Bone Mineral Accrual in Physically Active Girls. With Special Reference to Reduction in Physical Activity Level and Use of Oral Contraceptives

Adolescence is an important time for acquiring high peak bone mass. Physical activity is known to be beneficial to bone development. The effect of estrogen-progestin contraceptives (EPC) is still controversial. Altogether 142 (52 gymnasts, 46 runners, and 42 controls) adolescent women participated in this study, which is based on two 7-year (n =142), one 6-year (n =140) and one 4-year (n =122) follow-ups. Information on physical activity, menstrual history, sexual maturation, nutrition, living habits and health status was obtained through questionnaires and interviews. The bone mineral density (BMD) and content (BMC) of lumbar spine (LS) and femoral neck (FN) were measured by dual- energy X-ray absoptiometry. Calcaneal sonographic measurements were also made. The physical activity of the athletes participating in this study decreased after 3-year follow-up. High-impact exercise was beneficial to bones. LS and FN BMC was higher in gymnasts than in controls during the follow-up. Reduction in physical activity had negative effects on bone mass. LS and FN BMC increased less in the group having reduced their physical activity more than 50%, compared with those continuing at the previous level (1.69 g, p=0.021; 0.14 g, p=0.015, respectively). The amount of physical activity was the only significant parameter accounting for the calcaneal sonography measurements at 6-year follow-up (11.3%) and reduced activity level was associated with lower sonographic values. Long-term low-dose EPC use seemed to prevent normal bone mass acquisition. There was a significant trend towards a smaller increase in LS and FN BMC among long-term EPC users. In conclusion, this study confirms that high-impact exercise is beneficial to bones and that the benefits are partly maintained even after a clear reduction in training level at least for 4 years. Continued exercise is needed to retain all acquired benefits. The bone mass gained and maintained can possibly be maximized in adolescence by implementing high-impact exercise for youngsters. The peak bone mass of the young women participating in the study may be reached before the age of 20. Use of low-dose EPCs seems to suppress normal bone mass acquisition.

Effect of hydrodynamics on modelling, monitoring and control of crystallization

Crystallization is a purification method used to obtain crystalline product of a certain crystal size. It is one of the oldest industrial unit processes and commonly used in modern industry due to its good purification capability from rather impure solutions with reasonably low energy consumption. However, the process is extremely challenging to model and control because it involves inhomogeneous mixing and many simultaneous phenomena such as nucleation, crystal growth and agglomeration. All these phenomena are dependent on supersaturation, i.e. the difference between actual liquid phase concentration and solubility. Homogeneous mass and heat transfer in the crystallizer would greatly simplify modelling and control of crystallization processes, such conditions are, however, not the reality, especially in industrial scale processes. Consequently, the hydrodynamics of crystallizers, i.e. the combination of mixing, feed and product removal flows, and recycling of the suspension, needs to be thoroughly investigated. Understanding of hydrodynamics is important in crystallization, especially inlargerscale equipment where uniform flow conditions are difficult to attain. It is also important to understand different size scales of mixing; micro-, meso- and macromixing. Fast processes, like nucleation and chemical reactions, are typically highly dependent on micro- and mesomixing but macromixing, which equalizes the concentrations of all the species within the entire crystallizer, cannot be disregarded. This study investigates the influence of hydrodynamics on crystallization processes. Modelling of crystallizers with the mixed suspension mixed product removal (MSMPR) theory (ideal mixing), computational fluid dynamics (CFD), and a compartmental multiblock model is compared. The importance of proper verification of CFD and multiblock models is demonstrated. In addition, the influence of different hydrodynamic conditions on reactive crystallization process control is studied. Finally, the effect of extreme local supersaturation is studied using power ultrasound to initiate nucleation. The present work shows that mixing and chemical feeding conditions clearly affect induction time and cluster formation, nucleation, growth kinetics, and agglomeration. Consequently, the properties of crystalline end products, e.g. crystal size and crystal habit, can be influenced by management of mixing and feeding conditions. Impurities may have varying impacts on crystallization processes. As an example, manganese ions were shown to replace magnesium ions in the crystal lattice of magnesium sulphate heptahydrate, increasing the crystal growth rate significantly, whereas sodium ions showed no interaction at all. Modelling of continuous crystallization based on MSMPR theory showed that the model is feasible in a small laboratoryscale crystallizer, whereas in larger pilot- and industrial-scale crystallizers hydrodynamic effects should be taken into account. For that reason, CFD and multiblock modelling are shown to be effective tools for modelling crystallization with inhomogeneous mixing. The present work shows also that selection of the measurement point, or points in the case of multiprobe systems, is crucial when process analytical technology (PAT) is used to control larger scale crystallization. The thesis concludes by describing how control of local supersaturation by highly localized ultrasound was successfully applied to induce nucleation and to control polymorphism in reactive crystallization of L-glutamic acid.

Omistajanvaihdospalvelujen valtakunnallinen evaluointi 2014

Omistajanvaihdoksista on totuttu Suomessa keskustelemaan lähinnä yrittäjien ikääntymisen yhteydessä. On pohdittu ikääntyvien yrittäjien liiketoiminnan jatkuvuutta ja työpaikkojen säilyttämistä. Keskustelu on jäänyt jälkeen eurooppalaisesta valtavirrasta, jossa omistajanvaihdokset nähdään jo enemmän yrityskentän dynamiikan asiana kuin yrittäjien eläköitymisestä johtuvana ongelmana, joka pitää ratkaista. Omistajanvaihdosten on aika arkipäiväistyä ja omistajanvaihdospalvelujen aika vakiintua. Omistajanvaihdosten tarvitsemat asiantuntijapalvelut poikkeavat esimerkiksi alkavien yrittäjien ja kasvuyritysten palveluista. Näiden palvelujen kehittyminen ja aseman vahvistaminen on olennainen osa omistajanvaihdosten edistämistä. Lisäksi omistajanvaihdosten edistäminen on jatkossa nähtävä entistä enemmän osana yrittäjyyden edistämistä ja kasvuyrittäjyyden edistämistä. Uusi omistaja, joka panostaa yrityksen kehittämiseen, on piristysruiske yritykselle. Yritys- ja liiketoimintakaupoilla mahdollistetaan yritysten kasvuhyppäyksiä, joita kansantalous kipeästi tarvitsee. Yrityskauppamarkkinoiden on oltava toimivat, jotta omistajanvaihdosten potentiaali elinkeinoelämän dynamiikan edistämisessä saadaan täysin käyttöön. Tässä selvityksessä päivitetään valtakunnallinen ja alueellinen tilanne omistajanvaihdospalvelujen osalta sekä arvioidaan, missä määrin edellisen evaluoinnin yhteydessä annetut suositukset on otettu eri alueilla käyttöön. Tämän selvityksen tulosten pohjalta voidaan todeta, että yritysten omistajanvaihdospalvelujen kehittyminen ELY-keskusalueilla vuosina 2010–2014 on ollut vaihtelevaa. Suurella osalla alueita kehittyminen on ollut vähäistä, joskin myös lähtötilanteet ovat olleet erilaisia palvelujen tason suhteen. Myös kokemusta omistajanvaihdosilmiöstä on näinä vuosina kertynyt kaikilla alueilla. Kenties nyt ollaan valmiimpia ottamaan rohkeitakin askeleita eteenpäin kohti ammattimaisesti ja ajoissa toteutettuja omistajanvaihdoksia. Yrityskauppamarkkinoiden kehittäminen ja omistajanvaihdosten edistäminen alueilla edellyttää, että valtakunnan tasolla tunnistetaan ja tiedostetaan omistajanvaihdosten potentiaali liiketoimintaympäristön dynamiikan parantamiseen. Keskeisten toimijoiden yhteistyön lisääminen niin valtakunnan tasolla kuin alueillakin on yksi toteutettavissa oleva toimenpide, jonka seurauksena omistajanvaihdosten asema osana yritysten kehittämisstrategioita vahvistuu. Lisäksi tärkeää on online-kauppapalvelujen kehittäminen, matalan kynnyksen neuvontapalvelujen järjestäminen, omistajanvaihdosten säännöllinen medianäkyvyys ja jatkuvat herättelyvaiheen toimenpiteet.