Percolation and cooperation with mobile agents: Geometric and strategy clusters

We study the conditions for persistent cooperation in an off-lattice model of mobile agents playing the Prisoner's Dilemma game with pure, unconditional strategies. Each agent has an exclusion radius rP, which accounts for the population viscosity, and an interaction radius rint, which defines the instantaneous contact network for the game dynamics. We show that, differently from the rP=0 case, the model with finite-sized agents presents a coexistence phase with both cooperators and defectors, besides the two absorbing phases, in which either cooperators or defectors dominate. We provide, in addition, a geometric interpretation of the transitions between phases. In analogy with lattice models, the geometric percolation of the contact network (i.e., irrespective of the strategy) enhances cooperation. More importantly, we show that the percolation of defectors is an essential condition for their survival. Differently from compact clusters of cooperators, isolated groups of defectors will eventually become extinct if not percolating, independently of their size

On the Modeling of Droplet Evaporation on Superhydrophobic Surfaces

When a drop of water is placed on a rough surface, there are two possible extreme regimes of wetting: the one called Cassie-Baxter (CB) with air pockets trapped underneath the droplet and the one characterized by the homogeneous wetting of the surface, called the Wenzel (W) state. A way to investigate the transition between these two states is by means of evaporation experiments, in which the droplet starts in a CB state and, as its volume decreases, penetrates the surface's grooves, reaching a W state. Here we present a theoretical model based on the global interfacial energies for CB and W states that allows us to predict the thermodynamic wetting state of the droplet for a given volume and surface texture. We first analyze the influence of the surface geometric parameters on the droplet's final wetting state with constant volume, and show that it depends strongly on the surface texture. We then vary the volume of the droplet keeping fixed the geometric surface parameters to mimic evaporation and show that the drop experiences a transition from the CB to the W state when its volume reduces, as observed in experiments. To investigate the dependency of the wetting state on the initial state of the droplet, we implement a cellular Potts model in three dimensions. Simulations show a very good agreement with theory when the initial state is W, but it disagrees when the droplet is initialized in a CB state, in accordance with previous observations which show that the CB state is metastable in many cases. Both simulations and theoretical model can be modified to study other types of surface.Comment: 23 pages, 7 figure

Eigenvalue estimates for submanifolds of warped product spaces

We give lower bounds for the fundamental tone of open sets in minimal submanifolds immersed into warped product spaces of type $N^n \times_f Q^q$, where $f \in C^\infty(N)$. We also study the essential spectrum of these minimal submanifolds.Comment: 17 page

Hemangiomas de la infancia, manejo actual

ResumenDurante años se ha usado una nomenclatura imprecisa para designar a las “Anomalías Vasculares de la Infancia”. Esto ha contribuido a diagnósticos erróneos y como consecuencia, a tratamientos inadecuados. La clasificación actual las separa en dos grandes grupos: las malformaciones vasculares y un gran grupo de tumores vasculares, que incluyen principalmente a los clásicos hemangiomas de la infancia y a “nuevos tumores vasculares” que tienen una evolución distinta. Recientemente nuevos hallazgos asociados a las anomalías vasculares de la infancia ha obligado a establecer cambios en el diagnóstico y manejo de estas lesiones con un fuerte énfasis en el manejo multidisciplinario. En el presente artículo se analizan los hemangiomas de la infancia con sus características clínicas, asociaciones con otras patologías y evolución. Se plantean alternativas de estudio y tratamiento.SummaryFor years, a confusing nomenclature has been used in the classification of "Children’s Vascular Anomalies." This has contributed to misdiagnosis and consequently inappropriate treatments. The current classification divides them in two groups: vascular malformations and a large group of vascular tumors, including mainly children’s classic infantile hemangiomas and "new vascular tumors" that have a different behavior. In recent years new findings associated with vascular anomalies have led to changes in diagnosis and management, focusing in a personalized and multidisciplinary approach. This article discusses infantile hemangiomas in terms of their clinical picture, associated diseases and evolution. Study and treatment modalities are analyzed

Complement activation and protein adsorption by carbon nanotubes

As a first step to validate the use of carbon nanotubes as novel vaccine or drug delivery devices, their interaction with a part of the human immune system, complement, has been explored. Haemolytic assays were conducted to investigate the activation of the human serum complement system via the classical and alternative pathways. Western blot and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) techniques were used to elucidate the mechanism of activation of complement via the classical pathway, and to analyse the interaction of complement and other plasma proteins with carbon nanotubes. We report for the first time that carbon nanotubes activate human complement via both classical and alternative pathways. We conclude that complement activation by nanotubes is consistent with reported adjuvant effects, and might also in various circumstances promote damaging effects of excessive complement activation, such as inflammation and granuloma formation. C1q binds directly to carbon nanotubes. Protein binding to carbon nanotubes is highly selective, since out of the many different proteins in plasma, very few bind to the carbon nanotubes. Fibrinogen and apolipoproteins (AI, AIV and CIII) were the proteins that bound to carbon nanotubes in greatest quantit

Analisa Faktor-faktor Yang Mendorong Keputusan Konsumen Dalam Memilih Artotel Butik Hotel Surabaya

Penelitian ini dilakukan untuk mengetahui faktor-faktor apa saja yang mendorong keputusan konsumen dalam memilih Artotel Butik Hotel Surabaya, serta seberapa besar kontribusi dari masing-masing faktor tersebut. Penulis menggunakan Artotel Butik Hotel Surabaya, karena Hotel ini tergolong baru dan berbeda dari hotel-hotel lainnya. Artotel Butik Hotel Surabaya menjadi satu-satuya hotel yang mengutamakan konsep kontemporer desain di setiap sudut ruangan serta memiliki galeri seni. Hasil penelitian menunjukkan bahwa terdapat lima faktor yang terbentuk, yaitu faktor motivasi dan persepsi, peran dan gaya hidup, media promosi, empati, serta desain fisik. Masing-masing faktor tersebut berkontribusi cukup besar dalam mendorong para konsumen untuk memilih Artotel Butik Hotel Surabaya