Confined optical phonon modes in polar tetrapod nanocrystals detected by resonant inelastic light scattering

We investigated CdTe nanocrystal tetrapods of different sizes by resonant inelastic light scattering at room temperature and under cryogenic conditions. We observe a strongly resonant behavior of the phonon scattering with the excitonic structure of the tetrapods. Under resonant conditions we detect a set of phonon modes that can be understood as confined longitudinal-optical phonons, surface-optical phonons, and transverse-optical phonons in a nanowire picture.Comment: 12 pages, 4 figure

Role of anisotropy in the F\"orster energy transfer from a semiconductor quantum well to an organic crystalline overlayer

We consider the non-radiative resonant energy transfer from a two-dimensional Wannier exciton (donor) to a Frenkel exciton of a molecular crystal overlayer (acceptor). We characterize the effect of the optical anisotropy of the organic subsystem on this process. Using realistic values of material parameters, we show that it is possible to change the transfer rate within typically a factor of two depending on the orientation of the crystalline overlayer. The resonant matching of donor and acceptor energies is also partly tunable via the organic crystal orientation.Comment: 6 pages, 8 figure

Band gap renormalization in photoexcited semiconductor quantum wire structures in the GW approximation

We investigate the dynamical self-energy corrections of the electron-hole plasma due to electron-electron and electron-phonon interactions at the band edges of a quasi-one dimensional (1D) photoexcited electron-hole plasma. The leading-order $GW$ dynamical screening approximation is used in the calculation by treating electron-electron Coulomb interaction and electron-optical phonon Fr\"{o}hlich interaction on an equal footing. We calculate the exchange-correlation induced band gap renormalization (BGR) as a function of the electron-hole plasma density and the quantum wire width. The calculated BGR shows good agreement with existing experimental results, and the BGR normalized by the effective quasi-1D excitonic Rydberg exhibits an approximate one-parameter universality.Comment: 11 pages, 3 figure

“Exit Italy”? social and spatial (im)mobilities as conditions of protracted displacement

This article examines how the experience of protracted displacement interacts with mobility desires and practices of a diverse population of asylum-seekers, refugees and undocumented migrants in Italy. Drawing from ethnographic data collected in different Italian localities and among different nationalities, we focus on participants’ translocal connections, both as ways ‘out of limbo’ and as factors in protracted legal and socio-economic precariousness. We propose an interpretation of complex spatial mobilities to understand under what conditions spatial mobility translates into an improvement in the living conditions of migrants, producing upward socio-economic mobility, and under what conditions spatial mobility perpetuates marginality and isolation. Although translocal connections provide space for action, migrants risk being trapped in a loop of movements between different countries and different localities within Italy, without the possibility to achieve legal protection in any of these

Variación espacio-temporal de las poblaciones de áfidos, parasitoides e hiperparasitoides en el cultivo de frutilla

Fil: Cingolani, María Fernanda. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios en Parasitología y Vectores; ArgentinaFil: Liljesthröm, Gerardo G.. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios en Parasitología y Vectores; ArgentinaFil: Greco, Nancy Mabel. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios en Parasitología y Vectores; Argentin

Detection and quantitation analysis of cocaine and metabolites in fixed liver tissue and formalin solutions.

This study reports the results of the detection and quantitation of cocaine and its metabolites in liver tissues fixed in formalin and in the formalin solutions in which the same tissues were fixed. Toxicological analyses were performed on formalin-fixed liver samples from four cases of death of cocaine abusers and on formalin solutions (10% buffered, pH 7) in which the samples were preserved. Analyses carried out at the time of autopsy on body fluids and tissues allowed identification of cocaine and the metabolite benzoylecgonine. Liver tissue samples were preserved in formalin solutions for four weeks before analysis. Results only showed the presence of benzoylecgonine in the studied materials. The mean levels of recovery of benzoylecgonine in fixed tissues were 12.31% in liver and 84.47% in formalin from liver. Results indicated that benzoylecgonine has good stability, even in biological specimens subjected to chemical fixation

Valence band spectroscopy in V-grooved quantum wires

We present a combined theoretical and experimental study of the anisotropy in the optical absorption of V-shaped quantum wires. By means of realistic band structure calculations for these structures, we show that detailed information on the heavy- and light-hole states can be singled out from the anisotropy spectra {\em independently of the electron confinement}, thus allowing accurate valence band spectroscopy.Comment: To be published in Appl. Phys. Lett. (8 pages in REVTeX, two postscipt figures

Modification of micro-channel filling flow by poly(dimethylsiloxane) surface functionalization with fluorine—Substituted aminonaphthols

Microfluidics based on the capillarity-induced filling of elastomeric channels by a suitable liquid or solution represents a useful route for realizing portable diagnostic devices designed without additional mechanical or electrical micropumps. In this study, an elastomeric mold made of poly(dimethylsiloxane) (PDMS), containing relief patterns placed in intimate contact with a silicon substrate, is utilized to create a continuous network of rectangular micro-channels for the motion of water fluid. The immobilization on activated PDMS surface of suitable functional molecules such as hydrophilic and hydrophobic fluorine-containing aminonaphthols, obtained through a straightforward and versatile synthetic procedure, allowed us to modulate PDMS surface properties depending on the structural characteristics of the employed derivative. In this context, the incorporation of fluorine groups is important for improving biocompatibility of the resulting device, providing surfaces that could be chemically and biologically inert as well as resistant to surface adhesion phenomena. The functionalization from liquid phase of PDMS replicas, involving a covalent derivatization via silanization reaction of the above mentioned compounds to an oxidized PDMS surface, resulted in a successful modification of microfluidic motion of water in rectangular capillaries, moreover contact angle values evidence also how wettability of PDMS films could be modulated, with the fluorinated aminonaphthols fuctionalized PDMS exhibiting higher contact angles. (C) 2009 Elsevier B.V. All rights reserved

The third transitional Identity of migrant adolescents. The case of Hotel House an Italian multi-ethnic skyscraper-ghetto

The adolescent\u2019s identity achievement is a complex task, even more so if they are migrants living in a particular context of ethnic ghettoization. Hotel House is an enormous, isolated condominium situated on the outskirts of Porto Recanati, a small Italian town. It is a unique reality poorly studied from a social psychological perspective. The present paper aims to measure the perceived levels of self-concept clarity, self-determination, ethnic group identification, relationship with parents, depression and life satisfaction in a group of 91 adolescents (11\u201319 years; 30% females; 1.5 immigrant\u2019s generation) living in this context. The analysis shows low levels of self-concept clarity and self-determination, especially in female adolescents, quite satisfactory relationships with their parents and medium levels of group identification and life satisfaction. The identification with their ethnic subgroups seems to provide a third transitional identity which works as a temporary link between native country values and host country values. The regression analysis shows significant associations: self-determination is negatively associated with depression and positively associated with the perception of life satisfaction; the father\u2019s closeness is a negative predictor for depression and a positive predictor for life satisfaction; mother\u2019s closeness is negatively associated with depression

Microsurgery robots: addressing the needs of high-precision surgical interventions

Robots can help surgeons perform better quality operations, leading to reductions in the hospitalisation time of patients and in the impact of surgery on their postoperative quality of life