X-ray photoelectron spectroscopy studies of non-stoichiometric superconducting NbB2+x

Polycrystalline samples of NbB2+x with nominal composition (B/Nb) = 2.0, 2.1, 2.2, 2.3, 2.4 and 2.5 were studied by X-ray photoelectron spectroscopy (XPS). The spectra revealed Nb and B oxides on the surface of the samples, mainly B2O3 and Nb2O5. After Ar ion etching the intensity of Nb and B oxides decreased. The Nb 3d5/2 and B 1s core levels associated with the chemical states (B/Nb) were identified and they do not change with etching time. The Binding Energy of the Nb 3d5/2 and B 1s core levels increase as boron content increases, suggesting a positive chemical shift in the core levels. On the other hand, analysis of Valence Band spectra showed that the contribution of the Nb 4d states slightly decreased while the contribution of the B 2p(pi) states increased as the boron content increased. As a consequence, the electronic and superconducting properties were substantially modified, in good agreement with band-structure calculations.Comment: 10 pages, 7 figures, 1 tabl

Histochemical and enzymatic differences in skeletal muscle from Svalbard reindeer during the summer and winter

Enzyme activities and fibre properties in four muscles from Svalbard reindeer, collected during the summer, have been compared with corresponding muscles during the winter. In two muscles, gluteobiceps and semimembranosus, oxidative capacity is higher in winter than in summer; in the other two muscles, semitendinosus and longissimus dorsi, there is no difference with time of the year. The capacity to oxidize fatty acids is low in winter compared with summer, especially in semitendinosus and longissimus. These changes are similar in both sexes. Histochemical studies of the three main fibre types, I (BetaR), HA (°cR) and IIB (aW), from the four muscles show that in male reindeers the muscle fibres are narrower at the end of the winter season than during the summer. The decrease of muscle tissue amounts to about one third of the total volume (33%), of which I accounts for 5%, IIA for 2% and IIB for 26%. The results indicate that the Svalbard reindeer use lean tissue in general, and IIB fibres in particular, in order to survive the hostile arctic winter period at Svalbard.Histokemiska och enzymatiska skillnader i skelettmuskel från Svalbardren mellan sommar och vinter.Abstract in Swedish / Sammandrag: Enzymaktiviteter och fiberegenskaper i fyra av Svalbardrenens muskler, insamlade under sommaren, har jåmforts med motsvarande muskler insamlade under vintern. I två muskler, gluteobiceps och semimembranosus, år oxidativa kapaciteten hogre under vintern an under sommaren; i de andra två musklerna, semitendinosus och longissimus dorsi, foreligger ingen skillnad i detta avseende. Kapaciteten att oxidera fettsyror år låg under vintern jåmfort med sommaren, speciellt i semitendinosus och longissimus. Inga konsskillnader foreligger i dessa avseenden. Histokemiska studier av de tre huvudtyperna av muskelfibrer, fiR (I), ocR (IIA) och (IIB), från de fyra musklerna visar att hos handjuren år fibrerna tunnare vid slutet av vintersåsongen jåmfort med sommaren. Denna minskning i muskelvåvnad uppgår till en tredjedel av totala volymen (33%). Harav svarar ftR for 5%, ^R tor 2% och for 26%. Resultaten antyder att Svalbardrenen anvånder muskelvåvnad, speciellt QcW fibrer, for att overleva undri den hårda arktiska vinterperioden på Svalbard

The Evolving Role of Supply Chain Managers in global Channels of Distribution and Logistics Systems

Cataloged from PDF version of article.Purpose – Supply chains have become a strategic strength to many firms due to the nature of the globalization of business. The past roles of supply chain managers have changed dramatically and now also include various new duties that will enhance firm competitiveness due to their boundary spanning nature and the new focus of learning organizations. The paper aims to discuss these issues. Design/methodology/approach – This was a theoretically developed paper exploring trust, learning organizations, and supply chains. Findings – Researchers are now focussing on the relationship among the supply chain network through the paradigm of relational marketing as the governance structures of contractual arrangements globally cannot be anticipated. Originality/value – The research through the lens of relational marketing explores how supply chain managers’ core duties are now compounded by global/cultural nuances in respect to implicit knowledge acquisition and relationship development through strong-form trust

Ethnographic Investigations of Commercial Aquaculture as a Rural Development Technique in Tamil Nadu, India

Since the 1960s, international aid organizations and governments have invested millions of dollars in promoting aquaculture as a way to stimulate local economies and improve food security. India is one such country, incorporating aquaculture research and extension programs as part of their development plans as early as 1971. India’s aquaculture promotion efforts gained momentum in 2004, following the Indian Ocean tsunami of 2004. The government sees aquaculture as a post-disaster development tool and a method to increase community resilience in rural areas of India. Aquaculture currently constitutes nearly half of global seafood production today. Due to this importance, and the attention such practices receive through funding and extension, many scholars have focused on the social impacts that aquaculture practices have on rural communities. In particular, scholars have investigated the effects of aquaculture on environmental conditions, food security, livelihoods, gender relations, and social conflict. However, more scholarship is needed concerning the historical legacies that have contributed to how aquaculture is promoted and practiced, particularly connections to the Green Revolution. Furthermore, there needs to be more research about commercial aquaculture as a post-disaster development strategy. My research – based on 9 months of ethnographic fieldwork and archival analysis in Tamil Nadu, India – contributes to this body of literature. I synthesized post-development theory with that of environmental risk and vulnerability, building upon the work of scholars such as James Ferguson, Tania Li, and Piers Blaikie. My analysis uncovers large disparities between the goals of aquaculture development programs and actual aquaculture outcomes. I attribute this to the technocratic governance structure of the aquaculture industry, which leads to a lack of engagement and participation between aquaculture managers, researchers, and practitioners. This lack of engagement ultimately makes the communities in which aquaculture is being practiced more vulnerable to anthropogenic and natural disturbances. Additionally, I found that aquaculture practices in the study site are causing significant changes to local agrarian structures, particularly through changes to labor. These changes have implications for social stratification and disempowerment of women. Overall, these findings contribute to the anthropological study of aquaculture as well as to theories of post-development

Quantum-dot-based optical polarization conversion

We report circular-to-linear and linear-to-circular conversion of optical polarization by semiconductor quantum dots. The polarization conversion occurs under continuous wave excitation in absence of any magnetic field. The effect originates from quantum interference of linearly and circularly polarized photon states, induced by the natural anisotropic shape of the self assembled dots. The behavior can be qualitatively explained in terms of a pseudospin formalism.Comment: 5 pages, 3 figures; a reference adde

On the master equation approach to kinetic theory: linear and nonlinear Fokker--Planck equations

We discuss the relationship between kinetic equations of the Fokker-Planck type (two linear and one non-linear) and the Kolmogorov (a.k.a. master) equations of certain N-body diffusion processes, in the context of Kac's "propagation of chaos" limit. The linear Fokker-Planck equations are well-known, but here they are derived as a limit N->infty of a simple linear diffusion equation on (3N-C)-dimensional N-velocity spheres of radius sqrt(N) (with C=1 or 4 depending on whether the system conserves energy only or energy and momentum). In this case, a spectral gap separating the zero eigenvalue from the positive spectrum of the Laplacian remains as N->infty,so that the exponential approach to equilibrium of the master evolution is passed on to the limiting Fokker-Planck evolution in R^3. The non-linear Fokker-Planck equation is known as Landau's equation in the plasma physics literature. Its N-particle master equation, originally introduced (in the 1950s) by Balescu and Prigogine (BP), is studied here on the (3N-4)-dimensional N-velocity sphere. It is shown that the BP master equation represents a superposition of diffusion processes on certain two-dimensional sub-manifolds of R^{3N} determined by the conservation laws for two-particle collisions. The initial value problem for the BP master equation is proved to be well-posed and its solutions are shown to decay exponentially fast to equilibrium. However, the first non-zero eigenvalue of the BP operator is shown to vanish in the limit N->infty. This indicates that the exponentially fast approach to equilibrium may not be passed from the finite-N master equation on to Landau's nonlinear kinetic equation.Comment: 20 pages; based on talk at the 18th ICTT Conference. Some typos and a few minor technical fixes. Modified title slightl

Anomalous in-plane magneto-optical anisotropy of self-assembled quantum dots

We report on a complex nontrivial behavior of the optical anisotropy of quantum dots that is induced by a magnetic field in the plane of the sample. We find that the optical axis either rotates in the opposite direction to that of the magnetic field or remains fixed to a given crystalline direction. A theoretical analysis based on the exciton pseudospin Hamiltonian unambiguously demonstrates that these effects are induced by isotropic and anisotropic contributions to the heavy-hole Zeeman term, respectively. The latter is shown to be compensated by a built-in uniaxial anisotropy in a magnetic field B_c = 0.4 T, resulting in an optical response typical for symmetric quantum dots.Comment: 5 pages, 3 figure