37 research outputs found
Bifurcations of equilibria in DNA elasticity
No full textDNA molecules in the familiar double helical B form are treated here as though they have rod-like structures obtained by stacking the
nearly planar base pairs comprising them one on top of another with each rotated by approximately one-tenth of a full turn with respect
to its immediate predecessor in the stack. As each base in a base pair is attached to the sugar-phosphate backbone chain of one of the
two DNA strands that have come together to form the Watson-Crick structure, and each phosphate group in a backbone chain bears one electronic charge, two such charges are associated with each base pair. Thus, each base pair is subject to not only the elastic forces and moments exerted on it by its neighboring base pairs but also to remote electrostatic forces that, because they are only partially screened out by positively charged counter ions, can render the molecule's equilibrium configurations sensitive to changes in the concentration c of salt in the medium.
The observation that the step from one base pair to the next can be one of several distinct types, each having its own mechanical properties that depend on the nucleotide composition of the step, and the assumption that a base pair is rigid, led to the development of a theory of sequence dependent DNA elasticity [Coleman, Olson, and Swigon, J. Chem. Phys. 118 ,7127-7140, (2003)]. The theory of DNA molecules in aqueous solution developed here is based on but goes beyond that theory. It takes into account the intramolecular electrostatic interactions of the negatively charged phosphate groups in the molecule and the impenetrability of the DNA molecule for cases in which the
electrostatic repulsive forces do not suffice to avoid self penetration. The theory permits one to calculate equilibrium configurations, to determine their stability, and to study the dependence of them on salt concentration and on all kinds of end conditions.
When the intramolecular electrostatic forces are taken into account, the equations of mechanical equilibrium for a DNA molecule with N+1 base pairs are a system of mu*N non-linear equations, where mu, the number of kinematical variables describing the relative displacement and orientation of adjacent base pairs is in general 6; it reduces to 3 when base-pair steps are assumed to be inextensible and non-shearable. An efficient numerically stable computational scheme is here presented for
solving those equations and determining the mechanical stability of the calculated equilibrium configurations. That scheme is employed to compute and analyze bifurcation diagrams in which c is the bifurcation parameter and to show that, for an intrinsically curved molecule, small changes in c can have a strong effect on stable
equilibrium configurations. Cases are presented in which self-contact must be taken into account even though the intramolecular electrostatic forces of repulsion are strong.Ph.D.Includes bibliographical references (p. 106-110)
LAMENTATIONS D’UN PATRIARCHISTE : ANALYSE D’AH ! LES FEMMES… D’ISAÏE BITON KOULIBALY COMME UNE RÉPLIQUE AUX ÉCRITS FEMINISTES
No full textThe French-language novel of Black Africa is characterised by an abundance of women\u27s literature, in which men are often presented as the main oppressors of women. In most of these works, men are vilified, blamed and held responsible for the subaltern, oppressed and submissive condition of women. These black women writers denounce patriarchy as a system that perpetuates the inferiorisation and marginalisation of women. In this context, this article argues that Isaïe Biton Koulibaly\u27s collection of short stories, Ah! Les femmes, is a response to African feminist narratives. Its main aim is to absolve men of any guilt while highlighting women\u27s shortcomings, both in the marital sphere and beyond. By focusing on patriarchy as a starting point, we show that the short stories in Ah! Les femmes... are a pretext for arguing for the return of patriarchy. The author seems to illustrate, through her short stories that African women are irredeemably flawed and therefore undeserving of the privileges they enjoy in contemporary Africa. Through the author\u27s work, it is clear that there is a desire to restore the retrograde patriarchal ideology, a system vigorously opposed by African feminist activists in their writings. It is concluded that writers, both men and women, should give priority to promoting gender complementarity in their works rather than adopting partisan positions.
Résumé Le roman francophone d’Afrique noire se caractérise par une production littéraire féminine foisonnante, où l’homme est souvent présenté comme le principal oppresseur des femmes. Dans la plupart de ces œuvres, il est diffamé, culpabilisé et tenu responsable de la condition subalterne, opprimée et soumise des femmes. Ces écrivaines noires dénoncent le patriarcat comme un système perpétuant l’infériorisation et la marginalisation des femmes. Dans ce contexte, cet article soutient que le recueil de nouvelles, Ah ! Les femmes d’Isaïe Biton Koulibaly constitue une réponse aux récits féministes africains. Son objectif principal est de dédouaner l’homme de toute culpabilité tout en mettant en lumière les défauts des femmes, aussi bien dans la sphère conjugale qu’au-delà. En se focalisant sur le patriarcat comme réflexion de base, nous démontrons que les nouvelles dans Ah ! Les femmes … sont un prétexte pour plaider le retour du patriarcat. L’auteur semble illustrer, à travers ses nouvelles, que les femmes africaines portent des défauts irrémédiables et par la suite, ne méritent pas les privilèges dont elles jouissent en Afrique contemporaine. A travers l’œuvre de l’auteur, il apparait clairement une volonté de restaurer l’idéologie patriarcale rétrograde, un système vigoureusement combattu par les activistes féministes africaines dans leurs écrits. Il est conclu que les écrivains, hommes comme femmes, devraient privilégier la promotion de la complémentarité des genres dans leurs œuvres plutôt que d’adopter des positions partisanes
LONG-TERM OUTCOME WITH CARDIAC-RESYNCHRONIZATION THERAPY IN UNITED STATES AND EUROPEAN PATIENTS: MADIT-CRT
No full text102-06: Risk of Life-Threatening Cardiac Events in Some Long QT Syndrome Patients Treated with β-Blockers
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Percutaneous left atrial appendage occlusion in the prevention of stroke in atrial fibrillation: a systematic review
No full textTrends in Atrial Fibrillation Management—Results from a National Multi-Center Urgent Care Network Registry
No full textBackground: Atrial fibrillation (AF) is a common diagnosis in patients presenting to urgent care centers (UCCs), yet there is scant research regarding treatment in these centers. While some of these patients are managed within UCCs, some are referred for further care in an emergency department (ED). Objectives: We aimed to identify the rate of patients referred to an ED and define predictors for this outcome. We analyzed the rates of AF diagnosis and hospital referral over the years. Finally, we described trends in patient anticoagulation (AC) medication use. Methods: This retrospective study included 5873 visits of patients over age 18 visiting the TEREM UCC network with a diagnosis of AF over 11 years. Multivariate analysis was used to identify predictors for ED referral. Results: In a multivariate model, predictors of referral to an ED included vascular disease (OR 1.88 (95% CI 1.43–2.45), p < 0.001), evening or night shifts (OR 1.31 (95% CI 1.11–1.55), p < 0.001; OR 1.68 (95% CI 1.32–2.15), p < 0.001; respectively), previously diagnosed AF (OR 0.31 (95% CI 0.26–0.37), p < 0.001), prior treatment with AC (OR 0.56 (95% CI 0.46–0.67), p < 0.001), beta blockers (OR 0.63 (95% CI 0.52–0.76), p < 0.001), and antiarrhythmic medication (OR 0.58 (95% CI 0.48–0.69), p < 0.001). Visits diagnosed with AF increased over the years (p = 0.030), while referrals to an ED decreased over the years (p = 0.050). The rate of novel oral anticoagulant prescriptions increased over the years. Conclusions: The rate of referral to an ED from a UCC over the years is declining but remains high. Referrals may be predicted using simple clinical variables. This knowledge may help to reduce the burden of hospitalizations
168-01: One-Year Follow-Up of the Prospective Registry of Patients Using The Wearable Defibrillator (WEARIT-II Registry)
No full textLa Influencia del ambiente filosófico en el arte de la Grecia Clásica (s. VI y V a C.)
Get PDFThis article analyzes the influence of the philosophical environment on the development of classical Greek art, focusing on sculpture from the 6th and 5th centuries BCE. Starting from the question of how ideas and philosophy affect artistic creation, it examines the transition from mythological and naturalistic thought to rationalism, as reflected in the aesthetic and technical evolution of sculpture. Through a comparison between “The Brothers Cleobis and Biton” by Polymedes of Argos and “The Discobolus” by Myron, the article highlights the shift from Egyptian rigidity to naturalistic movement as a manifestation of spirit and philosophical thought. The analysis draws on the contributions of Hegel, Plato, and Maritain, who argue that art is an expression of intellect and cultural context. It concludes that classical Greek sculpture is a privileged testimony to the interaction between philosophy, culture, and creativity, and that the artwork serves as a vehicle for truth and beauty, always referring to its author and its era.El presente trabajo buscó vislumbrar la influencia del ambiente filosófico en el desarrollo del arte griego clásico, centrándose en la escultura de los siglos VI y V a.C. A partir de la pregunta sobre cómo las ideas y la filosofía inciden en la creación artística, se examinó la transición desde el pensamiento mitológico y naturalista hacia el racionalismo, reflejada en la evolución estética y técnica de la escultura. Mediante la comparación entre “Los hermanos Cleobis y Biton” de Polímedes y “El discóbolo” de Mirón, se evidenció el paso de la rigidez del primer estilo griego (influencia egipcia) al movimiento naturalista posterior, como manifestación del pensamiento filosófico. El análisis se apoyó en Hegel, Platón y Maritain. Se concluyó que la escultura griega clásica constituye un testimonio de la interacción entre filosofía, cultura y creatividad, y que la obra de arte es vehículo de verdad y belleza, remitiendo siempre a su autor
Predictors of long‐term mortality with cardiac resynchronization therapy in mild heart failure patients with left bundle branch block
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