenced mitochondrial DNA (mtDNA) from ancient Iberian bear remains and analyzed them as a serial clataset, monitoring changes in diversity and occurrence of European haplogroups over time. Using these data, we show that the Iberian bear population has experienced a dynamic, recent evolutionary history. Not only has the population undergone mitochondrial gene flow from other European brown bears, but the effective population size also has fluctuated substantially. We conclude that the Iberian bear population has been a fluid evolutionary unit, developed by gene flow from other populations and population bottlenecks, far from being in genetic equilibrium or isolated from other brown bear populations. Thus, the current situation is highly unusual and the population may in fact be isolated for the first time in its history.
N/A / Link / Valdiosera , C. / 2008

Although the three-dimensional structures of both human retinol-binding protein (RBP) and transthyretin (TTR) are known, the binding sites have not been defined. In this study we have epitope-mapped a rabbit antiserum against human RBP using synthetic peptides corresponding to all potentially antigenic sites. Immunoreactivity was seen with peptides corresponding to amino acid residues 46-54, 137-146, 143-153, and 172-182 of RBP. Since previous studies have demonstrated that these antibodies bind equally well to free RBP and to the RBP-TTR complex, we conclude that neither the loop region around amino acid residue 50, the N-terminal part of the alpha-helix, nor the C-terminus of RBP is located in or close to the TTR binding site. Our results support the hypothesis that one of the entrance loops is involved in the TTR binding.
N/A / Link / Melhus , Håkan / 1995

A new birkeniid anaspid, Cowielepis ritchiei gen. et sp. nov., from the mid Silurian Cowie Harbour fish bed in Scotland is described on the basis of three specimens. Although sharing characters with various well-known anaspids, it possesses a unique combination of features that justifies the establishment of a new genus. Cowielepis is characterized by a single row of dorsolateral scales and a distinctive skull roof pattern with a large pineal plate and elongated posterior plates. The presence of paired ventrolateral fins in C. ritchiei supports previous suggestions that all anaspids possess such fins, but leaves open the question of homology with the gnathostome pectoral fin.
N/A / Link / Blom , Henning / 2008

One- and two-step syntheses for the F-18-labelling of 6-[(S)-(4-chlorophenyl)(1H-1,2,4-triazol-1-yl)methyl]-1-(2-[F-18]fluoroe thyl)-1H-benzotriazole, [F-18]FVOZ, 1 and 6-[(S)-(4-chlorophenyl)(1H-1,2,4-triazol-1-yl)methyl]-1-[2-(2-[18F]fluor oethoxy)ethyl]-1H-benzotriazole, [F-18]FVOO, 2 were developed. In the two-step synthesis, the nucleophilic fluorination step was performed by reacting (S)-6-[(4-chlorophenyl)-(1H-1,2,4-triazol-1-yl)methyl]-1H-benzotriazole (VOZ) with either the F-18-labelled ethane-1,2-diyl bis(4-methylbenzenesulfonate) or the oxydiethane-2,1-diyl bis(4-methylbenzenesulfonate). The radiochemical yields were in the range of 9-13% after the 110-120 min total syntheses and the specific radioactivities were 175 +/- 7 GBq/mu mol and 56 GBq/mu mol for compounds 1 and 2, respectively. In the one-step synthesis, the precursor 2-{6-[(4-chlorophenyl)(1H-1,2,4-triazol-1-yl)methyl]-1H-1,2,3-benzotriaz ol-1-yl}ethyl 4-methylbenzenesulfonate (7) or 1-[2-(2-bromoethoxy)ethyl]-6-[(4-chlorophenyl)(1H-1,2,4-triazol-1-yl)met hyl]-1H-benzotriazole (8) was directly labelled via, an 18F nucleophilic substitution to give the corresponding tracer. The labelled compounds were obtained in 36-99% radioichemical yield after 75-min syntheses. The specific radioactivities are 100 GBq/mu mol for compound 1 and 80 GBq/pmol for compound 2. In vitro autoradiography using frozen rat brains illustrated specific binding in the medial amygdala, the bed nucleus of stria terminalis and the preoptic area, all of which corresponded well to the result of C-11-labelled vorozole.
N/A / Link / Erlandsson , Maria / 2008

The tribe Bovini contains a number of commercially and culturally important species, such as cattle. Understanding their evolutionary time scale is important for distinguishing between post-glacial and domestication-associated population expansions, but estimates of bovine divergence times have been hindered by a lack of reliable calibration points. We present a Bayesian phylogenetic analysis of 481 mitochondrial D-loop sequences, including 228 radiocarbon-dated ancient DNA sequences, using a multi-demographic coalescent model. By employing the radiocarbon dates as internal calibrations, we co-estimate the bovine phylogeny and divergence times in a relaxed-clock framework. The analysis yields evidence for significant population expansions in both taurine and zebu cattle, European aurochs and yak clades. The divergence age estimates support domestication-associated expansion times (less than 12 kyr) for the major haplogroups of cattle. We compare the molecular and palaeontological estimates for the Bison-Bos divergence.
N/A / Link / Ho , Simon Y. W. / 2008

In various cardio-pulmonary diseases lung mass is considerably increased due to intrapulmonary fluid accumulation, i.e. extravascular lung water (EVLW). Generally, inertance is a physical system parameter that is mass-dependent. We hypothesized that changes in lung mass influence the inertive behavior of the respiratory system. EVLW and intrathoracic blood volume (ITBV) were compared with respiratory system inertance (I(rs)) in four piglets before and after broncho-alveolar lavage (BAL) that induced surfactant deficiency with interstitial edema. EVLW and ITBV were determined using the double-indicator dilution technique, I(rs) by multiple linear regression analysis. Measurements were taken before, and 1 and 2 h after BAL. EVLW increased threefold (from 6.2+/-0.8 mL/kg at baseline to 17.7+/-0.9 mL/kg (p < 0.001) after BAL). I(rs) increased by 35% (from 0.17+/-0.02 to 0.23+/-0.04 cmH(2)O s(2)/L (p = 0.036) after BAL) and was tightly correlated to EVLW (r(2) = 0.95, p < 0.023). ITBV did not change significantly after BAL. We conclude that I(rs) reflects actual changes in lung mass and thus hints at fluid accumulation within the lung.
N/A / Link / Schumann , S. / 2008

N/A / Link / Andersson , Eva / 2004

Uppsala universitet Farmaci
91-554-2719-7 / Link / Lindqvist , Thomas / 1991

Erythropoietin (EPO) and iron deficiency as causes of anemia in patients with limited renal function or end-stage renal disease are well addressed. The concomitant impairment of red blood cell (RBC) survival has been largely neglected. Properties of the uremic environment like inflammation, increased oxidative stress and uremic toxins seem to be responsible for the premature changes in RBC membrane and cytoskeleton. The exposure of antigenic sites and breakdown of the phosphatidylserine asymmetry promote RBC phagocytosis. While the individual response to treatment with EPO-stimulating agents (ESA) depends on both the RBC's lifespan and the production rate, uniform dosing algorithms do not meet that demand. The clinical use of mathematical models predicting ESA-induced changes in hematocrit might be greatly improved once independent estimates of RBC production rate and/or lifespan become available, thus making the concomitant estimation of both parameters unnecessary. Since heme breakdown by the hemoxygenase pathway results in carbon monoxide (CO) which is exhaled, a simple CO breath test has been used to calculate hemoglobin turnover and therefore RBC survival and lifespan. Future research will have to be done to validate and implement this method in patients with kidney failure. This will result in new insights into RBC kinetics in renal patients. Eventually, these findings are expected to improve our understanding of the hemoglobin variability in response to ESA.
N/A / Link / Kruse , Anja / 2008

The installation of elements in the main linac of future linear colliders can only be done with a limited precision. The inevitable misalignments lead to unacceptable emittance growth. Beam-based alignment, e. g., one-to-one correction, dispersion free steering, or ballistic alignment, is necessary to reduce the emittance growth. In some cases, this is, however, not sufficient. For further reduction of the emittance growth, so-called emittance tuning bumps have to be used. A general strategy for the design of emittance tuning bumps has been developed and tested. Simulations suggest that the method can be conveniently used to understand the weaknesses of existing emittance tuning bumps and to significantly improve their performance in terms of, e. g., emittance reduction capability and convergence speed. An example of an application is the design of ten orthogonal knobs that, according to simulations, can reduce the normalized emittance growth in the Compact Linear Collider (CLIC) main linac from 23.8 to 0.34 nm with convergence within two iterations. Four orthogonal knobs have also been designed for the International Linear Collider (ILC). Simulations show that these knobs converge within a single iteration and reduce normalized emittance growth from 3.8 to 0.05 nm.
N/A / Link / Eliasson , Peder / 2008

We describe Serre functors for (generalisations of) the category O associated with a semisimple complex Lie algebra. In our approach, projective-injective modules, that is modules which are both, projective and injective, play an important role. They control the Serre functor in the case of a quasi-hereditary algebra having a double centraliser with respect to a projective-injective module whose endomorphism ring is a symmetric algebra. As an application of the double centraliser property together with our description of Serre functors, we prove three conjectures of Khovanov about the projective-injective modules in the parabolic category O-0(mu)(SIn).
N/A / Link / Mazorchuk , Volodymyr / 2008

Uppsala universitet Samhällsvetenskap
This thesis is primarily based on a case study on how the Internet affects the advertising industry in Oslo, Norway, and on how the digitization of advertising adds to our understanding of the geography of innovation and urban and regional development. The study argues that the Internet fundamentally changes and challenges the advertising industry, and that advertising merges into market communication and even user experience and product development. The interactive nature of the Internet and its parallel social and commercial worlds contribute to transcend the role of a traditional medium and to coalescence between production and consumption. Despite the fact that those involved in online and traditional advertising are located close to each other in Oslo, the extent of collective learning, knowledge externalities and innovation has been scarce. The study shows that the creative destruction of this industrial sector is ignited by actors outside the traditional advertising industry. Due to path dependency along one-way mass communication media incumbents within the advertising industry have left room for new actors, such as web agencies and technology consultants, to explore and take market share in online market communication services. The reconfiguration of market communication is regarded as the result of an industry mutation across advertising and ICT, and creates a need for bridging skills and competencies across creative, strategic and interactive domains. The implications of such an industry mutation across diverse sectors are used to discuss the evolutionary potential of the related variety perspective. The study argues that localized industrial change may be conceptualised in terms of a cyclical relationship between externalities from localisation economies and urbanisation economies respectively. The implications of the findings from the case study are in this way used to discuss more general drivers of urban and regional development.
978-91-506-2108-2 / Link / Bugge , Markus M / 2009

In vivo studies of hepatobiliary disposition are challenging. The hepatobiliary system is complex, as its physiological localization, complex cellular structure with numerous transporters and enzymes, and the interindividual variability in protein expression and biliary flow will all affect the in vivo disposition of a drug under investigation. The research included in this thesis has focused on the involvement of hepatic transport proteins in the hepatobiliary disposition of rosuvastatin. The impact that several transport inhibitors had on the pharmacokinetics of rosuvastatin was investigated in healthy volunteers and in pigs. The effects were considerable, following inhibition of sinusoidal transport proteins by cyclosporine and rifampicin. These inhibitors significantly reduced the hepatic extraction of rosuvastatin by 50 and 35%, respectively, and the plasma exposure increased by factors of 9.1 and 6.3, respectively. Drug-drug interactions (DDI) resulting in markedly higher plasma exposures are important from a drug safety perspective as increased extrahepatic exposure of statins is associated with an increased risk of severe side-effects, such as myopathy which in rare cases could develop into rhabdomyolysis. The DDI caused by cyclosporine and rifampicin can probably be attributed to inhibition of hepatic uptake transporters. In contrast, inhibition of canalicular transporters by imatinib did not significantly affect the pharmacokinetics of rosuvastatin, which suggests that the intracellular concentration of the inhibitor in the hepatocyte was insufficient to affect the transport of rosuvastatin, or that imatinib is not a sufficiently potent inhibitor in vivo. Furthermore, gemfibrozil administered as a single dose into the jejunum in healthy volunteers and pigs did not affect the plasma or biliary pharmacokinetics of rosuvastatin. The previously reported DDI in humans upon repeated dosing with gemfibrozil might be explained by the accumulation of metabolites able to affect the disposition of rosuvastatin. The investigations presented in this thesis conclude that transport proteins are of considerable importance for the hepatobiliary disposition of rosuvastatin in vivo. The Loc-I-Gut catheter can be applied for the investigation of biliary accumulation and to determine bile specific metabolites, however it has limitations when conducting quantitative measurements. In the porcine model, hepatic bile can be collected for up to six hours and enables the determination of the hepatic extraction in vivo.
978-91-554-7648-9 / Link / Bergman , Ebba / 2009

Uppsala universitet Medicin
91-554-1597-0 / Link / Danielsson , Bengt R. G. / 1984

BackgroundLong-term blood pressure (BP) progression and its importance as a predictor of clinical outcome have not been well characterized across different periods.MethodsWe evaluated period trends for 3 BP variables (long-term slope and mean BP during a baseline period of 16 years, and last baseline value) in an earlier period (1953- 1971, n = 1644, mean participant age, 61 years) and in a later period (1971-1990, n = 1040, mean participant age, 58 years) in participants in the Framingham Heart Study who initially did not have hypertension. In addition, we explored the relation of BP to cardiovascular disease incidence and all-cause mortality in the 2 periods, each with up to 16 years of follow-up.ResultsLong-term slope, mean, and last baseline BP measurements were significantly lower in the later period (P < ;. 001). Rates of hypertension control (BP < , 140/90 mmHg) were higher in the later vs the earlier period (32% vs 23%, P < ;. 001). Multivariate hazard ratios for the relation of BP to outcomes were generally lower in the later period, this was statistically significant for the relation of last baseline BP to all-cause mortality (hazard ratio for 1-SD increase in systolic BP, 1.02 vs 1.25, P=.03, hazard ratio for diastolic BP, 1.00 vs 1.23, P=. 04).ConclusionsWe found evidence that BP levels in the community have changed over time, coinciding with improved rates of hypertension control and attenuation of BP-mortality relations. These findings are consistent with the hypothesis that hypertension treatment in the community has altered the natural history of BP progression and its relation to clinical outcome.
N/A / Link / Ingelsson , Erik / 2008

We have developed an integrated platform for rolling circle amplification (RCA) and circle-to-circle amplification (C2CA) of circular probe (padlock probe) and subsequent microchip electrophoretic detection of a specific gene on a poly(methyl methacrylate) microchip. RCA and C2CA were successfully carried out at a steady temperature of 37 degrees C in the sample well of the microchip, and their respective product was detected on the same channel of the microchip, which was prefilled with a polymer separation matrix and fluorescent dye. Using a species-specific padlock probe for bacterial pathogen V. cholerae, a 25-ng bacterial genomic DNA could be detected in less than 65 min (including RCA and microchip electrophoresis) by this platform. Stable dsDNA C2CA product of genomic DNA for V. cholerae can be detected with the introduced integrated platform. Furthermore, the usefulness of this technique for the monitoring of RCA was demonstrated. This integrated platform provides a sensitive, fast, high-throughput, and reproducible method for signal amplification and detection of the padlock probes in the same microchip and is a promising tool for highly specific gene detection strategies.
N/A / Link / Mahmoudian , Laili / 2008

Following influenza, the elderly and those with chronic heart/lung diseases are often affected by bacterial complications such as pneumonia. Whether neutrophil and monocyte functions are affected differently in patients with or without complications is less well known. Therefore, blood neutrophil and monocyte surface receptor expressions were measured in patients with influenza A, with or without complications, by means of flow cytometry. Neutrophil expressions of the adhesion molecules CD11b and CD66b were increased in influenza A, with the highest expression of CD11b in uncomplicated influenza. Monocyte expressions of CD11b and CD18 were also higher in influenza compared with bacterial infection and healthy controls. Neutrophil expressions of the phagocyte receptors CD64 and CD32 and the complement receptor CD35 were impaired in influenza with and without pneumonia compared with bacterial infection, whereas the expressions in monocytes were increased in all infected groups. The expression of the phagocyte receptor CD16 on neutrophils was impaired in all infected groups. Our results suggest increased recruitment of neutrophils and monocytes to infected areas by up-regulation of adhesion molecules in influenza that may be involved in the inflammatory response during infection. In contrast, depression of phagocyte receptor expression on neutrophils in patients with influenza pneumonia may contribute to increased susceptibility to bacterial infections and impaired clearance of encapsulated bacteria such as pneumococci.
N/A / Link / Pauksens , Karlis / 2008

Uppsala universitet Matematik
We consider the number of vertices that must be removed from a graph G in order that the remaining subgraph have no component with more than k vertices. Our principal observation is that, if G is a sparse random graph or a random regular graph on n vertices with n -> infinity, then the number in question is essentially the same for all values of k that satisfy both k -> infinity and k = o(n).
N/A / Link / Janson , Svante / 2008

We have screened a collection of haploid yeast knockout strains for increased sensitivity to 5-fluorouracil (5-FU). A total of 138 5-FU sensitive strains were found. Mutants affecting rRNA and tRNA maturation were particularly sensitive to 5-FU, with the tRNA methylation mutant trm10 being the most sensitive mutant. This is intriguing since trm10, like many other tRNA modification mutants, lacks a phenotype under normal conditions. However, double mutants for nonessential tRNA modification enzymes are frequently temperature sensitive, due to destabilization of hypomodified tRNAs. We therefore tested if the sensitivity of our mutants to 5-FU is affected by the temperature. We found that the cytotoxic effect of 5-FU is strongly enhanced at 38 degrees C for tRNA modification mutants. Furthermore, tRNA modification mutants show similar synthetic interactions for temperature sensitivity and sensitivity to 5-FU. A model is proposed for how 5-FU kills these mutants by reducing the number of tRNA modifications, thus destabilizing tRNA. Finally, we found that also wild-type cells are temperature sensitive at higher concentrations of 5-FU. This suggests that tRNA destabilization contributes to 5-FU cytotoxicity in wild-type cells and provides a possible explanation why hyperthermia can enhance the effect of 5-FU in cancer therapy.
N/A / Link / Gustavsson , Marie / 2008

Uppsala universitet Medicin
N/A / Link / Melhus , Håkan / 1998

The extraction of one-diode model parameters from a current-voltage (J-V) curve is problematic, since the model is one-dimensional while real devices are indeed three-dimensional. The parameters obtained by fitting the model curve to experimental data depend on how the current is collected, and more specifically the geometry of the contact. This is due to the non-uniform lateral current flow in the window layers, which leads to different parts of the device experiencing different front contact voltage drop, and hence different operating points on the ideal J-V curve. In this work, finite element simulations of three-dimensional contact structures are performed and compared to experimental data on Cu(In,Ga)Se2-based solar cell devices. It is concluded that the lateral current flow can influence the extracted parameters from the one-diode model significantly if the resistivity of the front contact material is high, or if there is no current collecting grid structure. These types of situations may appear in damp heat-treated cells and module type cells, respectively.
N/A / Link / Malm , Ulf / 2008

N/A / Link / Andersson , Ann-Catrin /

In the Middle to Late Ordovician a boost of marine biodiversity occurred which is regarded as the most rapid diversity in Earth’s history, and termed the Great Ordovician Biodiversification Event. This time is also unique in that at least four marine meteorite craters with a good record of post-impact sediments are preserved in Baltoscandia. Catastrophic impacts can serve as constructive events and produce wide-ranging environments providing new ecological niches for a diverse biota to occupy. Additionally, they generate distinctive patterns of biological destruction and recovery. This, and the study of distribution and ecospace utilisation of Late Ordovician faunas, has been analysed in two almost contemporary (around 455 million years ago) meteorite craters (Lockne and Tvären, Sweden). Within the confined space of the impact craters environments varied from shallow and reef-like to over 200 m in depth and from well oxygenated to hypoxic. These types of environments favored colonization of different individual groups. In Tvären rhynchonelliformean brachiopod assemblages from the shallow crater rim include a range of morphotypes, not established elsewhere in the crater. Within the crater depression rhynchonelliformean brachiopods were not established until the upper third of the remaining crater fill. Colonization of post-impact faunas varies dependent on topography, depth and susbstrate within the impact craters. This is recognised for scolecodonts in Tvären and for gastropod-like mollusks, linguliform and craniiform brachiopods in both of the craters, as they inhabit a wide range of ecospace. A succession of different taxa is observed from the deepest part of each crater and upwards towards inferably more shallow, higher energy, water settings. The development of new community types and narrowly-defined niches in the craters helped further drive both α and β biodiversity during a critical phase of the Great Ordovician Biodiversification Event.
978-91-554-7639-7 / Link / Frisk , Åsa M / 2009