Origin and evolution of photoluminescence from Si nanocrystals embedded in a SiO2 matrix

A detailed analysis of the photoluminescence (PL) from Si nanocrystals (NCs) embedded in a silicon-rich SiO2 matrix is reported. The PL spectra consist of three Gaussian bands (peaks A,B, and C), originated from the quantum confinement effect of Si NCs, the interface state effect between a Si NC and a SiO2 matrix, and the localized state transitions of amorphous Si clusters, respectively. The size and the surface chemistry of Si NCs are two major factors affecting the transition of the dominant PL origin from the quantum confinement effect to the interface state recombination. The larger the size of Si NCs and the higher the interface state density (in particular, Si = O bonds), the more beneficial for the interface state recombination process to surpass the quantum confinement process, in good agreement with Qin's prediction in Qin and Li [Phys. Rev. B 68, 85309 (2003)]. The realistic model of Si NCs embedded in a SiO2 matrix provides a firm theoretical support to explain the transition trend.

Effects of electric field on the electronic structure and optical properties of quantum rods with wurtzite structure

The Hamiltonian of wurtzite quantum rods with an ellipsoidal boundary under electric field is given after a coordinate transformation. The electronic structure and optical properties are studied in the framework of the effective-mass envelope-function theory. The quantum-confined Stark effect is illustrated by studying the change of the electronic structures under electric field. The transition probabilities between the electron and hole states decrease sharply with the increase of the electric field. The polarization factor increases with the increase of the electric field. Effects of the electric field and the shape of the rods on the exciton effect are also investigated. The exciton binding energy decreases with the increase of both the electric field and the aspect ratio. In the end, considering the exciton binding energy, we calculated the band gap variation of size- and shape-controlled colloidal CdSe quantum rods, which is in good agreement with experimental results.

Quantum information processing with superconducting qubits in a microwave field

We investigate the quantum dynamics of a Cooper-pair box with a superconducting loop in the presence of a nonclassical microwave field. We demonstrate the existence of Rabi oscillations for both single- and multiphoton processes and, moreover, we propose a new quantum computing scheme (including one-bit and conditional two-bit gates) based on Josephson qubits coupled through microwaves.

Resonant tunneling theory of planar quantum dot structures

The ballistic transport in the semiconductor, planar, circular quantum dot structures is studied theoretically. The transmission probabilities show apparent resonant tunneling peaks, which correspond to energies of bound states in the dot. By use of structures with different angles between the inject and exit channels, the resonant peaks can be identified very effectively. The perpendicular magnetic field has obvious effect on the energies of bound states in the quantum dot, and thus the resonant peaks. The treatment of the boundary conditions simplifies the problem to the solution of a set of linear algebraic equations. The theoretical results in this paper can be used to design planar resonant tunneling devices, whose resonant peaks are adjustable by the angle between the inject and exit channels and the applied magnetic field. The resonant tunneling in the circular dot structures can also be used to study the bound states in the absence and presence of magnetic field.

Conditions for the local manipulation of all bipartite Gaussian states

We provide a general, necessary, and sufficient condition for the possibility of transforming a mixed bipartite Gaussian state with arbitrarily many modes to another one under arbitrary local Gaussian channels, which do not include classical communication. Moreover, by means of this condition we present a necessary criterion that can be used to check the possibility of a state transformation between two mixed Gaussian states. At the same time, we prove that our criterion can be reduced to the Eisert-Plenio criterion when the mode number is chosen as 1 per side.

The Impact of AIDS on Government Service Delivery: The Case of the Zambia Wildlife Authority

Background: The loss of working-aged adults to HIV/AIDS has been shown to increase the costs of labor to the private sector in Africa. There is little corresponding evidence for the public sector. This study evaluated the impact of AIDS on the capacity of a government agency, the Zambia Wildlife Authority (ZAWA), to patrol Zambia’s national parks. Methods: Data were collected from ZAWA on workforce characteristics, recent mortality, costs, and the number of days spent on patrol between 2003 and 2005 by a sample of 76 current patrol officers (reference subjects) and 11 patrol officers who died of AIDS or suspected AIDS (index subjects). An estimate was made of the impact of AIDS on service delivery capacity and labor costs and the potential net benefits of providing treatment. Results: Reference subjects spent an average of 197.4 days on patrol per year. After adjusting for age, years of service, and worksite, index subjects spent 62.8 days on patrol in their last year of service (68% decrease, p<0.0001), 96.8 days on patrol in their second to last year of service (51% decrease, p<0.0001), and 123.7 days on patrol in their third to last year of service (37% decrease, p<0.0001). For each employee who died, ZAWA lost an additional 111 person-days for management, funeral attendance, vacancy, and recruitment and training of a replacement, resulting in a total productivity loss per death of 2.0 person-years. Each AIDS-related death also imposed budgetary costs for care, benefits, recruitment, and training equivalent to 3.3 years’ annual compensation. In 2005, AIDS reduced service delivery capacity by 6.2% and increased labor costs by 9.7%. If antiretroviral therapy could be provided for $500/patient/year, net savings to ZAWA would approach $285,000/year. Conclusion: AIDS is constraining ZAWA’s ability to protect Zambia’s wildlife and parks. Impacts on this government agency are substantially larger than have been observed in the private sector. Provision of ART would result in net budgetary savings to ZAWA and greatly increase its service delivery capacity.

Bring ART into the ACT

ACT is compared with a particular type of connectionist model that cannot handle symbols and use non-biological operations that cannot learn in real time. This focus continues an unfortunate trend of straw man "debates" in cognitive science. Adaptive Resonance Theory, or ART, neural models of cognition can handle both symbols and sub-symbolic representations, and meets the Newell criteria at least as well as these models.

Art markets

SCOPUS: ch.b

Volcanic Gas Workshop Features State-of-the-Art Measurement Techniques

info:eu-repo/semantics/published

Art, adolescence and Social Work: Anja, the invisible manager

This article has been written with the intention of being able to analyse the contributions of art —theatre, in this case— to the practice of social work. For this purpose, we have chosen to read the social reality in which we intervene through the lens of social constructionism. This helps us to rescue the social and subjective side of art, and, moreover, to recover the depathologization of the subject in professional intervention. Thus, using a practical case taken from work with adolescents in the German FSJ programme, hand-in-hand with a young girl called Anja we trace the developmental and sociological aspects of adolescence in order to later address certain common points of art and psychosocial work. Art will hence be redefined as a transitional object allowing questions to be addressed relating to (self-) perception, attachment, communication and changes in conduct as the ultimate goal of professional action. Lastly, we note the limitations and risks of art-based intervention, in order to conclude with a final synopsis.

La otra Ley de Foucault. Una lectura crítica

Few studies have addressed the relationship between law and power in the works of Michel Foucault. Some authors emphasize that law performs a completely secondary role in the diagram of power of modernity, while others argue that there is a close link between power relations and the law. Foucault's Law by Golden and Fitzpatrick aims to renew these discussions and reconstruct another law of Foucault. In this paper I make a critical reading of this work, highlighting the faulty presentation that the authors carried out of the works of Foucault.

Non-agrocultural co-peratives and economy transformation in Cuba: politic processes and strategies

Contribution of co-operatives has been demonstrated since the 1970s as the main development line in agricultural production in Cuba. In contrast, there has been a late recognition of urban co-operatives, even if the need of transformations based on the realization of property in different territorial scenarios had been identified. The article analyses the reform processes launched since the first decade of the 21st century focusing on the nature of the initiatives fostering formation and promotion of nonagricultural co-operatives including follow up of their performance. The potential and limitations of the recent experiences are examined in order to reflect on the organizational processes and transformations from the point of view of their members. To conclude, some questions are posed about whether these co-operatives are capable of avoiding the impact of earlier employment circumstances and of developing strategies aimed at reinforcing voluntary membership and autonomy on which they are founded.

Social economy and economic crisis in the basque country abstract

This article examines the socio-economic evolution of the social economy sector in the Basque Country during the 2008-2014 period of economic crisis. Data have been obtained within a framework of collaboration between university, Basque Government and private sector of the social economy. The results suggest that such entities have evolved better, both in terms of number of enterprises and employment, than the general economy of the Basque Country, while the context of public policies aimed at social economy has worsened over the years. However, in economic terms (measured through the Gross Value Added generated), they have not been able to cope with the crisis in equal conditions to the general economy. The main contribution of this research lies in that, unlike similar studies, it discusses the evolution of the whole sector of the social economy, taking as reference a broad period of the current economic crisis.

The influence of gender in the direction of Spanish cooperative societies on profitability and indebtedness: an empirical analysis

In this paper the claim for the market for a new business management to ensure the presence of women in decision -making to respond to new social needs addressed. Thus, this paper analyzes the influence of gender diversity of the directors on the profitability and the level of debt for a sample of 5,199 Spanish cooperatives. Unlike capitalist societies, these organizations have a number of peculiarities in their government, and that the partners are themselves major time, agents and customers. The study focuses on the Spanish context, where there is an open debate on the importance of women's business management, as in other countries, driven by the proliferation of legislation on gender equality, being, in addition, Spain, the pioneer in having specific legislation on Social Economy. The results show that cooperatives with greater female representation in theirs Boards have higher profitability. On the other hand, those Boards with a higher percentage of women show a lower level of indebtedness.