Carbon dioxide and methane exchange between a boreal pristine lake and the atmosphere

Lakes serve as sites for terrestrially fixed carbon to be remineralized and transferred back to the atmosphere. Their role in regional carbon cycling is especially important in the Boreal Zone, where lakes can cover up to 20% of the land area. Boreal lakes are often characterized by the presence of a brown water colour, which implies high levels of dissolved organic carbon from the surrounding terrestrial ecosystem, but the load of inorganic carbon from the catchment is largely unknown. Organic carbon is transformed to methane (CH4) and carbon dioxide (CO2) in biological processes that result in lake water gas concentrations that increase above atmospheric equilibrium, thus making boreal lakes as sources of these important greenhouse gases. However, flux estimates are often based on sporadic sampling and modelling and actual flux measurements are scarce. Thus, the detailed temporal flux dynamics of greenhouse gases are still largely unknown. ----- One aim here was to reveal the natural dynamics of CH4 and CO2 concentrations and fluxes in a small boreal lake. The other aim was to test the applicability of a measuring technique for CO2 flux, i.e. the eddy covariance (EC) technique, and a computational method for estimation of primary production and community respiration, both commonly used in terrestrial research, in this lake. Continuous surface water CO2 concentration measurements, also needed in free-water applications to estimate primary production and community respiration, were used over two open water periods in a study of CO2 concentration dynamics. Traditional methods were also used to measure gas concentration and fluxes. The study lake, Valkea-Kotinen, is a small, humic, headwater lake within an old-growth forest catchment with no local anthropogenic disturbance and thus possible changes in gas dynamics reflect the natural variability in lake ecosystems. CH4 accumulated under the ice and in the hypolimnion during summer stratification. The surface water CH4 concentration was always above atmospheric equilibrium and thus the lake was a continuous source of CH4 to the atmosphere. However, the annual CH4 fluxes were small, i.e. 0.11 mol m-2 yr-1, and the timing of fluxes differed from that of other published estimates. The highest fluxes are usually measured in spring after ice melt but in Lake Valkea-Kotinen CH4 was effectively oxidised in spring and highest effluxes occurred in autumn after summer stratification period. CO2 also accumulated under the ice and the hypolimnetic CO2 concentration increased steadily during stratification period. The surface water CO2 concentration was highest in spring and in autumn, whereas during the stable stratification it was sometimes under atmospheric equilibrium. It showed diel, daily and seasonal variation; the diel cycle was clearly driven by light and thus reflected the metabolism of the lacustrine ecosystem. However, the diel cycle was sometimes blurred by injection of hypolimnetic water rich in CO2 and the surface water CO2 concentration was thus controlled by stratification dynamics. The highest CO2 fluxes were measured in spring, autumn and during those hypolimnetic injections causing bursts of CO2 comparable with the spring and autumn fluxes. The annual fluxes averaged 77 (±11 SD) g C m-2 yr-1. In estimating the importance of the lake in recycling terrestrial carbon, the flux was normalized to the catchment area and this normalized flux was compared with net ecosystem production estimates of -50 to 200 g C m-2 yr-1 from unmanaged forests in corresponding temperature and precipitation regimes in the literature. Within this range the flux of Lake Valkea-Kotinen yielded from the increase in source of the surrounding forest by 20% to decrease in sink by 5%. The free water approach gave primary production and community respiration estimates of 5- and 16-fold, respectively, compared with traditional bottle incubations during a 5-day testing period in autumn. The results are in parallel with findings in the literature. Both methods adopted from the terrestrial community also proved useful in lake studies. A large percentage of the EC data was rejected, due to the unfulfilled prerequisites of the method. However, the amount of data accepted remained large compared with what would be feasible with traditional methods. Use of the EC method revealed underestimation of the widely used gas exchange model and suggests simultaneous measurements of actual turbulence at the water surface with comparison of the different gas flux methods to revise the parameterization of the gas transfer velocity used in the models.

Spatially dependent correlation functions in the Anderson model

We report results from a first principles calculation of spatially dependent correlation functions around a magnetic impurity in metals described by the nondegenerate Anderson model. Our computations are based on a combination of perturbative scaling theory and numerical renormalization group methods. Results for the conduction election charge density around the impurity and correlation functions involving the conduction electron and impurity charge and spin densities will be presented. The behavior in various regimes including the mixed valent regime will be explored.

Nonlinear mixture autoregressive model: economic applications

The aim of this dissertation is to model economic variables by a mixture autoregressive (MAR) model. The MAR model is a generalization of linear autoregressive (AR) model. The MAR -model consists of K linear autoregressive components. At any given point of time one of these autoregressive components is randomly selected to generate a new observation for the time series. The mixture probability can be constant over time or a direct function of a some observable variable. Many economic time series contain properties which cannot be described by linear and stationary time series models. A nonlinear autoregressive model such as MAR model can a plausible alternative in the case of these time series. In this dissertation the MAR model is used to model stock market bubbles and a relationship between inflation and the interest rate. In the case of the inflation rate we arrived at the MAR model where inflation process is less mean reverting in the case of high inflation than in the case of normal inflation. The interest rate move one-for-one with expected inflation. We use the data from the Livingston survey as a proxy for inflation expectations. We have found that survey inflation expectations are not perfectly rational. According to our results information stickiness play an important role in the expectation formation. We also found that survey participants have a tendency to underestimate inflation. A MAR model has also used to model stock market bubbles and crashes. This model has two regimes: the bubble regime and the error correction regime. In the error correction regime price depends on a fundamental factor, the price-dividend ratio, and in the bubble regime, price is independent of fundamentals. In this model a stock market crash is usually caused by a regime switch from a bubble regime to an error-correction regime. According to our empirical results bubbles are related to a low inflation. Our model also imply that bubbles have influences investment return distribution in both short and long run.

Transport properties of phosphomolybdate and phosphotungstate glasses

The d.c. conductivity of phosphomolybdate and phosphotungstate glasses is discussed. The conductivity of these glasses is due to the hopping of electrons between two valence states (Mo5+ to Mo6+ or W5+ W6+). In some of the glasses, the activation energy itself is found to be a function of temperature. This appears to be due to thermally activated and variable-range hopping mechanisms operating in different temperature regimes. The relation between conductivity and the [M5+]/[Mtotal](M ≡ Mo, W) ratio does not show any systematic variation. This anomaly can be understood using the structural models of these glasses. In contrast, Mott's theory and the Triberis and Friedman model have been used to obtain conductivity parameters such as the percolation distance Rij and 2agrRij (agr is the tunnelling probability). The conductivity parameter 2agrRij is quite useful to resolve the controversy regarding the tunnelling term exp(2agrRij) existing in the literature. For low values of 2agrRij, it is shown that the exp (2agrRij) term is very significant.

Governmental rationalities and the local dimension of European politics. A study of the Interreg IV programme "Alpenrhein-Bodensee-Hochrhein"

The thesis aims at investigating the local dimension of the EU cohesion policy through the utilization of an alternative approach, which aims at the analysis of discourse and structures of power. The concrete case under analysis is the Interreg IV programme “Alpenrhein-Bodensee-Hochrhein”, which is conducted in the border region between Germany, Switzerland, Austria and the principality of Liechtenstein. The main research question is stated as such: What governmental rationalities can be found at work in the field of EU cross-border cooperation programmes? How is directive action and cooperation envisioned? How coherent are the different rationalities, which are found at work? The theoretical framework is based on a Foucaultian understanding of power and discourse and utilizes the notion of governmentalities as a way to de-stabilize the understanding of directive action and in order to highlight the dispersed and heterogeneous nature of governmental activity. The approach is situated within the general field of research on the European Union connected to basic conceptualisations such as the nature of power, the role of discourse and modes of subjectification. An approach termed “analytics of government”, based on the work of researchers like Mitchell Dean is introduced as the basic framework for the analysis. Four dimensions (visiblities, subjectivities, techniques/practices, problematisations) are presented as a set of tools with which governmental regimes of practices can be analysed. The empirical part of the thesis starts out with a discussion of the general framework of the European Union's cohesion policy and places the Interreg IV Alpenrhein-Bodensee-Hochrhein programme in this general context. The main analysis is based on eleven interviews which were conducted with different individuals, participating in the programme on different levels. The selection of interview partners aimed at maximising heterogeneity through including individuals from all parts of the programme region, obtaining different functions within the programme. The analysis reveals interesting aspects pertaining to the implementation and routine aspects of work within initiatives conducted under the heading of the EU cohesion policy. The central aspects of an Interreg IV Alpenrhein-Bodensee-Hochrhein – governmentality are sketched out. This includes a positive perception of the work atmosphere, administrative/professional characterisation of the selves and a de-politicization of the programme. Characteristic is the experience of tensions by interview partners and the use of discoursive strategies to resolve them. Negative perceptions play an important role for the specific governmental rationality. The thesis contributes to a better understanding of the local dimension of the European Union cohesion policy and questions established ways of thinking about governmental activity. It provides an insight into the working of power mechanisms in the constitution of fields of discourse and points out matters of practical importance as well as subsequent research questions.

A thermogravimetric study of the oxidative growth of Al2O3/Al alloy composites

The oxidation of liquid Al–Mg–Si alloys at 900–1400 °C was studied by thermogravimetric analysis (TGA). The development of a semi-protective surface layer of MgO/MgAl2O4 allows the continuous formation of an Al2O3-matrix composite containing an interpenetrating network of metal microchannels at 1000–1350 °C. An initial incubation period precedes bulk oxidation, wherein Al2O3 grows from a near-surface alloy layer by reaction of oxygen supplied by the dissolution of the surface oxides and Al supplied from a bulk alloy reservoir through the microchannel network. The typical oxidation rate during bulk growth displays an initial acceleration followed by a parabolic deceleration in a regime apparently limited by Al transport to the near-surface layer. Both regimes may be influenced by the Si content in this layer, which rises due to preferential Al and Mg oxidation. The growth rates increase with temperature to a maximum at ~1300 °C, with a nominal activation energy of 270 kJ/mole for an Al-2.85 wt. % Mg-5.4 wt. % Si alloy in O2 at furnace temperatures of 1000–1300 °C. An oscillatory rate regime observed at 1000–1075 °C resulted in a banded structure of varying Al2O3-to-metal volume fraction.

Litter quality and its response to water level drawdown in boreal peatlands at plant species and community level

Changes in the structure of plant communities may have much more impact on ecosystem carbon (C) cycling than any phenotypic responses to environmental changes. We studied these impacts via the response of plant litter quality, at the level of species and community, to persistent water-level (WL) drawdown in peatlands. We studied three sites with different nutrient regimes, and water-level manipulations at two time scales. The parameters used to characterize litter quality included extractable substances, cellulose, holocellulose, composition of hemicellulose (neutral sugars, uronic acids), Klason lignin, CuO oxidation phenolic products, and concentrations of C and several nutrients. The litters formed four chemically distinct groups: non-graminoid foliar litters, graminoids, mosses and woody litters. Direct effects of WL drawdown on litter quality at the species level were overruled by indirect effects via changes in litter type composition. The pristine conditions were characterized by Sphagnum moss and graminoid litters. Short-term (years) responses of the litter inputs to WL drawdown were small. In longterm (decades), total litter inputs increased, due to increased tree litter inputs. Simultaneously, the litter type composition and its chemical quality at the community level greatly changed. The changes that we documented will strongly affect soil properties and C cycle of peatlands.

Room temperature creep in amorphous alloys: Influence of initial strain and free volume

The role of imposed strain on the room temperature time-dependent deformation behavior of bulk metallic glasses (BMGs) was systematically investigated through spherical nanoindentation creep experiments. The results show that creep occurred even at very low strains within elastic regimes and, interestingly, a precipitous increase in creep rate was found in plastic regimes, with BMG that had a higher free volume exhibiting greater creep rates. The results are discussed in terms of prevailing mechanisms of elastic/plastic deformation of amorphous alloys. (c) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Testing the efficacy of a chilli-tobacco rope fence as a deterrent against crop-raiding elephants

Chilli-based repellents have shown promise as deterrents against crop-raiding elephants in Africa. We experimented with ropes coated with chilli-based repellent as a cheap alternative to existing elephant cropraid deterrent methods in India. Three locations (Buxa Tiger Reserve, Wyanad Wildlife Sanctuary and Hosur Forest Division) representing varying rainfall regimes from high to low, and with histories of intense elephant-agriculture conflict, were selected for the experiments that were conducted over 2-3 months during the pre-harvest period of the kharif season in late 2006. Chilli and tobacco powder mixed with waste oil was applied to ropes strung around agricultural fields of 1.4-5.5 km perimeter and elephant approaches were monitored. Elephants breached the rope fences a few times at all three study sites. Female-led herds were far more deterred (practically 100% reduction) than were solitary males (c. 50%) by the chilli-tobacco rope. Efficacy of this method as a deterrent was significantly better in the low-rainfall regime relative to medium and high-rainfall regimes. The initial promising results present a case for more rigorous experimentation; these would help determine if the elephants avoiding the rope are responding physiologically to the chilli-tobacco smell or merely reacting cautiously to a novel substance in their environment.

Soft matter electrolytes based on polymethylmetacrylate dispersions in lithium bis(trifluoromethanesulfonyl)imide/1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ionic liquids

Ion transport in a polymer-ionic liquid (IL) soft matter composite electrolyte is discussed here in detail in the context of polymer-ionic liquid interaction and glass transition temperature The dispersion of polymethylmetacrylate (PMMA) in 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6) and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMITFSI) resulted in transparent composite electrolytes with a jelly-like consistency The composite ionic conductivity measured over the range -30 C to 60 C was always lower than that of the neat BMITFSI/BMIPF6 and LiTFSI-BMITFSI/LiTFSI-BMIPF6 electrolytes but still very high (>1 mS/cm at 25 degrees C up to 50 wt% PMMA) While addition of LiTFSI to IL does not influence the glass T-g and T-m melting temperature significantly dispersion of PMMA (especially at higher contents) resulted in increase in T-g and disappearance of T-m In general the profile of temperature-dependent ionic conductivity could be fitted to Vogel-Tamman-Fulcher (VTF) suggesting a solvent assisted ion transport However for higher PMMA concentration sharp demarcation of temperature regimes between thermally activated and solvent assisted ion transport were observed with the glass transition temperature acting as the reference point for transformation from one form of transport mechanism to the other Because of the beneficial physico-chemical properties and interesting ion transport mechanism we envisage the present soft matter electrolytes to be promising for application in electrochromic devices (C) 2010 Elsevier Ltd All rights reserved

Rauhan atomi, sodan koodi : Suomalaisen atomivoimaratkaisun teknopolitiikka 1955-1970

This dissertation investigates the atomic power solution in Finland between 1955 - 1970. During these years a national arrangement for atomic energy technology evolved. The foundations of the Finnish atomic energy policy; the creation of basic legislation and the first governmental bodies, were laid between 1955 - 1965. In the late 1960's, the necessary technological and political decisions were made in order to purchase the first commercial nuclear reactor. A historical narration of this process is seen in the international context of "atoms for peace" policies and Cold War history in general. The geopolitical position of Finland made it necessary to become involved in the balanced participation in international scientific-technical exchange and assistive nuclear programs. The Paris Peace Treaty of 1947 categorically denied Finland acquisition of nuclear weapons. Accordingly, from the "Geneva year" of 1955, the emphasis was placed on peaceful purposes for atomic energy as well as on the education of national professionals in Finland. An initiative for the governmental atomic energy commission came from academia but the ultimate motive behind it was an anticipated structural change in the supply of national energy. Economically exploitable hydro power resources were expected to be built within ten years and atomic power was seen as a promising and complementing new energy technology. While importing fuels like coal was out of the question, because of scarce foreign currency, domestic uranium mineral deposits were considered as a potential source of nuclear fuel. Nevertheless, even then nuclear energy was regarded as just one of the possible future energy options. In the mid-1960 s a bandwagon effect of light water reactor orders was witnessed in the United States and soon elsewhere in the world. In Finland, two separate invitations for bids for nuclear reactors were initiated. This study explores at length both their preceding grounds and later phases. An explanation is given that the parallel, independent and nearly identical tenders reflected a post-war ideological rivalry between the state-owned utility Imatran Voima and private energy utilities. A private sector nuclear power association Voimayhdistys Ydin represented energy intensive paper and pulp industries and wanted to have free choice instead of being associated themselves with "the state monopoly" in energy pricing. As a background to this, a decisive change had started to happen within Finnish energy policy: private and municipal big thermal power plants became incorporated into the national hydro power production system. A characteristic phenomenon in the later history is the Soviet Union s effort to bid for the tender of Imatran Voima. A nuclear superpower was willing to take part in competition but not on a turnkey basis as Imatran Voima had presumed. As a result of many political turns and four years of negotiations the first Finnish commercial light water reactor was ordered from the East. Soon after this the private nuclear power group ordered its reactors from Sweden. This work interprets this as a reasonable geopolitical balance in choosing politically sensitive technology. Conceptually, social and political dimensions of new technology are emphasised. Negotiations on the Finnish atomic energy program are viewed as a cooperation and a struggle, where state-oriented and private-oriented regimes pose their own macro level views and goals (technopolitical imaginaries) and defend and advance their plans and practical modes of action (schemata). Here, not only technologists but even political actors are seen to contribute to technopolitical realisations.

Interaction Energy Based Protein Structure Networks

The three dimensional structure of a protein is formed and maintained by the noncovalent interactions among the amino acid residues of the polypeptide chain These interactions can be represented collectively in the form of a network So far such networks have been investigated by considering the connections based on distances between the amino acid residues Here we present a method of constructing the structure network based on interaction energies among the amino acid residues in the protein We have investigated the properties of such protein energy based networks (PENs) and have shown correlations to protein structural features such as the clusters of residues involved in stability formation of secondary and super secondary structural units Further we demonstrate that the analysis of PENs in terms of parameters such as hubs and shortest paths can provide a variety of biologically important information such as the residues crucial for stabilizing the folded units and the paths of communication between distal residues in the protein Finally the energy regimes for different levels of stabilization in the protein structure have clearly emerged from the PEN analysis

Dynamic Structure Factor of Sponge Phases

We predict the dynamic light scattering intensity S(q,t) for the L3 phase (anomalous isotropic phase) of dilute surfactant solutions. Our results are based on a Landau-Ginzburg approach, which was previously used to explain the observed static structure factor S(q, 0). In the extreme limit of small q, we find a monoexponential decay with marginal or irrelevant hydrodynamic interactions. In most other regimes the decay of S(q,t) is strongly nonexponential; in one case, it is purely algebraic at long times.

Aperiodic Variability in the Cane-Zebiak Model: A Diagnostic Study

The finite predictability of the coupled ocean-atmosphere system is determined by its aperiodic variability. To gain insight regarding the predictability of such a system, a series of diagnostic studies has been carried out to investigate the role of convergence feedback in producing the aperiodic behavior of the standard version of the Cane-Zebiak model. In this model, an increase in sea surface temperature (SST) increases atmospheric heating by enhancing local evaporation (SST anomaly feedback) and low-level convergence (convergence feedback). The convergence feedback is a nonlinear function of the background mean convergence field. For the set of standard parameters used in the model, it is shown that the convergence feedback contributes importantly to the aperiodic behaviour of the model. As the strength of the convergence feedback is increased from zero to its standard value, the model variability goes from a periodic regime to an aperiodic regime through a broadening of the frequency spectrum around the basic periodicity of about 4 years. Examination of the forcing associated with the convergence feedback reveals that it is intermittent, with relatively large amplitude only during 2 or 3 months in the early part of the calendar year. This seasonality in the efficiency of the convergence feedback is related to the strong seasonality of the mean convergence over the eastern Pacific. It is shown that if the mean convergence field is fixed at its March value, aperiodic behavior is produced even in the absence of annual cycles in the other mean fields. On the, other hand, if the mean convergence field is fixed at its September value, the coupled model evolution remains close to periodic, even in the presence of the annual cycle in the other fields. The role of convergence feedback on the aperiodic variability of the model for other parameter regimes is also examined. It is shown that a range exists in the strength of the SST anomaly feedback for which the model variability is aperiodic even without the convergence feedback. It appears that in the absence of convergence feedback, enhancement of the strength of the air-sea coupling in the model through other physical processes also results in aperiodicity in the model.

A thermodynamic protocol for explaining subcriticality and other subtle features in self-deflagrating solids

A novel universal approach to understand the self-deflagration in solids has been attempted by using basic thermodynamic equation of partial differentiation, where burning mte depends on the initial temperature and pressure of the system. Self-deflagrating solids are rare and are reported only in few compounds like ammonium perchlorate (AP), polystyrene peroxide and tetrazole. This approach has led us to understand the unique characteristics of AP, viz. the existence of low pressure deflagration limit (LPL 20 atm), hitherto not understood sufficiently. This analysis infers that the overall surface activation energy comprises of two components governed by the condensed phase and gas phase processes. The most attractive feature of the model is the identification of a new subcritical regime I' below LPL where AP does not burn. The model is aptly supported by the thermochemical computations and temperature-profile analyses of the combustion train. The thermodynamic model is further corroborated from the kinetic analysis of the high pressure (1-30 atm) DTA thermograms which affords distinct empirical decomposition rate laws in regimes I' and 1 (20-60 atm). Using Fourier-Kirchoff one dimensional heat transfer differential equation, the phase transition thickness and the melt-layer thickness have been computed which conform to the experimental data.