Field induced phase transitions in the helimagnet Ba2CuGe2O7

We present a theoretical study of the two-dimensional spiral antiferromagnet Ba2CuGe2O7 in the presence of an external magnetic field. We employ a suitable nonlinear sigma model to calculate the T=0 phase diagram and the associated low-energy spin dynamics for arbitrary canted fields, in general agreement with experiment. In particular, when the field is applied parallel to the c axis, a previously anticipated Dzyaloshinskii-type incommensurate-to-commensurate phase transition is actually mediated by an intermediate phase, in agreement with our earlier theoretical prediction confirmed by the recent observation of the so-called double-k structure. The sudden pi/2 rotations of the magnetic structures observed in experiment are accounted for by a weakly broken U(1) symmetry of our model. Finally, our analysis suggests a nonzero weak-ferromagnetic component in the underlying Dzyaloshinskii-Moriya anisotropy, which is important for quantitative agreement with experiment.Comment: 17 pages, 14 figures. Corrected typos in the abstrac

Artikulations- und Intonationsveränderungen als Ausdrucksweisen der sozialen Distanz : (soziale Funktionen phonostilistischer Merkmale in der Konversation)

Die Beschreibungen der phonologischen und phonetischen Gebrauchsmerkmale erschöpfen sich aus der Sicht der informellen Kommunikation bekanntlich vorwiegend in den sprecherbezogenen phonologischen Prozessen, die dominant mit einer durch natürliches Sprechtempo bedingten ausspracheerleichternden Funktion einhergehen. Auch verfügt die moderne Interaktionslinguistik über Kenntnisse einiger linguistischer Funktionen von Intonation. Dennoch wissen wir immer noch sehr wenig über die soziale (d. h. auch strategische) Funktionalität der artikulatorischen und prosodischen (also der segmentalen und suprasegmentalen) Merkmale im Gesprächsverhalten. Dieser Beitrag setzt sich zum Ziel, die kontextsensitiven konversationsphonologischen Sprachmerkmale und ihre soziale Funktionsweise im Alltagsgespräch zu skizzieren. Die Problematik der Herangehensweise an die Erfassung der sozialen Bedeutung von konversationeller Phonetik, Phonologie und Prosodie wird anhand von drei exemplarischen Analysen der Kontextualisierung der sozialen Distanz in den Gesprächen bei verschiedenen informellen Gruppen Jugendlicher beleuchtet

Ultrafast light-induced magnetization dynamics in ferromagnetic semiconductors

We develop a theory of the magnetization dynamics triggered by ultrafast optical excitation of ferromagnetic semiconductors. We describe the effects of the strong carrier spin relaxation on the nonlinear optical response by using the Lindblad semigroup method. We demonstrate magnetization control during femtosecond timescales via the interplay between circularly polarized optical excitation, hole-spin damping, polarization dephasing, and the Mn-hole spin interactions. Our results show a light-induced magnetization precession and relaxation for the duration of the optical pulse.Comment: 4 pages, 2 figure

Biological-Chemical Oxidation of Ore Minerals at Pezinok Deposit

The article presents results of leaching experiments of the comparison between chemical and biological-chemical leaching, at the same conditions in solution, of ores from the Sb-(Au-) base metal deposit Pezinok (Malé Karpaty Mts., Western Carpathians, Slovakia). The research study shows the oxidation order and the progression of present ore minerals (löllingite, arsenopyrite, stibnite, native Sb, gudmundite, berthierite, pyrite, sphalerite and chalcopyrite). There are discussed differences between chemical and biological-chemical leaching activity of various ore minerals at the surface of polished sections. The extent of the leaching of sulphide minerals is significantly higher than that without bacteria

Intermediate phase in the spiral antiferromagnet Ba_2CuGe_2O_7

The magnetic compound Ba_2CuGe_2O_7 has recently been shown to be an essentially two-dimensional spiral antiferromagnet that exhibits an incommensurate-to-commensurate phase transition when a magnetic field applied along the c-axis exceeds a certain critical value H_c. The T=0 dynamics is described here in terms of a continuum field theory in the form of a nonlinear sigma model. We are thus in a position to carry out a complete calculation of the low-energy magnon spectrum for any strength of the applied field throughout the phase transition. In particular, our spin-wave analysis reveals field-induced instabilities at two distinct critical fields H_1 and H_2 such that H_1 < H_c < H_2. Hence we predict the existence of an intermediate phase whose detailed nature is also studied to some extent in the present paper.Comment: 15 pages, 11 figures, 2 table

Born poor:early childhood development and health in marginalised Roma communities

This thesis regards research on early childhood disparities in health and development between marginalized Roma communities (MRCs) and the majority population in Slovakia. The research aims to identify the factors contributing to these disparities and propose interventions to address them.Key findings reveal higher levels of chronic stress among mothers in MRCs, indicated by elevated hair cortisol concentrations (HCC). Socioeconomic factors play a mediating role in the relationship between MRC residence and maternal stress. Children from MRCs exhibit poorer mental health and psychomotor development compared to their majority population peers, with maternal HCC correlating with children's mental health.The study highlights the negative impact of maternal stress on children's mental health, leading to harsher discipline practices. The latter partially mediates the negative impact, but the anticipated serial mediation was not fully supported.Professionals identified 90 measures to support healthy early childhood development in MRCs, categorized into four clusters. Enhancing living conditions was prioritized as the most urgent need, while community interventions focusing on cultural capital transfer were deemed most feasible. However, financial and institutional barriers were identified, particularly for measures related to improving living conditions and access to basic infrastructure.The research emphasizes the importance of targeted interventions to reduce socioeconomic disadvantages, maternal stress, and promote positive parenting practices. Culturally appropriate programs and a multi-sectoral strategy for early childhood education and care are crucial to address these disadvantages effectively. This study calls for evidence-based policies and interventions to support the healthy development of children in MRCs

When They Are Gone: How We Grieve

Dr. Chovan reflects on his roots through the lens of grief.https://digitalcommons.otterbein.edu/is/1000/thumbnail.jp

The importance of efficient designs in discrete choice experiments for environmental valuation

Master in Economics: Empirical Applications and Policies. Academic Year 2021-2022.Discrete Choice Experiments (DCEs) are considered to be an appealing approach that is nowadays frequently used among researchers in many fields. No exception is their application in the field of environmental valuation, where we usually deal with relatively small sample sizes. This Master thesis analyzes the efficiency of different experimental designs used in DCEs. Moreover, it tries to examine the effect of prior parameter values in generation of efficient designs for a DCE. All the results are applied on a real case study devoted to climate change adaptations of winemakers in the Rioja region, Spain. The results are obtained through simulation exercises, which are emphasized to be crucial for checking our statistical design before conducting a DCE. The conclusions highlight the use of a specific method to set the prior parameter values necessary for the generation of an efficient design. Finally, the simulation exercises also draw conclusions regarding the trustworthiness of results obtained in the real case study