Effects of macronutrients upon buoyancy regulation by metalimnetic Oscillatoria agardhii in Deming Lake, Minnesota

Gas-vacuolate filaments of Oscillatoria agardhii form a metalimnetic layer in Deming Lake, Minnesota. The environmental factors which affect buoyancy and the physiological processes which mediate changes in buoyancy were determined. Buoyant filaments lost their buoyancy in a few hours when incubated at light intensities above those found in situ (approximately 15 mumol photons m-2 s-1, or 1% of the surface value). The rate of buoyancy loss was accelerated by the addition of 10 muM phosphate at irradiances >200 mumol photons m-2 s-1. The effect of nutrient additions on buoyancy was also investigated over a longer time period by incubating metalimnetic samples in situ. The samples were deployed for 6 days at a depth where the irradiance was 8% of the surface value. As found in short-term experiments, the addition of phosphate resulted in the largest decrease in buoyancy. However, the addition of ammonia in addition to phosphate attenuated the buoyancy loss on day 2, and on day 6 the filaments in these treatments were almost completely buoyant. The physiological status of the filaments in these treatments was assayed by analysis of elemental ratios of C, N and P, and by measurement of cellular chlorophyll, polysaccharide and protein. In addition, the cellular content of gas vesicles was determined. The construction of ballast balance sheets from these data indicated that changes in buoyancy were primarily due to differences in the amount of polysaccharide ballast in the cells. However, in another set of in situ experiments, the increase in measured ballast molecules did not explain the observed loss of buoyancy. We hypothesized that another, undetected ballast-providing molecule had accumulated in the cells

Planning to speak in L1 and L2

Item does not contain fulltextThe leading theories of sentence planning - Hierarchical Incrementality and Linear Incrementality - differ in their assumptions about the coordination of processes that map preverbal information onto language. Previous studies showed that, in native (L1) speakers, this coordination can vary with the ease of executing the message-level and sentence-level processes necessary to plan and produce an utterance. We report the first series of experiments to systematically examine how linguistic experience influences sentence planning in native (L1) speakers (i.e., speakers with life-long experience using the target language) and non-native (L2) speakers (i.e., speakers with less experience using the target language). In all experiments, speakers spontaneously generated one-sentence descriptions of simple events in Dutch (L1) and English (L2). Analyses of eye-movements across early and late time windows (pre- and post-400 ms) compared the extent of early message-level encoding and the onset of linguistic encoding. In Experiment 1, speakers were more likely to engage in extensive message-level encoding and to delay sentence-level encoding when using their L2. Experiments 2-4 selectively facilitated encoding of the preverbal message, encoding of the agent character (i.e., the first content word in active sentences), and encoding of the sentence verb (i.e., the second content word in active sentences) respectively. Experiment 2 showed that there is no delay in the onset of L2 linguistic encoding when speakers are familiar with the events. Experiments 3 and 4 showed that the delay in the onset of L2 linguistic encoding is not due to speakers delaying encoding of the agent, but due to a preference to encode information needed to select a suitable verb early in the formulation process. Overall, speakers prefer to temporally separate message-level from sentence-level encoding and to prioritize encoding of relational information when planning L2 sentences, consistent with Hierarchical Incrementality.33 p

Green public transport? : Policy processes concerning the transitions to alternative fuels in public transport in Linköping and Helsingborg 1976-2005

Föreliggande avhandling studerar kommunala policyprocesser i en fråga där ett flertal olika policyområden ingår: övergången till alternativa drivmedel i kollektivtrafiken. Genom att undersöka hur och varför sådana policyer utvecklats i två kommuner bidrar studien dels till att förklara hur policy utvecklas på kommunal nivå; dels till att skapa förståelse för policyskapande där olika policyområden ingår. Genom fallstudier har policyprocesserna vid övergången till biogas i stadsbusstrafiken i Linköpings och Helsingborgs kommuner undersökts. Studien är processorienterad och fokuserar huvudsakligen på hur och varför aktörer, utifrån sina resurser, intressen, problemdefinitioner och lösningar, kan påverka policy. Resultaten visar hur policyprocesserna vid övergången till biogas präglats av traditionella policyområden där aktörer, intressen och resurser skilt sig åt beroende på sektor. Samtidigt visar avhandlingen att en sammankoppling mellan policyområdena för energi, miljö och transport varit väsentligt för att aktörer skulle kunna driva igenom sina förslag. För att göra detta har gränsgångare – policyentreprenörer som gått över gränserna för de tre policyområdena – varit centrala genom att initiera breda samarbeten där aktörer företrädande energi, miljö och kollektivtrafik identifierat och eftersträvat ett gemensamt mål.This thesis studies municipal policy processes where several policy sectors are involved: the transition to alternative fuels in public transport. Examining how and why those policies have developed in two municipalities, the study will contribute to explain how policy are shaped on a municipal level and also contribute to further knowledge of policy processes where different sectors are involved. Through case studies, the policy processes concerning the introduction of biogas in city buses in the municipalities of Linköping and Helsingborg have been studied. The study is process oriented and mainly focuses on how and why actors with their resources, interests, problem definitions and solutions, can influence policy. The results show that the processes consisted of traditional policy sectors where actors, interests and resources differed between the sectors. In addition, the thesis shows that a connection between the energy, environment and transport policy sectors has been essential for policy development. Boundary walkers – that is, policy entrepreneurs that crossed the boundaries between the three sectors – have been central to initiate broad collaborations where actors representing energy, environment and public transport identified and strived to a common goal

Dependencies first: Eye tracking evidence from sentence production in Tagalog

Item does not contain fulltextThe 35th annual meeting of the Cognitive Science Societ

High resolution simulation of recent Arctic and Antarctic stratospheric chemical ozone loss compared to observations

Simulations of polar ozone losses were performed using the three-dimensional high-resolution (1° × 1°) chemical transport model MIMOSA-CHIM. Three Arctic winters 1999–2000, 2001–2002, 2002–2003 and three Antarctic winters 2001, 2002, and 2003 were considered for the study. The cumulative ozone loss in the Arctic winter 2002–2003 reached around 35% at 475K inside the vortex, as compared to more than 60% in 1999–2000. During 1999–2000, denitrification induces a maximum of about 23% extra ozone loss at 475K as compared to 17% in 2002–2003. Unlike these two colder Arctic winters, the 2001–2002 Arctic was warmer and did not experience much ozone loss. Sensitivity tests showed that the chosen resolution of 1° ×1° provides a better evaluation of ozone loss at the edge of the polar vortex in high solar zenith angle conditions. The simulation results for ozone, ClO, HNO3, N2O, and NOy for winters 1999–2000 and 2002–2003 were compared with measurements on board ER-2 and Geophysica aircraft respectively. Sensitivity tests showed that increasing heating rates calculated by the model by 50% and doubling the PSC (Polar Stratospheric Clouds) particle density (from 5 × 10-3 to 10-2 cm-3) refines the agreement with in situ ozone, N2O and NOy levels. In this configuration, simulated ClO levels are increased and are in better agreement with observations in January but are overestimated by about 20% in March. The use of the Burkholder et al. (1990) Cl2O2 absorption cross-sections slightly increases further ClO levels especially in high solar zenith angle conditions. Comparisons of the modelled ozone values with ozonesonde measurement in the Antarctic winter 2003 and with Polar Ozone and Aerosol Measurement III (POAM III) measurements in the Antarctic winters 2001 and 2002, shows that the simulations underestimate the ozone loss rate at the end of the ozone destruction period. A slightly better agreement is obtained with the use of Burkholder et al. (1990) Cl2O2 absorption cross-sections