Shape Memory Effect and Properties Memory Effect of Polyurethane

The relationship between shape and properties memory effect, especially viscoelastic properties of polyurethane under study is the main aim of this research work. Tensile tests have been performed in order to introduce 100% of deformation in the polyurethane samples. Under this deformation, stress–relaxation experiments have been performed in order to eliminate the residual stresses. This deformation of the samples has been fixed by cooling. Recovery tests, then, were carried out at different isothermal temperatures that varied from 30 C to 60 C. Viscoelastic behavior has been studied by a biparabolic model and by using the Cole–Cole method. It was shown that this model describes the behavior of the polymer at the different states of shape memory tests. The constants of this model then have been determined. This study leads to a better understanding of the mechanism of shape memory effect. The comparison between the virgin polymer and the polymer after a recovery test by DMTA (dynamic mechanical thermal analysis) and by Cole–Cole method has illustrated that the polymer does not obtain its initial properties even when it was totally regained its initial shape. These results have been confirmed by three successive shape memory tests on the same sample and by comparing the mechanical characteristics of different cycles because ‘‘shape memory effect’’ and ‘‘properties memory effect’’ do not follow the same mechanisms

Interplay of genetic, epigenetic and transcription factors in the regulation of transcriptional variation in Plasmodium falciparum

Programa de Doctorat en Biomedicina / Tesi realitzada a l'Institut de Salut Global de Barcelona (ISGlobal)[eng] The most severe form of malaria, caused by Plasmodium falciparum parasites, still kills over half a million people every year, most of them children under the age of five. Despite huge research efforts, reduction in the global burden of disease has stalled in recent years. P. falciparum has a very complex life cycle including, among other steps, sexual reproduction in female Anopheles mosquitos and an asexual intra-erythoricitic development cycle (IDC) inside the human host, which causes the disease. During the IDC, the parasite needs to continuously adapt to changes in its environment including fluctuations in blood temperature, concentration of nutrients and other metabolites, presence of drugs, and a constant fight against the host’s immune system. In this thesis, we have studied the adaptation mechanisms of P. falciparum to this plethora of challenges, with a special focus on clonally variant genes (CVGs). In P. falciparum, CVGs are a set of genes, participating in host-parasite interactions, which can be found both in a transcriptionally active state, characterized by euchromatin, or a transcriptionally silenced state, characterized by heterochromatin. The state of CVGs is inherited by the progeny of a parasite, with stochastic switches occurring at a low frequency. Parasites with the most optimal patterns of CVGs expression are continuously selected as the environment changes, leading to adaptation and survival of the infecting population. In the first paper of this thesis, we have analyzed subcloned parasite populations to characterize, with unprecedented detail, the heterochromatin distribution associated with the active and silenced states of CVGs. This has allowed us to define different kinds of heterochromatin transitions between the active and silenced states of CVGs and has given us new insights on the regulation of var genes (one of the main virulence factors for malaria) and into the regulation of sexual conversion, a process crucial for malaria transmission. Continuing with CVG regulation, in the second paper of the thesis, we have analyzed how patterns of CVG expression are established at the onset of human infections, after passage through transmission stages. Our results suggest a loss of the epigenetic memory during transmission stages and a reset of the heterochromatin patterns that drive CVG expression. Similar patterns of CVG expression arose in different infected individuals, suggesting that the activation probability of a given CVG is an intrinsic property of the gene. In the third paper of the thesis, we have further studied the sexual conversion phenomenon. We have generated a conditional over-expression system for pfap2-g, the CVG that acts as master regulator of sexual conversion, achieving sexual conversion rates of ~90% after induction. Our results have provided new insights on how heterochromatin at different positions affects expression of pfap2-g and have allowed us to characterize the transcriptional profile of the initial stages of sexual commitment with unprecedented sensitivity. Finally, in the fourth paper of this thesis, we have studied the adaptation of the parasite to heat-shock, which happens in natural infections due to fever episodes. We expected CVGs to participate in this phenomenon, but instead we have identified pfap2-hs, a non-clonally variant transcription factor (TF), as the main driver of the heat-shock response in P. falciparum. AP2-HS acts as the functional homolog of HSF1 (a TF that drives the heat-shock response from yeast to mammals, but is absent in P. falciparum), driving a very tight transcriptional response to heat-shock, characterized by the up-regulation of hsp70 and hsp90. Although the presence of directed responses had previously been demonstrated for other cues, it is the first time that the transcription factor driving such a response is identified in P. falciparum. Taken together, the results of this thesis have broadened our knowledge of the regulation of adaptive mechanisms in P. falciparum. Learning about this deadly parasite’s defense mechanisms will be instrumental to design better strategies to fight it back in the future

Interplay of genetic, epigenetic and transcription factors in the regulation of transcriptional variation in Plasmodium falciparum

[eng] The most severe form of malaria, caused by Plasmodium falciparum parasites, still kills over half a million people every year, most of them children under the age of five. Despite huge research efforts, reduction in the global burden of disease has stalled in recent years. P. falciparum has a very complex life cycle including, among other steps, sexual reproduction in female Anopheles mosquitos and an asexual intra-erythoricitic development cycle (IDC) inside the human host, which causes the disease. During the IDC, the parasite needs to continuously adapt to changes in its environment including fluctuations in blood temperature, concentration of nutrients and other metabolites, presence of drugs, and a constant fight against the host’s immune system. In this thesis, we have studied the adaptation mechanisms of P. falciparum to this plethora of challenges, with a special focus on clonally variant genes (CVGs). In P. falciparum, CVGs are a set of genes, participating in host-parasite interactions, which can be found both in a transcriptionally active state, characterized by euchromatin, or a transcriptionally silenced state, characterized by heterochromatin. The state of CVGs is inherited by the progeny of a parasite, with stochastic switches occurring at a low frequency. Parasites with the most optimal patterns of CVGs expression are continuously selected as the environment changes, leading to adaptation and survival of the infecting population. In the first paper of this thesis, we have analyzed subcloned parasite populations to characterize, with unprecedented detail, the heterochromatin distribution associated with the active and silenced states of CVGs. This has allowed us to define different kinds of heterochromatin transitions between the active and silenced states of CVGs and has given us new insights on the regulation of var genes (one of the main virulence factors for malaria) and into the regulation of sexual conversion, a process crucial for malaria transmission. Continuing with CVG regulation, in the second paper of the thesis, we have analyzed how patterns of CVG expression are established at the onset of human infections, after passage through transmission stages. Our results suggest a loss of the epigenetic memory during transmission stages and a reset of the heterochromatin patterns that drive CVG expression. Similar patterns of CVG expression arose in different infected individuals, suggesting that the activation probability of a given CVG is an intrinsic property of the gene. In the third paper of the thesis, we have further studied the sexual conversion phenomenon. We have generated a conditional over-expression system for pfap2-g, the CVG that acts as master regulator of sexual conversion, achieving sexual conversion rates of ~90% after induction. Our results have provided new insights on how heterochromatin at different positions affects expression of pfap2-g and have allowed us to characterize the transcriptional profile of the initial stages of sexual commitment with unprecedented sensitivity. Finally, in the fourth paper of this thesis, we have studied the adaptation of the parasite to heat-shock, which happens in natural infections due to fever episodes. We expected CVGs to participate in this phenomenon, but instead we have identified pfap2-hs, a non-clonally variant transcription factor (TF), as the main driver of the heat-shock response in P. falciparum. AP2-HS acts as the functional homolog of HSF1 (a TF that drives the heat-shock response from yeast to mammals, but is absent in P. falciparum), driving a very tight transcriptional response to heat-shock, characterized by the up-regulation of hsp70 and hsp90. Although the presence of directed responses had previously been demonstrated for other cues, it is the first time that the transcription factor driving such a response is identified in P. falciparum. Taken together, the results of this thesis have broadened our knowledge of the regulation of adaptive mechanisms in P. falciparum. Learning about this deadly parasite’s defense mechanisms will be instrumental to design better strategies to fight it back in the future

Narrow-line coherently combined tapered laser diodes in a Talbot external cavity with a volume Bragg grating

We present the phase locking of an array of index-guided tapered laser diodes. An external cavity based on the self-imaging Talbot effect has been built. A volume Bragg grating is used as the output coupler to stabilize and narrow the spectrum at 976 nm. A power of 1.7 W is achieved in the in-phase single main lobe mode with a high visibility. We have checked that each emitter is locked to the Bragg wavelength with a 100 pm spectrum linewidth. The experimental results compare well with numerical simulations performed with two-dimensional wide-angle finite difference beam propagation method

Photoinduced dynamics in protonated aromatic amino acid

UV photoinduced fragmentation of protonated aromatics amino acids have emerged the last few years, coming from a situation where nothing was known to what we think a good understanding of the optical properties. We will mainly focus this review on the tryptophan case. Three groups have mostly done spectroscopic studies and one has mainly been involved in dynamics studies of the excited states in the femtosecond/picosecond range and also in the fragmentation kinetics from nanosecond to millisecond. All these data, along with high level ab initio calculations, have shed light on the role of the different electronic states of the protonated molecules upon the fragmentation mechanisms

Simulations expérimentale et numérique de réfractaires verriers électrofondus riches en zircone

International audienceLes réfractaires électrofondus à Très Haute Teneur en Zircone sont utilisés dans la construction des fours verriers. Le fond de la zone fusion est constitué de dalles de THTZ (88%vol ZrO2, 12%vol phase vitreuse), matériau choisi pour sa faible conductivité thermique, sa forte réfractarité et son inertie chimique. Le THTZ est élaboré par électrofusion, coulé dans des moules puis refroidi de manière contrôlée jusqu'à température ambiante, domaine où le matériau se caractérise par un comportement fragile. Lors de la première mise en chauffe du four ("attrempage"), des contraintes internes d'origine thermique sont générées au sein des dalles. L'objectif de l'étude est alors d'estimer ce champ de contraintes. L'étude a tout d'abord consisté à simuler expérimentalement la chauffe d'une dalle de THTZ dans un four verrier pendant l'attrempage. Pour ce faire, nous avons développé et utilisé un dispositif expérimental consistant à poser une dalle de THTZ instrumentée en thermocouples sur une plaque chauffée à une vitesse contrôlée. Les données thermiques ainsi obtenues ont permis, via un calcul numérique thermique (code de calcul ZéBuLoN, Centre des Matériaux), de déterminer les coefficients d'échange aux interfaces dalle/air et dalle/plaque chauffante. Puis, à partir de cela, un calcul numérique mécanique nous a permis de déterminer les contraintes générées par l'attrempage dans la dalle

Protocol for a systematic scoping review of reasons given to justify the performance of randomised controlled trials.

IntroductionRandomised controlled trials (RCTs) are widely viewed to generate the most reliable medical knowledge. However, RCTs are not always scientifically necessary and therefore not always ethical. Unfortunately, it is not clear when an RCT is not necessary or how this should be established. This study seeks to systematically catalogue justifications offered throughout the medical and ethics literature for performing randomisation within clinical trials.Methods and analysisWe will systematically search electronic databases of the medical literature including MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Cochrane Clinical Trials Register, Web of Science Proceedings, ClinicalTrials.gov; databases of philosophical literature including Philosopher's Index, Phil Papers, JSTOR, Periodicals Archive Online, Project MUSE, National Reference Centre for Bioethics; the library catalogue at the University of Ottawa; bibliographies of retrieved papers; and the grey literature. We will also pursue suggestions from experts in the fields of medical ethics, philosophy and clinical trial methodology. Article screening, selection and data extraction will be performed by two independent reviewers based on prespecified inclusion/exclusion criteria. A third reviewer will be consulted to resolve any discrepancies. We will then extract the reasons given to justify randomisation using methodology established to extract data in a defensible, systematic manner. We will track the reasons given, their frequency of use and changes over time. Finally, using grounded theory, we will combine the reasons into broader themes. These themes will form the foundation of our subsequent analysis from qualitative and quantitative perspectives. This review will map existing arguments that clinicians, ethicists and philosophers use to ethically justify randomisation in clinical trials.Ethics and disseminationNo research ethics board approval is necessary because we are not examining patient-level data. This protocol complies with the reported guidance for conducting systematic scoping reviews. The findings of this paper will be disseminated via presentations and academic publication. In a subsequent phase of this research, we hope to engage with stakeholders and translate any recommendations derived from our findings into operational guidelines

Le non-recours aux prestations sociales et sanitaires : quelles implications pour la citoyenneté sociale?

Since the 1960s, a specific stream of literature in the field of social welfare has been concerned with the phenomenon of non-take-up, i.e. people who are entitled to social benefits but do not receive them. This issue of non-take-up is becoming increasingly salient and reaching policy agendas, including in Switzerland. It questions both the conditions of access to social benefits and their adequacy or even legitimacy when some people prefer not to claim their rights. What does non-take-up say about the aims of social policies and the way they are perceived by concerned people? What does it say about the underlying norms of those policies and the ways these norms are incorporated or contested by (potential) beneficiaries? What does it say about the public service and its capacity to reach its communities and support them? This special issue starts with an introduction to the topic of non-take-up of health and social benefits, focusing more specifically on the case of Switzerland. Building on this state of the art, the agenda is further developed to explore what non-take-up of social benefits says about the reconfiguration of the relationship between citizens and the state. The five authors of the special issues contribute to this new research agenda in three different ways: by emphasizing the temporal dimension of non-take-up; by supporting a view of recipients as capable and critical actors; and by arguing for a systemic and relational approach to non-take-up.Seit den 1960er Jahren befasst sich eine spezifische Literaturströmung der Soziologie des Wohlfahrtsstaates mit dem Phänomen des Nichtbezuges, d.h. mit Menschen, die Anspruch auf Sozialleistungen haben, diese aber nicht erhalten. In den letzten Jahren gewann diese Thematik zunehmend an Aufmerksamkeit und erreicht die politische Agenda, auch in der Schweiz. Wenn einige Menschen es vorziehen, ihre Rechte nicht in Anspruch zu nehmen, stellt es sowohl die Bedingungen für den Zugang zu Sozialleistungen als auch deren angemessene Ausgestaltung oder gar deren Legitimität in Frage. Was sagt der Nichtbezug über die vorherrschende Sozialpolitik aus? Können wir daraus etwas über die zugrunde liegenden Normen dieser Politik lernen? Wie kann der Nichtbezug aus der Perspektive von Betroffenen verstanden werden? Übernehmen die (potenziell) Anspruchsberechtigten die vorherrschenden Normen oder ist er ein Ausdruck des Widerstandes? Können öffentliche Dienste ihren Auftrag der Grundversorgung von vulnerablen Gruppen überhaupt erfüllen, wenn diese den Angeboten fernbleiben? Diese Sonderausgabe beginnt mit einer Einführung in das Thema des Nichtbezuges von Gesundheits- und Sozialleistungen und konzentriert sich dabei besonders auf den Forschungsstand in der Schweiz. Auf dieser Auslegeordnung aufbauend wird das Thema anschliessend analytisch weiterentwickelt. Damit wird eine Einordnung des Nichtbezuges möglich, die zur Analyse der Beziehung von BürgerInnen und Wohlfahrtsstaat genutzt werden kann. Die fünf Autoren des Sonderhefts tragen auf drei verschiedene Arten zu dieser neuen Forschungsagenda bei: indem sie die zeitliche Dimension des Nichtbezuges betonen; indem sie eine Sichtweise der Betroffenen als fähige und kritische Akteure unterstützen; und indem sie für einen systemischen und relationalen Ansatz des Nichtbezuges plädieren.Que nous apprend le non-recours sur les objectifs des politiques sociales et la manière dont ceux-ci sont perçus par les populations concernées ? Que nous dit-il des normes qui sous-tendent ces politiques, de leur approbation ou de leur rejet par les publics concernés? Que nous apprend-il sur le fonctionnement des services publics et leur capacité à atteindre et soutenir les populations précarisées ? Ce numéro spécial s'ouvre sur une introduction à la question du non-recours aux prestations sociales et de santé. Celle-ci dresse un bref état des savoirs, y compris en Suisse; sur cette base, elle propose de mobiliser l'analyse du non-recours pour éclairer la reconfiguration des relations entre l'Etat et les citoyen.e.s. Les cinq contributions qui suivent participent à ce nouvel agenda de recherche de trois manières: en mettant en évidence la dimension temporelle du non-recours; en considérant les publics des politiques sociales en tant qu'acteurs capables et critiques et en plaidant pour une approche systémique et relationnelle du non-recours