Frontal plane pelvic motion during gait captures hip osteoarthritis related disability

Gait analysis has widely been accepted as an objective measure of function and clinical outcome. Ambulatory accelerometer-based gait analysis has emerged as a clinically more feasible alternative to optical motion capture systems but does not provide kinematic characterisation to identify disease dependent mechanisms causing walking disability. This study investigated the potential of a single inertial sensor to derive frontal plane motion of the pelvis (i.e. pelvic obliquity) and help identify hip osteoarthritis (OA) related gait alterations. Patients with advanced unilateral hip OA (n = 20) were compared to patients with advanced unilateral knee OA (n = 20) and to a healthy control group (n = 20). Kinematic characterisation of frontal plane pelvic motion during gait demonstrated decreased range of motion and increased asymmetry for hip OA patients specifically. </jats:p

The effective action of D6-branes in N=1 type IIA orientifolds

We use a Kaluza-Klein reduction to compute the low-energy effective action for the massless modes of a spacetime-filling D6-brane wrapped on a special Lagrangian 3-cycle of a type IIA Calabi-Yau orientifold. The modifications to the characteristic data of the N=1 bulk orientifold theory in the presence of a D6-brane are analysed by studying the underlying Type IIA supergravity coupled to the brane worldvolume in the democratic formulation and performing a detailed dualisation procedure. The N=1 chiral coordinates are found to be in agreement with expectations from mirror symmetry. We work out the Kahler potential for the chiral superfields as well as the gauge kinetic functions for the bulk and the brane gauge multiplets including the kinetic mixing between the two. The scalar potential resulting from the dualisation procedure can be formally interpreted in terms of a superpotential. Finally, the gauging of the Peccei-Quinn shift symmetries of the complex structure multiplets reproduces the D-term potential enforcing the calibration condition for special Lagrangian 3-cycles.Comment: 48 pages, v2: typos corrected, references adde

Holomorphic variables in magnetized brane models with continuous Wilson lines

We analyze the action of the target-space modular group in toroidal type IIB orientifold compactifications with magnetized D-branes and continuous Wilson lines. The transformation of matter fields agree with that of twisted fields in heterotic compactifications, constituting a check of type I/heterotic duality. We identify the holomorphic N = 1 variables for these compactifications. Matter fields and closed string moduli are both redefined by open string moduli. The redefinition of matter fields can be read directly from the perturbative Yukawa couplings, whereas closed string moduli redefinitions are obtained from D-brane instanton superpotential couplings. The resulting expressions reproduce and generalize, in the presence of internal magnetic fields, previous results in the literature.Comment: 9 pages, no figures; v2: conventions for Wilson lines changed, major simplifications in expressions, discussions extended, typos corrected, some references adde

Seasonal cycle of precipitation variability in South America on intraseasonal timescales

The seasonal cycle of the intraseasonal (IS) variability of precipitation in South America is described through the analysis of bandpass filtered outgoing longwave radiation (OLR) anomalies. The analysis is discriminated between short (10--30 days) and long (30--90 days) intraseasonal timescales. The seasonal cycle of the 30--90-day IS variability can be well described by the activity of first leading pattern (EOF1) computed separately for the wet season (October--April) and the dry season (May--September). In agreement with previous works, the EOF1 spatial distribution during the wet season is that of a dipole with centers of actions in the South Atlantic Convergence Zone (SACZ) and southeastern South America (SESA), while during the dry season, only the last center is discernible. In both seasons, the pattern is highly influenced by the activity of the Madden--Julian Oscillation (MJO). Moreover, EOF1 is related with a tropical zonal-wavenumber-1 structure superposed with coherent wave trains extended along the South Pacific during the wet season, while during the dry season the wavenumber-1 structure is not observed. The 10--30-day IS variability of OLR in South America can be well represented by the activity of the EOF1 computed through considering all seasons together, a dipole but with the stronger center located over SESA. While the convection activity at the tropical band does not seem to influence its activity, there are evidences that the atmospheric variability at subtropical-extratropical regions might have a role. Subpolar wavetrains are observed in the Pacific throughout the year and less intense during DJF, while a path of wave energy dispersion along a subtropical wavetrain also characterizes the other seasons. Further work is needed to identify the sources of the 10--30-day-IS variability in South America

Anderson localization in Bose-Einstein condensates

The understanding of disordered quantum systems is still far from being complete, despite many decades of research on a variety of physical systems. In this review we discuss how Bose-Einstein condensates of ultracold atoms in disordered potentials have opened a new window for studying fundamental phenomena related to disorder. In particular, we point our attention to recent experimental studies on Anderson localization and on the interplay of disorder and weak interactions. These realize a very promising starting point for a deeper understanding of the complex behaviour of interacting, disordered systems.Comment: 15 pages review, to appear in Reports on Progress in Physic

Yukawa couplings and masses of non-chiral states for the Standard Model on D6-branes on T6/Z6'

The perturbative leading order open string three-point couplings for the Standard Model with hidden USp(6) on fractional D6-branes on T6/Z6' from arXiv:0806.3039 [hep-th], arXiv:0910.0843 [hep-th] are computed. Physical Yukawa couplings consisting of holomorphic Wilsonian superpotential terms times a non-holomorphic prefactor involving the corresponding classical open string Kaehler metrics are given, and mass terms for all non-chiral matter states are derived. The lepton Yukawa interactions are at leading order flavour diagonal, while the quark sector displays a more intricate pattern of mixings. While N=2 supersymmetric sectors acquire masses via only two D6-brane displacements - which also provide the hierarchies between up- and down-type Yukawas within one quark or lepton generation -, the remaining vector-like states receive masses via perturbative three-point couplings to some Standard Model singlet fields with vevs along flat directions. Couplings to the hidden sector and messengers for supersymmetry breaking are briefly discussed.Comment: 52 pages (including 8p. appendix); 5 figures; 14 tables; v2: discussion in section 4.1.3 extended, footnote 5 added, typos corrected, accepted by JHE

Flux and Instanton Effects in Local F-theory Models and Hierarchical Fermion Masses

We study the deformation induced by fluxes and instanton effects on Yukawa couplings involving 7-brane intersections in local F-theory constructions. In the absence of non-perturbative effects, holomorphic Yukawa couplings do not depend on open string fluxes. On the other hand instanton effects (or gaugino condensation on distant 7-branes) do induce corrections to the Yukawas. The leading order effect may also be captured by the presence of closed string (1,2) IASD fluxes, which give rise to a non-commutative structure. We check that even in the presence of these non-perturbative effects the holomorphic Yukawas remain independent of magnetic fluxes. Although fermion mass hierarchies may be obtained from these non-perturbative effects, they would give identical Yukawa couplings for D-quark and Lepton masses in SU(5) F-theory GUT's, in contradiction with experiment. We point out that this problem may be solved by appropriately normalizing the wavefunctions. We show in a simple toy model how the presence of hypercharge flux may then be responsible for the difference between D-quarks and Lepton masses in local SU(5) GUT's.Comment: 84 pages, 1 figure. v2: minor corrections and references adde

Molecular recognition of histone lysine methylation by the Polycomb group repressor dSfmbt

Polycomb group (PcG) proteins repress transcription by modifying chromatin structure in target genes. dSfmbt is a subunit of the Drosophila melanogaster PcG protein complex PhoRC and contains four malignant brain tumour (MBT) repeats involved in the recognition of various mono- and dimethylated histone peptides. Here, we present the crystal structure of the four-MBT-repeat domain of dSfmbt in complex with a mono-methylated histone H4 peptide. Only a single histone peptide binds to the four-MBT-repeat domain. Mutational analyses show high-affinity binding with low peptide sequence selectivity through combinatorial interaction of the methyl-lysine with an aromatic cage and positively charged flanking residues with the surrounding negatively charged surface of the fourth MBT repeat. dSfmbt directly interacts with the PcG protein Scm, a related MBT-repeat protein with similar methyl-lysine binding activity. dSfmbt and Scm co-occupy Polycomb response elements of target genes in Drosophila and they strongly synergize in the repression of these target genes, suggesting that the combined action of these two MBT proteins is crucial for Polycomb silencing

Remarks on quiver gauge theories from open topological string theory

We study effective quiver gauge theories arising from a stack of D3-branes on certain Calabi-Yau singularities. Our point of view is a first principle approach via open topological string theory. This means that we construct the natural A-infinity-structure of open string amplitudes in the associated D-brane category. Then we show that it precisely reproduces the results of the method of brane tilings, without having to resort to any effective field theory computations. In particular, we prove a general and simple formula for effective superpotentials