Kondo and Dicke effect in quantum-dots side coupled to a quantum wire

Electron tunneling through quantum-dots side coupled to a quantum wire, in equilibrium and nonequilibrium Kondo regime, is studied. The mean-field finite-$U$ slave-boson formalism is used to obtain the solution of the problem. We have found that the transmission spectrum shows a structure with two anti-resonances localized at the renormalized energies of the quantum dots. The DOS of the system shows that when the Kondo correlations are dominant there are two Kondo regimes with its own Kondo temperature. The above behavior of the DOS can be explained by quantum interference in the transmission through the two different resonance states of the quantum dots coupled to common leads. This result is analogous to the Dicke effect in optics. We investigate the many body Kondo states as a function of the parameters of the system.Comment: 5 figures. To appear in Phys. Rev.

Transport in random quantum dot superlattices

We present a novel model to calculate single-electron states in random quantum dot superlattices made of wide-gap semiconductors. The source of disorder comes from the random arrangement of the quantum dots (configurational disorder) as well as spatial inhomogeneities of their shape (morphological disorder). Both types of disorder break translational symmetry and prevent the formation of minibands, as occurs in regimented arrays of quantum dots. The model correctly describes channel mixing and broadening of allowed energy bands due to elastic scattering by disorder

Working Memory and Syntactic Processing in Bilingual and Monolingual Children

The purpose of this study was to examine the relationship between complex auditory working memory, syntactic knowledge, and complex sentence comprehension in bilingual and monolingual children using both offline (behavioral)and online(eye-tracking)measures. There were 19 children in the monolingual group and 19 children in the bilingual group with an average age of 11 years. The children listened to sentences, while looking at a screen with three images of the three nouns in the sentence. They were instructed to select the doer of the action (agent). Their eye movements were recorded as they completed this task. The four sentence types were: subject verb object (SVO), subject relative (SR), passive (PAS), and object relative (OR). Both groups of children had better sentence comprehension accuracy of SVO and SR sentences than PAS and OR sentences. Children with higher working memory tended to obtain better scores than children with lower working memory. This effect was strongest in the PAS and OR sentences. Additionally, for PAS and OR sentences, bilingual children with similar levels of working memory as the monolingual children obtained lower scores of sentence comprehension. Children with high working memory were slower to respond. Bilingual children selected the answers more quickly than the monolingual children. Children with high working memory focused on the agent less than children with low working memory. Bilingual children had mixed results relating to their focus of attention

Mothers Know Best: Guidance for Healthcare Providers on Early Identification of Perinatal Mental Health Disorders

Introduction: The perinatal period has been associated with an increased risk of developing psychiatric disorders among women. Perinatal mental health disorders (PMHD) are highly prevalent, yet highly underrecognized and untreated. The involvement of medical providers, especially obstetrics/gynecology and pediatric providers, in the early identification of PMHD is critical to ensure women with PMHD receive appropriate supports. However, providers lack the education, training, and ability to identify and screen for PMHD as well as the knowledge of appropriate referrals. Objective: This study explores the existing issues with healthcare providers’ early identification practices of PMHD from the perspective of ten mothers and to with the purpose of making recommendations to improve the early identification process. Results: Qualitative analysis revealed two main themes: 1) the importance of perinatal mental health training for providers, and 2) the importance of ongoing, relational screening. Conclusion: There is an enormous need for increased involvement of medical providers in the early identification process. Medical providers should be provided with education and training to increase their PMHD screening practices, expand their knowledge on the presentation of PHMD and connect women with appropriate supports

Optical Spectroscopy of X-Mega targets in the Carina Nebula - VI. FO 15: a new O-Type double-lined eclipsing binary

We report the discovery of a new O-type double-lined spectroscopic binary with a short orbital period of 1.4 days. We find the primary component of this binary, FO 15, to have an approximate spectral type O5.5Vz, i.e. a Zero-Age-Main-Sequence star. The secondary appears to be of spectral type O9.5V. We have performed a numerical model fit to the public ASAS photometry, which shows that FO 15 is also an eclipsing binary. We find an orbital inclination of ~ 80 deg. From a simultaneous light-curve and radial velocity solution we find the masses and radii of the two components to be 30 +/- 1 and 16 +/- 1 solar masses and 7.5 +/- 0.5 and 5.3 +/- 0.5 solar radii. These radii, and hence also the luminosities, are smaller than those of normal O-type stars, but similar to recently born ZAMS O-type stars. The absolute magnitudes derived from our analysis locate FO 15 at the same distance as Eta Carinae. From Chandra and XMM X-ray images we also find that there are two close X-ray sources, one coincident with FO 15 and another one without optical counterpart. This latter seems to be a highly variable source, presumably due to a pre-main-sequence stellar neighbour of FO 15.Comment: 11 pages, 9 figures, 3 tables. Accepted for publication in MNRAS. Higher resolution version available at http://lilen.fcaglp.unlp.edu.ar/papers2006.htm