Interaction-Free Measurements of Optical Semitransparent Objects

We substitute the fully absorbing obstacle in the Elitzur-Vaidman experiment by a semitransparent object and show that the probabilities of detection can be manipulated in dependence of the transparency of such an object. Then, we connect our results with the delayed choice experiment proposed by Wheeler. It is found that the transparency of the obstacle determines either a particle-like or a wave-like behaviour of a test photon

Phenomenological research on professsional knowledge and educational relationship building

Following Dewey’s (1997) and Schwab’s (2013) ideas, Clandinin & Connelly (1992) developed their notion of teacher as curriculum maker, it means, the “teacher not so much as a maker of curriculum but as a part of it and to imagine a place for contexts, culture (Dewey´s notion of interaction), and temporality (both past and future contained in Dewey´s notion of continuity)” (p.365). In this way, teachers are not seen as implementers of curricular plans but as part of the curriculum making process. In other words, they understand that students create their curriculum in their experience at school when they interact with teachers and the environment. Therefore, the educational relationship creates the framework where learning can take place and students can build knowledge (Atkinson, 2015); it means, relationships generate meeting places that allow the making and reshaping of curriculum. If teaching takes place in the relationship, it means recognition (and acceptance) of the other person, of the otherness. It supposes trying to come into relation with the other, and it implies also acceptance of the uncertainty that otherness has. Therefore, education Is not about the implementation of an education programme in order to achieve (pre)determined results. It is not about intervention on students, but it is an experience of relationship where each one constructs their own story (Molina, Blanco & Arbiol, 2016). In short, curriculum is made through experiences that are lived in relation and, therefore, we could say that education is an act of relationship (Piussi, 2006). In this way, education does not require that teachers have the most appropriate knowledge and programme for every situation; the educational experience is unpredictable and ineffable, we cannot anticipate or face it completely (Van Manen, 2015). Thus, teaching requires becoming aware of how we build relationships and how we see the other person (Contreras, 2002).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Absolute elastic differential cross sections for electron scattering by C6H5CH3 and C6H5CF3 at 1.5–200 eV: a comparative experimental and theoretical study with C6H6

We present absolute differential cross sections DCS for elastic scattering from two benzene derivatives C6H5CH3 and C6H5CF3. The crossed-beam method was used in conjunction with the relative flow technique using helium as the reference gas to obtain absolute values. Measurements were carried out for scattering angles 15° –130° and impact energies 1.5–200 eV. DCS results for these two molecules were compared to those of C6H6 from our previous study. We found that 1 these three molecules have DCS with very similar magnitudes and shapes over the energy range 1.5–200 eV, although DCS for C6H5CF3 increase steeply toward lower scattering angles due to the dipole moment induced long-range interaction at 1.5 and 4.5 eV, and 2 that the molecular structure of the benzene ring significantly determines the collision dynamics. From the measured DCS, elastic integral cross sections have been calculated. Furthermore, by employing a corrected form of the independent-atom method known as the screen corrected additive rule, DCS calculations have been carried out without any empirical parameter fittings, i.e., in an ab initio nature. Results show that the calculated DCS are in excellent agreement with the experimental values at 50, 100, and 200 eV

Completeness and Nonclassicality of Coherent States for Generalized Oscillator Algebras

The purposes of this work are (1) to show that the appropriate generalizations of the oscillator algebra permit the construction of a wide set of nonlinear coherent states in unified form; and (2) to clarify the likely contradiction between the nonclassical properties of such nonlinear coherent states and the possibility of finding a classical analog for them since they are P-represented by a delta function. In (1) we prove that a class of nonlinear coherent states can be constructed to satisfy a closure relation that is expressed uniquely in terms of the Meijer G-function. This property automatically defines the delta distribution as the P-representation of such states. Then, in principle, there must be a classical analog for them. Among other examples, we construct a family of nonlinear coherent states for a representation of the su(1,1) Lie algebra that is realized as a deformation of the oscillator algebra. In (2), we use a beam splitter to show that the nonlinear coherent states exhibit properties like anti-bunching that prohibit a classical description for them. We also show that these states lack second order coherence. That is, although the P-representation of the nonlinear coherent states is a delta function, they are not full coherent. Therefore, the systems associated with the generalized oscillator algebras cannot be considered `classical' in the context of the quantum theory of optical coherence.Comment: 26 pages, 10 figures, minor changes, misprints correcte

Theoretical study of loss compensation in long-range dielectric loaded surface plasmon polariton waveguides

In this paper, a theoretical study of loss compensation in long-range dielectric loaded surface plasmon waveguides (LR-DLSPPs) is presented. Although extendable to other gain materials, rare-earth doped double tungstates are used as gain material in this work. Two different structures are studied and the effect of the different waveguide geometrical parameters on the material gain required to fully compensate the propagation losses are reported. The simulations were performed at 1.55 micrometer wavelength. A material gain as low as 12.5 dB/cm was determined as sufficient to obtain complete loss compensation in one of the proposed waveguide structures supporting sub-micron lateral mode dimension

Giant optical gain in a rare-earth-ion-doped waveguide amplifier

For optical amplification, typically rare-earth-ion (RE) doped fiber amplifiers (RDFA) or semiconductor optical amplifiers (SOAs) are selected. Despite the weak transition cross-sections of RE ions and their low doping level in silica fibers, resulting in very low gain per unit length, the extremely long interaction lengths realized in fibers can lead to significant overall gain. SOAs can deliver similarly high overall gain over much shorter distances, which makes them suitable for providing on-chip gain. Very high material gain in the nanometer-wide recombination region of a III-V semiconductor, but small overlap with the usually µm-sized signal beam results in a modal gain of several hundred dB/cm. In contrast, the gain per unit length in RE-doped integrated waveguides has hardly exceeded a few dB/cm. Here we demonstrate an ultra-high modal gain of 950 dB/cm in a RE-doped waveguide amplifier, comparable to the modal gain reported for SOAs. The potassium double tungstates KGd(WO4)2, KY(WO4)2, and KLu(WO4)2 are excellent host materials for RE-doped lasers, partly thanks to the high transition cross-sections of RE ions in these hosts. In 2006, the first planar KY(WO4)2:Yb3+ waveguide laser was demonstrated. Co-doping the layer with Gd3+ and Lu3+ ions offers the possibility for lattice matching with the undoped KY(WO4)2 substrate and a significantly enhanced refractive index contrast, hence improved mode confinement. Microstructuring by Ar+ beam etching resulted in channel waveguides, in which lasing with 418 mW output power at 1023 nm and 71% slope efficiency vs. launched pump power was demonstrated. Replacing Y3+ in the layer completely by Gd3+ and Yb3+ ions results in highly doped channel waveguides with a refractive-index contrast of >2 x 10-2. These novel dielectric micro-structures combine a high dopant concentration, large transition cross-sections, and strong light confinement, all features that are crucial for achieving high optical gain, in a single device. When pumping such a KGd0.447Lu0.078Yb0.475(WO4)2 channel waveguide with a 932-nm Ti:Sapphire laser via a microscope objective, high inversion of the Yb3+ system is obtained. Signal light at the zero-phonon line at 980.6 nm, which is the wavelength of highest absorption and emission cross-section, exhibits a small-signal modal gain of 950 dB/cm, exceeding the gain per unit length previously reported in RE-doped materials by two orders of magnitude, thus paving the way for applications of on-chip integrated RE-doped amplifiers

Caracterización de cepas aviares de enterococcus faecalis mediante la prueba de letalidad embrionaria

Enterococus faecalis (E. faecalis) es el agente causante de la Artropatía Amiloide (AA) en las aves. Dada la dificultad de estimar el riesgo que suponen las cepas de campo de esta bacteria, en la presente experiencia se caracterizaron 68 cepas de E. faecalis mediante la prueba de letalidad embrionaria (ELA) utilizando la tasa de mortalidad embrionaria (TME). Se realizaron un total de 10 ELAs con subgrupos de 7 u 8 cepas y dos grupos control (positivo y negativo). Se utilizaron 100 huevos fecundados por cepa y grupo control. Según la cepa, se inocularon de 3 a 24 unidades formadoras de colonias (ufc) en la cavidad alantoidea de embriones de 10 días de edad. Durante 7 días se registró diariamente la TME mediante ovoscopia. La ELA fue capaz de diferenciar las cepas de E. faecalis con respecto a la TME que produjeron. Se clasificaron 26 cepas de E. faecalis como avirulentas (TME80%) y las 37 cepas restantes presentaron moderada virulencia con una TME de 40 a 80%. La mayor TME se registró 3 días post inoculación. A partir del 4° día apenas se obsevó mortalidad embrionaria, por lo que la ELA podría ser optimizada reduciendo el tiempo de observación a 4 días. Se puede concluir que la ELA es una herramienta fiable y útil para predecir la virulencia de cepas aviares de E. faecalis utilizando la TME. Las cepas altamente patógenas probadas podrían ser candidatas para el desarrollo de vacunas autógenas