Comment on: `Pipe Network Model for Scaling of Dynamic Interfaces in Porous Media'

We argue that a proposed exponent identity [Phys. Rev. Lett 85, 1238 (2000)] for interface roughening in spontaneous imbibition is wrong. It rests on the assumption that the fluctuations are controlled by a single time scale, but liquid conservation imposes two distinct time scales.Comment: 1 page, to appear in Phys. Rev. Let

Synnytyskokemus matkasynnyttäjän näkökulmasta : sisällönanalyysia verkkojulkaisuista

Synnytyssairaaloiden määrä on vähentynyt 20:lla vuodesta 1992 vuoteen 2014, kun pienimpiä synnytysyksiöitä on lakkautettu. Tämän seurauksena matkasynnytysten lukumäärät ovat alkaneet lisääntyä. Opinnäytetyön tarkoituksena oli selvittää ja tutkia naisten kokemuksia matkasynnytyksestä. Tutkimuksessa keskityttiin selvittämään muun muassa synnyttäjien saaman ohjauksen laatua, sitä oliko äiti osannut varautua matkasynnytykseen etukäteen sekä kokonaiskokemusta tapahtuneesta. Opinnäytetyö toteutettiin tutkimalla erilaisia verkosta löytyviä kirjoituksia aiheesta. Tutkimusmateriaaliksi valittiin sekä viisi blogikirjoitusta sekä satunnaisotos keskustelupalstakirjoituksia. Näistä tehtiin sisällönanalyysi ja tulokset jäsenneltiin eri kategorioihin. Sisällönanalyysin perusteella voidaan todeta, että valtaosa naisista koki matkasynnytyksen tilanteestaan huolimatta positiivisena. Positiivisen synnytyskokemuksen muodostumiseen vaikutti muun muassa terveydenhuollon henkilöiden ammattitaito, äidin toiveiden kunnioittaminen sekä nopea synnytys. Ohjaukseen oltiin positiivisista synnytyskokemuksista huolimatta tyytymättömiä. Puhelinohjaus koettiin useassa tapauksessa tilanteeseen sopimattomaksi ja synnyttäjät laiminlöivät saatuja ohjeita. Tutkimuksessa havaittiin, että ohjaus, joka huomioi äidin toiveet synnytyksen kulusta, koettiin usein hyväksi ja siitä oltiin kiitollisia. Varautumiseen vaikutti selkeästi edellinen nopea synnytys sekä synnytyssairaalan kaukainen sijainti. Pääosin äidit eivät kuitenkaan olleet osanneet varautua synnyttämään sairaalan ulkopuolisissa oloissa. Tutkimuksen perusteella voidaan todeta, että vaikka synnyttäjät vain harvoissa tapauksissa olivat pitäneet matkasynnytystä mahdollisena, olivat synnytyskokemukset naisten näkökulmasta pääosin positiivisia. Osa synnyttäneistä oli tyytyväisiä oman kehonsa toimintaan synnytystilanteessa ja siihen, että oli saanut mahdollisuuden luonnollisesti etenevään synnytykseen ilman kipulääkitystä.The amount of maternity hospitals has reduced in the last 20 years. From 1992 to 2014 the number of these hospitals has decreased with 20 units. This research focuses on women’s experiences of out-of-hospital birth through the words of mothers who have lived through that experience. The aim of the study was to explore and examine how woman experienced the outof-hospital birth, what was her subjective perception of the instructions given by the professionals during the labor and whether the parturient had prepared for the out-of-hospital birth. The data consists of five blog posts and randomly chosen writings on two different online forums and the data was analysed using the method of content analysis. The results show that in spite of the exceptional situation, most of the mothers experienced the out-of-hospital labor positively. What effected the childbirth experience positively were, health care professionals workmanship, respect of the wishes of the mother and fast labor. The quality of the instructions were perceived as unfulfilling. Because the instructions on the phone were experienced irrelevant in relation to the situation and mothers neglected some of the instructions that were given to them. This research shows that instructions that were taken into account the mothers wishes on stages of labor, was experienced good and mothers were thankful. A previous fast childbirth and a distant location of a maternity hospital was clearly affecting to one’s preparation. Most of the mothers were not prepared to give labor anywhere else but in a hospital. On the basis of the study it can be concluded, that although in rare cases were the mothers did think out-of-hospital birth was possible, were the experiences mostly positive. Most of the women were satisfied with the functioning of their bodies during the labor and one of the important facts was that they have had the possibility for a natural childbirth

Multiscale modelling of microstructure formation in polymerc asting

A data bank approach to multi-scale modelling of polymer solidification under flow and holding conditions is presented with applications to injection molding. The latent heat of solidification, which acts as an input parameter for large scale simulations, is determined as a function of different process dependent parameters such as the flow speed, supersaturation and geometric properties including the seed density of emerging spherulitic microstructures. Supersaturation and flow velocities are obtained from the larger scale simulation code as input values as function of which the released latent heat can be obtained from the pre-computed data bank thereby offering a possibility to circumvent the spatial and temporal coarse-graining problem associated with large scale simulations

Nonequilibrium generating functional and dynamics of coarse-grained variables

A generating functional formalism is developed to facilitate the derivation of coarse-grained dynamics of macroscopically relevant variables in various types of many-body problems. The relevant variables can be found either by using symmetry analysis of the action or experimental data. The outcome of the coarse-graining process is a set of coupled partial differential equations for the expectation values of the relevant observables. The set of the macroscopically important observables consists typically of conserved variables and order operators, which are related to the broken symmetries of the system. Symmetry breaking (spontaneous or explicit) in the formalism can be dynamically induced by coupling the system to a generalized heat bath. The nonequilibrium generating functional formalism is applied to coarse-graining of generalized hydrodynamics of macroscopic quantum phenomena such as Bose fluids and superconductors, and finally classical fluids. The method is by no means restricted to fluids, but can be applied to condensed matter problems as well. High density systems are in general more problematic and it remains to be seen if one can come up with more powerful approximation methods within the current formalism in the future. The generating functional formalism is shown to reproduce in the specific limits the well-known ground state, finite temperature and time-dependent density functional theories in the quantum regime. We enlarge the set of relevant variables to include also non-conserved order-operators and show how to form generalized density functional theories, which can be by construction linked to the phase-transition behaviour of the system. They are extensions of the traditional density functional theories that were not developed to describe phase changes but only facilitated the expression of the system's (free) energy in terms of the conserved density variable (e.g. number density of electrons). We develop a generalized density functional theory (effective action of the generating functional) for superconductors and superfluids. For superconductors it is shown by simple symmetry analysis that the relevant order parameter is the pair field of two electrons. Coarse-graining out the phononic degrees of freedom is shown to lead to a retarded effective interaction between the electrons. In the local static limit (effective interaction between electrons static) the theory reduces to the time-dependent Ginzburg-Landau theory. Similarly, by symmetry arguments, the order parameter of a weakly interacting Bose fluid is identified and its dynamics in the tree level approximation is shown to follow the Gross-Pitaevskii equation. Higher order corrections can be systematically produced. Classical molecular dynamics and stochastic cellular automata types of higher level descriptions can be mapped into the same formalism using commonly known techniques. It is also shown how to connect the static and dynamic density functionals to phase-field models (models of critical dynamics), which are commonly used in materials science modelling. A specific example is provided for a liquid-gas-solid system. The phase-field modelling is then applied to the derivation of dynamics of the liquid-gas phase boundaries and triple lines for which a new projection operator technique is developed. We explain in detail how to go from microscopics to macroscopics and relate the effective parameters on each level to each other. For example, we express the macroscopic surface tensions from the phase-field model in terms of the molecular dynamics simulation parameters. We also discuss how to extract the relevant cross-over time and length scales from the theoretical description and relate them to the experimentally measurable ones. It is shown how the coupling of the triple line and the liquid-gas boundary leads to emergence of memory effects. For confined geometry we also derive a new form for the restoring force acting on the contact line. The phase-field model of the liquid-gas-solid system is first discussed without explicit hydrodynamics from the point of view of diffuse mass transfer and then hydrodynamic effects (momentum conservation) are added. Evolution equations are derived for the mass, momentum and energy densities representing the proper set of macro variables of simple fluids. The derivation is based on a macroscopic Poisson bracket formulation of phase-field dynamics. Navier-Stokes equations are obtained with extra force terms arising from wall-fluid interactions and capillary stresses. It is also shown how the hydrodynamics boundary conditions for stress tensor can be derived from the bulk fields alone in the sharp interface limit. Some mechanisms for generation of the no-slip boundary condition are also hypothesized. These results are important because they show how in general boundary conditions and corrections to them can be derived and how the numerical implementation can benefit from such a formulation of hydrodynamics, where all boundary conditions are expressed in terms of bulk fields alone. Again, these results have wider applicability than the setting where they have been derived. The advantage of a systematic coarse-graining procedure enables us to clarify the role of the order parameter concept in the phase-field description of one and two component fluids. We also consider different ways of including gravitational effects and apply dimensional analysis to obtain a condition for the onset of capillary turbulence. Finally, we present some new formalism for stochastic processes, where the relevant field variables are embedded in an environment characterized by quenched disorder. Whenever some lower dimensional (e.g. defect) structures are projected out of the bulk field evolution equations containing either frozen of coarse-graining generated noise fields, a more complicated effective stochastic noise component will appear in the projected equation of motion of the defect. In particular, the effective noise can be long-ranged even if the quenched background disorder is not. Several condensed matter and hydrodynamical examples describing dynamics of interfaces and line-like objects such as polymers and domain wall defects are considered.reviewe

Interface dynamics and kinetic roughening in fractals

We consider the dynamics and kinetic roughening of single-valued interfaces in two-dimensional fractal media. Assuming that the local height difference distribution function of the fronts obeys Levý statistics with a well-defined power-law decay exponent, we derive analytic expressions for the local scaling exponents. We also show that the kinetic roughening of the interfaces displays anomalous scaling and multiscaling in the relevant correlation functions. For invasion percolation models, the exponents can be obtained from the fractal geometry of percolation clusters. Our predictions are in excellent agreement with numerical simulations.Peer reviewe

Nettikiusaaminen ja siihen puuttuminen peruskoulun opettajien näkökulmasta

Tämän tutkimuksen tarkoituksena oli selvittää, millaisia käsityksiä peruskoulun opettajilla on nettikiusaamisesta, ja kuinka opettajat pystyvät puuttumaan nettikiusaamiseen. Nuorten sosiaalisen median käytön yleisyys ja sosiaalisen median merkitys on johtanut siihen, että nuoret viettävät entistä enemmän aikaa netissä. Netin käyttö ja sen merkitys on kuitenkin luonut pohjaa myös nettikiusaamisen eri muotojen mahdollistamiselle. Koska nettikiusaaminen voi tapahtua nuorelle myös koulupäivän aikana, ja osapuolina voi olla koulun oppilaat, opettajia velvoitetaan puuttumaan siihen, mikäli sitä havaitaan tai se tulee muutoin ilmi. Opettajien käsityksiä nettikiusaamisesta tarkasteltiin tutkimuksessa nuorten sosiaalisen mediaympäristön, muuttuvan sosiaalisen median ja nettikiusaamisen erityispiirteiden kautta. Nettikiusaamiseen puuttumista tarkasteltiin suhteessa KiVa Koulu® -ohjelman yleisten ja kohdennettujen toimenpiteiden kautta (Salmivalli & Poskiparta, 2012). Tutkimus on laadullinen ja empiirinen. Tutkielman aineisto kerättiin haastattelemalla kolmea peruskoulun opettajaa keväällä 2023 puolistrukturoidun teemahaastattelun avulla. Opettajien työtehtävät, ikä, työkokemus ja koulutustausta erosivat merkittävästi toisistaan. Haastattelut toteutettiin yksilöhaastatteluina ja haastattelujen litteroinnissa hyödynnettiin Teams-palvelun transkriptio-ominaisuutta valmiin litteraatin muodostamiseen. Haastatteluiden kesto oli keskimäärin 32 minuuttia. Aineistoa analysoitiin sekä induktiivisen että deduktiivisen sisällönanalyysin menetelmin. Tutkimuksessa selvisi, että opettajilla oli erilaisia käsityksiä nettikiusaamisesta ja sen piirteistä. He nostivat esille sosiaalisen median käytön ja merkityksen nuorten keskuudessa. Nettikiusaamista pidettiin perinteiseen koulukiusaamiseen verraten erilaisena, eivätkä perinteisen kiusaamisen tunnuspiirteet (Salmivalli, 2010), tahallisuus ja toistuvuus, välttämättä toteudu nettikiusaamisessa. Opettajat tunnistivat myös sosiaalisen median muuttumisen tahdin ja teknologian luomat mahdollisuudet nettikiusaamiselle. Nettikiusaamiseen puuttumisessa opettajat korostivat erityisesti kodin ja koulun välistä yhteistyötä ja vastuun jakamista, sillä nettikiusaaminen voi tapahtua kouluajan ulkopuolella ja kiusaamisen osapuolet eivät välttämättä ole samasta koulusta. Opettajat korostivat nettikiusaamisen ehkäisemisessä mediakasvatuksen ja tunnekasvatuksen tärkeyttä

Interface Equations for Capillary Rise in Random Environment

We consider the influence of quenched noise upon interface dynamics in 2D and 3D capillary rise with rough walls by using phase-field approach, where the local conservation of mass in the bulk is explicitly included. In the 2D case the disorder is assumed to be in the effective mobility coefficient, while in the 3D case we explicitly consider the influence of locally fluctuating geometry along a solid wall using a generalized curvilinear coordinate transformation. To obtain the equations of motion for meniscus and contact lines, we develop a systematic projection formalism which allows inclusion of disorder. Using this formalism, we derive linearized equations of motion for the meniscus and contact line variables, which become local in the Fourier space representation. These dispersion relations contain effective noise that is linearly proportional to the velocity. The deterministic parts of our dispersion relations agree with results obtained from other similar studies in the proper limits. However, the forms of the noise terms derived here are quantitatively different from the other studies

Phase field modeling of wetting on structured surfaces

We study the dynamics and equilibrium profile shapes of contact lines for wetting in the case of a spatially inhomogeneous solid wall with stripe defects. Using a phase-field model with conserved dynamics, we first numerically determine the contact line behavior in the case of a stripe defect of varying width. For narrow defects, we find that the maximum distortion of the contact line and the healing length are related to the defect width, while for wide defects, they saturate to constant values. This behavior is in quantitative agreement with experimental data. In addition, we examine the shape of the contact line between two stripe defects as a function of their separation. Using the phase-field model, we also analytically estimate the contact line configuration, and find good qualitative agreement with the numerical results.Comment: 25 pages, 8 figure

Interface pinning in spontaneous imbibition

Evaporation and gravity induced pinning in spontaneous imbibition are examined within a phase field formalism. Evaporation is introduced via a nonconserving term and gravity through a convective term that constrains the influx of liquid. Their effects are described by dimensionless coupling constants ε and g, respectively. From liquid conservation, the early time behavior of the average interface position follows H(t)∼t1/2 until a crossover time t*(g,ε). After that the pinning height Hp(g,ε) is approached exponentially in time, in accordance with mean field theory. The statistical roughness of the interface is described by an exponent χ≃1.25 at all stages of the rise, but the dynamic length scale controlling roughness crosses over from ξ×∼H1/2 to a time independent pinning length scale ξp(ε,g).Peer reviewe