5,112 research outputs found
The 2D/3D dynamics of wall-bounded low-Rm magnetohydrodynamic (MHD) turbulence
No full textWith this experimental study, we give evidence that the dynamics of low-Rm MHD turbulence depends on the diffusion length l_z, which corresponds to the distance over which the Lorentz force is able to diffuse momentum before it is balanced by inertia
The Crisis of 2007-09: Nature, Causes, and Reactions
No full textThis is a pre-copy-editing, author-produced PDF of an article accepted for publication in Journal of Interntional Economic Law following peer review. The definitive publisher-authenticated version [Journal of International Economic Law 13(3):531-550 2010] is available online at: http://jiel.oxfordjournals.org/content/13/3/531.ful
Triangular Constellations in Flows
No full textParticles advected on the surface of a fluid can exhibit fractal clustering. The local structure of a fractal set is described by its dimension , which is the exponent of a power-law relating the mass in a ball to its radius : . It is desirable to characterise the {\em shapes} of constellations of points sampling a fractal measure, as well as their masses. The simplest example is the distribution of shapes of triangles formed by triplets of points, which we investigate for fractals generated by chaotic dynamical systems. The most significant parameter describing the triangle shape is the ratio of its area to the radius of gyration squared. We show that the probability density of has a phase transition: is independent of and approximately uniform below a critical flow compressibility , which we estimate. For the distribution appears to be described by two power laws: when , and when
Exact two-dimensionalization of low-magnetic-Reynolds-number flows subject to a strong magnetic field
No full textWe investigate the behavior of flows, including turbulent flows, driven by a horizontal body-force and subject to a vertical magnetic field, with the following question in mind: for very strong applied magnetic field, is the flow mostly two-dimensional, with remaining weak three-dimensional fluctuations, or does it become exactly 2D, with no dependence along the vertical? We restrict attention to low-magnetic-Reynolds number (Rm) flow. Because liquid metals have low magnetic Prandtl number, such low- flows can have a kinetic Reynolds number as large as one million and therefore be strongly turbulent. We first focus on the quasi-static approximation, i.e. the asymptotic limit of vanishing magnetic Reynolds number Rm << 1: we prove that the flow becomes exactly 2D asymptotically in time, regardless of the initial condition and provided the interaction parameter N is larger than a threshold value. We call this property absolute two-dimensionalization: the attractor of the system is necessarily a (possibly turbulent) 2D flow. We then consider the full-magnetohydrodynamic equations and we prove that, for low enough Rm and large enough N, the flow becomes exactly two-dimensional in the long-time limit provided the initial vertically-dependent perturbations are infinitesimal. We call this phenomenon linear two-dimensionalization: the (possibly turbulent) 2D flow is an attractor of the dynamics, but it is not necessarily the only attractor of the system. Some 3D attractors may also exist and be attained for strong enough initial 3D perturbations. These results shed some light on the existence of a dissipative anomaly for magnetohydrodynamic flows subject to a strong external magnetic field
The Decay of Wall Bounded MHD Turbulence at Low RM
No full textWe have developed a new spectral method to simulate flows with very fine boundary layers present. We apply it to calculate the evolution of freely decaying MHD turbulence between isolating walls. By comparison them with results obtained in fully periodic domain we quantify the influence of the channel walls on the character of freely decaying MHD turbulence
Emotional abuse in sport: A case study of trichotillomania in a prepubescent female gymnast
No full textThis article is made available through the Brunel Open Access Publishing Fund. Copyright @ 2013 Gervis M, et al. This is an open-access article distributed under
the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and
source are credited.Despite improved legislation in most countries, child abuse in sport continues to exist but is a problem which is often under reported or ignored. In elite sport ‘suffering’ is not uncommon and hence sometimes child abuse is sometimes unrecognised, de-emphasised or easily dismissed as part of a collective experience that is perceived to be necessary to ‘create’ elite athletes. However, even swearing, anger, raised voices and negative comments directed at child athletes by coaches is considered abuse and can, when regular and routine, cause long term wellbeing and health issues. Self-harm can be a consequence and here self-harm in the form of trichotillomania, self hair-pulling, is reported for the first time as a secondary consequence of abuse. The 12 year old female gymnast, subject of this case study, presented with this impulse control disorder as defined by the American Psychiatric Association and was successfully treated using cognitive behavioural therapy. However, the training environment, including coach behaviour, did not change and so the gymnast remained at risk of recurrence of self-harm. Such environments in sport have many characteristics in common with and reminiscent of religious cults; sacrifice, isolation, shared obsession, a charismatic leader, and often in the presence of severe calorie restriction. As a consequence of ageing, growth, injury and an unchanging abusive environment, a year later the gymnast retired from the sport
A basis of a certain module for the hyperalgebra and some applications
No full textIn the hyperalgebra of the -th Frobenius kernel of the algebraic group , we construct a basis of the
-module generated by a certain element which was given by the
author before. As its applications, we also prove some results on the
-modules and the algebra .Comment: 30 page
Borromini tuscolano
No full textLa pubblicazione propone, in versione ampliata e aggiornata, la chiave di lettura già avanzata dall’autore alcuni anni or sono in relazione all’intervento seicentesco voluto dalla famiglia Falconieri sulla più antica delle Ville Tuscolane, la Rufina, ritenendone valida la consolidata attribuzione al Borromini.
Nel volume viene data un’ampia dimostrazione dell’efficacia dell’interazione “documenti storici-rilievo architettonico”, nella ricostruzione delle fasi evolutive di una fabbrica e di come questo momento d’analisi, ove insufficientemente approfondito, possa indurre a considerazioni erronee.
Infatti, l’ipotesi diffusa in vari contributi sull’argomento riguardo alla forma dell’originario Casino della Rufina – e in particolare alla posizione della loggia verso Roma – è suffragata soltanto da incisioni d’epoca e non è mai stata scientificamente comprovata dal riscontro di un rilievo, né dal confronto attento con la pianta del nucleo originario della fabbrica conservata nelle Carte Strozzi presso l’Archivio di Stato di Firenze, ignorata o considerata – con una certa superficialità – come inattendibile.
L’ipotesi qui sostenuta valuta la “logica” dell’addizione alla Villa Rufina basandosi su considerazioni relative sia ai vari documenti iconografici sia all’attendibilità di ciascuno; il tutto è inoltre riferito al completo rilevamento dell’opera nel suo stato attuale.
Discutendo ipotesi diverse (anche attributive) emerse nel frattempo e sviluppando le considerazioni precedentemente avanzate grazie anche a un nuovo apparato iconografico che vede sfruttate le potenzialità della modellazione 3D applicate ai criteri del rilievo filologico, il lavoro tende a ribadire l’efficacia di tale metodo d’indagine, basato sul rilievo delle attuali condizioni dell’opera in associazione all’imprescindibile analisi storico-documentale.
Attraverso il medesimo impianto scientifico procedurale è inoltre sviluppata la ricostruzione filologica del fronte settentrionale, basata anche su documentazione fotografica d’epoca parzialmente inedita. Si intende così offrire un iniziale – seppur parziale – contributo alla rilettura dell’ultima fase (quella novecentesca) che ha contrassegnato la fabbrica, vedendola già alterata ai primi del XX secolo, quindi compromessa dagli eventi bellici e infine trasformata dalle operazioni di restauro/ripristino del complesso, che hanno riproposto solo parzialmente e in modo generico la precedente morfologia del manufatto.This publication proposes, in an expanded and updated version, the key that the Author had already advanced in an earlier essay which was published ten years ago, concerning the 17th century intervention on the Villa Rufina: the first one of the Ville Tuscolane (summer residences for the papal circle that rose, in the late Renaissance, on the hills at the south of Rome). The Authors assumes also to be valid the well-established attribution of this work to Francesco Borromini.
In this volume a wide demonstration is offered of the efficacy, for the aim of a reliable reconstruction of the evolutionary phases of a certain building, of the interaction between the historical documents and the architectural survey, showing also how this time of analysis can lead to incorrect or misleading considerations, when it is not carried out enough deeply.
In the second phase (the expansion of the 17th century) which characterized all the Ville Tuscolane, the Rufina, at the time owned by the Falconieri (family), was the subject of an extensive renewal. With this intervention the first bulding that had initiated the “modern rediscovery” of building activity in these places (being, in fact, the originator of the Complex) was considerably transformed with regard to its material structure, appearance and relationship with the environment. For the devising of the general plan, it is commonly ascribed to Francesco Borromini, on the basis more of archive documents than of its style.
If the decoration of the Villa has been extensively and reliably studied, the same cannot be said about the transformations that the old building underwent, especially with regard to the lost loggia towards Rome. The hypothesis that has gradually taken root, about the location of this lodge, in the various papers published on the subject, is in fact supported only by some engravings of the time (in which the Villa is depicted in a pseudo-perspectival view and only as an element amongst the many others of the Complex). It has never been scientifically proved by the check of a survey, or by a careful comparison with the plan of the original nucleus of the original factory map stored in the “Carte Strozzi” at the State Archives of Florence, that has been ignored or considered – with some superficiality – as unreliable.
The hypothesis the Author suggested since the previous essay, evaluates the “logic” of the addition Borromini made to the Villa Rufina detaching itself from these assumptions and basing itself on some specific considerations concerning the iconographic documents that have been published over the years in various contributions, evaluating the reliability of each of them. These considerations were also related to a comprehensive survey of the work in its current state, as the so far published surveys are partial or were carried out on the structure as extensively damaged by the war.
In the volume are also discussed several different hypotheses that emerged in the meantime, also on the allocation of the project, as the attribution to Borromini – which in the past had seen ups and downs, from the header of the engraving by Alessandro Specchi to the evidences provided by Paolo Portoghesi and by Angela Negro, taken from the Falconieri-Carpegna archive – has recently been the subject of a new attempt of denial.
Developing the considerations already advanced before, and using a new display of subsidiary iconography that sees the exploitation of the potential of 3d modeling when applied to the criteria of the philological surveying, this study aims at a confirmation of the effectiveness of this method of investigation, which is based on a survey of the work in its positive state in conjunction with an unavoidable historical-documentary analysis.
On the basis of this same scientific procedural system, taking as well in account many historical photographic documents, so far unpublished, is also developed a philological reconstruction of the northern front, that is proposed in the last chapter. The aim is to provide a first – although partial – contribution to the re-reading of the last phase (the 20th century), which marked the building, that had already been altered in the early years of the 20th century, then compromised by the war and finally transformed by the restoration and rehabilitation of the complex, which reconstructed the pre-existing morphology only in a partial and general way
FLOWERING LOCUS C -dependent and -independent regulation of the circadian clock by the autonomous and vernalization pathways
No full textBackground
The circadian system drives pervasive biological rhythms in plants. Circadian clocks integrate endogenous timing information with environmental signals, in order to match rhythmic outputs to the local day/night cycle. Multiple signaling pathways affect the circadian system, in ways that are likely to be adaptively significant. Our previous studies of natural genetic variation in Arabidopsis thaliana accessions implicated FLOWERING LOCUS C (FLC) as a circadian-clock regulator. The MADS-box transcription factor FLC is best known as a regulator of flowering time. Its activity is regulated by many regulatory genes in the "autonomous" and vernalization-dependent flowering pathways. We tested whether these same pathways affect the circadian system.
Results
Genes in the autonomous flowering pathway, including FLC, were found to regulate circadian period in Arabidopsis. The mechanisms involved are similar, but not identical, to the control of flowering time. By mutant analyses, we demonstrate a graded effect of FLC expression upon circadian period. Related MADS-box genes had less effect on clock function. We also reveal an unexpected vernalization-dependent alteration of periodicity.
Conclusion
This study has aided in the understanding of FLC's role in the clock, as it reveals that the network affecting circadian timing is partially overlapping with the floral-regulatory network. We also show a link between vernalization and circadian period. This finding may be of ecological relevance for developmental programing in other plant species
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