Single-photon tunneling via localized surface plasmons

Strong evidence of a single-photon tunneling effect, a direct analog of single-electron tunneling, has been obtained in the measurements of light tunneling through individual subwavelength pinholes in a gold film covered with a layer of polydiacetylene. The transmission of some pinholes reached saturation because of the optical nonlinearity of polydiacetylene at a very low light intensity of a few thousand photons per second. This result is explained theoretically in terms of a "photon blockade," similar to the Coulomb blockade phenomenon observed in single-electron tunneling experiments. Single-photon tunneling may find applications in the fields of quantum communication and information processing.

Determining factors of the innovative behavior of cooperatives: an analysis of the case of Castilla y Le��n

Cooperatives have a long historical experience in the Spanish economy and have demonstrated their ability to compete against traditional firms in the market. To maintain this capability, while taking advantage of the competitive advantages associated with their idiosyncrasies as social economy enterprises, they should take into consideration that the economy is increasingly globalized and increasingly knowledge-based, especially with regards to technological content. As a consequence, the innovative capacity appears to be a key aspect in order to be able to challenge competitors. This article characterizes the innovative behavior of cooperatives in the region of Castile and Leon and analyses the internal and external factors affecting their innovative performance, based on data from a survey of 581 cooperatives. The results of the empirical analysis, which is performed by multivariate binary logistic regression on various types of innovation, lead us to identify the size of the organizations, the existence of planning, the R & D activities and the human capital as the main determining factors.

Disabled Children Negotiating School Life: Agency, Difference and Teaching Practice

This paper explores the school experiences of seven 11���14 year old disabled children, and focuses on their agency as they negotiated a complex, changing, and often challenging social world at school where ���difference��� was experienced in negative ways. The paper draws on ethnographic data from a wider three-year study that explores the influence of school experiences on both disabled and non-disabled children���s identity as they make the transition from primary to secondary school in regular New Zealand schools (although the focus of the present paper is only on the experiences of disabled children). The wider study considers how Maori (indigenous people of Aotearoa/New Zealand) and Pakeha (New Zealanders of NZ European descent) disabled children and their non- disabled matched peers (matched for age, gender and classroom) understand their personal identity, and how factors relating to transition (from primary to secondary school); culture; impairment (in the case of disabled children); social relationships; and school experience impact on children���s identities. Data on Maori children���s school experiences is currently being collected, and is not yet available for inclusion in this paper. On the basis of our observations in schools we will illustrate how disabled children felt and were made to feel different through an array of structural barriers such as separate provision for disabled students, and peer and teacher attitudes to diversity. However, we agree with Davis, Watson, Shakespeare and Corker���s (2003) interpretation that disabled children���s rights and participation at school are also under attack from a ���deeper cultural division��� (p. 205) in schools based on discourses of difference and normality. While disabled students in our study were trying to actively construct and shape their social and educational worlds, our data also show that teachers and peers have the capacity to either support or supplant these attempts to be part of the group of ���all children���. We suggest that finding solutions that support disabled children���s full inclusion and participation at school requires a multi-faceted and systemic approach focused on a pedagogy for diverse learners, and on a consistent and explicitly inclusive policy framework centred on children���s rights.

Competence in research planning in the fourth level of Spanish Secondary Education: a case study

In the last years, ���Inquiry-Based Science Education��� methodologies (IBSE) are being recommended by European institutions in order to improve the competence levels and the attitudes towards science of primary and secondary school students. Therefore, the aim of this study is to test the effectiveness of an IBSE methodology, the Methodology of Problem Solving as an Investigation (MPSI), for the teaching-learning process of planning of experiments in the fourth level of Spanish Secondary Education. By means of the students��� solutions for a series of open problems, the progress in the learning of the competences related to the planning of experiments has been analyzed, along with the influence of the methodology on the development of these competencies. The results show a students��� command from higher to lower levels on: emission of hypothesis, design of the experiment, qualitative analysis, identification of variables and reformulation of the open problem. Furthermore, the Methodology has contributed to an improvement of the scientific competence in the area of planning experiments.

Far-Field Optical Microscopy with a Nanometer-Scale Resolution Based on the In-Plane Image Magnification by Surface Plasmon Polaritons

A new far-field optical microscopy capable of reaching nanometer-scale resolution is developed using the in-plane image magnification by surface plasmon polaritons. This approach is based on the optical properties of a metal-dielectric interface that may provide extremely large values of the effective refractive index neff up to 103 as seen by surface polaritons, and thus the diffraction limited resolution can reach nanometer-scale values of lambda/2neff. The experimental realization of the microscope has demonstrated the optical resolution better than 60 nm at 515 nm illumination wavelength.

Stable hydrogen isotope ratios of lignin methoxyl groups as a palaeoclimate proxy

��� Stable isotope ratios of organic compounds are valuable tools for determining the geographical origin, identity, authenticity or history of samples from a vast range of sources such as sediments, plants and animals, including humans. ��� Hydrogen isotope ratios (d2H values) of methoxyl groups in lignin from wood of trees grown in different geographical areas were measured using compound-specificpyrolysis isotope ratio mass spectrometry analysis. ��� Lignin methoxyl groups were depleted in 2H relative to both meteoric water andwhole wood. A high correlation (r2=0.91) was observed between the d2 H valuesof the methoxyl groups and meteoric water, with a relatively uniform fractionation of ���216��19 recorded with respect to meteoric water over a range of d2H values from ���110 in northern Norway to + 20��� in Yemen. Thus, woods from northernlatitudes can be clearly distinguished from those from tropical regions. By contrast, the d2H values of bulk wood were only relatively poorly correlated (r 2 = 0.47) with those of meteoric water. ��� Measurement of the d 2H values of lignin methoxyl groups is potentially a powerful tool that could be of use not only in the constraint of the geographical origin of lignified material but also in paleoclimate, food authenticity and forensic investigations.

Inscribir el declive en el tiempo. Detroit: Auge y crisis de la ciudad industrial

A comienzos del siglo XX, Detroit era una ciudad din��mica en pleno desarrollo. Pronto se convirti�� en la cuarta ciudad de Estados Unidos, la capital de la naciente industria automovil��stica. El crecimiento se prolong�� hasta finales de los a��os 50, cuando, a pesar del auge econ��mico de Estados Unidos y de su ��rea metropolitana, Detroit comenz�� a mostrar los primeros signos de estancamiento. La crisis se ha prolongado hasta hoy, cuando Detroit constituye el paradigma de la ciudad industrial en declive. Estas dos im��genes contrapuestas, el auge y la crisis, no parecen explicar por s�� mismas las causas de la intensidad y persistencia del declive de Detroit. Analizar las interacciones entre crecimiento econ��mico, pol��ticas p��blicas locales y desarrollo urbano a lo largo del tiempo permitir�� subrayar las continuidades y comprender en qu�� medida el declive de Detroit ancla sus ra��ces en el modelo planteado durante la etapa de auge.

Measurements of the XUV transmission of aluminium with a soft x-ray laser

We have used XUV lasers to make absolute measurements of the photoabsorption coefficient of Al at energies just below that of the L3 absorption edge at 72.7 eV. Transmission measurements at photon energies of 53.7 and 63.3 eV have been made using Ne-like Ni and Ge XUV lasers. The XUV laser output was recorded in first and second orders using a flat-field spectrometer. Al foils with steps of various thicknesses were placed over the first order diffracted signal, while the second order diffraction was used to monitor the beam profile at each position. The transmission data agree extremely well with the original measurements at these wavelengths made by Henke and co-workers (Henke B L, Gullikson E M and Davis J C 1993 At. Data Nucl. Data Tables 54 18 1), but are in conflict with subsequent measurements which are currently in common use (Gullikson E M, Denham P, Mrowka S and Underwood J H 1994 Phys. Rev. B 49 16 283). The exact values of the absorption coefficients in this region of the spectrum have significant implications for the diagnosis of the energy and intensity output of XUV lasers.