External signal-activated liposomal drug delivery systems

Modern drug discovery gives rise to a great number of potential new therapeutic agents, but in some cases the efficient treatment of patient may not be achieved because the delivery of active compounds to the target site is insufficient. Thus, drug delivery is one of the major challenges in current pharmaceutical research. Numerous nanoparticle-based drug carriers, e.g. liposomes, have been developed for enhanced drug delivery and targeting. Drug targeting may enhance the efficiency of the treatment and, importantly, reduce unwanted side effects by decreasing drug distribution to non-target tissues. Liposomes are biocompatible lipid-based carriers that have been studied for drug delivery during the last 40 years. They can be functionalized with targeting ligands and sensing materials for triggered activation. In this study, various external signal-assisted liposomal delivery systems were developed. Signals can be used to modulate drug permeation or release from the liposome formulation, and they provide accurate control of time, place and rate of activation. The study involved three types of signals that were used to trigger drug permeation and release: electricity, heat and light. Electrical stimulus was utilized to enhance the permeation of liposomal DNA across the skin. Liposome/DNA complex-mediated transfections were performed in tight rat epidermal cell model. Various transfection media and current intensities were tested, and transfection efficiency was evaluated non-invasively by monitoring the concentration of secreted reporter protein in cell culture medium. Liposome/DNA complexes produced gene expression, but electrical stimulus did not enhance the transfection efficiency significantly. Heat-sensitive liposomal drug delivery system was developed by coating liposomes with biodegradable and thermosensitive poly(N-(2-hydroxypropyl) methacrylamide-mono/dilactate polymer. Temperature-triggered liposome aggregation and contents release from liposomes were evaluated. The cloud point temperature (CP) of the polymer was set to 42 °C. Polymer-coated liposome aggregation and contents release were observed above CP of the polymer, while non-coated liposomes remained intact. Polymer precipitates above its CP and interacts with liposomal bilayers. It is likely that this induces permeabilization of the liposomal membrane and contents release. Light-sensitivity was introduced to liposomes by incorporation of small (< 5 nm) gold nanoparticles. Hydrophobic and hydrophilic gold nanoparticles were embedded in thermosensitive liposomes, and contents release was investigated upon UV light exposure. UV light-induced lipid phase transitions were examined with small angle X-ray scattering, and light-triggered contents release was shown also in human retinal pigment epithelial cell line. Gold nanoparticles absorb light energy and transfer it into heat, which induces phase transitions in liposomes and triggers the contents release. In conclusion, external signal-activated liposomes offer an advanced platform for numerous applications in drug delivery, particularly in the localized drug delivery. Drug release may be localized to the target site with triggering stimulus that results in better therapeutic response and less adverse effects. Triggering signal and mechanism of activation can be selected according to a specific application.

Kohti hyvää suometsien hoitoa : harvennusten ja kunnostusojitusten vaikutus ojitusaluemänniköiden puuntuotokseen ja metsänkasvatuksen taloustulokseen

This thesis examines the impacts of silvicultural activities on productivity and financial returns of Scots pine (Pinus sylvestris L.) stands on drained peatlands in Finland. The effects of ditch network maintenance operations (DNM) and thinnings, with different timings and intensities, were studied. Based on stand development simulations, the best regimes for different types of stands according to site type, climatic area, and stand silvicultural status were defined from the viewpoint of both wood production and financial profitability. Certain aspects affecting the management outcomes, such as the timing of the first thinning, were examined using data from thinning experiments. Long-term predictions of the impacts of different management regimes were carried out by simulating the development of well-representative model-stands which were composed from appropriate inventory data sets. The MOTTI stand simulator used to perform the simulations enables the predictions by utilizing specific models for drained peatland stands. In addition to natural stand dynamics, these models describe the effects of silvicultural treatments on the development of a given stand. The mean annual increment of merchantable wood (MAImerch) was used as the measure of wood productivity, and the financial feasibility of the regimes was compared using net present value (NPV) analysis. Silvicultural treatments, when applied to appropriately match stand condition, increased both the productivity and financial returns of stand management. Applying DNM resulted in a small increase in MAImerch. When thinning was introduced along with DNM, their combined effect on wood productivity was considerable. According to current operational practices, DNM is generally combined with thinning. In some cases, e.g., in sites of low productivity, the need for DNM may become apparent prior to the thinning stage. As for profitability, thinnings proved to be crucial. The regimes with heavy and late thinnings were generally more profitable than those with normal thinnings. Further, early thinning (relative to stand volume) lacked appeal when seeking a financially profitable removal from the first thinning. In young stands with an initially poor silvicultural condition, however, applying even a low-yielding first thinning considerably increased the NPV when compared to a regime with no thinning at all. Generally, the regimes resulting in the best profitability included heavier thinnings and fewer DNM and thinning treatments than did the regimes resulting in the best yield results. This study demonstrates considerable potential for profitable wood production-oriented management in pine stands on drained peatlands despite their challenging circumstances and long rotations. The results can be used for defining new and more site-specific silvicultural guidelines for various types of drained, pine-dominated peatland stands within the entire range of boreal conditions.

Effects of living crown reduction on needle element status of Scots pine

A wide range of biotic and abiotic factors, operating over different time perspectives and intensities, cause defoliation and a rapid decrease in the crown size of trees. Scleroderris canker disease [Gremmeniella abietina (Lagerb.) Morelet] has caused widespread crown reduction and tree mortality in Scots pine (Pinus sylvestris L) in forests in Scandinavia during the last three decades. In the 1980's, attempts were made to show, on the basis of the higher foliar N and S concentrations of affected pines in the diseased area, that sulphur and nitrogen deposition predispose trees to G. abietina. Unfortunately, in many studies on defoliated trees, exceptionally high or low needle mineral nutrient concentrations are still often interpreted as one of the causes of tree injury and not, conversely, as the result. In this thesis, three different field experiments, with foliar analysis as the main study method, were conducted in order to asses the possible long-term effects of living crown reduction on the needle nutrient concentrations of Scots pine trees in southern Finland. The crown ratio and length of the living crown were used to estimate the amount of defoliation in the reduced canopies. The material for the partial studies was collected and a total of 968 foliar samples were analysed individually (15-17 elements/sample) on a total of 488 sample trees (140 diseased, 116 pruned and 232 control trees) during the years 1987-1996 in 13 Scots pine stands. All the three experiments of this thesis provided significant evidence that severe, disease-induced defoliation or artificial pruning of the living branches can induce long-lasting nutritional changes in the foliage of the recovering trees under the typical growing conditions for Scots pine. The foliar concentrations of all the 17 mineral nutrients/elements analysed were affected, to a varying degree, by artificial pruning during the following three years. Although Scots pine, as an evergreen conifer, is considered to have low induced chemical responses to defoliation, this study proved experimentally under natural forest conditions that severe artificial pruning or disease-induced defoliation of Scots pine trees may induce biologically significant changes in the concentrations of most of the important macro- and micronutrients, as well as of carbon, in refoliated needles. Concerning the studies in this thesis, I find the results significant in providing new information about the long-term effects of rapid living crown reduction on the foliar nutrient and element status of Scots pine trees. Key words: Foliar analysis, defoliation, needle loss, pruning, nutrients, Pinus sylvestris, Gremmeniella abietina

Wind drift of snowfall between the radar volume and ground

This study evaluates how the advection of precipitation, or wind drift, between the radar volume and ground affects radar measurements of precipitation. Normally precipitation is assumed to fall vertically to the ground from the contributing volume, and thus the radar measurement represents the geographical location immediately below. In this study radar measurements are corrected using hydrometeor trajectories calculated from measured and forecasted winds, and the effect of trajectory-correction on the radar measurements is evaluated. Wind drift statistics for Finland are compiled using sounding data from two weather stations spanning two years. For each sounding, the hydrometeor phase at ground level is estimated and drift distance calculated using different originating level heights. This way the drift statistics are constructed as a function of range from radar and elevation angle. On average, wind drift of 1 km was exceeded at approximately 60 km distance, while drift of 10 km was exceeded at 100 km distance. Trajectories were calculated using model winds in order to produce a trajectory-corrected ground field from radar PPI images. It was found that at the upwind side from the radar the effective measuring area was reduced as some trajectories exited the radar volume scan. In the downwind side areas near the edge of the radar measuring area experience improved precipitation detection. The effect of trajectory-correction is most prominent in instant measurements and diminishes when accumulating over longer time periods. Furthermore, measurements of intensive and small scale precipitation patterns benefit most from wind drift correction. The contribution of wind drift on the uncertainty of estimated Ze (S) - relationship was studied by simulating the effect of different error sources to the uncertainty in the relationship coefficients a and b. The overall uncertainty was assumed to consist of systematic errors of both the radar and the gauge, as well as errors by turbulence at the gauge orifice and by wind drift of precipitation. The focus of the analysis is error associated with wind drift, which was determined by describing the spatial structure of the reflectivity field using spatial autocovariance (or variogram). This spatial structure was then used with calculated drift distances to estimate the variance in radar measurement produced by precipitation drift, relative to the other error sources. It was found that error by wind drift was of similar magnitude with error by turbulence at gauge orifice at all ranges from radar, with systematic errors of the instruments being a minor issue. The correction method presented in the study could be used in radar nowcasting products to improve the estimation of visibility and local precipitation intensities. The method however only considers pure snow, and for operational purposes some improvements are desirable, such as melting layer detection, VPR correction and taking solid state hydrometeor type into account, which would improve the estimation of vertical velocities of the hydrometeors.

Atomic Layer Deposition of Electroluminescent ZnS, SrS, and BaS Thin Films

The light emitted by flat panel displays (FPD) can be generated in many different ways, such as for example alternating current thin film electroluminescence (ACTFEL), liquid crystal display (LCD), light emitting diode (LED), or plasma display panel (PDP) technologies. In this work, the focus was on ACTFEL devices and the goal was to develop new thin film processes for light emitting materials in ACTFEL devices. The films were deposited with the atomic layer deposition (ALD) method, which has been utilized in the manufacturing of ACTFEL displays since the mid-1980s. The ALD method is based on surface-controlled self-terminated reactions and a maximum of one layer of the desired material can be prepared during one deposition cycle. Therefore, the film thickness can be controlled simply by adjusting the number of deposition cycles. In addition, both large areas and deep trench structures can be covered uniformly. During this work, new ALD processes were developed for the following thin film materials: BaS, CuxS, MnS, PbS, SrS, SrSe, SrTe, SrS1-xSex, ZnS, and ZnS1-xSex. In addition, several ACTFEL devices were prepared where the light emitting material was BaS, SrS, SrS1-xSex, ZnS, or ZnS1-xSex thin film that was doped with Ce, Cu, Eu, Mn, or Pb. The sulfoselenide films were made by substituting the elemental selenium for sulfur on the substrate surface during film deposition. In this way, it was possible to replace a maximum of 90% of the sulfur with selenium, and the XRD analyses indicated that the films were solid solutions. The polycrystalline BaS, SrS, and ZnS thin films were deposited at 180-400, 120-460, and 280-500 °C, respectively, and the processes had a wide temperature range where the growth rate of the films was independent of the deposition temperature. The electroluminescence studies showed that the doped sulfoselenide films resulted in low emission intensity. However, the emission intensities and emission colors of the doped SrS, BaS, and ZnS films were comparable with those found in earlier studies. It was also shown that the electro-optical properties of the different ZnS:Mn devices were different as a consequence of different ZnS:Mn processes. Finally, it was concluded that because the higher deposition temperature seemed to result in a higher emission intensity, the thermal stability of the reactants has a significant role when the light emitting materials of ACTFEL devices are deposited with the ALD method.

Functional genes and gene array analysis as tools for monitoring hydrocarbon biodegradation

Bioremediation, which is the exploitation of the intrinsic ability of environmental microbes to degrade and remove harmful compounds from nature, is considered to be an environmentally sustainable and cost-effective means for environmental clean-up. However, a comprehensive understanding of the biodegradation potential of microbial communities and their response to decontamination measures is required for the effective management of bioremediation processes. In this thesis, the potential to use hydrocarbon-degradative genes as indicators of aerobic hydrocarbon biodegradation was investigated. Small-scale functional gene macro- and microarrays targeting aliphatic, monoaromatic and low molecular weight polyaromatic hydrocarbon biodegradation were developed in order to simultaneously monitor the biodegradation of mixtures of hydrocarbons. The validity of the array analysis in monitoring hydrocarbon biodegradation was evaluated in microcosm studies and field-scale bioremediation processes by comparing the hybridization signal intensities to hydrocarbon mineralization, real-time polymerase chain reaction (PCR), dot blot hybridization and both chemical and microbiological monitoring data. The results obtained by real-time PCR, dot blot hybridization and gene array analysis were in good agreement with hydrocarbon biodegradation in laboratory-scale microcosms. Mineralization of several hydrocarbons could be monitored simultaneously using gene array analysis. In the field-scale bioremediation processes, the detection and enumeration of hydrocarbon-degradative genes provided important additional information for process optimization and design. In creosote-contaminated groundwater, gene array analysis demonstrated that the aerobic biodegradation potential that was present at the site, but restrained under the oxygen-limited conditions, could be successfully stimulated with aeration and nutrient infiltration. During ex situ bioremediation of diesel oil- and lubrication oil-contaminated soil, the functional gene array analysis revealed inefficient hydrocarbon biodegradation, caused by poor aeration during composting. The functional gene array specifically detected upper and lower biodegradation pathways required for complete mineralization of hydrocarbons. Bacteria representing 1 % of the microbial community could be detected without prior PCR amplification. Molecular biological monitoring methods based on functional genes provide powerful tools for the development of more efficient remediation processes. The parallel detection of several functional genes using functional gene array analysis is an especially promising tool for monitoring the biodegradation of mixtures of hydrocarbons.

Imaging of knee injuries with special focus on tibial plateau fractures

Acute knee injury is a common event throughout life, and it is usually the result of a traffic accident, simple fall, or twisting injury. Over 90% of patients with acute knee injury undergo radiography. An overlooked fracture or delayed diagnosis can lead to poor patient outcome. The major aim of this thesis was retrospectively to study imaging of knee injury with a special focus on tibial plateau fractures in patients referred to a level-one trauma center. Multi-detector computed tomography (MDCT) findings of acute knee trauma were studied and compared to radiography, as well as whether non-contrast MDCT can detect cruciate ligaments with reasonable accuracy. The prevalence, type, and location of meniscal injuries in magnetic resonance imaging (MRI) were evaluated, particularly in order to assess the prevalence of unstable meniscal tears in acute knee trauma with tibial plateau fractures. The possibility to analyze with conventional MRI the signal appearance of menisci repaired with bioabsorbable arrows was also studied. The postoperative use of MDCT was studied in surgically treated tibial plateau fractures: to establish the frequency and indications of MDCT and to assess the common findings and their clinical impact in a level-one trauma hospital. This thesis focused on MDCT and MRI of knee injuries, and radiographs were analyzed when applica-ble. Radiography constitutes the basis for imaging acute knee injury, but MDCT can yield information beyond the capabilities of radiography. Especially in severely injured patients , sufficient radiographs are often difficult to obtain, and in those patients, radiography is unreliable to rule out fractures. MDCT detected intact cruciate ligaments with good specificity, accuracy, and negative predictive value, but the assessment of torn ligaments was unreliable. A total of 36% (14/39) patients with tibial plateau fracture had an unstable meniscal tear in MRI. When a meniscal tear is properly detected preoperatively, treatment can be combined with primary fracture fixation, thus avoiding another operation. The number of meniscal contusions was high. Awareness of the imaging features of this meniscal abnormality can help radiologists increase specificity by avoiding false-positive findings in meniscal tears. Postoperative menisci treated with bioabsorbable arrows showed no difference, among different signal intensities in MRI, among menisci between patients with operated or intact ACL. The highest incidence of menisci with an increased signal intensity extending to the meniscal surface was in patients whose surgery was within the previous 18 months. The results may indicate that a rather long time is necessary for menisci to heal completely after arrow repair. Whether the menisci with an increased signal intensity extending to the meniscal surface represent improper healing or re-tear, or whether this is just the earlier healing feature in the natural process remains unclear, and further prospective studies are needed to clarify this. Postoperative use of MDCT in tibial plateau fractures was rather infrequent even in this large trauma center, but when performed, it revealed clinically significant information, thus benefitting patients in regard to treatment.

On the behaviour of some physical parameterization methods in high-resolution numerical weather prediction models

Modern-day weather forecasting is highly dependent on Numerical Weather Prediction (NWP) models as the main data source. The evolving state of the atmosphere with time can be numerically predicted by solving a set of hydrodynamic equations, if the initial state is known. However, such a modelling approach always contains approximations that by and large depend on the purpose of use and resolution of the models. Present-day NWP systems operate with horizontal model resolutions in the range from about 40 km to 10 km. Recently, the aim has been to reach operationally to scales of 1 4 km. This requires less approximations in the model equations, more complex treatment of physical processes and, furthermore, more computing power. This thesis concentrates on the physical parameterization methods used in high-resolution NWP models. The main emphasis is on the validation of the grid-size-dependent convection parameterization in the High Resolution Limited Area Model (HIRLAM) and on a comprehensive intercomparison of radiative-flux parameterizations. In addition, the problems related to wind prediction near the coastline are addressed with high-resolution meso-scale models. The grid-size-dependent convection parameterization is clearly beneficial for NWP models operating with a dense grid. Results show that the current convection scheme in HIRLAM is still applicable down to a 5.6 km grid size. However, with further improved model resolution, the tendency of the model to overestimate strong precipitation intensities increases in all the experiment runs. For the clear-sky longwave radiation parameterization, schemes used in NWP-models provide much better results in comparison with simple empirical schemes. On the other hand, for the shortwave part of the spectrum, the empirical schemes are more competitive for producing fairly accurate surface fluxes. Overall, even the complex radiation parameterization schemes used in NWP-models seem to be slightly too transparent for both long- and shortwave radiation in clear-sky conditions. For cloudy conditions, simple cloud correction functions are tested. In case of longwave radiation, the empirical cloud correction methods provide rather accurate results, whereas for shortwave radiation the benefit is only marginal. Idealised high-resolution two-dimensional meso-scale model experiments suggest that the reason for the observed formation of the afternoon low level jet (LLJ) over the Gulf of Finland is an inertial oscillation mechanism, when the large-scale flow is from the south-east or west directions. The LLJ is further enhanced by the sea-breeze circulation. A three-dimensional HIRLAM experiment, with a 7.7 km grid size, is able to generate a similar LLJ flow structure as suggested by the 2D-experiments and observations. It is also pointed out that improved model resolution does not necessary lead to better wind forecasts in the statistical sense. In nested systems, the quality of the large-scale host model is really important, especially if the inner meso-scale model domain is small.

Scattering and Refraction as Contrast Mechanisms in X-Ray Imaging

Differentiation of various types of soft tissues is of high importance in medical imaging, because changes in soft tissue structure are often associated with pathologies, such as cancer. However, the densities of different soft tissues may be very similar, making it difficult to distinguish them in absorption images. This is especially true when the consideration of patient dose limits the available signal-to-noise ratio. Refraction is more sensitive than absorption to changes in the density, and small angle x-ray scattering on the other hand contains information about the macromolecular structure of the tissues. Both of these can be used as potential sources of contrast when soft tissues are imaged, but little is known about the visibility of the signals in realistic imaging situations. In this work the visibility of small-angle scattering and refraction in the context of medical imaging has been studied using computational methods. The work focuses on the study of analyzer based imaging, where the information about the sample is recorded in the rocking curve of the analyzer crystal. Computational phantoms based on simple geometrical shapes with differing material properties are used. The objects have realistic dimensions and attenuation properties that could be encountered in real imaging situations. The scattering properties mimic various features of measured small-angle scattering curves. Ray-tracing methods are used to calculate the refraction and attenuation of the beam, and a scattering halo is accumulated, including the effect of multiple scattering. The changes in the shape of the rocking curve are analyzed with different methods, including diffraction enhanced imaging (DEI), extended DEI (E-DEI) and multiple image radiography (MIR). A wide angle DEI, called W-DEI, is introduced and its performance is compared with that of the established methods. The results indicate that the differences in scattered intensities from healthy and malignant breast tissues are distinguishable to some extent with reasonable dose. Especially the fraction of total scattering has large enough differences that it can serve as a useful source of contrast. The peaks related to the macromolecular structure come to angles that are rather large, and have intensities that are only a small fraction of the total scattered intensity. It is found that such peaks seem to have only limited usefulness in medical imaging. It is also found that W-DEI performs rather well when most of the intensity remains in the direct beam, indicating that dark field imaging methods may produce the best results when scattering is weak. Altogether, it is found that the analysis of scattered intensity is a viable option even in medical imaging where the patient dose is the limiting factor.

Macroseismology as a Component of Seismicity Assessments in an Intraplate Region: Studies of Northern Europe with Emphasis on Finland

This work focuses on the role of macroseismology in the assessment of seismicity and probabilistic seismic hazard in Northern Europe. The main type of data under consideration is a set of macroseismic observations available for a given earthquake. The macroseismic questionnaires used to collect earthquake observations from local residents since the late 1800s constitute a special part of the seismological heritage in the region. Information of the earthquakes felt on the coasts of the Gulf of Bothnia between 31 March and 2 April 1883 and on 28 July 1888 was retrieved from the contemporary Finnish and Swedish newspapers, while the earthquake of 4 November 1898 GMT is an example of an early systematic macroseismic survey in the region. A data set of more than 1200 macroseismic questionnaires is available for the earthquake in Central Finland on 16 November 1931. Basic macroseismic investigations including preparation of new intensity data point (IDP) maps were conducted for these earthquakes. Previously disregarded usable observations were found in the press. The improved collection of IDPs of the 1888 earthquake shows that this event was a rare occurrence in the area. In contrast to earlier notions it was felt on both sides of the Gulf of Bothnia. The data on the earthquake of 4 November 1898 GMT were augmented with historical background information discovered in various archives and libraries. This earthquake was of some concern to the authorities, because extra fire inspections were conducted in three towns at least, i.e. Tornio, Haparanda and Piteå, located in the centre of the area of perceptibility. This event posed the indirect hazard of fire, although its magnitude around 4.6 was minor on the global scale. The distribution of slightly damaging intensities was larger than previously outlined. This may have resulted from the amplification of the ground shaking in the soft soil of the coast and river valleys where most of the population was found. The large data set of the 1931 earthquake provided an opportunity to apply statistical methods and assess methodologies that can be used when dealing with macroseismic intensity. It was evaluated using correspondence analysis. Different approaches such as gridding were tested to estimate the macroseismic field from the intensity values distributed irregularly in space. In general, the characteristics of intensity warrant careful consideration. A more pervasive perception of intensity as an ordinal quantity affected by uncertainties is advocated. A parametric earthquake catalogue comprising entries from both the macroseismic and instrumental era was used for probabilistic seismic hazard assessment. The parametric-historic methodology was applied to estimate seismic hazard at a given site in Finland and to prepare a seismic hazard map for Northern Europe. The interpretation of these results is an important issue, because the recurrence times of damaging earthquakes may well exceed thousands of years in an intraplate setting such as Northern Europe. This application may therefore be seen as an example of short-term hazard assessment.

Canopy processes, fluxes and microclimate in a pine forest

Interaction between forests and the atmosphere occurs by radiative and turbulent transport. The fluxes of energy and mass between surface and the atmosphere directly influence the properties of the lower atmosphere and in longer time scales the global climate. Boreal forest ecosystems are central in the global climate system, and its responses to human activities, because they are significant sources and sinks of greenhouse gases and of aerosol particles. The aim of the present work was to improve our understanding on the existing interplay between biologically active canopy, microenvironment and turbulent flow and quantify. In specific, the aim was to quantify the contribution of different canopy layers to whole forest fluxes. For this purpose, long-term micrometeorological and ecological measurements made in a Scots pine (Pinus sylvestris) forest at SMEAR II research station in Southern Finland were used. The properties of turbulent flow are strongly modified by the interaction between the canopy elements: momentum is efficiently absorbed in the upper layers of the canopy, mean wind speed and turbulence intensities decrease rapidly towards the forest floor and power spectra is modulated by spectral short-cut . In the relative open forest, diabatic stability above the canopy explained much of the changes in velocity statistics within the canopy except in strongly stable stratification. Large eddies, ranging from tens to hundred meters in size, were responsible for the major fraction of turbulent transport between a forest and the atmosphere. Because of this, the eddy-covariance (EC) method proved to be successful for measuring energy and mass exchange inside a forest canopy with exception of strongly stable conditions. Vertical variations of within canopy microclimate, light attenuation in particular, affect strongly the assimilation and transpiration rates. According to model simulations, assimilation rate decreases with height more rapidly than stomatal conductance (gs) and transpiration and, consequently, the vertical source-sink distributions for carbon dioxide (CO2) and water vapor (H2O) diverge. Upscaling from a shoot scale to canopy scale was found to be sensitive to chosen stomatal control description. The upscaled canopy level CO2 fluxes can vary as much as 15 % and H2O fluxes 30 % even if the gs models are calibrated against same leaf-level dataset. A pine forest has distinct overstory and understory layers, which both contribute significantly to canopy scale fluxes. The forest floor vegetation and soil accounted between 18 and 25 % of evapotranspiration and between 10 and 20 % of sensible heat exchange. Forest floor was also an important deposition surface for aerosol particles; between 10 and 35 % of dry deposition of particles within size range 10 30 nm occurred there. Because of the northern latitudes, seasonal cycle of climatic factors strongly influence the surface fluxes. Besides the seasonal constraints, partitioning of available energy to sensible and latent heat depends, through stomatal control, on the physiological state of the vegetation. In spring, available energy is consumed mainly as sensible heat and latent heat flux peaked about two months later, in July August. On the other hand, annual evapotranspiration remains rather stable over range of environmental conditions and thus any increase of accumulated radiation affects primarily the sensible heat exchange. Finally, autumn temperature had strong effect on ecosystem respiration but its influence on photosynthetic CO2 uptake was restricted by low radiation levels. Therefore, the projected autumn warming in the coming decades will presumably reduce the positive effects of earlier spring recovery in terms of carbon uptake potential of boreal forests.

An Empirical Study of the Mixture of Time and Movements in Prices

This paper investigates the persistent pattern in the Helsinki Exchanges. The persistent pattern is analyzed using a time and a price approach. It is hypothesized that arrival times are related to movements in prices. Thus, the arrival times are defined as durations and formulated as an Autoregressive Conditional Duration (ACD) model as in Engle and Russell (1998). The prices are defined as price changes and formulated as a GARCH process including duration measures. The research question follows from market microstructure predictions about price intensities defined as time between price changes. The microstructure theory states that long transaction durations might be associated with both no news and bad news. Accordingly, short durations would be related to high volatility and long durations to low volatility. As a result, the spread will tend to be larger under intensive moments. The main findings of this study are 1) arrival times are positively autocorrelated and 2) long durations are associated with low volatility in the market.

Stand growth and management scenarios for Paraserianthes falcataria smallholder plantations in Indonesia

Paraserianthes falcataria is a very fast growing, light wood tree species, that has recently gained wide interest in Indonesia for industrial wood processing. At the moment the P. falcataria plantations managed by smallholders are lacking predefined management programmes for commercial wood production. The general objective of this study was to model the growth and yield of Paraserianthes falcataria stands managed by smallholders in Ciamis, West Java, Indonesia and to develop management scenarios for different production objectives. In total 106 circular sample plots with over 2300 P. falcataria trees were assessed on smallholder plantation inventory. In addition, information on market prices of P. falcataria wood was collected through rapid appraisals among industries. A tree growth model based on Chapman-Richards function was developed on three different site qualities and the stand management scenarios were developed under three management objectives: (1) low initial stand density with low intensity stand management, (2) high initial stand density with medium intensity of intervention, (3) high initial stand density and strong intensity of silvicultural interventions, repeated more than once. In general, the 9 recommended scenarios have rotation ages varying from 4 to 12 years, planting densities from 4x4 meters (625 trees ha-1) to 3x2 meters (1666 trees ha-1) and thinnings at intensities of removing 30 to 60 % of the standing trees. The highest annual income would be generated on high-quality with a scenario with initial planting density 3x2 m (1666 trees ha-1) one thinning at intensity of removing 55 % of the standing trees at the age of 2 years and clear cut at the age of 4 years.