Predictive modelling of human walking over a complete gait cycle

An inverse dynamics multi-segment model of the body was combined with optimisation techniques to simulate normal walking in the sagittal plane on level ground. Walking is formulated as an optimal motor task subject to multiple constraints with minimisation of mechanical energy expenditure over a complete gait cycle being the performance criterion. All segmental motions and ground reactions were predicted from only three simple gait descriptors (inputs): walking velocity, cycle period and double stance duration. Quantitative comparisons of the model predictions with gait measurements show that the model reproduced the significant characteristics of normal gait in the sagittal plane. The simulation results suggest that minimising energy expenditure is a primary control objective in normal walking. However, there is also some evidence for the existence of multiple concurrent performance objectives. Keywords: Gait prediction; Inverse dynamics; Optimisation; Optimal motor tas

Geochemistry and petrogenesis of volcanic rocks from Daimao Seamount (South China Sea) and their tectonic implications

The South China Sea (SCS) experienced three episodes of seafloor spreading and left three fossil spreading centers presently located at 18°N, 17°N and 15.5°N. Spreading ceased at these three locations during magnetic anomaly 10, 8, and 5c, respectively. Daimao Seamount (16.6. Ma) was formed 10. my after the cessation of the 17°N spreading center. Volcaniclastic rocks and shallow-water carbonate facies near the summit of Daimao Seamount provide key information on the seamount's geologic history. New major and trace element and Sr-Nd-Pb isotopic compositions of basaltic breccia clasts in the volcaniclastics suggest that Daimao and other SCS seamounts have typical ocean island basalt-like composition and possess a 'Dupal' isotopic signature. Our new analyses, combined with available data, indicate that the basaltic foundation of Daimao Seamount was formed through subaqueous explosive volcanic eruptions at 16.6. Ma. The seamount subsided rapidly (>. 0.12. mm/y) at first, allowing the deposition of shallow-water, coral-bearing carbonates around its summit and, then, at a slower rate (<. 0.12. mm/y). We propose that the parental magmas of SCS seamount lavas originated from the Hainan mantle plume. In contrast, lavas from contemporaneous seamounts in other marginal basins in the western Pacific are subduction-related

Surface location of alkaline-earth atom impurities on helium nanodroplets

There has been notable uncertainty regarding the degree of solvation of alkaline-earth atoms, especially Mg, in free He-4 nanodroplets. We have measured the electron energy dependence of the ionization yield of picked-up atoms. There is a qualitative shape difference between the yield curves of species solvated in the middle of the droplet and species located in the surface region; this difference arises from the enhanced role played by the Penning ionization process in the latter case. The measurements demonstrate that Mg, Ca, Sr and Ba all reside at or near the droplet surface.Comment: 11 pages, 3 figure

The Coulomb interaction and the inverse Faddeev-Popov operator in QCD

We give a proof of a local relation between the inverse Faddeev-Popov operator and the non-Abelian Coulomb interaction between color charges

Octet baryon masses in next-to-next-to-next-to-leading order covariant baryon chiral perturbation theory

We study the ground-state octet baryon masses and sigma terms using the covariant baryon chiral perturbation theory (ChPT) with the extended-on-mass-shell (EOMS) renormalization scheme up to next-to-next-to-next-to-leading order (N$^3$LO). By adjusting the available 19 low-energy constants (LECs), a reasonable fit of the $n_f=2+1$ lattice quantum chromodynamics (LQCD) results from the PACS-CS, LHPC, HSC, QCDSF-UKQCD and NPLQCD collaborations is achieved. Finite-volume corrections to the lattice data are calculated self-consistently. Our study shows that N$^3$LO BChPT describes better the light quark mass evolution of the lattice data than the NNLO BChPT does and the various lattice simulations seem to be consistent with each other. We also predict the pion and strangeness sigma terms of the octet baryons using the LECs determined in the fit of their masses. The predicted pion- and strangeness-nucleon sigma terms are $\sigma_{\pi N}=43(1)(6)$ MeV and $\sigma_{s N}=126(24)(54)$ MeV, respectively.Comment: 28 pages, 6 figures, minor revisions, typos corrected, version to appear in JHE

Ultraschnelle Desorption durch stoßartige Vibrationsanregung (DIVE): Anwendungen in Laserchirugie, Massenspektrometrie und Fortschritte in Richtung der ultimativen Grenzen von Biodiagnosen

DieWeiterentwicklung minimal-invasiver chirurgischer Eingriffe, räumlich aufgelöster Massenspektrometrie und von ioanalysen mit hohem Durchsatz, bedürfen neuartiger Methoden um Gewebe zu schneiden und zur Extraktion von biologischen Molekülen ohne Veränderung der molekularen Struktur. In dieser Arbeit wird ein lasergestützer Ablationsprozess verwandt, der in der Lage ist präzise Gewebeschnitte mit minimalem Kollateralschaden auszuführen und außerdem biologische Komplexe unter Erhalt der biologischen Funktionalität aus dem Gewebe extrahiert. Die Methode basiert auf dem erst kürzlich entwickelten Picosekunden Infrarotlaser (PIRL). Dieser ist speziell dazu entwickelt worden um selektiv die Vibrationsmoden vonWasser anzuregen und dabei die Bedingung von ultraschneller Desorption durch stoßartige Vibrationsanregung (DIVE) zu erfüllen. Die grundlegende Funktionsweise ist, dass die selektiv angeregten Wassermoleküle als Treibmittel dienen um ganze biologische Strukturen aus der Oberfläche herauszulösen. Der Extraktionsprozess verläuft dabei schneller als alle thermischen schädlichen Effekte oder Fragmentation welche die Eigenschaften der Moleküle verändern würden. Die Ablation unter der DIVE Bedingung wird erstmals auf sechs verschiedene Gewebe des Auges angewandt und erzielt dabei präzise, gut kontrollierbare, reproduzierbare und minimal-invasive Schnitte. Unter anderem konnte die berührungslose und aplanationsfreie Hornhauttrepanation gezeigt werden. Massenspektrometrie und andere analytische Methoden zeigen, dass eine große Anzahl von Proteinen unterschiedlichster molekularer Massen durch die PIRL Ablation aus dem Gewebe extrahiert wird und dass diese Proteine in der Ablationswolke weder durch Fragmentation noch durch andere chemische Prozesse verändert sind. Mit unterschiedlichten Mikroskopie- und biochemischen Analysemethoden wird gezeigt, dass nanoskalige Einzelmolekülproteine, Viren und Zellen in der Ablationswolke morphologisch und funktional identisch mit ihren Kontrollproben sind. Die PIRL Ablation eröffnet neueWege für die Laserbehandlung in der Ophtamologie und kann dazu verwendet werden die chemische Aktivität in situ und in vivo zu erfassen. Das wichtigste Ergebnis ist die zerstörungsfreie Extraktion von biologischen Komplexen, was eine räumliche kompositorische Rekonstruktion ermöglicht, die nur durch die Größe des Laserfokusses begrenzt ist. Dies bietet enorme Entwicklungsmöglichkeiten für schnelle Hochdurchsatz-Biodiagnosen.The prospects for minimally invasive surgery, spatial imaging with mass spectrometry and rapid high throughput biodiagnosis require new means of tissue incision and biomolecule extraction with conserved molecular structure. Towards this aim, a laser ablation process is utilized in this dissertation, which is capable of performing precise tissue incision with minimal collateral damage and extracting intact biological entities with conserved biological functions. The method is based on the recently developed Picosecond Infrared Laser (PIRL) designed to excite selectively the water vibrational modes under the condition of ultrafast Desorption by Impulsive Vibrational Excitation (DIVE). The basic concept is that the selectively excited water molecules act as propellant to ablate whole biological complexes into the plume, faster than any thermal deleterious effect or fragmentation that would mask molecular identities. The PIRL ablation under DIVE condition is applied for the first time to six types of ocular tissues, rendering precise and minimally invasive incisions in a well-controlled and reproducible way. An eminent demonstration is the contact-free and applanation-free corneal trephination with the PIRL. Mass spectrometry and other analytical techniques show that great abundance of proteins with various molecular weights are extracted from the tissue by the PIRL ablation, and that fragmentation or other chemical alternation does not occur to the proteins in the ablation plume. With various microscope imaging and biochemical analysis methods, nano-scale single protein molecules, viruses and cells in the ablation plume are found to be morphologically and functionally identical to their corresponding controls. The PIRL ablation provides a new means to push the frontiers of laser surgery in ophthalmology and can be applied to resolve chemical activities in situ and in vivo. The most important finding is the conserved nature of the extracted biological entities, rendering compositional reconstruction possible at the spatial limit of the laser focus, which has conspicuous potential in advancing rapid highthroughput biodiagnosis

Ultrafast initialization and QND-readout of a spin qubit via control of nanodot-vacuum coupling

Ultrafast initialization enables fault-tolerant processing of quantum information while QND readout enables scalable quantum computation. By spatially assembling photon resonators and wave-guides around an n-doped nanodot and by temporally designing optical pump pulses, an efficient quantum pathway can be established from an electron spin to a charged exciton to a cavity photon and finally to a flying photon in the waveguide. Such control of vacuum-nanodot coupling can be exploited for ultrafast initialization and QND readout of the spin, which are particularly compatible with the optically driven spin quantum computers.Comment: 4 pages 3 figure