Subduction and obduction processes in the Swiss Alps

The significance of the Brianconnais domain in the Alpine orogen is reviewed in the light of data concerning its collision with the active Adriatic margin and the passive Helvetic margin. The Brianconnais which formerly belonged to the Iberian plate, was located on the northern margin of the Alpine Tethys (Liguro-Piemont ocean) since its opening in the early-Middle Jurassic. Together with the Iberian plate the Brianconnais terrane was separated from the European plate in the Late Jurassic-Early Cretaceous, following the northern Atlantic, Bay of Biscay, Valais ocean opening. This was accompanied by the onset of subduction along the northern margin of Adria and the closure of the Alpine Tethys. Stratigraphic and metamorphic data regarding this subduction and the geohistory of the Brianconnais allows the scenario of subduction-obduction processes during the Late Cretaceous-early Tertiary in the eastern and western Alps to be specified. HP-LT metamorphism record a long-lasting history of oceanic subduction-accretion, followed in the Middle Eocene by the incorporation of the Brianconnais as an exotic terrane into the accretionary prism. Middle to Late Eocene cooling ages of the Brianconnais basement and the presence of pelagic, anorogenic sedimentation lasting until the Middle Eocene on the Brianconnais preclude any sort of collision before that time between this domain and the active Adria margin or the Helvetic margin. This is confirmed by plate reconstructions constrained by magnetic anomalies in the Atlantic domain. Only a small percentage of the former Brianconnais domain was obducted, most of the crust and lithospheric roots were subducted. This applies also to domains formerly belonging to the southern Alpine Tethys margin (Austroalpine-inner Carpathian domain). It is proposed that there was a single Palaeogene subduction zone responsible for the Alpine orogen formation (from northern Spain to the East Carpathians), with the exception of a short-lived Late Cretaceous partial closure of the Valais ocean. Subduction in the western Tethyan domain originated during the closure of the Meliata ocean during the Jurassic incorporating the Austroalpine-Carpathian domain as terranes during the Cretaceous. The subduction zone propagated into the northern margin of Adria and then to the northern margin of the Iberian plate, where it gave birth to the Pyrenean-Provencal orogenic belt. This implies the absence of a separated Cretaceous subduction zone within the Austro-Carpathian Penninic ocean. Collision of Iberia with Europe forced the subduction to jump to the SE margin of Iberia in the Eocene, creating the Apenninic orogenic wedge and inverting the vergence of subduction from south- to north-directed. (C) 1998 Elsevier Science B.V. All rights reserved.

Agent based simulation to optimise emergency departments

Nowadays, many of the health care systems are large and complex environments and quite dynamic, specifically Emergency Departments, EDs. It is opened and working 24 hours per day throughout the year with limited resources, whereas it is overcrowded. Thus, is mandatory to simulate EDs to improve qualitatively and quantitatively their performance. This improvement can be achieved modelling and simulating EDs using Agent-Based Model, ABM and optimising many different staff scenarios. This work optimises the staff configuration of an ED. In order to do optimisation, objective functions to minimise or maximise have to be set. One of those objective functions is to find the best or optimum staff configuration that minimise patient waiting time. The staff configuration comprises: doctors, triage nurses, and admissions, the amount and sort of them. Staff configuration is a combinatorial problem, that can take a lot of time to be solved. HPC is used to run the experiments, and encouraging results were obtained. However, even with the basic ED used in this work the search space is very large, thus, when the problem size increases, it is going to need more resources of processing in order to obtain results in an acceptable time.

Social mobility in 20th century, Switzerland

The study of social mobility enables us to assess the extent to which a given society is "open". Addressing this issue is particularly crucial in our democratic societies, where it is expected that the place of individuals in society should no longer be determined at birth, but rather by individual quality. The present inquiry investigates this issue in the context of Switzerland, a country characterised by specific institutional settings, notably through the close association its educational system shares with the labour market. Through a detailed empirical analysis based on robust statistical analyses carried out from a unique tailor-made dataset, I demonstrate that Swiss society has not become more open throughout the twentieth century. Although some barriers have lost some salience, Swiss society has overall remained extremely rigid. In particular, because it channels individuals into highly segmented tracks very early on, the Swiss educational system does not attenuate social background differences. Thus, Switzerland is found in a particular configuration where an individual's place in society is highly determined not only by his or her educational attainment, but also by his or her social background. In other words, Switzerland constitutes a sort of "non-meritocratic meritocracy". - L'étude de la mobilité sociale permet d'évaluer dans quelle mesure une société donnée est « ouverte ». S'intéresser à cette question est particulièrement crucial dans nos sociétés démocratiques, où il est attendu que la place des individus ne soit plus déterminée à la naissance, mais plutôt par les qualités individuelles. La présente étude examine cette question dans le cadre de la Suisse, un pays aux caractéristiques institutionnelles spécifiques, particulièrement de part le lien étroit que son système éducatif entretien avec le marché du travail. A travers une analyse empirique détaillée fondée sur des analyses statistiques robustes menées à partir d'un jeu de données unique construit sur-mesure, je démontre que la société suisse n'est pas devenue plus ouverte au cours du 20ème siècle. Même si certaines barrières ont perdu de l'importance, dans son ensemble, la société suisse est restée extrêmement rigide. En particulier, parce qu'il oriente très tôt les individus dans des filières fortement segmentées, le système éducatif suisse n'atténue pas les différences entre milieux sociaux. Ainsi, la Suisse se trouve dans une configuration particulière où, d'une part, la place d'un individu dans la société est hautement déterminée par son niveau d'étude et, d'autre part, par son origine sociale. En d'autres termes, la Suisse apparaît comme une sorte de « méritocratie non-méritocratique ».

Concepció, disseny i implantació d'un sistema de proves psicomètriques de rendiment acadèmic per a la matèria d'Història de la Música

Amb aquest projecte s'ha treballat en la direcció de: 1) Implementar un nou recurs en un projecte global de millora de la qualitat docent i d’aplicació de les TIC a l’ensenyament de les diferents assignatures de la matèria d’Història de la Música a la UdL en curs des de fa alguns anys. Concretament, diverses eines per a l’autoavaluació de l’alumnat a través d’un banc de preguntes segons el format de les proves psicomètriques (proves objectives en l’avaluació del rendiment acadèmic dels estudiants o d’elecció múltiple). 2) Arribar a disposar d’un extens banc de preguntes d’elecció múltiple i correcció objectiva en diferents formats, ordenades per blocs, temes, nivells de dificultat, etc., que reuneixin els criteris mínims de fiabilitat, objectivitat i validesa necessaris per a una correcta avaluació del rendiment acadèmic. Entenem que l’avaluació ha de tenir utilitats diferents que van més enllà de la simple puntuació de l’alumnat. Ha de servir també per millorar la docència, per facilitar l’aprenentatge de l’alumne, per assegurar un nivell de competència mínim, per discriminar entre estudiants o per informar la pròpia institució. 3) Aconseguir que l’alumne, a través de l’autoavaluació, entengui que aquest tipus de proves són instruments per continuar aprenent. En aquest sentit les proves d’elecció múltiple permeten tot un seguit d’opcions que ho afavoreixen. 4) Elaborar una eina amb capacitat de generar estadístiques, índex de discriminació i de fer l’anàlisi d’items, tot permetent anar redefinint i millorant els ítems.

The separate and combined effects of MHC genotype, parasite clone, and host gender on the course of malaria in mice.

BACKGROUND: The link between host MHC (major histocompatibility complex) genotype and malaria is largely based on correlative data with little or no experimental control of potential confounding factors. We used an experimental mouse model to test for main effects of MHC-haplotypes, MHC heterozygosity, and MHC x parasite clone interactions. We experimentally infected MHC-congenic mice (F2 segregants, homo- and heterozygotes, males and females) with one of two clones of Plasmodium chabaudi and recorded disease progression. RESULTS: We found that MHC haplotype and parasite clone each have a significant influence on the course of the disease, but there was no significant host genotype by parasite genotype interaction. We found no evidence for overdominance nor any other sort of heterozygote advantage or disadvantage. CONCLUSION: When tested under experimental conditions, variation in the MHC can significantly influence the course of malaria. However, MHC heterozygote advantage through overdominance or dominance of resistance cannot be assumed in the case of single-strain infections. Future studies might focus on the interaction between MHC heterozygosity and multiple-clone infections.

Research in psychopathology: epistemologic issues.

Etiologic research in psychiatry relies on an objectivist epistemology positing that human cognition is specified by the "reality" of the outer world, which consists of a totality of mind-independent objects. Truth is considered as some sort of correspondence relation between words and external objects, and mind as a mirror of nature. In our view, this epistemology considerably impedes etiologic research. Objectivist epistemology has been recently confronting a growing critique from diverse scientific fields. Alternative models in neurosciences (neuronal selection), artificial intelligence (connectionism), and developmental psychology (developmental biodynamics) converge in viewing living organisms as self-organizing systems. In this perspective, the organism is not specified by the outer world, but enacts its environment by selecting relevant domains of significance that constitute its world. The distinction between mind and body or organism and environment is a matter of observational perspective. These models from empirical sciences are compatible with fundamental tenets of philosophical phenomenology and hermeneutics. They imply consequences for research in psychopathology: symptoms cannot be viewed as disconnected manifestations of discrete localized brain dysfunctions. Psychopathology should therefore focus on how the person's self-coherence is maintained and on the understanding and empirical investigation of the systemic laws that govern neurodevelopment and the organization of human cognition.

Contextualizing the impact of work organization on employee satisfaction

The paper assesses the relationship between the use of alternative workplace practices (AWP) and job satisfaction. Using a unique employeremployee data set with rich information on both firm and employee characteristics we test whether there is a positive impact of AWPs on job satisfaction (motivation hypothesis) or it is negative (intensification hypothesis). We expand a growing empirical literature focusing on small and medium size firms from a southern European area. Our results show an overall positive effect, depending on the specific practice considered. We also obtain some sort of time-dependence with the effects turning from negative to positive once the practice has been implemented for some time. Keywords: Job satisfaction, work organization, unobserved heterogeneity.

Optimisation de la cryo microscopie électronique pour les études des minicercles d'ADN

RESUME : Bien que les propriétés physiques de la structure de l'ADN aient été intensivement étudiées pendant plus de 50 ans il y a encore beaucoup de questions importantes qui attendent des réponses. Par exemple, qu'arrive-t-il à la structure de la double hélice d'ADN nue (sans protéines liées) lorsqu'elle est fortement courbée, de la même manière que dans les nucléosomes? Cet ADN nu est-il facilement plié (il reste dans le régime élastique) ou réduit-il la contrainte de flexion en formant des sites hyperflexibles «kinks» (il sort du régime élastique en cassant l'empilement des paires de bases à certains endroits) ? La microscopie électronique peut fournir une réponse à cette question par visualisation directe des minicercles d'ADN de la longueur d'un tour de nucléosome (environ 90 paires de bases). Pour que la réponse soit scientifiquement valide, on doit observer les molécules d'ADN lorsqu'elles sont en suspension dans la solution d'intérêt et sans que des colorations, produits chimiques ou fixatifs n'aient été ajoutés, étant donné que ceux-ci peuvent changer les propriétés de l'ADN. La technique de la cryo-microscopie électronique (cryo-EM) développée par le groupe de Jacques Dubochet au début des années 80, permet la visualisation directe des molécules d'ADN suspendues dans des couche minces vitrifiées de solutions aqueuses. Toutefois, le faible contraste qui caractérise la cryo-EM combinée avec la très petite taille des minicercles d'ADN rendent nécessaire l'optimisation de plusieurs étapes, aussi bien dans la préparation des échantillons que dans le processus d'acquisition d'images afin d'obtenir deux clichés stéréo qui permettent la reconstruction 3-D des minicercles d'ADN. Dans la première partie de ma thèse, je décris l'optimisation de certains paramètres pour la cryoEM et des processus d'acquisition d'image utilisant comme objets de test des plasmides et d'autres molécules d'ADN. Dans la deuxième partie, je .décris comment j'ai construit les minicercles d'ADN de 94 bp et comment j'ai introduit des modifications structurelles comme des coupures ou des lacunes. Dans la troisième partie, je décris l'analyse des reconstructions des rninicercles d'ADN. Cette analyse, appuyée par des tests biochimiques, indique fortement que des molécules d'ADN sont capables de former de petites molécules circulaires de 94 bp sans dépasser les limites d'élasticité, indiquant que les minicercles adoptent une forme circulaire régulière où la flexion est redistribuée le long la molécule. ABSTRACT : Although physical properties of DNA structure have been intensively studied for over 50 years there are still many important questions that need to be answered. For example, what happens to protein-free double-stranded DNA when it is strongly bent, as in DNA forming nucleosomes? Is such protein-free DNA smoothly bent (i.e. it remains within elastic limits of DNA rigidity) or does it release its bending stress by forming sharp kinks (i.e. it exits the elastic regime and breaks the stacking between neighbouring base-pairs in localized regions)? Electron microscopy can provide an answer to this question by directly visualizing DNA minicircles that have the size of nucleosome gyres (ca 90 bp). For the answer to be scientifically valid, one needs to observe DNA molecules while they are still suspended in the solution of interest and no staining chemicals or fixatives have been added since these can change the properties of the DNA. CryoEM techniques developed by Jacques Dubochet's group beginning in the 1980's permit direct visualization of DNA molecules suspended in cryo-vitrified layers of aqueous solutions. However, a relatively weak contrast of cryo-EM preparations combined with the very small size of the DNA minicircles made it necessary to optimize many of the steps and parameters of the cryo-EM specimen preparation and image acquisition processes in order to obtain stereo-pairs of images that permit the 3-D reconstruction of the observed DNA minicircles. In the first part of my thesis I describe the optimization of the cryo-EM preparation and the image acquisition processes using plasmid size DNA molecules as a test object. In the second part, I describe how I formed the 94 by DNA minicircles and how I introduced structural modifications like nicks or gaps. In the third part, I describe the cryo-EM analysis of the constructed DNA minicircles. That analysis, supported by biochemical tests, strongly indicates that DNA minicircles as small as 94 by remain within the elastic limits of DNA structure, i.e. the minicircles adopt a regular circular shape where bending is redistributed along the molecules.

Cryo-negative staining reveals conformational flexibility within yeast RNA polymerase I.

The structure of the yeast DNA-dependent RNA polymerase I (RNA Pol I), prepared by cryo-negative staining, was studied by electron microscopy. A structural model of the enzyme at a resolution of 1.8 nm was determined from the analysis of isolated molecules and showed an excellent fit with the atomic structure of the RNA Pol II Delta4/7. The high signal-to-noise ratio (SNR) of the stained molecular images revealed a conformational flexibility within the image data set that could be recovered in three-dimensions after implementation of a novel strategy to sort the "open" and "closed" conformations in our heterogeneous data set. This conformational change mapped in the "wall/flap" domain of the second largest subunit (beta-like) and allows a better accessibility of the DNA-binding groove. This displacement of the wall/flap domain could play an important role in the transition between initiation and elongation state of the enzyme. Moreover, a protrusion was apparent in the cryo-negatively stained model, which was absent in the atomic structure and was not detected in previous 3D models of RNA Pol I. This structure could, however, be detected in unstained views of the enzyme obtained from frozen hydrated 2D crystals, indicating that this novel feature is not induced by the staining process. Unexpectedly, negatively charged molybdenum compounds were found to accumulate within the DNA-binding groove, which is best explained by the highly positive electrostatic potential of this region of the molecule, thus, suggesting that the stain distribution reflects the overall surface charge of the molecule.

Antibody isotype responses to egg antigens in human chronic Schistosomiasis mansoni before and after treatment

In the present communication we analyzed the levels of IgG1, IgG2, IgG3, IgG4 and IgE isotypes to soluble egg antigen of Schistosoma mansoni by ELISA in individuals from an endemic area for schistosomiasis in Northeast Brazil. The analysis was performed before and after treatment to evaluate the age-dependent pattern, and to identify differences in the reactivities to antigens. Our results suggest that schistosomiasis treatment would not interfere with this sort of immune response.

Are vectors able to learn about their hosts? A case study with Aedes aegypti mosquitoes

The way in which vectors distribute themselves amongst their hosts has important epidemiological consequences. While the role played by active host choice is largely unquestioned, current knowledge relates mostly to the innate response of vectors towards stimuli signalling the presence or quality of their hosts. Many of those cues, however, can be unpredictable, and therefore prevent the incorporation of the appropriate response into the vector's behavioural repertoire unless some sort of associative learning is possible. We performed a wide range of laboratory experiments to test the learning abilities of the mosquito, Aedes aegypti. Mosquitoes were exposed to choice procedures in (1) an olfactomenter and (2) a 'visual arena'. Our goal was to determine whether the mosquitoes were able to associate unconditional stimuli (blood feeding, human breath, vibration and electrical shock) with particular odours (citral, carvone, citronella oil and eugenol) and visual patterns (horizontal or vertical black bars) to which they had been previously observed to be responsive. We found no evidence supporting the hypothesis that associative learning abilities are present in adult Ae. aegypti. We discuss the possibilities that the assays employed were either inappropriate or insufficient to detect associative learning, or that associative learning is not possible in this species.

A Happy and a Healthy 2012

Many of us start the New Year with the best of intentions to lose weight, get fitter and eat well. It's that sense of new possibilities and fresh beginnings that can also help motivate changes in lifestyle. The Public Health Agency advises that making small changes to your own and your family's lifestyle can have a significant impact on improving overall health. Taking time to reflect, and making a plan, can all help. Choosing healthier food and increasing your physical activity will help maintain a healthy weight and prevent unwanted weight gain, which can have serious implications for a person's physical and mental health as it is associated with an increased risk of heart disease, stroke, type 2 diabetes, some cancers, respiratory problems, joint pain and depression.What can I do to improve my health?Make 1 or 2 small changes at a time - don't try to change your lifestyle radically or all at once as you're more likely to fail. Small changes in what you eat, or how active you are, are easier to make and more likely to be maintained.Mary Black, Assistant Director of Health and Wellbeing Improvement, PHA, said: "The New Year brings a time when many people reflect on their lives and very often eating more healthily is one of things they identify for change. I recommend setting a couple of small, achievable targets that can then be continued in the long term, for example:Eat breakfast everyday;Eat an extra portion of vegetables every day;Swap deep fried chips for oven chips;Choose fruit for between-meal snacks instead of a biscuit or bun;Begin to enjoy a hot drink on its own without feeling the need to have something sweet at the same time.Be active. Any sort of activity will be good for you. Think about how you can be more active each day. This doesn't have to involve running a marathon or joining a gym. Some suggestions include:· Go for walks with the children/family or friends. It's free! Walk on your lunch break;· Take the stairs instead of the elevator or escalator;· Park further away and walk to work/school;· Get off the bus a stop earlier and walk the rest;· Minimise the amount of time you are sitting down - take breaks from the computer at work or watching TV at home and walk around;· Children and adults can build up to the recommended daily activity levels in 10 minute sessions rather than doing it all in one session.Adults need at least 30 minutes, five days a week of moderate physical activity and children need 60 minutes of physical activity every day.Mary continued "It's easy for people to get into the habit of spending their spare time sitting down - watching TV, playing computer games, listening to their MP3 players - but being active will help you maintain a healthy weight and generally make you feel better. It can also improve your mood, reduce anxiety and protect against depression."It is what you do most of the time that really matters, so if you eat too much or don't exercise on any one day, don't worry too much - just accept it and get back to your new way of eating and being more active as soon as possible.

Survival responses in stressed organs

Apoptosis or programmed cell death is a regulated form of cell suicide executed by cysteine proteases, or "caspases", to maintain proper tissue homeostasis in multicellular organisms. Dysregulation of apoptosis leads to pathological complications including cancer, autoimmunity, neurodegenerative, and heart diseases. Beside their known function as the key executioners of apoptotic cell death, caspases were reported to mediate non-apoptotic functions. In this report we study the survival signals conveyed through caspase-3-mediated cleavage of Ras GTPase-activating proteins (RasGAP). Ubiquitously expressed, RasGAP senses caspase activity and controls the cell death/survival switch. RasGAP is cleaved once at low caspase activity and the generated N-terminal fragment (fragment N) induces a survival response by activating Ras/PI3K/Akt pathway. However, high caspase activity associated with increased stress leads to fragment Ν cleavage into fragments that do not mediate any detectable survival signals. In this thesis project we studied the role of fragment Ν in protecting stressed organs as well as in maintenance of their functionality. In response to stress in different organs, we found that mice lacking caspase-3 or unable to cleave RasGAP (Knock-In mice), and therefore unable to generate fragment N, were deficient in Akt activation and experienced increased apoptosis compared to wild-type mice. Augmented tissue damage and organ dysfunction in those mice highlight the importance of fragment Ν in activating Akt-mediated prosurvival pathway and in protection of organs during episodes of stress. In parallel we investigated the role of fragment Ν in regulating the activation of transcription factor NF-kB, a master regulator of inflammation. Sustained NF-kB activation may be detrimental by directly causing apoptosis or leading to a persistent damaging inflammation response. We found that fragment Ν is a potent inhibitor of NF-kB by favoring its nuclear export. Therefore, fragment Ν regulates NF-kB activity and contributes to a controlled response as well as maintenance of homeostasis in stressed cells. Importantly, these findings introduce new insights of how activated caspase-3 acts as a stress intensity sensor that controls cell fate by either initiating a fragment N- dependent cell resistance program or a cell suicide response. This identifies the pivotal role of fragment Ν in protection against patho-physiological damage, and encourages the development of therapies which aim to increase cell resistance to vigorous treatment. - L'apoptose, ou mort cellulaire programmée, est une forme contrôlée de suicide cellulaire exécuté par des protéines appelées caspases, dans le but de maintenir l'homéostasie des tissus sains dans les organismes multicellulaires. Un mauvais contrôle de l'apoptose peut mener à des pathologies comme le cancer, la neurodégénération et les maladies cardiaques et auto-immunes. En dehors de leur rôle connu d'exécutrices de l'apoptose, les caspases ont aussi été identifiées dans d'autres contextes non-apoptotiques. Dans ce projet, nous avons étudié les signaux de survie émis par le résultat du clivage de RasGAP par la caspase-3. Exprimée de façon ubiquitaire, RasGAP est sensible à l'activité de caspase-3 et contrôle la décision de la cellule à entreprendre la mort ou la survie cellulaire. A un taux d'activité faible, la caspase-3 clive RasGAP, ce qui mène à la génération d'un fragment N-terminal, appelé Fragment N, qui induit des signaux de survie via l'activation de la cascade Ras/PI3K/Akt. Cependant, lorsque l'activité de la caspase-3 augmente, le fragment N est clivé, ce qui a pour effet d'éliminer ces signaux de survie. Dans ce travail, nous avons étudié le rôle du Fragment N dans la protection des organes en état de stress et dans le maintien de leur fonctionnalité. En réponse à certains stress, nous avons découvert que les organes de souris n'exprimant pas la caspase-3 ou alors incapables de cliver RasGAP (souris Kl), et de ce fait n'ayant pas la possibilité de générer le Fragment N, perdaient leur faculté d'activer la protéine Akt et démontraient un taux d'apoptose plus élevé que des organes de souris sauvages. Le fait que les organes et tissus de ces souris manifestaient de graves dommages et dysfonctions met en évidence l'importance du Fragment N dans l'activation des signaux de survie via la protéine Akt et dans la neutralisation de l'apoptose induite par la caspase-3. En parallèle, nous avons investigué le rôle du Fragment N dans la régulation de l'activation de NF-kB, un facteur de transcription clé dans l'inflammation. Une activation soutenue de NF-kB peut être délétère par activation directe de l'apoptose ou peut mener à une réponse inflammatoire persistante. Nous avons découvert que le Fragment N, en favorisant l'export de NF-kB depuis le noyau, était capable de l'inhiber très efficacement. Le Fragment N régule donc l'activité de NF-kB et contribue au maintien de l'homéostasie dans des cellules stressées. Ces découvertes aident, de façon importante, à la compréhension de comment l'activation de la caspase-3 agit comme senseur de stress et décide du sort de la cellule soit en initiant une protection par le biais du fragment N, ou en induisant un suicide cellulaire. Cette étude définit le Fragment Ν comme ayant un rôle de pivot dans la protection contre des dommages patho-physiologiques, et ouvre des perspectives de développement de thérapies qui cibleraient à augmenter la résistance à divers traitements.

Localization of breakage points in knotted strings

It is a common macroscopic observation that knotted ropes or fishing lines under tension easily break at the knot. However, a more precise localization of the breakage point in knotted macroscopic strings is a difficult task. In the present work, the tightening of knots was numerically simulated, a comparison of strength of different knots was experimentally performed and a high velocity camera was used to precisely localize the site where knotted macroscopic strings break. In the case of knotted spaghetti, the breakage occurs at the position with high curvature at the entry to the knot. This localization results from joint contributions of loading, bending and friction forces into the complex process of knot breakage. The present simulations and experiments are in agreement with recent molecular dynamics simulations of a knotted polymer chain and with experiments performed on actin and DNA filaments. The strength of the knotted string is greatly reduced (down to 50%) by the presence of a knot, therefore reducing the resistance to tension of all materials containing chains of any sort. The present work with macroscopic strings revels some important aspects, which are not accessible by experiments with microscopic chains.

Assessing attachment cognitions and their associations with depression in youth with eating or drug misuse disorders.

The study investigates associations between attachment cognitions and depression symptoms in 71 15-25-year-olds, 26 of whom have eating disorders, and 20 of whom are drug misusers. Attachment cognitions were measured with the CaMir Q-sort, which provides indexes for secure, avoidant, and preoccupied attachment, as well as scores on 13 dimensions. The BDI-13 was used to measure depressive symptomatology. Consistent with the literature, BDI scores were associated with cognitions of preoccupied attachment. They were also related to cognitions of avoidant attachment, confirming Bowlby's theory on defensive exclusion. For participants with eating disorders, depressive symptomatology was related to preoccupation and parental interference, whereas for drug misusers, it was negatively related to security, preoccupation, parental support, and lack of parental concern. These findings help understand how attachment cognitions may participate in depressive symptomatology, namely in youth whose behavior problems may be associated with specific attachment experiences.