Updating the wave-particle duality

Updating the wave-particle duality María C. Boscá e-mail: [email protected] Departamento de Física Atómica, Molecular y Nuclear Universidad de Granada E-18071. Granada Spain The wave-particle-duality, the fundamental component of the new quantum formalism in Bohr’s opinion, must be reformulated by incorporating the results of some experiments accomplished in the last decades of twentieth century. The Bohr´s complementarity principle stated the mutual exclusiveness and joint full completeness of the two (classical) descriptions of quantum systems; after Einstein-Podolsky-Rosen’paper, the wave-particle duality, or wave-particle complementarity, could be expressed by stating that it is impossible to build up an experimental arrangement in which we observe at the same time both corpuscular and wave aspects. In a two-slit experiment, they would correspond, respectively, to the which-way knowledge and the observation of interference pattern. Bohr showed this mutual exclusivity in numerous examples , and linked it to the unavoidable disturbance inherent in any measurement event. In quantum mechanical formalism, the complementarity principle has a clear mathematical expression: two observables are complementary if precise knowledge of one of them implies that all possible outcomes of the other are equally probable; their extension to classical concepts (as wave and particle) is not concerned. In 1991 Scully et al published a variant of the two-slit experiment that incorporates two micromasers cavities and a laser beam to provide which-path information without net momentum transferred during the interaction ; the impossibility of know which slit an atom went through and still observe the interference fringes is preserved by the establishing of quantum correlations between the measuring apparatus and the system being observed. They claimed that complementarity, of which wave-particle duality would be to them a manifestation, is more fundamental than the uncertainty principle . In 1996 B-G. Englert, following an approach originally due to Wooters and Zurek , derived , without making use of Heisenberg’s uncertainty relation, an inequality that quantifies the mutual compatibility relation between fringe visibility and which-way information. The inequality, that they denominated as “interferometric duality”, has the expression D^2 + V^2 ≤ 1, where D stands for the distinguishability of the ways and V for the fringe visibility; both of them are mathematical expressions that can be measured to check experimentally the inequality . Today, it is clear that intermediate particle-wave behaviours exist and, in addition to that, there are single experiments in which both classical wave-like and particle-like behaviours are showed total and simultaneously on an individual system. For instance, in the Bose’s double-prism experiment , tunnelling and perfect anticoincidence were observed in single photon states. Consequently, the meaning of the wave-particle duality must incorporate the simultaneous use of the two classical descriptions in the interpretation of experiments, loosing their original mutual exclusivity , which is incorporated as an extreme case in the new interferometric duality, a continuous quantum concept . The wave-particle duality, therefore, must be formulated as an interpretative addition to quantum mechanics, to which is possible to renounce if any pretension of visualize quantum phenomena in terms of classical concepts and intuitions is abandoned

Spontaneous patterns in coherently driven polariton microcavities

We consider a polariton microcavity resonantly driven by two external lasers which simultaneously pump both lower and upper polariton branches at normal incidence. In this setup, we study the occurrence of instabilities of the pump-only solutions towards the spontaneous formation of patterns. Their appearance is a consequence of the spontaneous symmetry breaking of translational and rotational invariance due to interaction-induced parametric scattering. We observe the evolution between diverse patterns which can be classified as single pump, where parametric scattering occurs at the same energy as one of the pumps, and as two pump, where scattering occurs at a different energy. For two-pump instabilities, stripe and checkerboard patterns become the dominant steady-state solutions because cubic parametric scattering processes are forbidden. This contrasts with the single-pump case, where hexagonal patterns are the most common arrangements. We study the possibility of controlling the evolution between different patterns. Our results are obtained within a linear stability analysis and are confirmed by finite-size full numerical calculation

Feminismo y cáncer de mama, una estrecha relación

En estrecha relación con la etapa final de las transiciones demográfica y epidemiológica, el cáncer de mama (CM) es cada vez más frecuente en las mujeres. El número de casos aumenta en todo el mundo, con diferencias en la tasa de incidencia y mortalidad, según sea la región geográfica (Martínez-Montanez et al., 2009). Algunos factores han sido asociados a la ocurrencia de esta enfermedad, como los hábitos alimentarios, nuevas pautas de reproducción (disminución del número de hijos e hijas y de la práctica de lactancia materna) (Instituto de la Mujer 2007). Las desigualdades de género limitan la capacidad de las mujeres para proteger su salud (OMS 2009). (Párrafo extraído del texto a modo de resumen)Eje 13: La salud de nuestros cuerposFacultad de Humanidades y Ciencias de la Educació

Modulating the Optoelectronic Properties of Silver Nanowires Films: Effect of Capping Agent and Deposition Technique

[EN]Silver nanowires 90 nm in diameter and 9 m in length have been synthesized using different capping agents: polyvinyl pyrrolidone (PVP) and alkyl thiol of different chain lengths. The nanowire structure is not influenced by the displacement of PVP by alkyl thiols, although alkyl thiols modify the lateral aggregation of nanowires. We examined the effect of the capping agent and the deposition method on the optical and electrical properties of films prepared by Spray and the Langmuir-Schaefer methodologies. Our results revealed that nanowires capped with PVP and C8-thiol present the best optoelectronic properties. By using different deposition techniques and by modifying the nanowire surface density, we can modulate the optoelectronic properties of films. This strategy allows obtaining films with the optoelectronic properties required to manufacture touch screens and electromagnetic shielding

Con Lucas por el mundo de la Antropología Bíblica

Para elaborar este trabajo de ANTROPOLOGIA BIBLICA nos hemos propuesto hacer un enfoque sobre todo pastoral. Quisiéramos que un lector corriente captara el mensaje bíblico sobre el hombre, que inspira en sus raíces, por momentos olvidadas, la tradición cristiana. Toda la literatura hebrea y la historia de su influencia se caracteriza por la marca predominante de una concepción monista del hombre, mientras que la concepción dualista es la que mejor caracteriza la historia de la cultura helenista

Relaxation behavior of semiflexible polymers at very low frequencies

[EN] The dielectric activity of poly(monocyclohexylmethylene itaconate) (PMCI) and poly(dicyclohexylmethylene itaconate) (PDCI) in the glassy region and in the glass-rubber transition is studied by thermostimulated discharge current (TSDC) techniques. The spectra obtained by global TSDC experiments show a prominent alpha-glass-rubber relaxation peak with maxima located at 97 and 55 degrees C for PMCI and PDCI, respectively, following in decreasing order of temperature for a well developed beta absorption and a comparatively low intensity relaxation. Better resolution of the relaxation behavior of these polymers in the glassy region is obtained by calculating the components of the complex dielectric permittivity epsilon* at extremely low frequencies from partial TSDC experiments. The ac spectra thus obtained suggest that the beta absorption is composed by two relaxations, each of them presumably associated with the motions of a side group. The differences observed in these spectra with those reported for the beta mechanical relaxation reported for these polymers in the literature are interpreted in terms of the restrictions that the side groups produce in the conformational space of phase of the backbone. These restrictions also explain the small changes in enthalpy in the glass-rubber transition which preclude the possibility of obtaining the glass-rubber transition temperature of these polymers by differential scanning calorimetric techniques. (C) 1997 American Institute of Physics.Díaz Calleja, R.; Sanchis Sánchez, MJ.; Alvarez, C.; Riande, E. (1997). Relaxation behavior of semiflexible polymers at very low frequencies. Journal of Applied Physics. 81(8):3685-3691. doi:10.1063/1.364743S3685369181

Effectiveness of a Multifactorial Intervention in the First 1000 Days of Life to Prevent Obesity and Overweight in Childhood: Study Protoco

(1) Background: Obesity is a global health problem, and its prevention must be a priority goal of public health, especially considering the seriousness of the problem among children. It is known that fetal and early postnatal environments may favor the appearance of obesity in later life. In recent years, the impact of the programs to prevent obesity in childhood has been scarce. The aim of this research is to evaluate the effectiveness of an intervention based on the concept of early programming. (2) Methods: Non-randomized controlled trial design. Inclusion criteria are: two-year-old infants whose gestational period begins in the 14 months following the start of the intervention, and whose mothers have made the complete follow-up of their pregnancy in the same clinical unit of the study. The intervention will be developed over all the known factors that affect early programming, during pregnancy up to 2 years of life. Data will be collected through a data collection sheet by the paediatricians. A unibivariate and multivariate analysis of the data will be carried out. (3) Ethics and dissemination: The trial does not involve any risk to participants and their offspring. Signed informed consent is obtained from all participants. Ethical approval has been obtained. (4) Results: It is expected that this study will provide evidence on the importance of the prevention of obesity from the critical period of the first 1000 days of life, being able to establish this as a standard intervention in primary care

A Mainly Circum-Mediterranean Origin for West Eurasian and North African mtDNAs in Puerto Rico with Strong Contributions from the Canary Islands and West Africa

Maternal lineages of West Eurasian and North African origin account for 11.5% of total mitochondrial ancestry in Puerto Rico. Historical sources suggest that this ancestry arrived mostly from European migrations that took place during the four centuries of the Spanish colonization of Puerto Rico. This study analyzed 101 mitochondrial control region sequences and diagnostic coding region variants from a sample set randomly and systematically selected using a census-based sampling frame to be representative of the Puerto Rican population, with the goal of defining West Eurasian-North African maternal clades and estimating their possible geographical origin. Median-joining haplotype networks were constructed using HVR-I and –II sequences from various reference populations in search of shared haplotypes. A posterior probability analysis was performed to estimate the percentage of possible origins across wide geographic regions for the entire sample set and for the most common haplogroups on the island. Principal component analyses were conducted to place the Puerto Rican mtDNA set within the variation present amongst all reference populations. Our study shows that up to 38% of West Eurasian and North African mitochondrial ancestry in Puerto Rico most likely migrated from the Canary Islands. However, most of those haplotypes had previously migrated to the Canary Islands from elsewhere, and there are substantial contributions from various populations across the circum-Mediterranean region and from West African populations related to the modern Wolof and Serer peoples from Senegal and the nomad Fulani who extend up to Cameroon. In conclusion, the West Eurasian mitochondrial ancestry in Puerto Ricans is geographically diverse. However, haplotype diversity seems to be low and frequencies have been shaped by population bottlenecks, migration waves, and random genetic drift. Consequently, approximately 47% of mtDNAs of West Eurasian and North African ancestry in Puerto Rico probably arrived early in its colonial history

Perspectivas y retos de los extractos vegetales como aditivos alimentarios en rumiantes

Algunas plantas producen y almacenan compuestos secundarios que ejercen actividades beneficiosas en el organismo humano y animal. En lo que se refiere a su uso en alimentación animal, constituyen una alternativa natural a los aditivos antibióticos promotores del crecimiento, cuyo uso en rumiantes se ha centrado fundamentalmente en sus efectos sobre la fermentación rumial