Spin selective transport through helical molecular systems

Highly spin selective transport of electrons through a helically shaped electrostatic potential is demonstrated in the frame of a minimal model approach. The effect is significant even in the case of weak spin-orbit coupling. Two main factors determine the selectivity, an unconventional Rashba- like spin-orbit interaction, reflecting the helical symmetry of the system, and a weakly dispersive electronic band of the helical system. The weak electronic coupling, associated with the small dispersion, leads to a low mobility of the charges in the system and allows even weak spin-orbit interactions to be effective. The results are expected to be generic for chiral molecular systems displaying low spin-orbit coupling and low conductivity.Comment: 9 pages, 4 figures v2 (misprints corrected, new figures

Measurement of deformation gradients in hot rolling of AA3004

In this paper we describe an experimental technique developed to measure the deformation gradients and temperature in a single hot rolling pass of an AA3004 sample that was fitted with an insert. The insert had been previously hand engraved with a 1 × 1 mm grid pitch, and the analysis of the data digitally captured from the image of the deformed grid enabled the calculation of the components of the deformation gradient tensor. Four steel pins prevented relative motion between the insert and the rest of the sample. No detachment was observed between insert and sample after rolling. The temperature was measured during rolling using two embedded thermocouples, one close to the surface and the other in the centerline. The commercial finite element code ABAQUS was used to create a three-dimensional model of the rolling process. The recorded temperature was compared to the numerical values evaluated after tuning the heat transfer coefficient. The shape of the grid after rolling was checked against the deformed mesh using different friction coefficients in order to obtain the optimum match. The unusually large length of the insert enabled the rolling process to be stopped halfway so that a picture of the roll-gap area could be obtained. This provided a partially deformed grid that represented the transient state during rolling. The experimentally determined deformation gradient in this area as well as in the steady-state area agreed well with the finite element predictions. © 2005 Society for Experimental Mechanics

Big Data on Decision Making in Energetic Management of Copper Mining

Indexado en: Web of Science; Scopus.It is proposed an analysis of the related variables with the energetic consumption in the process of concentrate of copper; specifically ball mills and SAG. The methodology considers the analysis of great volumes of data, which allows to identify the variables of interest (tonnage, temperature and power) to reach to an improvement plan in the energetic efficiency. The correct processing of the great volumen of data, previous imputation to the null data, not informed and out of range, coming from the milling process of copper, a decision support systems integrated, it allows to obtain clear and on line information for the decision making. As results it is establish that exist correlation between the energetic consumption of the Ball and SAG Mills, regarding the East, West temperature and winding. Nevertheless, it is not observed correlation between the energetic consumption of the Ball Mills and the SAG Mills, regarding to the tonnages of feed of SAG Mill. In consequence, From the experimental design, a similarity of behavior between two groups of different mills was determined in lines process. In addition, it was determined that there is a difference in energy consumption between the mills of the same group. This approach modifies the method presented in [1].(a)http://www.univagora.ro/jour/index.php/ijccc/article/view/2784/106

Do Balance Demands Induce Shifts in Visual Proprioception in Crawling Infants?

The onset of hands-and-knees crawling during the latter half of the first year of life heralds pervasive changes in a range of psychological functions. Chief among these changes is a clear shift in visual proprioception, evident in the way infants use patterns of optic flow in the peripheral field of view to regulate their postural sway. This shift is thought to result from consistent exposure in the newly crawling infant to different patterns of optic flow in the central field of view and the periphery and the need to concurrently process information about self-movement, particularly postural sway, and the environmental layout during crawling. Researchers have hypothesized that the demands on the infant's visual system to concurrently process information about self-movement and the environment press the infant to differentiate and functionalize peripheral optic flow for the control of balance during locomotion so that the central field of view is freed to engage in steering and monitoring the surface and potentially other tasks. In the current experiment, we tested whether belly crawling, a mode of locomotion that places negligible demands on the control of balance, leads to the same changes in the functional utilization of peripheral optic flow for the control of postural sway as hands-and-knees crawling. We hypothesized that hands-and-knees crawlers (n = 15) would show significantly higher postural responsiveness to movements of the side walls and ceiling of a moving room than same-aged pre-crawlers (n = 19) and belly crawlers (n = 15) with an equivalent amount of crawling experience. Planned comparisons confirmed the hypothesis. Visual-postural coupling in the hands-and-knees crawlers was significantly higher than in the belly crawlers and pre-crawlers. These findings suggest that the balance demands associated with hands-and-knees crawling may be an important contributor to the changes in visual proprioception that have been demonstrated in several experiments to follow hands-and-knees crawling experience. However, we also consider that belly crawling may have less potent effects on visual proprioception because it is an effortful and attention-demanding mode of locomotion, thus leaving less attentional capacity available to notice changing relations between the self and the environment

La manufactura paperera catalana a la segona meitat del segle XVIII: una introducció

Aquesta comunicació és del treball preparatori d'una investigació de la indústria paperera catalana durant el segle XIX i el XX, amb l'objectiu d'esbrinar les raons de l'existència de dues trajectòries diferenciades com la de Girona (símbol de modernitat) i la de la comarca de l'Anoia i la de Francolí-Brugent (representant de la tradició). El marc conceptual del present estudi és deutor dels treballs de Jaume Torras i Elias, i pretén tractar els mecanismes bàsics sobre els que es var assentar la manufactura paperera durant la segona meitat del segle XVIII. Les fonts utilitzades són fonamentalment notarials precedents de l'Anxiu Notarial d'Igualada, complementades amb les aportacions documentals realitzades per Madurell i Valls

Treball, canvi tecnològic i sindicalisme en la indústria paperera de l'Anoia (1840-1923)

El procès d'industrialització va suposar grans canvis en el món del treball. Les antigues condicions laborals es van veure alterades, encara que no van desaparèixer totalment. En aquest treball s'analitza un cas de continuïtat tecnològica: la fabricació manual del paper. L'anàlisi es realitza sobre una de les zones més paradigmàtiques d'aquesta pauta, la comarca barcelonesa d'Anoia. La manufactura paperera es va caracteritzar per la general absència de gremis. Aquest buit va ser ocupat per les formes d'organització alternatives, com el compagnonnage francès, agrupacions obreres de la mà d'obra qualificada. En el Regne Unit aquestes forces van derivar a la creació de l' Original Society of Papermakers. No és té plena constància de la presència d'institucions similars a Catalunya, encara que algunes pistes senyalen la seva existència sota alguns mecanismes menys explícits. Alguns dels seus elements definitoris estaven presents en la gènesis del sindicalisme i van protagonitzar els conflictes encapçalats pels paperers, com les vages convocades entre el 1867 i 1883, 1908-1909 i 1917-191

Trabajo y materias primas en una manufactura preindustrial: el papel

En las Últimas aproximaciones al estudio de la Revolución Industrial se ha prestado especial atención al carnbio de las manufacturas tradicionales a la industria moderna. En general, la pauta de análisis seguida ha sido la aplicada a la manufactura textil, en la que buena parte del proceso productivo se realizaba bajo la fórmula de los cambios que se dieron, al omitir las manufacturas cuyos procesos de producción ya se hallaban previamente concentrados. El sector papelero, que se encuentra entre los principales factores que definen la manufactura tradicional del papel