Geometry of entangled states, Bloch spheres and Hopf fibrations

We discuss a generalization to 2 qubits of the standard Bloch sphere representation for a single qubit, in the framework of Hopf fibrations of high dimensional spheres by lower dimensional spheres. The single qubit Hilbert space is the 3-dimensional sphere S3. The S2 base space of a suitably oriented S3 Hopf fibration is nothing but the Bloch sphere, while the circular fibres represent the qubit overall phase degree of freedom. For the two qubits case, the Hilbert space is a 7-dimensional sphere S7, which also allows for a Hopf fibration, with S3 fibres and a S4 base. A main striking result is that suitably oriented S7 Hopf fibrations are entanglement sensitive. The relation with the standard Schmidt decomposition is also discussedComment: submitted to J. Phys.

Benefits and Risks of Weight-Loss Treatment for Older, Obese Women

Background: A key issue in the treatment of obesity in older adults is whether the health benefits of weight loss outweigh the potential risks with respect to musculoskeletal injury. Objective: To compare change in weight, improvements in metabolic risk factors, and reported musculoskeletal adverse events in middle-aged (50-59 years) and older (65-74 years), obese women. Materials and methods: Participants completed an initial 6-month lifestyle intervention for weight loss, comprised of weekly group sessions, followed by 12 months of extended care with biweekly contacts. Weight and fasting blood samples were assessed at baseline, month 6, and month 18; data regarding adverse events were collected throughout the duration of the study. Results: Both middle-aged (n = 162) and older (n = 56) women achieved significant weight reductions from baseline to month 6 (10.1 +/- 0.68 kg and 9.3 +/- 0.76 kg, respectively) and maintained a large proportion of their losses at month 18 (7.6 +/- 0.87 kg and 7.6 +/- 1.3 kg, respectively); there were no significant differences between the two groups with respect to weight change. Older women further experienced significant reductions in systolic blood pressure, HbA(1c), and C-reactive protein from baseline to month 6 and maintained these improvements at month 18. Despite potential safety concerns, we found that older women were no more likely to experience musculoskeletal adverse events during the intervention as compared with their middle-aged counterparts. Conclusion: These results suggest that older, obese women can experience significant health benefits from lifestyle treatment for obesity, including weight loss and improvements in disease risk factors. Further investigation of the impact of weight loss on additional health-related parameters and risks (eg, body composition, muscular strength, physical functioning, and injuries) in older adults is needed.National Heart, Lung and Blood Institute R18HL73326University of FloridaDivision of Statistics and Scientific Computatio

ZNF804A genotype modulates neural activity during working memory for faces

Copyright © 2013 S. Karger AG, Basel.Peer reviewedPublisher PD

Deflation in Südeuropa: Fluch oder Segen? Wie sollte die EZB reagieren?

Seit mehr als einem Jahr ist der Preisanstieg im Euroraum im Trend rückläufig. Angesichts der geringen Inflationsrate wird über ein mögliches Abrutschen in eine Deflation diskutiert. Wie groß ist diese Gefahr und wie sollte die EZB reagieren? Das wahrscheinlichere Szenario der nächsten Monate besteht nach Ansicht von Alfons J. Weichenrieder, Goethe-Universität Frankfurt, eher in einer sogenannten »Lowflation« – zu wenig Inflation – statt einer Deflation. Doch auch schon die Lowflation berge Probleme. Der starke strukturelle Anpassungsbedarf in den meisten Euroländern könnte nur von einer höheren Inflationsrate profitieren. In der Vergangenheit seien die Inflationsunterschiede zu gering gewesen, um die Unterschiede in der Wettbewerbsfähigkeit auszugleichen. Adalbert Winkler, Frankfurt School of Finance & Management, sieht in den Inflationsdifferentiale des Euroraums ein Anpassungsinstrument. Die Deflation in Südeuropa sei nur dann »ein Fluch«, wenn der Euroraum entweder nicht jenes Maß an Integration aufweise, das für einen erfolgreichen Anpassungsprozess erforderlich sei, oder die Deflation in Südeuropa nicht von einem entsprechenden Inflationsanstieg in Kerneuropa begleitet werde. Anja Rossen, Hamburgisches WeltWirtschaftsInstitut, hält die Deflationssorge für unbegründet. Zwar seien die Inflationsraten zurzeit im Euroraum gering, aber eine sich weiter erholende europäische Konjunktur spreche eher für mittelfristig zunehmende Inflationsraten. Sollte es dennoch zu einer Deflation kommen, so habe die EZB eine Reihe von Instrumenten, um diese zu bekämpfen. Nach Meinung von Olaf Schlotmann, Brunswick European Law School/Ostfalia, können selbst fallende Erzeugerpreise in Südeuropa das dort so dringend benötigte Wirtschaftswachstum auch mittelfristig nicht beschleunigen. Vielmehr werden die aktuell sehr niedrigen Inflationsraten die Tragfähigkeit der (Staats-)Schulden in Südeuropa weiter aushöhlen

Lowest order in inelastic tunneling approximation: Efficient scheme for simulation of inelastic electron tunneling data

We have developed an efficient and accurate formalism which allows the simulation at the ab initio level of inelastic electron tunneling spectroscopy data under a scanning tunneling microscope setup. It exploits fully the tunneling regime by carrying out the structural optimization and vibrational mode calculations for surface and tip independently. The most relevant interactions in the inelastic current are identified as the inelastic tunneling terms, which are taken into account up to lowest order, while all other inelastic contributions are neglected. As long as the system is under tunneling regime conditions and there is no physisorbed molecule on the surface or tip apex, this lowest order in inelastic tunneling (LOIT) approach reduces drastically the computational cost compared to related approaches while maintaining a good accuracy. Adopting the wide-band limit for both tip and surface further reduces calculation times significantly, and is shown to give similar results to when the full energy dependence of the Green's functions is taken into account. The LOIT is applied to the Cu(111)+CO system probed by a clean and a CO contaminated tip to find good agreement with previous works. Different parameters involved in the calculations such as basis sets, k sampling, tip-sample distance, or temperature, among others, are discussed in detail. © 2013 American Physical Society.J.C. acknowledges financial support from the Spanish Ministry of Innovation and Science under Contract No.MAT2010-18432.Peer Reviewe

Quantum effective potential, electron transport and conformons in biopolymers

In the Kirchhoff model of a biopolymer, conformation dynamics can be described in terms of solitary waves, for certain special cross-section asymmetries. Applying this to the problem of electron transport, we show that the quantum effective potential arising due to the bends and twists of the polymer enables us to formalize and quantify the concept of a {\it conformon} that has been hypothesized in biology. Its connection to the soliton solution of the cubic nonlinear Schr\"{o}dinger equation emerges in a natural fashion.Comment: to appear in J. Phys.