RESUMEN
In an iterated two-person game, for instance prisoner's dilemma or the snowdrift game, there exist strategies that force the payoffs of the opponents to be equal. These equalizer strategies form a subset of the more general zero-determinant strategies that unilaterally set the payoff of an opponent. A challenge in the attempts to understand the role of these strategies in the evolution of animal behavior is the lack of iterations in the fights for mating opportunities or territory control. We show that an arbitrary two-parameter strategy may possess a corresponding equalizer strategy which produces the same result: statistics of the fight outcomes in the contests with competitors are the same for each of these two strategies. Therefore, analyzing only the equalizer strategy space may be sufficient to predict animal behavior if nature, indeed, reduces (marginalizes) complex strategies to equalizer strategy space. The work's main finding is that there is a unique equalizer strategy that predicts fight outcomes without symmetric cooperation responses. The lack of symmetric cooperation responses is a common trait in conflict escalation contests that generally require a clear winner. In addition, this unique strategy does not assess information of the opponent's state. The method bypasses the standard analysis of evolutionary stability. The results fit well the observations of combat between male bowl and doily spiders and support an empirical assumption of the war of attrition model that the species use only information regarding their own state during conflict escalation.
Asunto(s)
Conducta Animal/fisiología , Conducta Competitiva/fisiología , Teoría del Juego , Modelos Biológicos , Animales , Evolución Biológica , Conducta Cooperativa , Arañas/fisiologíaRESUMEN
Out of thermal equilibrium, an environment imposes effective mechanical forces on nanofabricated devices as well as on microscopic chemical or biological systems. Here we address the question of how to calculate these forces together with the response of the system from first principles. We show that an ideal gaslike environment, even near thermal equilibrium, can enforce a specific steady state on the system by creating effective potentials in otherwise homogeneous space. An example of stable and unstable rectifications of thermal fluctuations is presented using a modified Feynman-Smoluchowski ratchet with two degrees of freedom. Moreover, the stability of a steady configuration depends on its chiral symmetry. The transition rate probabilities and the corresponding kinetic equations are derived for a complex mechanical system with arbitrary degrees of freedom. This work, therefore, extends the applicability of mechanical systems as a toy model playground of statistical physics for active and living matter with multiple degrees of freedom.
RESUMEN
Momentum transfer between matter and electromagnetic field is analyzed. The related equations of motion and conservation laws are derived using relativistic formalism. Their correspondence to various, at first sight self-contradicting, experimental data (the so-called Abraham-Minkowski controversy) is demonstrated. A new, Casimir-like, quantum phenomenon is predicted: contribution of vacuum fluctuations to the motion of dielectric liquids in crossed electric and magnetic fields. Velocities of about 50 nm/s can be expected due to the contribution of high frequency vacuum modes. The proposed phenomenon could be used in the future as an investigating tool for zero fluctuations. Other possible applications lie in fields of microfluidics or precise positioning of micro-objects, e.g., cold atoms or molecules.
RESUMEN
Holographic lithography is an ideal technique for fabricating three-dimensional photonic crystals. However, a critical stage in the fabrication is the minute alignment of the layers with one another. We present a simple moirelike alignment technique with better than 20-nm translation resolution and 45-murad rotation resolution. This technique can easily be extended to other situations when low-cost, high-precision alignment is needed.
RESUMEN
This paper describes the histopathological examination of an autopsy case featuring reconstruction of an edentulous maxilla by means of uncoated blade implants made of Titanaloy (TI6AL4V) inserted by the first author two years and seven months prior to the patient's death. The naturally induced reparative processes which encourage the success of this method and the optimal geometric flexibility allowed by the use of delicate blades are also examined. The significance of fibro-osseous tissue in blade implant support systems and the term "osseo-integration" often used in implantological literature will be discussed. The present study allows the following conclusions to be drawn: (1) Blade implants can be made in the maxilla. Provided sinus elevation is performed, blade implantation is feasible even when only minimal vertical quantities of bone are available in the distal regions. (2) Even if the opposing jaw bone (in this case the mandible) presents a complete natural dentition, blade implantation therapy remains feasible. (3) As the findings in this study show, the dynamic formation of calcified and non-calcified connective tissue around and within an endosseous implant is a totally natural reaction ensuring (a) fixation, (b) shock absorption, (c) the prevention of infection, and (d) the prevention of epithelial downgrowth. (4) Properly placed blade implants can be subjected to functional loading after six post-operative weeks and do not require a two-stage operative process, with a healing period of three to four months between the first and second surgical interventions. This often-cited three-to-four-month ossification period is thus unnecessary. (5) This case study clearly refutes the claims made by some authors (Tetsch, 1983; Strunz and Tetsch, 1985; Schramm-Scherrer and Tetsch, 1986) to the effect that (1) the maxilla cannot be implanted, and (2) blade implantology is doomed to failure, whether practiced in the maxilla or the mandible.
Asunto(s)
Implantación de Cuchilla (Odontología) , Seno Maxilar/cirugía , Implantes Dentales , Femenino , Humanos , Seno Maxilar/patología , Persona de Mediana Edad , OseointegraciónAsunto(s)
Diseño de Equipo , Prótesis e Implantes , Materiales Biocompatibles , Placas Óseas , Humanos , SuizaRESUMEN
Congestive heart failure has never been described in patients with dysplastic stenotic pulmonary valve without associated shunt lesions. We describe two patients with mild pulmonic stenosis due to valvular dysplasia associated with cardiomyopathy who developed severe congestive heart failure. Since the small pressure gradients across the pulmonary valve cannot cause this complication, we suggest that it resulted from the associated hypertrophic non-obstructive cardiomyopathy. The presence of cardiomyopathy may alter the clinical presentation and prognosis of patients with dysplastic pulmonary valve. In some cases, like our two cases, the cardiomyopathy rather than the valvular lesion should be considered the main disease.
Asunto(s)
Cardiomiopatías/complicaciones , Insuficiencia Cardíaca/etiología , Estenosis de la Válvula Pulmonar/complicaciones , Válvula Pulmonar/anomalías , Cardiomegalia/complicaciones , Cardiomegalia/diagnóstico por imagen , Cardiomiopatías/diagnóstico por imagen , Digoxina/administración & dosificación , Insuficiencia Cardíaca/diagnóstico , Insuficiencia Cardíaca/tratamiento farmacológico , Humanos , Lactante , Recién Nacido , Masculino , Estenosis de la Válvula Pulmonar/diagnóstico por imagen , RadiografíaAsunto(s)
Cardiopatías Congénitas/diagnóstico , Lentigo/diagnóstico , Síndrome de Noonan/diagnóstico , Adolescente , Cardiomiopatías/complicaciones , Cardiomiopatías/diagnóstico , Niño , Preescolar , Diagnóstico Diferencial , Femenino , Trastornos del Crecimiento/complicaciones , Cardiopatías Congénitas/complicaciones , Humanos , Lactante , Lentigo/complicaciones , Masculino , Válvula Pulmonar/anomalías , SíndromeRESUMEN
Congenital cutaneous hemangioma associated with congenital heart disease is extremely rare. We report four infants with congenital cavernous hemangioma of the face and neck and coarctation of the aorta. Three also had congenital aneurysm of a subclavian or innominate artery. One patient also had mild congenital valvular aortic stenosis. The unusual combination of lesions may represent a new syndrome.
Asunto(s)
Aneurisma/congénito , Coartación Aórtica/complicaciones , Neoplasias de Cabeza y Cuello/congénito , Hemangioma Cavernoso/congénito , Tronco Braquiocefálico , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Arteria Subclavia , SíndromeRESUMEN
Dysplastic pulmonary valve is usually associated with extreme right axis deviation. A mean manifest electrical QRS axis of + 160 degrees or less was present in 11 of 30 cases of DPV studied by us. In 9 of these cases associated left ventricular hypertrophic non-obstructive cardiomyopathy was found. We suggest that a normal mean manifest electrical QRS axis in the presence of dysplastic stenotic pulmonary valve indicates the presence of associated cardiomyopathy.