Fitting Linear Mixed-Effects Models using lme4

Maximum likelihood or restricted maximum likelihood (REML) estimates of the parameters in linear mixed-effects models can be determined using the lmer function in the lme4 package for R. As for most model-fitting functions in R, the model is described in an lmer call by a formula, in this case including both fixed- and random-effects terms. The formula and data together determine a numerical representation of the model from which the profiled deviance or the profiled REML criterion can be evaluated as a function of some of the model parameters. The appropriate criterion is optimized, using one of the constrained optimization functions in R, to provide the parameter estimates. We describe the structure of the model, the steps in evaluating the profiled deviance or REML criterion, and the structure of classes or types that represents such a model. Sufficient detail is included to allow specialization of these structures by users who wish to write functions to fit specialized linear mixed models, such as models incorporating pedigrees or smoothing splines, that are not easily expressible in the formula language used by lmer.Comment: 51 pages, including R code, and an appendi

Regulation of Ribulose Bisphosphate Carboxylase Activity in Intact Wheat Leaves by Light, CO2, and Temperature

The activity of the enzyme ribulose bisphosphate carboxylase (RuBPCase) was estimated after rapidly extracting it from intact wheat leaves pretreated under different light and CO2 levels. No HCO3− was added to the extraction buffer since it is shown to inhibit RuBPCase. The activity increased as light intensity or CO2 concentration during pretreatment was increased. Enzyme activity increased as temperature during pretreatment was decreased. Light activation did not affect the affinity of RuBPCase for CO2. A Km of 30 μM CO2 under air level O2 was determined. CO2, light and temperature are three main limiting factors of photosynthesis. It seems that the activity of RuBPCase is regulated by these factors according to the requirements for CO2 fixatio

Influence of Inorganic Phosphate on Photosynthesis of Wheat Chloroplasts: II. RIBULOSE BISPHOSPHATE CARBOXYLASE ACTIVITY

Isolated wheat chloroplasts were pre-incubated in the dark in the presence of various concentrations of inorganic phosphate with or without carbon dioxide, oxaloacetate, glycerate, and 3-phosphoglycerate. The effect of subsequent illumination on photosynthetic oxygen evolution, ribulose bisphosphate carboxylase activity, ATP content, and ribulose bisphosphate content was investigated. Inorganic phosphate had little effect on ribulose bisphosphate carboxylase activity in darkness or during the initial phase of illumination, but it prevented the decline in activity that occurred during later stages of illumination, when photoreduction of CO2 was decreasing in rate. Addition of inorganic phosphate to chloroplasts illuminated without phosphate restored the ribulose bisphosphate carboxylase activity, increased the ATP, and decreased the ribulose bisphosphate in the organelles. The responses to CO2, oxaloacetate, glycerate, and 3-phosphoglycerate suggest that the decreased activity of ribulose bisphosphate carboxylase during photosynthesis results from ATP consumption. Purified ribulose bisphosphate carboxylase was activated by inorganic phosphate, but this activation did not occur in the presence of ATP. ATP inhibited ribulose bisphosphate carboxylase when it was present in combination with various photosynthetic metabolites. Inactivation of ribulose bisphosphate carboxylase in chloroplasts, illuminated in the absence of inorganic phosphate, is not due to lack of activation by inorganic phosphate or ATP. It may result from decreased stromal p

Influence of Temperature and O2 Concentration on Photosynthesis and Light Activation of Ribulosebisphosphate Carboxylase Oxygenase in Intact Leaves of White Clover (Trifolium repens L.)

Detached leaves of white clover (Trifolium repens L.) were kept for 1 h under various conditions of temperature, oxygen concentration and light intensity. Rates of photosynthesis were measured where appropriate and then ribulosebisphosphate carboxylase oxygenase (RuBPCO) was extracted rapidly and its initial activity measured immediately. The extracted activity increased with increased intensity of illumination of the leaves. Where leaves were pretreated at low light intensity, the lower the temperature of the leaves the higher the extracted activity of RuBPCO. At high light intensity temperature did not affect the activity of subsequently extracted RuBPCO but the light intensity which was necessary for maximum activity increased with temperature. Activity of RuBPCO from leaves pretreated in the dark was least when CO2 was low and temperature high. Leaves, pretreated at low temperatures and high light intensity in 20% O2, yielded higher activity in extracts than leaves pretreated under similar conditions but in 2% O2. A relatively weak temperature response of photosynthesis at low irradiances was associated with a decrease in extractable RuBPCO activity with increasing temperature. A strong temperature dependence of the oxygen inhibition of photosynthesis was associated with lower extractable RuBPCO activity in leaves pretreated at low oxygen concentration at low temperatures. With leaves from plants grown at low temperatures prior to treatment of leaves, oxygen inhibition of photosynthesis was less temperature dependent and activity of RuBPCO in extracts was not decreased by low O2 at low temperatures. Differences in the activation of RuBPCO appear to influence photosynthesis and account for an absence of oxygen inhibition of photosynthesis at low temperatures in plants grown in warm condition

Die Veränderungen der Hebammenausbildung seit 1970 in der Deutschschweiz und ihre Auswirkungen auf die Kompetenzen der Hebamme

Die Hebammen erlebten in den letzten Jahrzehnten aufgrund der Technisierung, Medikalisierung und veränderten Bedürfnisse der Gesellschaft eine Erneuerung des Berufsbildes. Dies hatte Auswirkungen auf die Hebammenausbildung mit den dazugehörigen Kompetenzen. Der Hebammenberuf wurde akademisiert. 2008 startete erstmals ein Studiengang für Hebammen auf Tertiärstufe in der Deutschschweiz. Das Ziel der vorliegenden Bachelorarbeit besteht darin, die Entwicklung der Ausbildung sowie den Kompetenzbereich der Hebamme seit 1970 hin zum heutigen Stand darzustellen. Diese Bachelorarbeit ist in Form einer themengeleiteten Arbeit mit historischen Aspekten geschrieben. Die Fragestellung wird anhand der Analyse von aktuellen Literatur und historischer Quellen bearbeitet, welche in den Staatsarchiven Bern, St. Gallen und Zürich sowie in diversen Schweizer Bibliotheken gefunden wurden. Die Quellenanalysen zeigten als relevante Ergebnisse, dass weniger eine Veränderung der Kompetenzen, sondern vielmehr Änderungen in der Struktur und Organisation der Hebammenausbildung seit 1970 in der Deutschschweiz stattgefunden haben. Die Schlussfolgerung zeigt, dass weitere gezielte Forschungen in der Hebammenwissenschaft der Schweiz in den Bereichen der Hebammenausbildung, der Lehre und der Berufsentwicklung notwendig sind. Parallel dazu sollte das Wissen zur Entwicklung der Hebammenausbildung und -kompetenzen strukturiert aufgearbeitet werden. Ansonsten schreitet der Verlust von Informationsquellen (z. B. Zeitzeuginnen und Zeitzeugen, Internetseiten, Archivdokumente) fort und erschwert die Aufarbeitung immer weiter

Regeneration of Ribulose 1,5-bisphosphate and Ribulose 1,5-bisphosphate carboxylase/oxygenase Activity Associated with Lack of Oxygen Inhibition of Photosynthesis at Low Temperature

The nature of the lack of oxygen inhibition of C3-photosynthesis at low temperature was investigated in white clover (Trifolium repens L.). Detached leaves were brought to steady-state photosynthesis in air (34 Pa p(CO2), 21 kPa p(O2), balance N2) at temperatures of 20°C and 8°C, respectively. Net photosynthesis, ribulose 1,5-bisphosphate (RuBP) and ATP contents, and ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBPCO) activities were followed before and after changing to 2·0 kPa p(O2). At 20°C, lowering p(O2) increased net photosynthesis by 37%. This increase corresponded closely with the increase expected from the effect on the kinetic properties of RuBPCO. Conversely, at 8°C net photosynthesis rapidly decreased following a decrease in p(O2) and then increased again reaching a steady-state level which was only 7% higher than at 21 kPa p(O2). The steady-state rates of RuBP and associated ATP consumption were both estimated to have decreased. ATP and RuBP contents decreased by 18% and 33% respectively, immediately after the change in p(O2) suggesting that RuBP regeneration was reduced at low p(O2) due to reduced photophosphorylation. Subsequently, RuBP content increased again. Steady-state RuBP content at 2·0 kPa p(O2) was 24% higher than at 21 kPa p(O2). RuBPCO activity decreased by 22%, indicating control of steady-state RuBP consumption by RuBPCO activity. It is suggested that lack of oxygen inhibition of photosynthesis at low temperature is due to decreased photophosphorylation at low temperature and low p(O2). This may be due to assimilate accumulation within the chloroplasts. Decreased photophosphorylation seems to decrease RuBP synthesis and RuBPCO activity, possibly due to an acidification of the chloroplast strom

Influence of Temperature on the Ratio of Ribulose Bisphosphate Carboxylase to Oxygenase Activities and on the Ratio of Photosynthesis to Photorespiration of Leaves

Lehnherr, B., Mächler, F. and Nösberger, J. 1985. Influence of temperature on the ratio of ribulose bisphosphate carboxylase to oxygenase activities and on the ratio of photosynthesis to photorespiration of leaves.—J. exp. Bot. 36: 1117-1125. Rates of net and gross photosynthesis of intact white clover leaves were measured by infrared gas analysis and by short term uptake of 14CO2 respectively. Ribulose bisphosphate carboxylase oxygenase (RuBPCO) was purified from young leaves and kinetic properties investigated in combined and separate assays. The ratio of carboxylase to oxygenase activities was compared with the ratio of photosynthesis to photorespiration at various temperatures and CO2 concentrations. The ratio of photosynthesis to photorespiration at 30 Pa p(CO2) was consistent with the ratio of carboxylase activity to oxygenase activity when each was measured above 20 °C. However, the ratio of photosynthesis to photorespiration increased with decreasing temperature, whereas the ratio of carboxylase to oxygenase activity was independent of temperature. This resulted in a disagreement between the measurements on the purified enzyme and intact leaf at low temperature. No disagreement between enzyme and leaf at low temperature occurred, when the ratio of photosynthesis to photorespiration was determined at increased CO2 concentrations. The results suggest an effect of low temperature and low CO2 concentration on the ratio of photosynthesis to photorespiration independent of the enzym

Winterthur entwickelt sich von der Energiestadt zur Smart City

Die Stadt Winterthur sieht technologische und gesellschaftliche Entwicklungen als Chance. Die der Nachhaltigkeit verschriebene 100 000-Einwohner-Stadt will sich deshalb zu einer Smart City entwickeln

Influence of Inorganic Phosphate on Photosynthesis of Wheat Chloroplasts: I. PHOTOSYNTHESIS AND ASSIMILATE EXPORT AT 5 °C AND 25 °C

Chloroplasts were isolated from 10 d old wheat seedlings and illuminated at 5 °C or 25 °C in various concentrations of PO43-. Photosynthetic oxygen evolution, ATP content, and export of triose phosphates and 3-phosphoglycerate were measured. Incorporation of 14C from NaH14CO3 into pentose monophosphates, fructose monophosphate, and glucose monophosphates was determined. The ATP content in illuminated chloroplasts decreased when the PO43- concentration in the medium was low. The ATP content increased when the PO43- concentration was increased. A higher PO43-. concentration in the medium was needed to increase the ATP at 5 °C than at 25 °C. This would suggest that PO43- deficiency occurs more readily at low than at high temperatures. More 14C was incorporated into photosynthetic metabolites within the chloroplasts at 5 °C than at 25 °C, indicating decreased assimilate export when the temperature was low. Dihydroxyacetone phosphate was preferentially exported when the PO43- concentration enabled a high rate of photosynthesis at 25 °C. However, under conditions of PO43- deficiency, either due to low PO43- concentration in the medium or due to low temperature, 3-phosphoglycerate was preferred for export. The results suggest that the relatively high photosynthetic rates at low temperature are due to increased concentrations of photosynthetic metabolites. The assimilate export at low temperature seems to be decreased due to decreased concentrations of dihydroxyacetone phosphate in the stroma. Preferential export of 3-phosphoglycerate at low temperature or at low PO43- concentration in the medium may be a consequence of high stromal concentrations of this metabolite. On the other hand, it could also be due to decreased stromal p