1,749 research outputs found

    Osteoporosis and vertebral trabecular bone health: an historico-anthropological perspective

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    This brief review article aims to recapitulate the history of osteoporosis from the most ancient observations to the current clinical definition, by offering a perspective on trabecular bone health and degeneration, which has become of paramount important both in clinical, radiological and biological anthropological studies

    Coherent Control of Trapped Bosons

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    We investigate the quantum behavior of a mesoscopic two-boson system produced by number-squeezing ultracold gases of alkali metal atoms. The quantum Poincare maps of the wavefunctions are affected by chaos in those regions of the phase space where the classical dynamics produces features that are comparable to hbar. We also investigate the possibility for quantum control in the dynamics of excitations in these systems. Controlled excitations are mediated by pulsed signals that cause Stimulated Raman Adiabatic passage (STIRAP) from the ground state to a state of higher energy. The dynamics of this transition is affected by chaos caused by the pulses in certain regions of the phase space. A transition to chaos can thus provide a method of controlling STIRAP.Comment: 17 figures, Appended a paragraph on section 1 and explained details behind the hamiltonian on section

    The Swiss Canton of Thurgau – not the Kingdom of Bavaria—was the first state to introduce compulsory vaccination against smallpox

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    In the wake of the COVID-19 pandemic, several countries introduced compulsory vaccination. Even earlier, in the infancy of the vaccination tradition, there used to be instances of compulsory vaccination against smallpox, one of the deadliest known enemies of human health until its utter eradication in 1980.In the scientific literature, the Kingdom of Bavaria (1805–1918) is often reported to have been the first state entity to have introduced compulsory vaccination in 1807. Nonetheless, it was the Canton of Thurgau (Kanton Thurgau or Thurgovia, Fig. 1a), in Eastern Switzerland, that first issued such an ordinance in 1806..

    COVID-19, a viral endocrinological disease?

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    Ever since Chinese health officials informed the WHO of the presence of 44 patients suffering from an anomalous pneumonia apparently linked with the Huanan Seafood Wholesale Market (Wuhan City) on 3rd January 2020, a conspicuous number of scientific publications on COVID-19 have understandably focused either on the main clinical presentation of the novel pathological entity or the response of the immune system to its pathogenic agent, thus following in the footsteps of the established hermeneutical research approach of contemporary infectivological studies..

    Inside UNLV

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    Conedy: a scientific tool to investigate Complex Network Dynamics

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    We present Conedy, a performant scientific tool to numerically investigate dynamics on complex networks. Conedy allows to create networks and provides automatic code generation and compilation to ensure performant treatment of arbitrary node dynamics. Conedy can be interfaced via an internal script interpreter or via a Python module

    Phase transitions and phase diagram of the ferroelectric perovskite NBT-BT by anelastic and dielectric measurements

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    The complex elastic compliance and dielectric susceptibility of (Na_{0.5}Bi_{0.5})_{1-x}Ba_{x}TiO_{3} (NBT-BT) have been measured in the composition range between pure NBT and the morphotropic phase boundary included, 0 <= x <= 0.08. The compliance of NBT presents sharp peaks at the rhombohedral/tetragonal and tetragonal/cubic transitions, allowing the determination of the tetragonal region of the phase diagram, up to now impossible due to the strong lattice disorder and small distortions and polarizations involved. In spite of ample evidence of disorder and structural heterogeneity, the R-T transition remains sharp up to x = 0.06, whereas the T-C transition merges into the diffuse and relaxor-like transition associated with broad maxima of the dielectric and elastic susceptibilities. An attempt is made at relating the different features in the anelastic and dielectric curves to different modes of octahedral rotations and polar cation shifts. The possibility is also considered that the cation displacements locally have monoclinic symmetry, as for PZT near the morphotropic phase boundary.Comment: 11 pages, 9 figures, submitted to Phys. Rev.

    Low-temperature phase transformations of PZT in the morphotropic phase-boundary region

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    We present anelastic and dielectric spectroscopy measurements of PbZr(1-x)Ti(x)O(3) with 0.455 < x < 0.53, which provide new information on the low temperature phase transitions. The tetragonal-to-monoclinic transformation is first-order for x < 0.48 and causes a softening of the polycrystal Young's modulus whose amplitude may exceed the one at the cubic-to-tetragonal transformation; this is explainable in terms of linear coupling between shear strain components and tilting angle of polarization in the monoclinic phase. The transition involving rotations of the octahedra below 200 K is visible both in the dielectric and anelastic losses, and it extends within the tetragonal phase, as predicted by recent first-principle calculations.Comment: 4 pages, 4 figure

    RHESSI Spectral Fits of Swift GRBs

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    One of the challenges of the Swift era has been accurately determining Epeak for the prompt GRB emission. RHESSI, which is sensitive from 30 keV to 17 MeV, can extend spectral coverage above the Swift-BAT bandpass. Using the public Swift data, we present results of joint spectral fits for 26 bursts co-observed by RHESSI and Swift-BAT through May 2007. We compare these fits to estimates of Epeak which rely on BAT data alone. A Bayesian Epeak estimator gives better correspondence with our measured results than an estimator relying on correlations with the Swift power law indices.Comment: 4 pages, 1 figure. To appear in the proceedings of Gamma Ray Bursts 2007, Santa Fe, New Mexico, November 5-9 200

    Genghis Khan's death (AD 1227): An unsolvable riddle or simply a pandemic disease?

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    The article examines Genghis Khan's death from the historico-medical perspective. Although several etiologies have been proposed over the years, most of these at a closer look appear to be later inventions by historians. A reassessment of the available evidence suggests instead bubonic plague as the most likely clinical scenario. Genghis Khan's death is also a reflection on the impact of pandemic diseases on leadership in ancient times as well as nowadays
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