Non Fermi Liquid Behaviour near a T=0T=0 spin-glass transition

In this paper we study the competition between the Kondo effect and RKKY interactions near the zero-temperature quantum critical point of an Ising-like metallic spin-glass. We consider the mean-field behaviour of various physical quantities. In the `quantum- critical regime' non-analytic corrections to the Fermi liquid behaviour are found for the specific heat and uniform static susceptibility, while the resistivity and NMR relaxation rate have a non-Fermi liquid dependence on temperature.Comment: 15 pages, RevTex 3.0, 1 uuencoded ps. figure at the en

Global Services Sourcing: Issues of Cost and Quality

Global Services Sourcing (GSS) is not an original concept. What is original about it is the media attention it seems to be getting. We have adopted the "then and now" philosophy in developing this report. We start by talking to the pioneers of global services sourcing, companies like General Electric, Nortel Networks and Citibank. The key learning from talking to these companies who have been sourcing their processes for more than a decade is that the long held view -- "went for cost, stayed for quality" about moving processes outside the company (in some cases outside the country) is too simplistic. Rather we found that "went for cost and quality, stayed for continued quality at competitive costs" is more in line with the strategy that that these companies employed. Next, our in depth questionnaire tries to capture the "now" of the global services sourcing industry. Since the pioneers had shone the arc light on quality we developed specific quality related questions. The results validated the pioneers' views: Of the companies that are engaged in services sourcing, 79% of respondents were using an offshore based provider. Perhaps in a sign of maturing of global services sourcing 62% chose to offshore their services to at least one country in addition to India, the current offshoring destination of choice. As far as country risk factors, legal risks (laws comparable to international standards - data security, intellectual property rights) followed by political risks were identified as the top areas of concern. The lesson for countries competing for offshored business and FDI inflows in services is that the robustness and fairness of the legal system is a major factor for companies especially in the face of concerns about loss of institutional knowledge. The overall satisfaction level with outsourcing was high at 68% but a sizeable chunk of respondents -- 26% were either unsatisfied or very unsatisfied with their outsourcing arrangements. Almost all of these unsatisfied firms have been outsourcing for 12 months or less, reinforcing the literature about thinking of outsourcing being a long term investment rather than a short term win

The (co-)occurrence of problematic video gaming, substance use, and psychosocial problems in adolescents

Aims. The current study explored the nature of problematic (addictive) video gaming and the association with game type, psychosocial health, and substance use. Methods. Data were collected using a paper and pencil survey in the classroom setting. Three samples were aggregated to achieve a total sample of 8478 unique adolescents. Scales included measures of game use, game type, the Video game Addiction Test (VAT), depressive mood, negative self-esteem, loneliness, social anxiety, education performance, and use of cannabis, alcohol and nicotine (smoking). Results. Findings confirmed problematic gaming is most common amongst adolescent gamers who play multiplayer online games. Boys (60%) were more likely to play online games than girls (14%) and problematic gamers were more likely to be boys (5%) than girls (1%). High problematic gamers showed higher scores on depressive mood, loneliness, social anxiety, negative self-esteem, and self-reported lower school performance. Nicotine, alcohol, and cannabis using boys were almost twice more likely to report high PVG than non-users. Conclusions. It appears that online gaming in general is not necessarily associated with problems. However, problematic gamers do seem to play online games more often, and a small subgroup of gamers – specifically boys – showed lower psychosocial functioning and lower grades. Moreover, associations with alcohol, nicotine, and cannabis use are found. It would appear that problematic gaming is an undesirable problem for a small subgroup of gamers. The findings encourage further exploration of the role of psychoactive substance use in problematic gaming

Crystal structure of monomeric human β-2- microglobulin reveals clues to its amyloidogenic properties

Dissociation of human β-2-microglobulin (β(2)m) from the heavy chain of the class I HLA complex is a critical first step in the formation of amyloid fibrils from this protein. As a consequence of renal failure, the concentration of circulating monomeric β(2)m increases, ultimately leading to deposition of the protein into amyloid fibrils and development of the disorder, dialysis-related amyloidosis. Here we present the crystal structure of a monomeric form of human β(2)m determined at 1.8-Å resolution that reveals remarkable structural changes relative to the HLA-bound protein. These involve the restructuring of a β bulge that separates two short β strands to form a new six-residue β strand at one edge of this β sandwich protein. These structural changes remove key features proposed to have evolved to protect β sheet proteins from aggregation [Richardson, J.&Richardson, D. (2002) Proc. Natl. Acad. Sci. USA 99, 2754–2759] and replaces them with an aggregationcompetent surface. In combination with solution studies using (1)H NMR, we show that the crystal structure presented here represents a rare species in solution that could provide important clues about the mechanism of amyloid formation from the normally highly soluble native protein

Drude weight and dc-conductivity of correlated electrons

The Drude weight $D$ and the dc-conductivity $\sigma_{dc} (T)$ of strongly correlated electrons are investigated theoretically. Analytic results are derived for the homogeneous phase of the Hubbard model in $d = \infty$ dimensions, and for spinless fermions in this limit with $1/d$-corrections systematically included to lowest order. It is found that $\sigma_{dc}(T)$ is finite for all $T > 0$, displaying Fermi liquid behavior, $\sigma_{dc} \propto 1/T^2$, at low temperatures. The validity of this result for finite dimensions is examined by investigating the importance of Umklapp scattering processes and vertex corrections. A finite dc-conductivity for $T > 0$ is argued to be a generic feature of correlated lattice electrons in not too low dimensions.Comment: 15 pages, uuencoded compressed PS-fil

Dynamical mean field theory for transition temperature and optics of CMR manganites

A tight binding parametrization of local spin density functional band theory is combined with a dynamical mean field treatment of correlations to obtain a theory of the magnetic transition temperature, optical conductivity and T=0 spinwave stiffness of a minimal model for the pseudocubic metallic $CMR$ manganites such a $La_{1-X}Sr_{x}MnO_{3}$. The results indicate that previous estimates of $T_{c}$ obtained by one of us (Phys. Rev. \textbf{B61} 10738-49 (2000)) are in error, that in fact the materials are characterized by Hunds coupling $J\approx 1.5eV$, and that magnetic-order driven changes in the kinetic energy may not be the cause of the observed 'colossal' magnetoresistive and multiphase behavior in the manganites, raising questions about our present understanding of these materials.Comment: Published version; 10 pages, 9 figure