6,085 research outputs found

    The Bone-Muscle Relationship in Men and Women

    Get PDF
    Muscle forces are a strong determinant of bone structure, particularly during the process of growth and development. The gender divergence in the bone-muscle relationship becomes strongly evident during adolescence. In females, growth is characterized by increased estrogen levels and increased mass and strength of bone relative to that of muscle, whereas in men, increases in testosterone fuel large increases in muscle, resulting in muscle forces that coincide with a large growth in bone dimensions and strength. In adulthood, significant age-related losses are observed for both bone and muscle tissues. Large decrease in estrogen levels in women appears to diminish the skeleton's responsiveness to exercise more than in men. In contrast, the aging of the muscle-bone axis in men is a function of age related declines in both hormones. In addition to the well-known age related changes in the mechanical loading of bone by muscle, newer studies appear to provide evidence of age- and gender-related variations in molecular signaling between bone and muscle that are independent of purely mechanical interactions. In summary, gender differences in the acquisition and age-related loss in bone and muscle tissues may be important for developing gender-specific strategies for using exercise to reduce bone loss with aging

    Entanglement Spectra of Interacting Fermions in Quantum Monte Carlo Simulations

    Full text link
    In a recent article T. Grover [Phys. Rev. Lett. 111, 130402 (2013)] introduced a simple method to compute Renyi entanglement entropies in the realm of the auxiliary field quantum Monte Carlo algorithm. Here, we further develop this approach and provide a stabilization scheme to compute higher order Renyi entropies and an extension to access the entanglement spectrum. The method is tested on systems of correlated topological insulators.Comment: 7+ pages, 5 figure

    Spontaneous particle-hole symmetry breaking of correlated fermions on the Lieb lattice

    Full text link
    We study spinless fermions with nearest-neighbor repulsive interactions (tt-VV model) on the two-dimensional three-band Lieb lattice. At half-filling, the free electronic band structure consists of a flat band at zero energy and a single cone with linear dispersion. The flat band is expected to be unstable upon inclusion of electronic correlations, and a natural channel is charge order. However, due to the three-orbital unit cell, commensurate charge order implies an imbalance of electron and hole densities and therefore doping away from half-filling. Our numerical results show that below a finite-temperature Ising transition a charge density wave with one electron and two holes per unit cell and its partner under particle-hole transformation are spontaneously generated. Our calculations are based on recent advances in auxiliary-field and continuous-time quantum Monte Carlo simulations that allow sign-free simulations of spinless fermions at half-filling. It is argued that particle-hole symmetry breaking provides a route to access levels of finite doping, without introducing a sign problem.Comment: 9 pages, 6 figures, added data for strong Coulomb repulsion and classical Ising-limi

    Praziquantel in clonorchiasis and opisthorchiasis

    Get PDF
    A single stool examination revealed pathogenic intestinal parasites in 462 (58%) of 796 vietnamese and cambodian refugees. 56 (7.0%) were infected with Clonorchis sinensis and/or Opisthorchis viverrini. These patients received Praziquantel in a dosage of 20 mg/kg bwt. p.day on 3 consecutive days. Parasitological controls were completed after 12 months. No further excretion of eggs could be detected in 88% of the patients. Concurrent infections with other trematodes and cestodes were also cured. Nematode infections remained uninfluenced. No change of haematological and biochemical parameters could be observed during therapy. Diarrhea and epigastric pain were common side effects, which are probably not effects of the drug itself. They rather seem to be due to the release of parasitic antigens. This is also indicated by a further increase of circulating Ig E after therapy

    Dimerized Solids and Resonating Plaquette Order in SU(N)-Dirac Fermions

    Full text link
    We study the quantum phases of fermions with an explicit SU(N)-symmetric, Heisenberg-like nearest-neighbor flavor exchange interaction on the honeycomb lattice at half-filling. Employing projective (zero temperature) quantum Monte Carlo simulations for even values of N, we explore the evolution from a weak-coupling semimetal into the strong-coupling, insulating regime. Furthermore, we compare our numerical results to a saddle-point approximation in the large-N limit. From the large-N regime down to the SU(6) case, the insulating state is found to be a columnar valence bond crystal, with a direct transition to the semimetal at weak, finite coupling, in agreement with the mean-field result in the large-N limit. At SU(4) however, the insulator exhibits a subtly different valence bond crystal structure, stabilized by resonating valence bond plaquettes. In the SU(2) limit, our results support a direct transition between the semimetal and an antiferromagnetic insulator.Comment: 5 pages, 6 figure

    Dynamical Signatures of Edge-State Magnetism on Graphene Nanoribbons

    Full text link
    We investigate the edge-state magnetism of graphene nanoribbons using projective quantum Monte Carlo simulations and a self-consistent mean-field approximation of the Hubbard model. The static magnetic correlations are found to be short ranged. Nevertheless, the correlation length increases with the width of the ribbon such that already for ribbons of moderate widths we observe a strong trend towards mean-field-type ferromagnetic correlations at a zigzag edge. These correlations are accompanied by a dominant low-energy peak in the local spectral function and we propose that this can be used to detect edge-state magnetism by scanning tunneling microscopy. The dynamic spin structure factor at the edge of a ribbon exhibits an approximately linearly dispersing collective magnonlike mode at low energies that decays into Stoner modes beyond the energy scale where it merges into the particle-hole continuum.Comment: 4+ pages including 4 figure

    A statistical method (cross-validation) for bone loss region detection after spaceflight.

    Get PDF
    Astronauts experience bone loss after the long spaceflight missions. Identifying specific regions that undergo the greatest losses (e.g. the proximal femur) could reveal information about the processes of bone loss in disuse and disease. Methods for detecting such regions, however, remains an open problem. This paper focuses on statistical methods to detect such regions. We perform statistical parametric mapping to get t-maps of changes in images, and propose a new cross-validation method to select an optimum suprathreshold for forming clusters of pixels. Once these candidate clusters are formed, we use permutation testing of longitudinal labels to derive significant changes

    Antiferromagnetism in the Hubbard Model on the Bernal-stacked Honeycomb Bilayer

    Full text link
    Using a combination of quantum Monte Carlo simulations, functional renormalization group calculations and mean-field theory, we study the Hubbard model on the Bernal-stacked honeycomb bilayer at half-filling as a model system for bilayer graphene. The free bands consisting of two Fermi points with quadratic dispersions lead to a finite density of states at the Fermi level, which triggers an antiferromagnetic instability that spontaneously breaks sublattice and spin rotational symmetry once local Coulomb repulsions are introduced. Our results reveal an inhomogeneous participation of the spin moments in the ordered ground state, with enhanced moments at the three-fold coordinated sites. Furthermore, we find the antiferromagnetic ground state to be robust with respect to enhanced interlayer couplings and extended Coulomb interactions.Comment: 4+ pages, 4 figures; final versio

    ОБОСНОВАНИЕ МЕТОДОВ РАСЧЕТОВ ПАРАМЕТРОВ ГИДРОТРАНСПОРТА ВыСОКОКОНЦЕНТРИРОВАННыХ ГИДРОСМЕСЕЙ

    No full text
    Днепропетровская область – крупный промышленный регион, в котором сосредоточены предприятия металлургической, химической и машинострои-тельной отраслей промышленности, расположенный на пересечении водных путей, железнодорожных и автомобильных магистралей, направленных к ме-сторождениям каменных углей и железной руды. Металлургические заводы, коксохимические комбинаты и тепловые электростанции являются крупней-шими потребителями воды, основного экологического ресурса планеты, а также основными источниками загрязнения водного бассейна региона. Несмотря на использование на таких предприятиях замкнутых циклов водоснабжения, про-блема аккумулирования жидких отходов остается для них актуальной и острой. Особенно актуальным это является для горно-обогатительных комбинатов (ГОК) Кривбасса, большая часть которых заканчивает эксплуатацию хранилищ отходов, построенных в 60-70 годы прошлого столетия. Дальнейшее развитие региона во многом определяется промышленным потенциалом этих предпри-ятий, поскольку они, с одной стороны, являются потребителями угля, железной руды и прочих ресурсов, чем обеспечивают работоспособность отечественных предприятий, а с другой стороны, выпускают продукцию, потребителями кото-рой являются многие предприятия страны
    corecore