D6PK AGCVIII Kinases Are Required for Auxin Transport and Phototropic Hypocotyl Bending in Arabidopsis.

Phototropic hypocotyl bending in response to blue light excitation is an important adaptive process that helps plants to optimize their exposure to light. In Arabidopsis thaliana, phototropic hypocotyl bending is initiated by the blue light receptors and protein kinases phototropin1 (phot1) and phot2. Phototropic responses also require auxin transport and were shown to be partially compromised in mutants of the PIN-FORMED (PIN) auxin efflux facilitators. We previously described the D6 PROTEIN KINASE (D6PK) subfamily of AGCVIII kinases, which we proposed to directly regulate PIN-mediated auxin transport. Here, we show that phototropic hypocotyl bending is strongly dependent on the activity of D6PKs and the PIN proteins PIN3, PIN4, and PIN7. While early blue light and phot-dependent signaling events are not affected by the loss of D6PKs, we detect a gradual loss of PIN3 phosphorylation in d6pk mutants of increasing complexity that is most severe in the d6pk d6pkl1 d6pkl2 d6pkl3 quadruple mutant. This is accompanied by a reduction of basipetal auxin transport in the hypocotyls of d6pk as well as in pin mutants. Based on our data, we propose that D6PK-dependent PIN regulation promotes auxin transport and that auxin transport in the hypocotyl is a prerequisite for phot1-dependent hypocotyl bending.

Bending modes of DNA directly addressed by cryo-electron microscopy of DNA minicircles.

We use cryo-electron microscopy (cryo-EM) to study the 3D shapes of 94-bp-long DNA minicircles and address the question of whether cyclization of such short DNA molecules necessitates the formation of sharp, localized kinks in DNA or whether the necessary bending can be redistributed and accomplished within the limits of the elastic, standard model of DNA flexibility. By comparing the shapes of covalently closed, nicked and gapped DNA minicircles, we conclude that 94-bp-long covalently closed and nicked DNA minicircles do not show sharp kinks while gapped DNA molecules, containing very flexible single-stranded regions, do show sharp kinks. We corroborate the results of cryo-EM studies by using Bal31 nuclease to probe for the existence of kinks in 94-bp-long minicircles.

Biomechanical stability of a posterior-alone fixation technique after craniovertebral junction realignment.

OBJECTIVE: The aim of the current study was to investigate the biomechanical stability and fixation strength provided by a posterior approach reconstruction technique to realign the craniovertebral junction.¦METHODS: We tested seven human cadaver occipito-cervical spines (occiput-C4) by applying pure moments of ±1.5 Nm on a spine tester. Each specimen was tested in the following modes: 1) intact; 2) injured; 3) spacers alone at C1-C2 articulation (S); 4) spacers plus C1-C2 Posterior Instrumentation (S+PI); and 5) spacers plus C1-C2 posterior instrumentation plus midline wiring (S+PI+MLW). C1-C2 range of motion for each construct was obtained in flexion-extension, lateral bending, and axial rotation.¦RESULTS: In all the loading modes, S, S+PI, and S+PI+MLW constructs significantly reduced range of motion compared with the intact and injured condition (P < 0.05). There was no statistical difference between any of the three instrumentation constructs (P > 0.05).¦CONCLUSIONS: This study investigated the biomechanics of the posterior approach technique for realignment of the craniovertebral junction and also made comparisons with additional posterior fixations. The stand-alone spacers were stable in all three loading modes. Posterior instrumentation increased the stability as compared to stand-alone spacers. The third point of fixation, carried out by using midline wiring, increased the stability further. However, there was not much difference in the stability imparted with the midline wiring versus without. The present study highlights the biomechanics of this novel concept and reaffirms the view that distraction of the C1-C2 articular facets and direct articular joint atlantoaxial fixation would be an ideal method of management of basilar invagination.

A note on moments of dividends

We reconsider a formula for arbitrary moments of expected discounted dividend payments in a spectrally negative L,vy risk model that was obtained in Renaud and Zhou (2007, [4]) and in Kyprianou and Palmowski (2007, [3]) and extend the result to stationary Markov processes that are skip-free upwards.

Parcours de vie, récit et moments forts : entre défis et ressources. Une recherche-intervention à l'Ecole Technique de Ste-Croix

La littérature sur les transitions, en particulier entre l'école obligatoire et l'école professionnelle ou l'école et la vie professionnelle, attire l'attention sur le fait que les parcours personnels sont aujourd'hui moins linéaires. Les transitions professionnelles sont alors décrites comme des moments de difficultés, de ruptures, de vulnérabilité pour les jeunes (Pagnossin & Armi, 2011 ; Rastoldo, Amos & Davaud, 2009). Dans notre domaine en psychologie « socioculturelle », si ces aspects ne sont pas négligés, l'accent est mis sur l'importance du travail de construction de sens par la personne : indépendamment des zigzags de sa vie, l'important est la mise en cohérence, les liens de sens qu'elle peut reconstruire entre les différentes sphères d'expériences qui constituent son identité. Et pour cela, les ressources sociales et institutionnelles (parents, enseignants, groupes de pairs, dispositifs de formation...) mais aussi matérielles et culturelles (chansons, poèmes, films, romans, récits, etc.) peuvent être très importantes (Masdonati & Zittoun, 2012 ; Zittoun, 2012). L'étude-intervention qui sera présentée dans ce document, réalisée auprès d'une classe d'apprentis de l'Ecole technique de Ste-Croix par un groupe d'étudiants en Master en psychologie (UniL), s'inscrit dans un mouvement plus large qui cherche à rendre compte du point de vue des acteurs (Muller Mirza & Perret-Clermont, 2015) liés à la question des transitions des jeunes : il s'agira ici de celui des apprentis eux-mêmes, de manière à explorer ce qu'ils vivent en termes de difficultés, de ressources utilisées et d'apprentissages réalisés, ainsi que celui des personnes qui les accompagnent dans ces processus, les enseignants. Cette étude visait non seulement à recueillir des informations auprès de ces personnes mais également à réaliser un travail de type réflexif, par la mise en place d'activités en classe destinées aux apprentis, basées sur le « récit de vie » comme outil psychologique.

Three essays on the psychology of investment and financial markets

Préface My thesis consists of three essays where I consider equilibrium asset prices and investment strategies when the market is likely to experience crashes and possibly sharp windfalls. Although each part is written as an independent and self contained article, the papers share a common behavioral approach in representing investors preferences regarding to extremal returns. Investors utility is defined over their relative performance rather than over their final wealth position, a method first proposed by Markowitz (1952b) and by Kahneman and Tversky (1979), that I extend to incorporate preferences over extremal outcomes. With the failure of the traditional expected utility models in reproducing the observed stylized features of financial markets, the Prospect theory of Kahneman and Tversky (1979) offered the first significant alternative to the expected utility paradigm by considering that people focus on gains and losses rather than on final positions. Under this setting, Barberis, Huang, and Santos (2000) and McQueen and Vorkink (2004) were able to build a representative agent optimization model which solution reproduced some of the observed risk premium and excess volatility. The research in behavioral finance is relatively new and its potential still to explore. The three essays composing my thesis propose to use and extend this setting to study investors behavior and investment strategies in a market where crashes and sharp windfalls are likely to occur. In the first paper, the preferences of a representative agent, relative to time varying positive and negative extremal thresholds are modelled and estimated. A new utility function that conciliates between expected utility maximization and tail-related performance measures is proposed. The model estimation shows that the representative agent preferences reveals a significant level of crash aversion and lottery-pursuit. Assuming a single risky asset economy the proposed specification is able to reproduce some of the distributional features exhibited by financial return series. The second part proposes and illustrates a preference-based asset allocation model taking into account investors crash aversion. Using the skewed t distribution, optimal allocations are characterized as a resulting tradeoff between the distribution four moments. The specification highlights the preference for odd moments and the aversion for even moments. Qualitatively, optimal portfolios are analyzed in terms of firm characteristics and in a setting that reflects real-time asset allocation, a systematic over-performance is obtained compared to the aggregate stock market. Finally, in my third article, dynamic option-based investment strategies are derived and illustrated for investors presenting downside loss aversion. The problem is solved in closed form when the stock market exhibits stochastic volatility and jumps. The specification of downside loss averse utility functions allows corresponding terminal wealth profiles to be expressed as options on the stochastic discount factor contingent on the loss aversion level. Therefore dynamic strategies reduce to the replicating portfolio using exchange traded and well selected options, and the risky stock.

Quantitative and qualitative research on brief systemic therapies carried out within the framework of an ambulatory consultation for couples and families

Abstract: This article presents both a brief systemic intervention method (IBS) consisting in 6 sessions developed in an ambulatory service for couples and families, and two research projects done in collaboration with the Institute for Psychotherapy of the University of Lausanne. The first project is quantitative and it aims at evaluating the effectiveness of ISB. One of its main feature is that outcomes are assessed at different levels of individual and family functioning: 1) symptoms and individual functioning; 2) quality of marital relationship; 3) parental and co-parental relationships; 4) familial relationships. The second project is a qualitative case study about a marital therapy which identifies and analyses significant moments of the therapeutic process from the patients' perspective. Methodology was largely inspired by Daniel Stem's work about "moments of meeting" in psychotherapy. Results show that patients' theories about relationship and change are important elements that deepen our understanding of the change process in couple and family therapy. The interest of associating clinicians and researchers for the development and validation of a new clinical model is discussed.

PKS2: A link between phototropin signalling and auxin transport - a study on how plants sense and respond to light.

The blue light photoreceptors phototropins (phot1 and phot2 in Arabidopsis thaliana (L.)) carry out various light responses of great adaptive value that optimize plant growth. These processes include phototropism (the bending of an organ induced by unequal light distribution), chloroplast movements, stomatal opening, leaf flattening and solar tracking. The biochemical pathways controlling these important blue light responses are just starting to be elucidated. The PHYTOCHROME KINASE SUBSTRATE (PKS1-4) proteins - the subject of this research - have recently been identified as novel phototropism signalling components. PKS1 (the founding member of this family) interacts in a same complex in vivo with phot1 and the important phot1 signalling element NON-PHOTOTROPIC HYPOCOTYL 3 (NPH3). This suggested that the PKS may act as early components of phot signalling. This work further investigates the role of this protein family during phototropin signalling Genetic experiments clearly showed that the PKS do not control chloroplast movements or stomatal opening. However, PKS2 plays a critical role with NPH3 during leaf flattening and solar tracking. Epistasis data indicated that both proteins act in phot1 and phot2 pathways, which is consistent with their in vivo interaction with both phototropins. Because phototropism, leaf flattening and solar tracking are developmental processes regulated by the hormone auxin, the role of PKS2 and NPH3 during auxin homeostasis was also investigated. Interestingly, PKS2 loss-of-function restores leaf flattening in the auxin transporter mutant aux1. Moreover, PKS2 and NPH3 are found in a same complex with AUX1 in vivo. Taken together, these results suggest that PKS2 may act with NPH3 as a connecting point between phot signalling and auxin transport. Further experiments were performed to explore the molecular mode of action of PKS2 and NPH3 in this process. The significance of these results is discussed.

Alliance evolutions over the course of short-term dynamic psychotherapy: A case study

Background: Alliance evolutions, i.e. ruptures and resolutions over the course of psychotherapy, have been shown to be important descriptive features in different forms of psychotherapy, and in particular in psychodynamic psychotherapy. This case study of a client presenting elements of adjustment disorder undergoing short-term dynamic psychotherapy is drawn from a systematic naturalistic study and aims at illustrating, on a session-by-session-level, the processes of alliance ruptures and resolutions, by comparing both the client's and the therapist's perspectives. Method: Two episodes of alliance evolution were more fully studied, in relation to the evolution of transference, as well as the client's defensive functioning and core conflictual theme. These concepts were measured by means of valid, reliable observer-rater methods, based on session transcripts: the Defense Mechanisms Rating Scales (DMRS) for defensive functioning and the Core Conflictual Relationship Theme (CCRT) for the conflicts. Alliance was measured after each session using the Helping Alliance questionnaire (HAq-II). Results: The results indicated that these episodes of alliance rupture and resolutions may be understood as key moments of the whole therapeutic process reflecting the client's main relationship stakes. Illustrations are provided based on the client's in-session processes and related to the alliance development over the course of the entire therapy.

Acute aphasia after right hemisphere stroke

Abstract Right hemispheric stroke aphasia (RHSA) rarely occurs in right- or left-handed patients with their language representation in right hemisphere (RH). For right-handers, the term crossed aphasia is used. Single cases, multiple cases reports, and reviews suggest more variable anatomo-clinical correlations. We included retrospectively from our stroke data bank 16 patients (right- and left-handed, and ambidextrous) with aphasia after a single first-ever ischemic RH stroke. A control group was composed of 25 successive patients with left hemispheric stroke and aphasia (LHSA). For each patient, we analyzed four modalities of language (spontaneous fluency, naming, repetition, and comprehension) and recorded eventual impairment: (1) on admission (hyperacute) and (2) between day 3 and 14 (acute). Lesion volume and location as measured on computed tomography (CT) and magnetic resonance imaging (MRI) were transformed into Talairach stereotaxic space. Nonparametric statistics were used to compare impaired/nonimpaired patients. Comprehension and repetition were less frequently impaired after RHSA (respectively, 56% and 50%) than after LHSA (respectively, 84% and 80%, P = 0.05 and 0.04) only at hyperacute phase. Among RHSA, fewer left-handers/ambidextrous than right-handers had comprehension disorders at second evaluation (P = 0.013). Mean infarct size was similar in RHSA and LHSA with less posterior RHSA lesions (caudal to the posterior commissure). Comprehension and repetition impairments were more often associated with anterior lesions in RHSA (Fisher's exact test, P < 0.05). Despite the small size of the cohort, our findings suggest increased atypical anatomo-functional correlations of RH language representation, particularly in non-right-handed patients. Rapport de synthèse : Des aphasies secondaires à un accident vasculaire ischémique cérébral (AVC) hémisphérique droit sont rarement rencontrées chez des patients droitiers ou gauchers avec une représentation du langage dans l'hémisphère droit. Chez les droitiers, on parle d'aphasie croisée. Plusieurs études sur le sujet ont suggéré des corrélations anatomocliniques plus variables. Dans notre étude, nous avons inclus rétrospectivement, à partir d'une base de données de patients avec un AVC, seize patients (droitiers, gauchers et ambidextres) souffrant d'une aphasie suite à un premier et unique AVC ischémique hémisphérique droit. Un groupe contrôle est composé de vingt-cinq patients successifs avec une aphasie suite à un AVC ischémique hémisphérique gauche. Pour chaque patient, nous avons analysé quatre modalités de langage, à savoir la fluence spontanée, la dénomination, la répétition et la compréhension et leur éventuelle atteinte à deux moments distincts : 1) à l'admission (phase hyperaiguë) et 2) entre le 3e et le 14e jour (phase aiguë). Le volume et la localisation de la lésion mesurés, soit sur un CT-scanner soit sur une imagerie par résonance magnétique cérébrale, ont été analysés à l'aide de l'échelle stéréotaxique de Talairach. Des statistiques non paramétriques ont été utilisées pour comparer les patients atteints et non atteints. . La compréhension et la répétition étaient moins souvent atteintes, seulement en phase hyperaiguë, après une aphasie suite à un AVC hémisphérique droit (resp. 56% et 50%) plutôt que gauche (resp. 84 % et 80%, p= 0.05 et 0.04). Parmi les aphasies suite à un AVC ischémique hémisphérique droit, moins de gauchers et d'ambidextres que de droitiers avaient des troubles de la compréhension lors de la seconde évaluation (p=0.013}. La .taille moyenne de la zone infarcie était semblable entre les aphasies droites et gauches, avec moins de lésions postérieures (caudale à la commissure postérieure) lors des aphasies droites. Les troubles de la répétition et de la compréhension étaient plus souvent associés à des lésions antérieures lors d'aphasie droite. (Fischer's exact test, p>0.05). Malgré la petite taille de notre cohorte de patients, ces résultats suggèrent une augmentation des corrélations anatomocliniques atypiques lors d'une représentation du langage dans l'hémisphère droit, surtout chez les patients non droitiers.

Le projet de Jésus. Une énigme non résolue ?

Parler d'une énigme non résolue, lorsqu'il est question de Jésus de Nazareth, paraît proche de la plaisanterie. Tout n'a-t-il pas été dit en 2000 ans de christianisme ? Le sujet n'est-il pas entièrement épuisé ? Or aujourd'hui, de nouvelles poussées viennent ébranler ce que l'on croyait acquis. Nous serions-nous laissés enfermer dans des réponses commodes, mais inexactes ? Daniel Marguerat avance cette question sur trois moments cruciaux de la vie du Galiléen : le baptême de Jésus par Jean le Baptiseur, le geste violent contre le Temple, et son exécution le 7 avril de l'an 30.