Precipitation controls on carbon and water relations in two African ecosystems

Understanding the interaction between precipitation and vegetation growth in water-limited ecosystems is vital for various livelihoods that depend on water resources. Precipitation is the primary driver of vegetation growth in dry ecosystems, while fog deposition is essential for the microclimate at dry coastal ecosystems and cloud forests. The analysis of soil moisture, which incorporates the action of climate, soil, and vegetation, is the key to understanding the carbon and water relations and the interaction between precipitation and vegetation. This thesis examines the impacts of precipitation variability on carbon and water relations in African savannas and the similarities in rainfall and fog deposition. The ecosystem-scale transpiration was estimated from eddy covariance measurements based on annually fitted water use efficiency and optimality hypothesis. The soil moisture measurements were analyzed using a hierarchy of soil moisture models with precipitation, NDVI, and potential evapotranspiration (PET) variability. The statistics of fog and rainfall were analyzed using an analogy with self-organized criticality. The annual evapotranspiration (ET) was comparable to the annual precipitation at the grazed savanna grassland. While the annual precipitation was highly variable, the estimated annual transpiration was nearly constant 55 % of ET. The transpiration (T) was reduced only during the drought year due to grass dieback-regrowth and possibly due to other changes in soil surface properties that enhanced evaporation. The annual net CO2 exchange (NEE) had large variation ranging from –58 (sink) to 198 (source) gC m-2 yr-1. The annual NEE was related to the maximum of remotely sensed vegetation index (NDVI), and the annual ecosystem respiration was strongly correlated with early season rainfall amount. The analysis of measured soil moisture across savannas showed that NDVI and PET adjustments to daily maximum ET are necessary for modeling depth averaged soil moisture. The soil moisture memory timescale, a rough measure of the time it takes for a soil column to forget the initial soil moisture state, was linearly related to daily mean precipitation intensity at semi-arid savannas. Both rainfall and fog time series showed approximate power-law relations for dry period and event size distributions consistent with self-organized criticality prediction. The spectral exponents of the on-off time series of the fog and rainfall exhibited an approximate f(-0.8) scaling, but the on-off switching was not entirely independent from the amplitude intermittency in fog and rainfall. The results show the role of short and long-term variability in precipitation and its consequences for the carbon and water cycle of semi-arid savannas with significant tree cover. These findings can be used to develop minimalist water balance models to understand how vegetation state affects water resources.Sateen ja kasvien vuorovaikutuksen ymmärtäminen on tärkeää kuivissa ekosysteemeissä, joissa kasvien aktiivisuus riippuu vesivaroista. Sade määrittää ensisijaisesti kasvillisuuden kasvua kuivissa ekosysteemeissä. Sumu on myös tärkeä tekijä kuivien rannikkoekosysteemien ja pilvimetsien mikroilmastoille. Maankosteutta tutkimalla voidaan ymmärtää veden ja hiilen kiertoa, sekä sateen ja kasvillisuuden vuorovaikutusta. Tässä väitöskirjassa tarkastellaan sateen vaihtelun vaikutusta hiilen ja veden kiertoon Afrikan savanneilla, sekä sateen ja sumun samankaltaisuutta. Maankosteutta tutkittiin neljällä eri Afrikan savannilla käyttäen malleja, joissa sadanta, normalisoitu kasvillisuusindeksi (NDVI) ja potentiaalinen haihdunta (PET) otettiin asteittain huomioon. Etelä-Afrikan laidunnetulla heinäsavannilla ekosyysteemin transpiraatio arvioitiin mikrometeorologisista kovarianssimittauksista (EC-menetelmä) määrittämällä vuosittainen vedenkäytön tehokkuus ja olettamalla optimaalinen suhde hiilen ja veden diffuusiolle ilmaraoista. Sumun ja sateen mittauksia analysoitiin nojautumalla itseorganisoituvasti kriittiseen teoriaan (self organized criticality, SOC). Vuosittainen haihdunta (ET) oli saman suuruinen vuosisateen kanssa laidunnetulla heinäsavannilla. Vuosittainen sademäärä vaihteli suuresti, mutta arvioitu vuosittainen transpiraatio oli kaikkina vuosina noin 55% vuosittaisesta haihdunnasta. Transpiraatio väheni vain erityisen kuivana vuonna, jolloin heinien lakastuminen ja uudelleen kasvu sekä muut maanpinnan ominaisuuksien muutokset lisäsivät haihduntaa maaperästä. Ekosysteemi vaihteli hiilen nielusta (–58 gC m-2 yr-1) hiilen lähteeksi (198 gC m-2 yr-1). Vuosittainen nettohiilenvaihto korreloi kaukokartoitusaineistosta arvioidun maksimaalisen kasvillisuusindeksin (NDVI) kanssa, kun taas vuosittainen kokonaishengitys korreloi alkukauden sademäärän kanssa. Eri savannien maankosteusmittauksien analysointi osoitti, että NDVI ja PET muuttujien vaikutus päivän maksimaaliseen haihduntaan täytyy ottaa huomioon syvyyskeskiarvoistetun maankosteuden mallintamisessa. Maaperän kosteuden aikasarjalle laskettiin niin kutsuttu muisti, joka kuvaa keskimääräistä ajanjaksoa, jossa maankosteus poikkea alkuarvostaan. Tämä muisti korreloi lineaarisesti päiväkeskiarvoisen sateen intensiteetin kanssa kuivilla savanneilla. Sateen ja sumun aikasarjoissa havaittiin likimääräinen potenssilaki kuivien ajanjaksojen ja sadetapahtuman sademäärän jakaumissa. Tämä havainto on yhdenmukainen SOC mallin kanssa. Binäärisen sade/ei-sade ja sumu/ei-sumu aikasarjojen tehospektri noudatteli likimääräisesti f(-0.8) potenssilakia, jossa f on taajuus. Kuitenkaan binääriset aikasarjat eivät olleet täysin riippumattomia sateen ja sumun amplitudin epäsäännöllisyydestä. Väitöskirjan tulokset osoittavat sateen lyhyen ja pitkän aikavälin vaihtelun seuraukset hiilen ja veden kierrolle kuivilla savanneilla. Näitä tuloksia voidaan jatkossa käyttää minimaalisten vesitasemallien kehittämisessä ja arvioidessa kasvillisuuden vaikutusta vesivaroihin

Obesity, Unemployment, and Earnings

The article analyses the effects of obesity—a clear signal of weight abnormality—on unemployment and earnings among Finnish men and women. Our empirical data consist of the last four waves (waves 4 to 8) of the Finnish section of the European Community Household Panel (ECHP) data collected between 1998 and 2001. According to our results, obese women have a significantly higher risk of unemployment (even after controlling for age, level of education and other related factors), than women who are not obese. Furthermore, the generally weaker occupational positions of obese women tend to translate to lower earnings. Overall, obese women are more likely to have weaker labour market attachment  and hold socio-economically weaker positions. Similar results were not found among men. Thus, our results indicate the presence of gender discrimination in the Finnish labour market. In the conclusions we further discuss weight related impacts on succeeding in the labour market, but also its role as a possible risk factor in drifting away from employment. We reflect on this issue as a form of inequality that can have an increasing significance in the future

Maankäyttö ja liikenneturvallisuus : pohdintaa suunnittelumenetelmien ja turvallisuustietojen kehittämistarpeista

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Dynamical Heart Beat Correlations during Running

Fluctuations of the human heart beat constitute a complex system that has been studied mostly under resting conditions using conventional time series analysis methods. During physical exercise, the variability of the fluctuations is reduced, and the time series of beat-to-beat RR intervals (RRIs) become highly non-stationary. Here we develop a dynamical approach to analyze the time evolution of RRI correlations in running across various training and racing events under real-world conditions. In particular, we introduce dynamical detrended fluctuation analysis and dynamical partial autocorrelation functions, which are able to detect real-time changes in the scaling and correlations of the RRIs as functions of the scale and the lag. We relate these changes to the exercise intensity quantified by the heart rate (HR). Beyond subject-specific HR thresholds the RRIs show multiscale anticorrelations with both universal and individual scale-dependent structure that is potentially affected by the stride frequency. These preliminary results are encouraging for future applications of the dynamical statistical analysis in exercise physiology and cardiology, and the presented methodology is also applicable across various disciplines.Comment: 19 pages, 10 figure

The Role of Philosophers in Bioethics

Blumenthal-Barby et al. (2022) present a nuanced and convincing case for the continued presence of moral and political philosophers in bioethics. We agree with the authors that philosophers should have a role in bioethical inquiry. However, we partly disagree on what that role should be. We assess the case taking our clues from a concern the authors mention – and another one that they do not directly address