Multichannel quantum-defect theory for slow atomic collisions

We present a multichannel quantum-defect theory for slow atomic collisions that takes advantages of the analytic solutions for the long-range potential, and both the energy and the angular-momentum insensitivities of the short-range parameters. The theory provides an accurate and complete account of scattering processes, including shape and Feshbach resonances, in terms of a few parameters such as the singlet and the triplet scattering lengths. As an example, results for $^{23}$Na-$^{23}$Na scattering are presented and compared close-coupling calculations.Comment: 8 pages, 3 figure

Changes in Monetary Policy Conduct and Their Effects on Banking Spreads

This paper explores whether monetary policy and the denomination of its operative instrument affects banks’ intermediation spread in the Chilean economy. After dividing the sample into pre- and post nominalization periods, the evidence shows a positive correlation between the monetary policy interest rate and banking spreads before the nominalization period, but loses significance in the post nominalization period. This is true for rises and cuts of the rate, so there is no evidence of asymmetries. Two additional interesting results are that i) the increase in the sector’s market concentration has prompted a reduction in intermediation spreads, and ii) the volatility of the market interest rate, controlling for the year 1998, generates an increase in them. Finally, it is worth noting that the sensitivity of banking spreads to the interest rate variance (that includes exchange rate depreciation and inflation in UF) has increased strongly during the nominalization period.

Linking Ultracold Polar Molecules

We predict that pairs of polar molecules can be weakly bound together in an ultracold environment, provided that a dc electric field is present. The field that links the molecules together also strongly influences the basic properties of the resulting dimer, such as its binding energy and predissociation lifetime. Because of their long-range character these dimers will be useful in disentangling cold collision dynamics of polar molecules. As an example, we estimate the microwave photoassociation yield for OH-OH cold collisions.Comment: 4 pages 2 figure

Observation of Feshbach-like resonances in collisions between ultracold molecules

We observe magnetically tuned collision resonances for ultracold Cs2 molecules stored in a CO2-laser trap. By magnetically levitating the molecules against gravity, we precisely measure their magnetic moment. We find an avoided level crossing which allows us to transfer the molecules into another state. In the new state, two Feshbach-like collision resonances show up as strong inelastic loss features. We interpret these resonances as being induced by Cs4 bound states near the molecular scattering continuum. The tunability of the interactions between molecules opens up novel applications such as controlled chemical reactions and synthesis of ultracold complex molecules

Looking at Chile’s Economic Dvelopment From an International Perspective

This paper examines the relative position of Chile through time and compared with other emerging and industrial economies, using various economic development indicators, particularly over the past two decades. It provides a descriptive analysis, without exploring causalities or testing hypotheses on the economic growth of the country, but it reveals the strengths and weaknesses that serve as the base for growth policy discussion. The comparison of economic development indicators shows that Chile is comparatively strong in macroeconomic stability, commercial and financial integration, quality of institutions, and in the progress of other structural reforms that are manifested in its well-developed capital market and private sector involvement in production. However, when it comes to quality of education, technological innovation efforts, infrastructure quality and quantity, and some social indicators, its performance is poor.

Novel technique for the CO₂ laser fabrication of optical devices with sub-micrometer ablation depth precision

We present novel techniques for the processing of fibre end face and cladding surfaces using a 9.6 µm CO2 laser. We investigate the effects of pulse duration on process parameters

Creation and manipulation of Feshbach resonances with radio-frequency radiation

We present a simple technique for studying collisions of ultracold atoms in the presence of a magnetic field and radio-frequency radiation (rf). Resonant control of scattering properties can be achieved by using rf to couple a colliding pair of atoms to a bound state. We show, using the example of 6Li, that in some ranges of rf frequency and magnetic field this can be done without giving rise to losses. We also show that halo molecules of large spatial extent require much less rf power than deeply bound states. Another way to exert resonant control is with a set of rf-coupled bound states, linked to the colliding pair through the molecular interactions that give rise to magnetically tunable Feshbach resonances. This was recently demonstrated for 87Rb [Kaufman et al., Phys. Rev. A 80:050701(R), 2009]. We examine the underlying atomic and molecular physics which made this possible. Lastly, we consider the control that may be exerted over atomic collisions by placing atoms in superpositions of Zeeman states, and suggest that it could be useful where small changes in scattering length are required. We suggest other species for which rf and magnetic field control could together provide a useful tuning mechanism.Comment: 21 pages, 8 figures, submitted to New Journal of Physic

Collisional and molecular spectroscopy in an ultracold Bose-Bose mixture

The route toward a Bose-Einstein condensate of dipolar molecules requires the ability to efficiently associate dimers of different chemical species and transfer them to the stable rovibrational ground state. Here, we report on recent spectroscopic measurements of two weakly bound molecular levels and newly observed narrow d-wave Feshbach resonances. The data are used to improve the collisional model for the Bose-Bose mixture 41K87Rb, among the most promising candidates to create a molecular dipolar BEC.Comment: 13 pages, 3 figure

Acrylamides with hydrolytically labile carbonate ester side chains as versatile building blocks for well-defined block copolymer micelles via RAFT polymerization

En route towards improved delivery systems for targeted chemotherapy, we propose a straightforward approach for the hydrophobic modification of the acrylamide N-(2-Hydroxyethyl) acrylamide (HEAm). An ethyl or benzyl group was introduced via a hydrolytically sensitive carbonate ester yielding HEAm-EC and HEAm-BC, respectively. Block copolymers of HEAm, respectively PEG and HEAm-EC or HEAm-BC were successfully synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization, obtaining a library of well-defined block copolymers with different degrees of polymerization (DP). To further explore the versatility of our approach in terms of polymer synthesis, self-assembly, drug solubilization and in vitro cell interaction, polyethylene glycol (PEG) and polyHEAm as hydrophilic polymer blocks were compared. The block copolymers formed micellar nanoparticles (10-100 nm) in PBS and could efficiently solubilize hydrophobic dyes and anti-cancer drugs. Benzyl carbonate ester side chains increased micellar stability and drug loading capacity. Moreover, PEG as hydrophilic block showed in comparison to HEAm more promising results concerning both colloidal stability and drug loading capacity. Confocal microscopy showed that the micelles could efficiently deliver a hydrophobic dye inside the cells. Finally, we also demonstrated efficient formulation of the anti-cancer drug paclitaxel with an in vitro cancer cell killing performance comparable or even better than the two commercial PTX nano-formulations Abraxane and Genexol-PM at equal drug dose. In conclusion, modification of HEAm through carbonate linkages offers a versatile platform for the design of degradable polymers with potential for biomedical applications