Scattering theory from microscopic first principles

We sketch a derivation of abstract scattering theory from the microscopic first principles defined by Bohmian mechanics. We emphasize the importance of the flux-across-surfaces theorem for the derivation, and of randomness in the impact parameter of the initial wave function---even for an, inevitably inadequate, orthodox derivation.Comment: To appear in Physica A, May 200

Bose-Einstein condensate as a quantum memory for a photonic polarization qubit

A scheme based on electromagnetically induced transparency is used to store light in a Bose-Einstein condensate. In this process, a photonic polarization qubit is stored in atomic Zeeman states. The performance of the storage process is characterized and optimized. The average process fidelity is 1.000 +/- 0.004. For long storage times, temporal fluctuations of the magnetic field reduce this value, yielding a lifetime of the fidelity of 1.1 +/- 0.2 ms. The write-read efficiency of the pulse energy can reach 0.53 +/- 0.05

Leptonic decay-constant ratio fK/fπf_K/f_\pi from lattice QCD using 2+1 clover-improved fermion flavors with 2-HEX smearing

We present a calculation of the leptonic decay-constant ratio $f_K/f_\pi$ in 2+1 flavor QCD. Our data set includes five lattice spacings and pion masses reaching down below the physical one. Special emphasis is placed on a careful study of all systematic uncertainties, especially the continuum extrapolation. Our result is perfectly compatible with the first-row unitarity constraint of the Standard Model.Comment: 19 pages, 6 figures, 3 tables; v2: added supplementary analysis, version published in Phys. Rev.

Systematic errors in partially-quenched QCD plus QED lattice simulations

At the precision reached in current lattice QCD calculations, electromagnetic effects are becoming numerically relevant. Here, electromagnetic effects are included by superimposing $\mathrm{U}(1)$ degrees of freedom on $N_f = 2+1$ QCD configurations from the Budapest-Marseille-Wuppertal Collaboration. We present preliminary results for the electromagnetic corrections to light pseudoscalars mesons masses and discuss some of the associated systematic errors.Comment: 7 pages, 2 figures, The XXIX International Symposium on Lattice Field Theory, July 10-16, 2011, Squaw Valley, Lake Tahoe, California, US

High-precision scale setting in lattice QCD

Scale setting is of central importance in lattice QCD. It is required to predict dimensional quantities in physical units. Moreover, it determines the relative lattice spacings of computations performed at different values of the bare coupling, and this is needed for extrapolating results into the continuum. Thus, we calculate a new quantity, $w_0$, for setting the scale in lattice QCD, which is based on the Wilson flow like the scale $t_0$ (M. Luscher, JHEP 1008 (2010) 071). It is cheap and straightforward to implement and compute. In particular, it does not involve the delicate fitting of correlation functions at asymptotic times. It typically can be determined on the few per-mil level. We compute its continuum extrapolated value in 2+1-flavor QCD for physical and non-physical pion and kaon masses, to allow for mass-independent scale setting even away from the physical mass point. We demonstrate its robustness by computing it with two very different actions (one of them with staggered, the other with Wilson fermions) and by showing that the results agree for physical quark masses in the continuum limit.Comment: 15 pages, 7 figures, 2 tables; Version published in JHE

Optical second-harmonic effect of sol-gel inorganic-organic nanocomposites

Communications: Second-order nonlinear optically (NLO) active materials have promising technical applications in optoelectronic devices. A general problem in NLO-active polymeric systems is the decay of orientational order with time. Results are presented which show that using inorganic-organic composite materials produced by the sol-gel process as a rigid matrix for oriented ÷(2) chromophores (Figure) may provide a means of overcoming this problem

Spectral functions of charmonium with 2+1 flavours of dynamical quarks

Finite temperature charmonium spectral functions in the pseudoscalar(PS) and vector(V) channels are studied in lattice QCD with 2+1 flavours of dynamical Wilson quarks, on fine isotropic lattices (with a lattice spacing of 0.057fm), with a non-physical pion mass of 545MeV. The highest temperature studied is approximately 1.4Tc. Up to this temperature no significant variation of the spectral function is seen in the PS channel. The V channel shows some temperature dependence, which seems to be consistent with a temperature dependent low frequency peak related to heavy quark transport, plus a temperature independent term at omega > 0. These results are in accord with previous calculations using the quenched approximation.Comment: Conference proceedings: The 32nd International Symposium on Lattice Field Theory - Lattice 2014 June 23-28, 2014 Columbia University, New York, New York This conference contribution draws heavily from the paper: arXiv:1401.5940 [hep-lat

Iatrogenic injury of the popliteal artery in orthopedic knee surgery: clinical results and development of a therapeutic algorithm

PURPOSE: Intraoperative injury to the popliteal artery is a rare complication of orthopedic surgery, however, it can have serious consequences, including major amputation. Recommendations for a standard approach are lacking. The aim of this study was to develop an interdisciplinary therapeutic algorithm to assist in complication management. METHODS: From 01/11 to 12/20, 16 arterial injuries after knee surgery were analyzed in a retrospective single-center study. Four cases involved recurrent orthopedic surgery. Procedures performed included eleven total knee arthoplasties (TKA), two TKA replacements, one arthroscopy, and two high tibial osteotomies. Clinical presentation of patients was hemorrhage (n = 2), ischemia (n = 7), the combination of both (n = 4), or pseudoaneurysm formation (n = 3). RESULTS: Ten patients underwent endovascular treatment, some as combined procedures: (stent)-PTA (n = 6), aspiration thrombectomy (n = 5), thrombin injection (n = 1), and embolization (n = 1). Six patients were treated surgically: four with bypass/interposition and one with a patch plasty and one as a hybrid procedure, respectively. Only autologous great saphenous vein was used. All extremities could be preserved. Functional impairment remained in six cases. CONCLUSION: Both endovascular and surgical procedures can be used to treat arterial injuries after knee surgery. Efficient standardized diagnosis and the involvement of vascular expertise are essential to prevent functional impairment or limb loss, as suggested in the algorithms

Remnant index theorem and low-lying eigenmodes for twisted mass fermions

We analyze the low-lying spectrum and eigenmodes of lattice Dirac operators with a twisted mass term. The twist term expels the eigenvalues from a strip in the complex plane and all eigenmodes obtain a non-vanishing matrix element with gamma-5. For a twisted Ginsparg-Wilson operator the spectrum is located on two arcs in the complex plane. Modes due to non-trivial topological charge of the underlying gauge field have their eigenvalues at the edges of these arcs and obey a remnant index theorem. For configurations in the confined phase we find that the twist mainly affects the zero modes, while the bulk of the spectrum is essentially unchanged.Comment: 10 pages, 4 figures. Two comments added. To appear in Phys. Lett.

Machine learning based identification of relevant parameters for functional voice disorders derived from endoscopic high-speed recordings

In voice research and clinical assessment, many objective parameters are in use. However, there is no commonly used set of parameters that reflect certain voice disorders, such as functional dysphonia (FD); i.e. disorders with no visible anatomical changes. Hence, 358 high-speed videoendoscopy (HSV) recordings (159 normal females (NF), 101 FD females (FDF), 66 normal males (NM), 32 FD males (FDM)) were analyzed. We investigated 91 quantitative HSV parameters towards their significance. First, 25 highly correlated parameters were discarded. Second, further 54 parameters were discarded by using a LogitBoost decision stumps approach. This yielded a subset of 12 parameters sufficient to reflect functional dysphonia. These parameters separated groups NF vs. FDF and NM vs. FDM with fair accuracy of 0.745 or 0.768, respectively. Parameters solely computed from the changing glottal area waveform (1D-function called GAW) between the vocal folds were less important than parameters describing the oscillation characteristics along the vocal folds (2D-function called Phonovibrogram). Regularity of GAW phases and peak shape, harmonic structure and Phonovibrogram-based vocal fold open and closing angles were mainly important. This study showed the high degree of redundancy of HSV-voice-parameters but also affirms the need of multidimensional based assessment of clinical data