Absolute continuity in periodic thin tubes and strongly coupled leaky wires

Using a perturbative argument, we show that in any finite region containing the lowest transverse eigenmode, the spectrum of a periodically curved smooth Dirichlet tube in two or three dimensions is absolutely continuous provided the tube is sufficiently thin. In a similar way we demonstrate absolute continuity at the bottom of the spectrum for generalized Schr\"odinger operators with a sufficiently strongly attractive $\delta$ interaction supported by a periodic curve in $\mathbb{R}^d, d=2,3$.Comment: LaTeX 2e, 10 page

MIMO capacity for deterministic channel models: sublinear growth

This is the second paper of the authors in a series concerned with the development of a deterministic model for the transfer matrix of a MIMO system. Starting from the Maxwell equations, we have described in \cite{BCFM} the generic structure of such a deterministic transfer matrix. In the current paper we apply the results of \cite{BCFM} in order to study the (Shannon-Foschini) capacity behavior of a MIMO system as a function of the deterministic spread function of the environment, and the number of transmitting and receiving antennas. The antennas are assumed to fill in a given, fixed volume. Under some generic assumptions, we prove that the capacity grows much more slowly than linearly with the number of antennas. These results reinforce previous heuristic results obtained from statistical models of the transfer matrix, which also predict a sublinear behavior.Comment: 12 pages, to appear in Math. Meth. Appl. Sc

Post-Conflict Affiliative Behaviors Towards Humans in Domestic Dogs (Canis familiaris)

Social species need conflict-resolution mechanisms to maintain group cohesion and diminish aggression. Reconciliation (affiliative contact between opponents) and consolation (affiliative contact between the victim and an uninvolved third party) have been postulated for this function in various species. The purpose of this work is to study post-conflict affiliative behaviors toward humans in domestic dogs. This study has looked into post-conflict affiliative behaviors in domestic dogs toward their owners. To this end, a conflict situation was created where the animal was scolded by one of the owners for “stealing” human food. Behaviors were recorded along a period of 3 min and 30 s before and after the scolding. Results show that dogs exhibit affiliative behaviors (significant increase in closeness, gazing, and tail wagging) as well as appeasement behaviors (averting eyes, low tail carriage, lowered ears, lip licking, and crouching) toward the owner that scolded them (reconciliation). In other words, this is the first work that presents reconciliation in dogs in a conflict situation with humans. It discusses the importance of this phenomenon in the dog-human bond.Fil: Cavalli, Camila María. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Grupo de Investigación del Comportamiento en Cánidos; ArgentinaFil: Dzik, Marina Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Médicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Médicas; ArgentinaFil: Carballo Pozzo Ardizzi, Fabricio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Ciencias Biológicas y Biomédicas del Sur. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Instituto de Ciencias Biológicas y Biomédicas del Sur; ArgentinaFil: Bentosela, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Médicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Médicas; Argentin

¿Pueden los perros domésticos (Canis lupus familiaris) reconocer expresiones emocionales humanas? Una revisión crítica de las evidencias

Las expresiones emocionales tienen un papel fundamental en las interacciones de especies sociales, brindando información acerca del emisor, las características e importancia del estímulo o situación que desencadena dichas interacciones, y también funcionan regulando los vínculos sociales. Los perros poseen notorias capacidades comunicativas hacia los humanos por lo que resulta interesante estudiar si estas habilidades se extienden al reconocimiento de las expresiones emocionales. Se han realizado diversas investigaciones acerca del reconocimiento de expresiones emocionales humanas en perros exponiendo a los mismos a una situación representada por personas durante la evaluación, así como mediante el uso de imágenes, videos y grabaciones. El análisis de las evidencias permite concluir que los perros podrían distinguir entre distintas emociones humanas ya sea en presencia de modelos en vivo o mediante la observación de imágenes y modulan su conducta conforme a esta discriminación, así como también pueden utilizar esta información como claves en la resolución de problemas. Sin embargo, aún no están claros los mecanismos que subyacen a estas habilidades.Emotional expressions play a critical role in the interactions among individuals, particularly, in social species. They provide information about the sender and the characteristics and importance of the triggering stimulus or situation, also regulating social ties. Dogs have notorious communication skills towards humans, which makes the study of their ability to recognize human emotional expressions an interesting endeavor. There have been several studies in which dogs have been tested using real people in an experimental situation as well as images, video and audio recordings of people's expressions. The evidence suggests that dogs can discriminate between different human emotions either in the presence of live models or by looking at images. This type of information has been shown to modulate their behavior and to be used as cues to solve problems. However, the mechanisms underlying these abilities are not fully understood yet.Fil: Helbling, Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Médicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Médicas; ArgentinaFil: Barrera, Gabriela Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Cs.veterinarias. Instituto de Ciencias Veterinarias del Litoral; ArgentinaFil: Bentosela, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Médicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Médicas; Argentin