Library

Notes: We extend a simple version of the citizen candidacy model (developed by Osborne-Slivinski (1996) and Besley-Coate (1997)) to an asymmetric information setting, in which the type of a given individual is assumed to be private information. Focusing on a particular class of perfect Bayesian equilibria, we show that there exist only two kinds of equilibria. In the first one, both non-median types become candidates and those equilibria generalize to any number of (potential) candidates. In the second one, only one of the non-median types chooses to become candidates for the election and those equilibria hold for a number of (potential) candidates at most equal to 3. This is in sharp contrast with the complete information framework in which only the median type individuals stand for office when the entry cost is sufficiently low.

Notes: 1. Temperature, organic carbon and oxygen consumption were measured over a year at 13 sites in four lowlands streams within the same region in North Zealand, Denmark with the objectives of determining: (i) spatial and seasonal differences between open streams, forest streams and streams with or without lakes, (ii) factors influencing the temperature dependence of oxygen consumption rate, (iii) consequences of higher temperature and organic content in lake outlets on oxygen consumption rate, and (iv) possible consequences of forecasted global warming on degradation of organic matter.2. High concentrations of easily degradable dissolved (DOC) and particulate organic carbon (POC) were found in open streams downstream of plankton-rich lakes, while high concentrations of recalcitrant DOC were found in a forest brook draining a forest swamp. Concentrations of predominantly recalcitrant POC and DOC were low in a groundwater-fed forest spring. Overall, DOC concentration was two to 18 times higher than POC concentrations.3. Oxygen consumption rate at 20 °C was higher during summer than winter, higher in open than shaded streams and higher in lake outlets than inlets. Rate was closely related to concentrations of chlorophyll and POC but not to DOC. The ratio of oxygen consumption rate to total organic concentrations (DOC + POC), serving as a measure of organic degradability, was highest downstream of lakes, intermediate in open streams and lowest in forest streams.4. Temperature coefficients describing the exponential increase of oxygen consumption rate between 4 and 20 °C averaged 0.121 °C−1 (Q10 of 3.35) in 70 measurements and showed no significant variations between seasons and stream sites or correlations with ambient temperature and organic content.5. Oxygen consumption rate was enhanced downstream of lakes during summer because of higher temperature and, more significantly, greater concentrations of degradable organic carbon. Oxygen consumption rates were up to seven times higher in the stream with three impoundments than in a neighbouring unshaded stream and 21 times higher than in the groundwater-fed forest spring.6. A regional climate model has calculated a dramatic 4–5 °C rise in air temperature over Denmark by 2070–2100. If this is realised, unshaded streams are estimated to become 2–3 °C warmer in summer and winter and 5–7 °C warmer in spring and, thereby, increase oxygen consumption rates at ambient temperature by 30–40% and 80–130%, respectively. Faster consumption of organic matter and dissolved oxygen downstream of point sources should increase the likelihood of oxygen stress of the stream biota and lead to the export of less organic matter but more mineralised nutrients to the coastal waters.

Notes: 1. Aquatic plant stands are flexible, mesh-like open structures that undergo modification in shape and experience a cascade of declining flow velocities and micro-scale Reynolds numbers with increasing distance into the stands. It is not possible to define or measure the frontal area of this open flexible plant structure. Total wetted area was used as a reference area for drag because it can be measured with high accuracy and it was the most suitable measure of plant size impeding the flow and absorbing light for photosynthetic production. What is important is that it is made absolutely clear which type of reference area that is used.2. Numerous important relationships in biology are open to discussion because of differences in dimensions between variables. Relating dimensionless drag coefficients to dimensionless Reynolds numbers resolve such discussions, but defining Reynolds numbers cause other problems. Relating drag coefficients to macro-scale Reynolds numbers would result in exactly the same form of relationship as to water velocity because macro-scale Reynolds numbers changed in direct proportion to water velocity in the experiments, while kinematic viscosity and characteristic length within species remained constant.

Notes: Plasmodium berghei is the causative agent of rodent malaria and is widely used as a model system to study the liver stage of Plasmodium parasites. The entry of P. berghei sporozoites into hepatocytes has extensively been studied, but little is known about parasite–host interaction during later developmental stages of the intracellular parasite. Growth of the parasite far beyond the normal size of the host cell is an important stress factor for the infected cell. Cell stress is known to trigger programmed cell death (apoptosis) and we examined several apoptotic markers in P. berghei-infected cells and compared their level of expression and their distribution to that of non-infected cells. As none of the apoptotic markers investigated were found altered in infected cells, we hypothesized that parasite infection might confer resistance to apoptosis of the host cell. Treatment with peroxide or serum deprivation induced apoptosis in non-infected HepG2 cells, whereas P. berghei-infected cells appeared protected, indicating that the parasite interferes indeed with the apoptotic machinery of the host cell. To prove the physiological relevance of these results, mice were infected with high numbers of P. berghei sporozoites and treated with tumour necrosis factor (TNF)-α/d-galactosamine to induce massive liver apoptosis. Liver sections of these mice, stained for degraded DNA, confirmed that infected cells containing viable parasites were protected from programmed cell death. However, in non-treated control mice as well as in TNF-α-treated mice a small proportion of dead intracellular parasites with degraded DNA were detected. Most hepatocytes containing dead parasites provoked an infiltration of immunocompetent cells, indicating that these cells are no longer protected from cell death.

Notes: In histological studies, it has frequently been demonstrated that ultraviolet (UV) exposure, in particular UVB, can induce significant thickening of the viable epidermis and/or stratum corneum. Since skin biopsy alters the original skin morphology and always requires an iatrogenic trauma, we aimed to introduce optical coherence tomography (OCT) in vivo for the investigation of changes of epidermal thickness (ET) following UVA1 and UVB irradiation. Twelve healthy subjects received daily 60 J/cm2 of UVA1 and 1.5 minimal erythema doses UVB on their upper back over 3 consecutive days. Twenty-four hours after the last irradiation, OCT assessments were performed on UV exposed and adjacent nonirradiated control sites. Data of ET as expressed by comparison of the averaged A-scans differed significantly between nonirradiated (94.2 ± 15.7 µm), UVA1 (105.4 ± 12.8 µm) and UVB (125.7 ± 22.1 µm) exposed sites. In comparison to the nonirradiated sites, UVA1 exposed skin showed significant (P = 0.022) increase of ET of 11% and UVB exposed sites a significant (P 〈 0.001) increase of 25%. ET of UVA1 and UVB exposed skin sites differed significantly (P =0.005). Our results obtained from OCT in vivo measurements confirm data of previous histological studies indicating that not only erythemogenic doses of UVB, but also suberythemogenic doses of UVA1 may have a significant impact on ET. OCT appears to be a promising bioengineering technique for photobiological studies. However, further studies are needed to establish its measurement precision and validity, and to investigate in vivo spectral dependence on UV induced skin changes such as skin thickening.

Notes: 1. Lobelia dortmanna is a common representative of the small isoetid plants dominating the vegetation in nutrient-poor lakes in Europe and North America. Because of large permeable root surfaces and continuous air lacunae Lobelia exchanges the majority of O2 and CO2 during photosynthesis across the roots. This leads to profound diel pulses of O2 and CO2 in sandy sediments with low microbial O2 consumption rates. The ready radial root loss of O2 may, however, make Lobelia very susceptible to more reducing sediments. Therefore, we grew Lobelia for 6 months on natural and organically enriched sandy sediments to test how: (i) root oxygenation influenced degradation of organic matter and depth profiles of N and C; (ii) Lobelia and microbial O2 consumption rates influenced pool size and depth penetration of O2 in the sediments; and (iii) sediment enrichment influenced growth and mineral nutrition of Lobelia.2. Naturally low-organic sediments (0.32% DW) accumulated organic C and N during the experiment as a result of growth of Lobelia and surface micro-algae. In contrast, surface layers of enriched sediments (0.58, 0.87 and 2.46% DW) lost organic C and N because of enhanced mineralisation rates because of oxygen availability. In deeper layers of enriched sediments no significant differences in organic C and N pools were found between plant-covered and plant-free sediments probably because faster organic degradation because of root oxygenation was balanced by release of organic matter from the plants and because short roots with dense Fe-Mn coatings in the most enriched sediments constrained O2 release.3. Depth-integrated O2 pools were much higher in light than darkness, higher in plant-covered than plant-free sediments and higher in sandy than in organically enriched sediments. All sediments had a primary O2 maximum 1–2 mm below the sediment surface in light because of photosynthesis of micro-algae. Plant-covered sediments of low organic content (0.32 and 0.58% DW) also had a secondary deep maximum (2–4 cm) because of higher O2 release from Lobelia roots than microbial O2 consumption. Nitrification occurred here resulting in depletion of NH〈inlineGraphic alt="inline image" href="urn:x-wiley:00465070:FWB1382:FWB_1382_mu1" location="equation/FWB_1382_mu1.gif"/〉 and accumulation of NO〈inlineGraphic alt="inline image" href="urn:x-wiley:00465070:FWB1382:FWB_1382_mu2" location="equation/FWB_1382_mu2.gif"/〉. In low organic sediments, oxygen pools increased with higher plant biomass both in light and darkness. The deep O2 and NO3 maxima disappeared in high organic sediments of greater O2 consumption rates and smaller O2 release rates.4. Lobelia was stressed by increasing O2 consumption rate of the sediments. Plant weight and leaf number declined twofold and maximum root length declined fourfold suggesting severe problems maintaining sufficient axial O2 transport to the root tips because of rapid radial O2 loss. Despite markedly higher nutrient concentrations in the enriched sediments, leaf-N declined twofold and leaf-P declined fourfold to growth-limiting levels. These responses can be explained by constrains on mycorrhisal activity, root metabolism and vascular transport because of O2 depletion. Management efforts to stop the decline and ensure the recovery of the isoetid vegetation should therefore focus on improving water quality as well as sediment suitability for growth.

Notes: Background  Atopic dermatis (AD) is a chronic disease that often requires long-term treatment. Topical corticosteroids are the usual therapy for patients with AD, but prolonged usage can result in skin atrophy and other side-effects.Objectives  In a randomized, double-blind, comparative study, to compare the efficacy and safety of a 6-month treatment period with 0·1% tacrolimus ointment vs. a corticosteroid ointment regimen in adults with moderate to severe AD.Methods  Treatment was applied twice daily for a maximum of 6 months. Patients in the tacrolimus treatment group (n = 487) applied 0·1% tacrolimus ointment to all affected areas over the whole body. The patients treated with the corticosteroid regimen (n = 485) applied 0·1% hydrocortisone butyrate ointment to affected areas on the trunk and extremities and 1% hydrocortisone acetate ointment to affected areas on the face and neck. The study primary endpoint was the response rate, i.e. the proportion of patients with at least 60% improvement in the modified Eczema Area and Severity Index (mEASI) between baseline and month 3.Results  By month 3, more patients in the 0·1% tacrolimus group responded to treatment (72·6% vs. 52·3% in the corticosteroid group, P 〈 0·001). The patients treated with 0·1% tacrolimus also showed greater improvement in mEASI, EASI, affected body surface area and physician and patient assessments of global response. Patients applying 0·1% tacrolimus ointment experienced more skin burning (52·4% vs. 13·8% in the corticosteroid group; P 〈 0·001). In most patients, skin burning was mild to moderate in severity and decreased rapidly after the first week of treatment. There was no increase in the incidence of infections or malignancies over time in either treatment group.Conclusions  Long-term treatment with 0·1% tacrolimus ointment is significantly more efficacious than a corticosteroid ointment regimen in adults with moderate to severe AD.

Notes: Both, the employment of leaching bacteria for metal winning as well as the mitigation ofbioleaching processes at AMD/ARD sites, require reliable monitoring methods for assessingbacterial activities. Therefore, we have developed a robust and rapid test system combining twosensitive analytical techniques: quantification of heat evolution by microcalorimetry anddetermination of all relevant inorganic sulfur species by chromatographic methods (IC and HPLC).Generally, only about 1 g of sample is sufficient for a complete analysis. The combined test hasbeen applied to various leaching biotopes such as bioreactors, columns, heaps and natural sites. Thebacterial activity of diverse sulfidic materials such as lignite and coal wastes, pure metal sulfidesand complex ores has been investigated. In our labs, microcalorimetry can be performed in therange of 5 to 80 °C, covering most of the temperature spectrum of leaching bacteria. Hence, theheat evolution values of samples as a direct measure for calculating leaching rates can be obtainedat nearly all relevant in situ temperatures. The combination with sulfur species determination resultsin additional information on leaching mechanisms (thiosulfate or polysulfide pathway) and generalleaching performance (e. g. accumulation of sulfur intermediates)

Notes: Attachment to metal sulfide surfaces is a prerequisite of bioleaching activity via thecontact mode [Rohwerder et al.: Appl. Microbiol. Biotechnol. Vol. 63 (2003), p. 239]. Until now,the mechanisms and possible variations of this attachment process among leaching bacteria is notwell understood. Therefore, we are studying the diversity in the attachment behaviour of differentstrains of the genus Acidithiobacillus, which is one of the main bacterial group involved in thebioleaching of metal sulfides. Among the species At. ferrooxidans, cells of the type strain (ATCC23270) were found to attach the least. Whereas bacterial cells of strains A2 and R1 attached themost. Other strains that were investigated in this study included At. ferrooxidans D-26 and R7.Highly likely, these strains exhibit different attachment behaviour due to specific variations in theirextracellular polymeric substance (EPS) composition as loss of part of the EPS has previously beenobserved to have a negative effect on attachment and bioleaching activities. Differences in severalEPS parameters such as the amount of complexed Fe(III) ions and the sugar composition arepossible reasons for the observed strain-specific attachment behaviour. In addition to attachmentassays and microscopic studies (AFM and epifluorescence), leaching activities of the strains werecomparatively investigated by short-term as well as growth experiments

Notes: Biofilm development plays a pivotal role in the bioleaching process. The attachment ofthe acidophilic chemolithotrophic Acidithiobacillus ferrooxidans to mineral surfaces is mediated byextracellular polymeric substances (EPS) involved in biofilm development. Previous work suggeststhat EPS composition of A. ferrooxidans is adapted to the energy source and, accordingly, thebacterium must be able to sense the surface to which attachment occurs with the consequenttriggering of the expression of different EPS-genes. Quorum sensing (QS) is recognized as one ofthe main regulators of biofilm formation. A. ferrooxidans possesses a functional QS type AI-1system and the analysis of culture supernatants revealed us that this bacterium is able to synthesizenine different homoserine lactones (AHLs) whose acyl-chain lengths oscillate between 8 and 16carbons and include an alcohol or a ketone function at the C3 position. The transcription levels ofthe afeI gene encoding for the AHL synthase are higher in cells grown in sulfur and thiosulfatemedia than in iron-grown cells, suggesting that biofilm formation in A. ferrooxidans would beregulated by the QS type AI-1 system. In the present study, the effect of several synthetic AHLsand analogues on the attachment of A. ferrooxidans to pyrite was analyzed. Preliminary resultssuggest that some of these molecules are changing the bacterial attachment to pyrite