Field induced spin reorientation transition in epitaxial La0.5Sr0.5CoO3 films

Strained epitaxial La0.5Sr0.5CoO3 films are grown on LaAlO3 substrate. Structural, electrical,and magnetic measurements were carried out. Out of plane lattice parameter of the film undergoes compressive strain and the coercivity is enhanced. The zero field cooled (ZFC) magnetization curve for a field applied parallel to the film plane shows a jump, which suggests a spin reorientation transition (SRT), while ZFC magnetization for a field applied perpendicular to the film plane is featureless. This jump in magnetization is shifted to higher temperatures when the magnetic field is reduced. The SRT is attributed to the strain in the film. (C) 2010 Elsevier B.V. All rights reserved.

Development of twist in an emerging magnetic flux tube by poloidal field accretion

Aims. Following an earlier proposal for the origin of twist in the magnetic fields of solar active regions, we model the penetration of a wrapped up background poloidal field into a toroidal magnetic flux tube rising through the solar convective zone.Methods. The rise of the straight, cylindrical flux tube is followed by numerically solving the induction equation in a comoving Lagrangian frame, while an external poloidal magnetic field is assumed to be radially advected onto the tube with a speed corresponding to the rise velocity.Results. One prediction of our model is the existence of a ring of reverse current helicity on the periphery of active regions. On the other hand, the amplitude of the resulting twist depends sensitively on the assumed structure ( diffuse vs. concentrated/intermittent) of the active region magnetic field right before its emergence, and on the assumed vertical profile of the poloidal field. Nevertheless, in the model with the most plausible choice of assumptions a mean twist comparable to the observations results.Conclusions. Our results indicate that the contribution of this mechanism to the twist can be quite significant, and under favourable circumstances it can potentially account for most of the current helicity observed in active regions.

On the alleged equivalence of certain field theories

Abstract. We critically examine some recent claims that certain field theories with and without boson kinetic energy terms are equivalent. We point out that the crucial element in these claims is the finiteness or otherwise of the boson wavefunction renormalisation constant. We show that when this constant is finite, the equivalence proof offered in the literature fails in a direct way. When the constant is divergent, the claimed equivalence is only a consequence of improper use of divergent quantities.

Despairing Justice and the Ethics of Legal Interpretation

This study discusses legal interpretation. The question is how legal texts, for instance laws, statutes and regulations, can and do have meaning. Language makes interpretation difficult as it holds no definite meanings. When the theoretical connection between semantics and legal meaning is loosened and we realise that language cannot be a means of justifying legal decisions, the responsibility inherent in legal interpretation can be seen in full. We are thus compelled to search for ways to analyse this responsibility. The main argument of the book is that the responsibility of legal interpretation contains a responsibility towards the text that is interpreted (and through the mediation of the text also towards the legal system), but not only this. It is not simply a responsibility to read and read well, but it transcends on a broader scale. It includes responsibility for the effects of the interpretation in a particular situation and with regard to the people whose case is decided. Ultimately, it is a responsibility to do justice. These two aspects of responsibility are conceptualised here as the two dimensions of the ethics of legal interpretation: the textual and the situational. The basic conception of language presented here is provided by Ludwig Wittgenstein s later philosophy, but the argument is not committed to only one philosophical tradition. Wittgenstein can be counterpointed in interesting ways by Jacques Derrida s ideas on language and meaning. Derrida s work also functions as a contrast to hermeneutic theories. It is argued that the seed to an answer to the question of meaning lies in the inter-personal and situated activity of interpretation and communication, an idea that can be discerned in different ways in the works of Wittgenstein, Derrida and Hans-Georg Gadamer. This way the question of meaning naturally leads us to think about ethics, which is approached here through the philosophy of Emmanuel Levinas. His thinking, focusing on topics such as otherness, friendship and hospitality, provides possibilities for answering some of the questions posed in this book. However, at the same time we move inside a normativity where ethics and politics come together in many ways. The responsibility of legal interpretation is connected to the political and this has to be acknowledged lest we forget that law always implies force. But it is argued here that the political can be explored in positive terms as it does not have to mean only power or violence.

Nonsingular cosmological models: the massive scalar field case

The nonminimal coupling of a massive self-interacting scalar field with a gravitational field is studied. Spontaneous symmetry breaking occurs in the open universe even when the sign on the mass term is positive. In contrast to grand unified theories, symmetry breakdown is more important for the early universe and it is restored only in the limit of an infinite expansion. Symmetry breakdown is shown to occur in flat and closed universes when the mass term carries a wrong sign. The model has a naturally defined effective gravitational coupling coefficient which is rendered time-dependent due to the novel symmetry breakdown. It changes sign below a critical value of the cosmic scale factor indicating the onset of a repulsive field. The presence of the mass term severely alters the behaviour of ordinary matter and radiation in the early universe. The total energy density becomes negative in a certain domain. These features make possible a nonsingular cosm

Effect of electric field on ammonium perchlorate decomposition

A novel method of detecting the charge-carrying species in inorganic decomposable salts is described. In ammonium perchlorate it is observed that the charge-carrying species at temperatures 150 and 230°C are oppositely charged; i.e., they are negatively charged (ClO−4 ions) at 230°C and positively charged (H+ or NH+4) at 150°C.

Gauge Field Theories, Quantum Space-Time and Some Applications

In this thesis, the possibility of extending the Quantization Condition of Dirac for Magnetic Monopoles to noncommutative space-time is investigated. The three publications that this thesis is based on are all in direct link to this investigation. Noncommutative solitons have been found within certain noncommutative field theories, but it is not known whether they possesses only topological charge or also magnetic charge. This is a consequence of that the noncommutative topological charge need not coincide with the noncommutative magnetic charge, although they are equivalent in the commutative context. The aim of this work is to begin to fill this gap of knowledge. The method of investigation is perturbative and leaves open the question of whether a nonperturbative source for the magnetic monopole can be constructed, although some aspects of such a generalization are indicated. The main result is that while the noncommutative Aharonov-Bohm effect can be formulated in a gauge invariant way, the quantization condition of Dirac is not satisfied in the case of a perturbative source for the point-like magnetic monopole.

Legal Reasoning in Context

This study in EU law analyses the reasoning of the Court of Justice (the Court of Justice of the European Union) in a set of its preliminary rulings. Preliminary rulings are answers to national courts questions on the interpretation (and validity) of EU law called preliminary references. These questions concern specific legal issues that have arisen in legal disputes before the national courts. The Court of Justice alone has the ultimate authority to interpret EU law. The preliminary rulings bind the national courts in the cases giving rise to the preliminary reference, and the interpretations of EU law offered in the preliminary rulings are considered generally binding on all instances applying EU law. EU law is often described as a dynamic legal order and the Court of Justice as at the vanguard of developing it. It is generally assumed that the Court of Justice is striving to realise the EU s meta-level purpose (telos): integration. Against this backdrop one can understand the criticism the Court of Justice is often faced with in certain fields of EU law that can be described as developing. This criticism concerns the Court s (negatively) activist way of not just stating the law but developing or even making law. It is difficult to analyse or prove wrong this accusation as it is not in methodological terms clearly established what constitutes judicial activism, or more exactly where the threshold of negative activism lies. Moreover, one popular approach to assessing the role of the Court of Justice described as integration through law has become fairly political, neglecting to take into consideration the special nature of law as both facilitating and constraining action, not merely a medium for furthering integration. This study offers a legal reasoning approach of a more legalist nature, in order to balance the existing mix of approaches to explaining what the Court of Justice does and how. Reliance on legal reasoning is found to offer a working framework for analysis, whereas the tools for an analysis based on activism are found lacking. The legal reasoning approach enables one to assess whether or not the Court of Justice is pertaining to its own established criteria of interpretation of EU law, and if it is not, one should look more in detail at how the interpretation fits with earlier case-law and doctrines of EU law. This study examines the reasoning of the Court of Justice in a set of objectively chosen cases. The emphasis of the study is on analysing how the Court of Justice applies the established criteria of interpretation it has assumed for itself. Moreover, the judgments are assessed not only in terms of reasoning but also for meaningful silences they contain. The analysis is furthermore contextualised by taking into consideration how the cases were commented by legal scholars, their substantive EU law context, and also their larger politico-historical context. In this study, the analysis largely shows that the Court of Justice is interpreting EU law in accordance with its previous practice. Its reasoning retains connection with the linguistic or semiotic criteria of interpretation, while emphasis lies on systemic reasoning. Moreover, although there are a few judgments where the Court of Justice offers clearly dynamic reasoning or what can be considered as substantive reasoning stemming from, for example, common sense or reasonableness, such reasons are most often given in addition to systemic ones. In this sense and even when considered in its broader context, the case-law analysed in this study does not portray a specifically activist image of the Court of Justice. The legal reasoning approach is a valid alternative for explaining how and why the Court of Justice interprets EU law as it does.

Plant communities of field margins : the effects of management and environmental factors on species composition and diversity

Agri-environmental schemes have so far resulted in only minor positive implications for the biodiversity of agricultural environments, in contrast to what has been expected. Land-use intensification has decreased landscape heterogeneity and the amount of semi-natural habitats. Field margins are uncultivated areas of permanent vegetation located adjacent to fields. Since the number of these habitats is high, investing in their quality may result in more diverse agricultural landscapes. Field margins can be considered as multifunctional habitats providing agronomic, environmental and wildlife services. This thesis aimed at examining the plant communities of different types of field margin habitats and the factors affecting their species diversity and composition. The importance of edaphic, spatial and management factors was studied on regional, landscape and habitat scales. Vegetation surveys were conducted on regional and landscape scales and a field experiment on cutting management was conducted on a habitat scale. In field margin plant communities, species appeared to be indicators of high or intermediate soil fertility and moist soil conditions. The plant species diversity found was rather low, compared with most species-rich agricultural habitats in Finland, such as dry meadows. Among regions, land-use history, main production line, natural species and human induced distribution, climate and edaphic factors were elements inducing differences in species composition. The lowest regional species diversity of field margins was related to intensive and long-term cereal production. Management by cutting and removal or grazing had a positive effect on plant species diversity. The positive effect of cutting and removal on species richness was also dependent on the adjacent source of colonizing species. Therefore, in species-poor habitats and landscapes, establishment of margins with diverse seed mixtures can be recommended for enhancing the development of species richness. However, seed mixtures should include only native species preferably local origin. Management by cutting once a year for 5 years did not result in a decline in dominance of a harmful weed species, Elymus repens, showing that E. repens probably needs cutting more frequently than once per year. Agri-environmental schemes should include long-term contracts with farmers for the establishment, and management by cutting and removal or grazing, of field margins that are several metres wide. In such schemes, the timing and frequency of management should be planned so as not to harm other taxa, such as the insects and birds that are dependent on these habitats. All accidental herbicide drifts to field margins should be avoided when spraying the cultivated area to minimize the negative effects of sprayings on vegetation. The harmful effects of herbicides can be avoided by organic farming methods.