Financial Literacy after Sarbanes-Oxley: Building It; Sustaining It

The core theme of the article is that financial literacy is a challenging goal, but an achievable one. Contrary to popular belief, finance is a diverse subject and the meaning of “financial literacy” varies on a business-by-business, job-by-job basis. Practically speaking, “financial literacy” is interwoven with “business literacy”, i.e., understanding the transactions, processes, markets, stakeholders, etc., that together comprise a business. This makes it hard to deploy generic educational solutions. Some managers need more than others. Some need different than others. My recommendation is not to look for a universal definition of literacy, but rather to treat your company as a collection of communities, each with its own need for financial knowledge and education. Using this approach, financial literacy programs can then be developed pragmatically, efficiently, and economically

Electronic structure of few-electron concentric double quantum rings

The ground state structure of few-electron concentric double quantum rings is investigated within the local spin density approximation. Signatures of inter-ring coupling in the addition energy spectrum are identified and discussed. We show that the electronic configurations in these structures can be greatly modulated by the inter-ring distance: At short and long distances the low-lying electron states localize in the inner and outer rings, respectively, and the energy structure is essentially that of an isolated single quantum ring. However, at intermediate distances the electron states localized in the inner and the outer ring become quasi-degenerate and a rather entangled, strongly-correlated system is formed.Comment: 16 pages (preprint format), 6 figure

Magnetic field dependence of hole levels in self-assembled InAs quantum dots

Recent magneto-transport experiments of holes in InGaAs quantum dots [D. Reuter, P. Kailuweit, A.D. Wieck, U. Zeitler, O. Wibbelhoff, C. Meier, A. Lorke, and J.C. Maan, Phys. Rev. Lett. 94, 026808 (2005)] are interpreted by employing a multi-band kp Hamiltonian, which considers the interaction between heavy hole and light hole subbands explicitely. No need of invoking an incomplete energy shell filling is required within this model. The crucial role we ascribe to the heavy hole-light hole interaction is further supported by one-band local-spin-density functional calculations, which show that Coulomb interactions do not induce any incomplete hole shell filling and therefore cannot account for the experimental magnetic field dispersion.Comment: 5 pages with 3 figures and one table. The paper has been submitted to Phys.Rev.

Spin-orbit effects in GaAs quantum wells: Interplay between Rashba, Dresselhaus, and Zeeman interactions

The interplay between Rashba, Dresselhaus and Zeeman interactions in a quantum well submitted to an external magnetic field is studied by means of an accurate analytical solution of the Hamiltonian, including electron-electron interactions in a sum rule approach. This solution allows to discuss the influence of the spin-orbit coupling on some relevant quantities that have been measured in inelastic light scattering and electron-spin resonance experiments on quantum wells. In particular, we have evaluated the spin-orbit contribution to the spin splitting of the Landau levels and to the splitting of charge- and spin-density excitations. We also discuss how the spin-orbit effects change if the applied magnetic field is tilted with respect to the direction perpendicular to the quantum well.Comment: 26 pages (with 3 figures included

Acció dels suavitzants téxtils emulsionats i microemulsionats en el medi aquàtic : ecotoxicitat i estudi histopatològic /

Consultable des del TDXTítol obtingut de la portada digitalitzadaEls suavitzants tèxtils, que pertanyen al grup de tensioactius catiònics, normalment són aplicats en forma d'emulsió. Una emulsió és una dispersió d'un líquid en un altre líquid (suavitzant + aigua), en la qual la mida de partícula és superior a 2 micres. No obstant aixó, s'ha aconseguit formar microemulsions de suavitzants a l'afegir uns agents microemulsionants que fan que aquests siguin sistemes coloïdals termodinàmicament estables. Aquests es caracteritzen per presentar una mida de partícula 100 vegades inferior a la de les emulsions, fet que els fa més eficients al penetrar dins els teixits i, per tant, milloren les seves propietats. L'estudi va ser plantejat per l'interès que determinades empreses tenien per treure al mercat suavitzants microemulsionats i saber quines diferències mediambientals havia entre aquests i els suavitzants en forma emulsionada. L'objectiu general d'aquest treball ha estat el donar una resposta al sector tèxtil sobre la forma d'acció dels suavitzants microemulsionats, així com avaluar el risc que suposa la seva presència en el medi aquàtic, tot comparant els resultats amb els obtinguts amb els mateixos suavitzants en forma emulsionada. L'estudi per dur a terme la valoració del risc de cinc suavitzants (DSDMAC, DSEMAMS, DSCEEMAMS, DSAEMIMS i DAAIMS) emulsionants i microemulsionats en el medi aquàtic s'ha plantejat en 4 fases. En primer lloc, per la caracterització del risc que suposa la seva presència en el medi aquàtic s'ha efectuat una sèrie de proves químiques i biològiques per a determinar la rapidesa amb què són eliminats del medi (DBO, DQO, Biodegradabilitat). En segon terme s'ha identificat sobre quins nivells tròfics pot actuar (bacteris, microalgues, crustacis i peixos). Després s'ha estimat la concentració/efecte en els diferents nivells tròfics a curt termini mitjançant assaigs de toxicitat aguda; les espècies utilitzades han estat el bacteri Photobacterium phosphoreum (CE50 15 min), tres espècies de microalgues, Chlorella vulgaris, Scenedesmus subspicatus i Selenastrum capricornutum (CI50 72h), el crustaci Daphnia magna (CE50 24h) i el teleòsti Oncorhynchus mykiss (CL50 96h). En darrer lloc, s'ha avaluat l' exposició a llarg termini mitjançant una prova de toxicitat crònica en Oncorhynchus mykiss en la qual s'ha dut a terme l'estudi histopatològic a microscopia òptica i electrònica de la brànquia i el fetge. L'estudi realitzat ens ha permès concloure que quatre dels cinc suavitzants estudiats són biodegradables tant en emulsió com en microemulsió, mentre que el cinquè (DSDMAC), no ho és. Pel que fa a les toxicitats agudes, les microemulsions són més tòxiques que les emulsions en totes les espècies estudiades; la causa de la seva major toxicitat no és deguda a la presencia dels agents microemulsionants, sinó a la menor mida de partícula. La variació en la resposta mostra la conveniència de realitzar assaigs multi-espècie a l'hora de determinar la toxicitat de qualsevol producte. Per últim, l'estudi histopatològic ha revelat que l'òrgan més afectat ha estat la brànquia dels peixos, tot i que les alteracions observades, tant en la brànquia com en el fetge, són de tipus inespecífic.Textile softeners, which belong to the group of cationic tensioactives, are usually applied in emulsion. An emulsion is a dispersion of a liquid in another (softener + water), in which the size of the particle is greater than 2 mm. Microemulsions can be done by further adding microemulsionating agents to cause the solution to be a thermodynamically stable colloidal systems. Microemulsions are characterized by the size of their particles, being 100 times lower than those of emulsions; this fact makes them more efficient when penetrating within weaves, and therefore, improve their properties. The present study was undertaken by the interest shown by some companies to introduce microemulsionated softeners into the market and to get knowledge about the environmental differences between these and the corresponding emulsionated softeners. The main goal of this work has been to provide an assessment to the textile sector about the mode of action of the microemulsionated tensioactives as well as to evaluate the environmental risk which involves their presence into the aquatic environments. In order to carry out the risk assessment of five emulsionated and microemulsionated softeners (DSDMAC, DSEMAMS, DSCEEMAMS, DSAEMIMS and DAAIMS) four stages have been considered. First of all, the risk has been set by means of chemical and biological tests to determine their ability to be removed from the environment (DBO, DQO, Biodegradation). Secondly, the trophic levels affected have been identified (bacteria, microalgae, crustaceans, fish) and, in a later stage, it has been estimated the concentration/effect for the different trophic levels by means of short term acute toxicity tests. The species considered have been bacteria (Photobacterium phosphoreum, EC50 15min), microalgae (Chlorella vulgaris, Scenedesmus subspicatus and Selenastrum capricornutum, IC50 72h), the crustacean Daphnia magna (EC50 24h) and the fish Oncorhynchus mykiss (LC50 96h). Finally, we performed a long term study by means of chronic toxicity testing in Oncorhynchus mykiss to evaluate histopathologic lesions of the gill and the liver, using optic and electron microscopy. Concluding remarks for this study would be that four of the five softeners considered are biodegradable both, in emulsionated and microemulsionated form, whereas one of them (DSDMAC) it is not. With regard to the results of the acute toxicity testing we found that the microemulsions are more toxic than the corresponding emulsion to all the species studied. This greater toxicity is not only caused by the presence of the microemulsionating agents, but because of the smaller particle size of the tensioactive. The differences in sensibility encountered in the different tests, strongly support the convenience to perform multispecies testing when determining the toxicity of any product. In the histopathologic study, the organ most affected has been the fish gill, although observed lesions were, in all the cases not specific

Vertically coupled double quantum rings at zero magnetic field

Within local-spin-density functional theory, we have investigated the `dissociation' of few-electron circular vertical semiconductor double quantum ring artificial molecules at zero magnetic field as a function of inter-ring distance. In a first step, the molecules are constituted by two identical quantum rings. When the rings are quantum mechanically strongly coupled, the electronic states are substantially delocalized, and the addition energy spectra of the artificial molecule resemble those of a single quantum ring in the few-electron limit. When the rings are quantum mechanically weakly coupled, the electronic states in the molecule are substantially localized in one ring or the other, although the rings can be electrostatically coupled. The effect of a slight mismatch introduced in the molecules from nominally identical quantum wells, or from changes in the inner radius of the constituent rings, induces localization by offsetting the energy levels in the quantum rings. This plays a crucial role in the appearance of the addition spectra as a function of coupling strength particularly in the weak coupling limit.Comment: 18 pages, 8 figures, submitted to Physical Review

Prevalence of resistance mutations related to integrase inhibitor S/GSK1349572 in HIV-1 subtype B raltegravir-naive and -treated patients

Objectives To compare the frequency of previously in vitro-selected integrase mutations (T124A, T124A/S153F, S153Y, T124A/S153Y and L101I/T124A/S153Y) conferring resistance to S/GSK1349572 between HIV-1 subtype B integrase inhibitor (INI)-naive and raltegravir-treated patients. Methods Integrase sequences from 650 INI-naive patients and 84 raltegravir-treated patients were analysed. Results The T124A mutation alone and the combination T124A/L101I were more frequent in raltegravir-failing patients than in INI-naive patients (39.3% versus 24.5%, respectively, P = 0.005 for T124A and 20.2% versus 10.0%, respectively, P = 0.008 for T124A/L101I). The S153Y/F mutations were not detected in any integrase sequence (except for S153F alone, only detected in one INI-naive patient). Conclusions T124A and T124A/L101I, more frequent in raltegravir-treated patients, could have some effect on raltegravir response and their presence could play a role in the selection of other mutations conferring S/GSK1349572 resistance. The impact of raltegravir-mediated changes such as these on the virological response to S/GSK1349572 should be studied further

Comparative replication capacity of raltegravir-resistant strains and antiviral activity of the new-generation integrase inhibitor dolutegravir in human primary macrophages and lymphocytes

To evaluate the replication capacity and phenotypic susceptibility to dolutegravir and raltegravir of wild-type and raltegravir-resistant HIV-1 strains in several cellular systems