Local Operations and Completely Positive Maps in Algebraic Quantum Field Theory

Einstein introduced the locality principle which states that all physical effect in some finite space-time region does not influence its space-like separated finite region. Recently, in algebraic quantum field theory, R\'{e}dei captured the idea of the locality principle by the notion of operational separability. The operation in operational separability is performed in some finite space-time region, and leaves unchanged the state in its space-like separated finite space-time region. This operation is defined with a completely positive map. In the present paper, we justify using a completely positive map as a local operation in algebraic quantum field theory, and show that this local operation can be approximately written with Kraus operators under the funnel property

Testing Ecological Theory with Lianas

Lianas constitute a diverse polyphyletic plant group that is advancing our understanding of ecological theory. Specifically, lianas are providing new insights into the mechanisms that control plant distribution and diversity maintenance. For example, there is now evidence that a single, scalable mechanism may explain local, regional, and pan‐tropical distribution of lianas, as well as the maintenance of liana species diversity. The ability to outcompete trees under dry, stressful conditions in seasonal forests provides lianas a growth advantage that, over time, results in relatively high abundance in seasonal forests and low abundance in aseasonal forests. Lianas may also gain a similar growth advantage following disturbance, thus explaining why liana density and diversity peak following disturbance at the local, forest scale. The study of ecology, however, is more than the effect of the environment on organisms; it also includes the effects of organisms on the environment. Considerable empirical evidence now indicates that lianas substantially alter their environment by consuming resources, suppressing tree performance, and influencing emergent properties of forests, such as ecosystem functioning, plant and animal diversity, and community composition. These recent studies using lianas are transcending classical tropical ecology research and are now providing novel insights into fundamental ecological theory

Treatment of symptomatic macromastia in a breast unit

BACKGROUND: Patients suffering from symptomatic macromastia are usually underserved, as they have to put up with very long waiting lists and are usually selected under restrictive criteria. The Oncoplastic Breast Surgery subspeciality requires a cross-specialty training, which is difficult, in particular, for trainees who have a background in general surgery, and not easily available. The introduction of reduction mammaplasty into a Breast Cancer Unit as treatment for symptomatic macromastia could have a synergic effect, making the scarce therapeutic offer at present available to these patients, who are usually treated in Plastic Departments, somewhat larger, and accelerating the uptake of oncoplastic training as a whole and, specifically, the oncoplastic breast conserving procedures based on the reduction mammaplasty techniques such as displacement conservative techniques and onco-therapeutic mammaplasty. This is a retrospective study analyzing the outcome of reduction mammaplasty for symptomatic macromastia in our Breast Cancer Unit. METHODS: A cohort study of 56 patients who underwent bilateral reduction mammaplasty at our Breast Unit between 2005 and 2009 were evaluated; morbidity and patient satisfaction were considered as end points. Data were collected by reviewing medical records and interviewing patients. RESULTS: Eight patients (14.28%) presented complications in the early postoperative period, two of them being reoperated on. The physical symptoms disappeared or significantly improved in 88% of patients and the degree of satisfaction with the care process and with the overall outcome were really high. CONCLUSION: Our experience of the introduction of reduction mammaplasty in our Breast Cancer Unit has given good results, enabling us to learn the use of different reduction mammaplasty techniques using several pedicles which made it possible to perform oncoplastic breast conserving surgery. In our opinion, this management policy could bring clear advantages both to patients (large-breasted and those with a breast cancer) and surgeons

Local Optical Probe of Motion and Stress in a multilayer graphene NEMS

Nanoelectromechanical systems (NEMSs) are emerging nanoscale elements at the crossroads between mechanics, optics and electronics, with significant potential for actuation and sensing applications. The reduction of dimensions compared to their micronic counterparts brings new effects including sensitivity to very low mass, resonant frequencies in the radiofrequency range, mechanical non-linearities and observation of quantum mechanical effects. An important issue of NEMS is the understanding of fundamental physical properties conditioning dissipation mechanisms, known to limit mechanical quality factors and to induce aging due to material degradation. There is a need for detection methods tailored for these systems which allow probing motion and stress at the nanometer scale. Here, we show a non-invasive local optical probe for the quantitative measurement of motion and stress within a multilayer graphene NEMS provided by a combination of Fizeau interferences, Raman spectroscopy and electrostatically actuated mirror. Interferometry provides a calibrated measurement of the motion, resulting from an actuation ranging from a quasi-static load up to the mechanical resonance while Raman spectroscopy allows a purely spectral detection of mechanical resonance at the nanoscale. Such spectroscopic detection reveals the coupling between a strained nano-resonator and the energy of an inelastically scattered photon, and thus offers a new approach for optomechanics

Chiral Polymerization in Open Systems From Chiral-Selective Reaction Rates

We investigate the possibility that prebiotic homochirality can be achieved exclusively through chiral-selective reaction rate parameters without any other explicit mechanism for chiral bias. Specifically, we examine an open network of polymerization reactions, where the reaction rates can have chiral-selective values. The reactions are neither autocatalytic nor do they contain explicit enantiomeric cross-inhibition terms. We are thus investigating how rare a set of chiral-selective reaction rates needs to be in order to generate a reasonable amount of chiral bias. We quantify our results adopting a statistical approach: varying both the mean value and the rms dispersion of the relevant reaction rates, we show that moderate to high levels of chiral excess can be achieved with fairly small chiral bias, below 10%. Considering the various unknowns related to prebiotic chemical networks in early Earth and the dependence of reaction rates to environmental properties such as temperature and pressure variations, we argue that homochirality could have been achieved from moderate amounts of chiral selectivity in the reaction rates.Comment: 15 pages, 6 figures, accepted for publication in Origins of Life and Evolution of Biosphere

Comparison of embedded and added motor imagery training in patients after stroke: Study protocol of a randomised controlled pilot trial using a mixed methods approach

Copyright @ 2009 Schuster et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background: Two different approaches have been adopted when applying motor imagery (MI) to stroke patients. MI can be conducted either added to conventional physiotherapy or integrated within therapy sessions. The proposed study aims to compare the efficacy of embedded MI to an added MI intervention. Evidence from pilot studies reported in the literature suggests that both approaches can improve performance of a complex motor skill involving whole body movements, however, it remains to be demonstrated, which is the more effective one.Methods/Design: A single blinded, randomised controlled trial (RCT) with a pre-post intervention design will be carried out. The study design includes two experimental groups and a control group (CG). Both experimental groups (EG1, EG2) will receive physical practice of a clinical relevant motor task ('Going down, laying on the floor, and getting up again') over a two week intervention period: EG1 with embedded MI training, EG2 with MI training added after physiotherapy. The CG will receive standard physiotherapy intervention and an additional control intervention not related to MI.The primary study outcome is the time difference to perform the task from pre to post-intervention. Secondary outcomes include level of help needed, stages of motor task completion, degree of motor impairment, balance ability, fear of falling measure, motivation score, and motor imagery ability score. Four data collection points are proposed: twice during baseline phase, once following the intervention period, and once after a two week follow up. A nested qualitative part should add an important insight into patients' experience and attitudes towards MI. Semi-structured interviews of six to ten patients, who participate in the RCT, will be conducted to investigate patients' previous experience with MI and their expectations towards the MI intervention in the study. Patients will be interviewed prior and after the intervention period.Discussion: Results will determine whether embedded MI is superior to added MI. Findings of the semi-structured interviews will help to integrate patient's expectations of MI interventions in the design of research studies to improve practical applicability using MI as an adjunct therapy technique

5D gravity and the discrepant G measurements

It is shown that 5D Kaluza-Klein theory stabilized by an external bulk scalar field may solve the discrepant laboratory G measurements. This is achieved by an effective coupling between gravitation and the geomagnetic field. Experimental considerations are also addressed.Comment: 13 pages, to be published in: Proceedings of the 18th Course of the School on Cosmology and Gravitation: The gravitational Constant. Generalized gravitational theories and experiments (30 April-10 May 2003, Erice). Ed. by G. T. Gillies, V. N. Melnikov and V. de Sabbata, (Kluwer), 13pp. (in print) (2003

Observation of Dirac plasmons in a topological insulator

Plasmons are the quantized collective oscillations of electrons in metals and doped semiconductors. The plasmons of ordinary, massive electrons are since a long time basic ingredients of research in plasmonics and in optical metamaterials. Plasmons of massless Dirac electrons were instead recently observed in a purely two-dimensional electron system (2DEG)like graphene, and their properties are promising for new tunable plasmonic metamaterials in the terahertz and the mid-infrared frequency range. Dirac quasi-particles are known to exist also in the two-dimensional electron gas which forms at the surface of topological insulators due to a strong spin-orbit interaction. Therefore,one may look for their collective excitations by using infrared spectroscopy. Here we first report evidence of plasmonic excitations in a topological insulator (Bi2Se3), that was engineered in thin micro-ribbon arrays of different width W and period 2W to select suitable values of the plasmon wavevector k. Their lineshape was found to be extremely robust vs. temperature between 6 and 300 K, as one may expect for the excitations of topological carriers. Moreover, by changing W and measuring in the terahertz range the plasmonic frequency vP vs. k we could show, without using any fitting parameter, that the dispersion curve is in quantitative agreement with that predicted for Dirac plasmons.Comment: 11 pages, 3 figures, published in Nature Nanotechnology (2013

Transport in holographic superfluids

We construct a slowly varying space-time dependent holographic superfluid and compute its transport coefficients. Our solution is presented as a series expansion in inverse powers of the charge of the order parameter. We find that the shear viscosity associated with the motion of the condensate vanishes. The diffusion coefficient of the superfluid is continuous across the phase transition while its third bulk viscosity is found to diverge at the critical temperature. As was previously shown, the ratio of the shear viscosity of the normal component to the entropy density is 1/(4 pi). As a consequence of our analysis we obtain an analytic expression for the backreacted metric near the phase transition for a particular type of holographic superfluid.Comment: 45 pages + appendice

Further investigation of confirmed urinary tract infection (UTI) in children under five years: a systematic review.

Background: Further investigation of confirmed UTI in children aims to prevent renal scarring and future complications. Methods: We conducted a systematic review to determine the most effective approach to the further investigation of confirmed urinary tract infection (UTI) in children under five years of age. Results: 73 studies were included. Many studies had methodological limitations or were poorly reported. Effectiveness of further investigations: One study found that routine imaging did not lead to a reduction in recurrent UTIs or renal scarring. Diagnostic accuracy: The studies do not support the use of less invasive tests such as ultrasound as an alternative to renal scintigraphy, either to rule out infection of the upper urinary tract (LR- = 0.57, 95%CI: 0.47, 0.68) and thus to exclude patients from further investigation or to detect renal scarring (LR+ = 3.5, 95% CI: 2.5, 4.8). None of the tests investigated can accurately predict the development of renal scarring. The available evidence supports the consideration of contrast-enhanced ultrasound techniques for detecting vesico-ureteric reflux (VUR), as an alternative to micturating cystourethrography (MCUG) (LR+ = 14.1, 95% CI: 9.5, 20.8; LR- = 0.20, 95%CI: 0.13, 0.29); these techniques have the advantage of not requiring exposure to ionising radiation. Conclusion: There is no evidence to support the clinical effectiveness of routine investigation of children with confirmed UTI. Primary research on the effectiveness, in terms of improved patient outcome, of testing at all stages in the investigation of confirmed urinary tract infection is urgently required