The subjective metric of remembered colors: A Fisher-information analysis of the geometry of human chromatic memory.

In order to explore the metric structure of the space of remembered colors, a computer game was designed, where players with normal color vision had to store a color in memory, and later retrieve it by selecting the best match out of a continuum of alternatives. All tested subjects exhibited evidence of focal colors in their mnemonic strategy. We found no concluding evidence that the focal colors of different players tended to cluster around universal prototypes. Based on the Fisher metric, for each subject we defined a notion of distance in color space that captured the accuracy with which similar colors where discriminated or confounded when stored and retrieved from memory. The notions of distance obtained for different players were remarkably similar. Finally, for each player, we constructed a new color scale, in which colors are memorized and retrieved with uniform accuracy

The Intersection of Interfacial Forces and Electrochemical Reactions

We review recent developments in experimental techniques that simultaneously combine measurements of the interaction forces or energies between two extended surfaces immersed in electrolyte solutions—primarily aqueous—with simultaneous monitoring of their (electro)chemical reactions and controlling the electrochemical surface potential of at least one of the surfaces. Combination of these complementary techniques allows for simultaneous real time monitoring of angstrom level changes in surface thickness and roughness, surface–surface interaction energies, and charge and mass transferred via electrochemical reactions, dissolution, and adsorption, and/or charging of electric double layers. These techniques employ the surface forces apparatus (SFA) combined with various “electrochemical attachments” for in situ measurements of various physical and (electro)chemical properties (e.g., cyclic voltammetry), optical imaging, and electric potentials and currents generated naturally during an interaction, as well as when electric fields (potential differences) are applied between the surfaces and/or solution—in some cases allowing for the chemical reaction equation to be unambiguously determined. We discuss how the physical interactions between two different surfaces when brought close to each other (<10 nm) can affect their chemistry, and suggest further extensions of these techniques to biological systems and simultaneous in situ spectroscopic measurements for chemical analysis

The importance of phytochemical studies in the formation of the pharmacist

Las plantas poseen una gran cantidad de metabolitos primarios y secundarios que le permiten crecer, multiplicarse, defenderse y sobrevivir. El metabolismo secundario de las plantas puede definirse como el nivel funcional del metabolismo que, aunque no es indispensable para el crecimiento y desarrollo del vegetal, lo es para la supervivencia de la especie. Dada la riqueza química de las plantas, éstas fueron consideradas la fuente natural de numerosos medicamentos y por ello fueron usadas en la medicina tradicional, popular o folklórica y sus cualidades fueron transmitidas a través de las culturas de los pueblos. El estudio fitoquímico de los vegetales permite conocer los principios activos y evaluar la complejidad de sus caminos de biosíntesis y degradación así como los mecanismos de regulación. En este trabajo analizamos la importancia de su estudio en la carrera de Farmacia.Secondary plant metabolism can be regarded as the functional level of plant metabolism that is non-essential for plant growth and development but indispensable for the survival of the species. Secondary plant metabolism compounds have been reported to exhibit a wide range of biological effects, including antibacterial, antiviral, antiinflammatory, antiallergic, free radical scavengers, antioxidant and others. For these reasons, plants were considered as natural medicine source and were widely used. The phytochemical study of plant components is indispensable to know the active principies, metabolic pathways of their synthesis, degradation and regulation mechanisms.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Valeur diagnostique des différentes formes parasitaires dans la Trypanosomose américaine expérimentale en immuno-fluorescence chez la Souris

L’Immuno-fluorescence indirecte a permis de détecter les anticorps contre les formes de culture et contre les formes sanguines de Trypanosoma cruzi chez la souris, et d’effectuer simultanément une comparaison. Il n’a pas été observé de différences significatives des taux pour les différentes formes parasitaires