The predictive role of raw bioelectrical impedance parameters in water compartments and fluid distribution assessed by dilution techniques in athletes

The aims of this study were to analyze the usefulness of raw bioelectrical impedance (BI) parameters in assessing water compartments and fluid distribution in athletes. A total of 202 men and 71 female athletes were analyzed. Total body water (TBW) and extracellular water (ECW) were determined by dilution techniques, while intracellular water (ICW) was calculated. Fluid distribution was calculated as the ECW/ICW ratio (E:I). Phase angle (PhA), resistance (R) and reactance (Xc) were obtained through BI spectroscopy using frequency 50kHz. Fat (FM) and fat\u2010free mass (FFM) were assessed by dual\u2010energy X\u2010ray absorptiometry. After adjusting for height, FM, FFM, age and sports category we observed that: PhA predicted ICW (females: \u3b2 = 1.62, p < 0.01; males: \u3b2 = 2.70, p < 0.01) and E:I (males and females: \u3b2 = 120.08; p < 0.01); R explained TBW (females: \u3b2 = 120.03; p < 0.01; males: \u3b2 = 120.06; p < 0.01) and ECW (females: \u3b2 = \u20130.02, p < 0.01; males: \u3b2 = 120.03, p < 0.01) and ICW (females: \u3b2 = \u20130.01, p < 0.053; males: \u3b2 = \u20130.03 p < 0.01); and Xc predicted ECW (females: \u3b2 = 120.06, p < 0.01; males: \u3b2 = 120.12, p < 0.01). A higher PhA is a good predictor of a larger ICW pool and a lower E:I, regardless of body composition, age, height, and sports category. Lower R is associated with higher water pools whereas ECW expansion is explained by lower Xc. Raw BI parameters are useful predictors of total and extracellular pools, cellular hydration and fluid distribution in athletes

Entanglement in quantum computers described by the XXZ model with defects

We investigate how to generate maximally entangled states in systems characterized by the Hamiltonian of the XXZ model with defects. Some proposed quantum computers are described by such model. We show how the defects can be used to obtain EPR states and W states when one or two excitations are considered.Comment: 4 pages, 1 figur

Two-particle localization and antiresonance in disordered spin and qubit chains

We show that, in a system with defects, two-particle states may experience destructive quantum interference, or antiresonance. It prevents an excitation localized on a defect from decaying even where the decay is allowed by energy conservation. The system studied is a qubit chain or an equivalent spin chain with an anisotropic ($XXZ$) exchange coupling in a magnetic field. The chain has a defect with an excess on-site energy. It corresponds to a qubit with the level spacing different from other qubits. We show that, because of the interaction between excitations, a single defect may lead to multiple localized states. The energy spectra and localization lengths are found for two-excitation states. The localization of excitations facilitates the operation of a quantum computer. Analytical results for strongly anisotropic coupling are confirmed by numerical studies.Comment: Updated version, 13 pages, 5 figures To appear in Phys. Rev. B (2003

Violation of self-similarity in the expansion of a 1D Bose gas

The expansion of a 1D Bose gas is investigated employing the Lieb-Liniger equation of state within the local density approximation. We show that during the expansion the density profile of the gas does not follow a self-similar solution, as one would expect from a simple scaling Ansatz. We carry out a variational calculation, which recovers the numerical results for the expansion, the equilibrium properties of the density profile, and the frequency of the lowest compressional mode. The variational approach allows for the analysis of the expansion in all interaction regimes between the mean field and the Tonks-Girardeau limits, and in particular shows the range of parameters for which the expansion violates self-similarity.Comment: 6 pages, 5 eps figure

\eta-superconductivity in the Hubbard chain with pair hopping

The ground state phase diagram of the 1D Hubbard chain with pair-hopping interaction is studied. The analysis of the model is performed using the continuum-limit field theory approach and exact diagonalization studies. At half-filling the phase diagram is shown to consist of two superconducting states with Cooper pair center-of-mass momentum Q=0 (BCS-\eta_0 phase) and Q=\pi (\eta_\pi-phase) and four insulating phases corresponding to the Mott antiferromagnet, the Peierls dimerized phase, the charge-density-wave (CDW) insulator as well as an unconventional insulating phase characterized by the coexistence of a CDW and a bond-located staggered magnetization. Away from half-filling the phase diagram consists of the superconducting BCS-\eta_0 and \eta_\pi phases and the metallic Luttinger-liquid phase. The BCS-\eta_0 phase exhibits smooth crossover from a weak-coupling BCS type to a strong coupling local-pair regime. The \eta_\pi phase shows properties of the doublon (zero size Cooper pair) superconductor with Cooper pair center-of-mass momentum Q=\pi. The transition into the \eta_\pi- paired state corresponds to an abrupt change in the groundstate structure. After the transition the conduction band is completely destroyed and a new \eta_\pi-pair band corresponding to the strongly correlated doublon motion is created.Comment: 15 pages Revtex, 15 embedded eps figure

Análise da superfície e osseointegração de implantes dentários com superfícies biomiméticas contedo Ca, Mg e F

Os tratamentos das superfícies dos implantes dentários osseointegráveis sofreram modificações significativas com o objetivo de melhorar a estabilidade primária e secundária. Entre as modificações destaca-se a deposição de íons, como flúor, cálcio e magnésio. Estes íons possuem baixa taxa de degradação no meio corpóreo e ótima interação biológica com as células e com os tecidos ósseos. No presente trabalho, para avaliar os efeitos do F, Ca e do Mg na osseointegração foram realizados ensaios in vitro e in vivo. Implantes foram inseridos em tíbias de coelhos e determinou-se os torques de inserção e remoção após 2, 4 e 8 semanas. Os ensaios in vivo foram complementados pela medida da rugosidade, molhabilidade e análise da superfície em microscopia eletrônica de varredura. Os resultados foram comparados com os obtidos com implantes com a superfície tratada com ácido (superfície Porous) e com deposição de flúor (superfície Porous Nano). Os resultados obtidos mostraram que o torque para remover os implantes Porous 8 semanas após a cirurgia foi de 16,96 + 1,32 N.cm, o tratado com flúor apresentou melhores resultados (17,93 ± 4,47 N.cm) e a superfície com Ca e Mg foi a que apresentou a interface osso-implante com menor resistência (10,83 + 1,20 N.cm). O maior torque indica que a adição de flúor facilita os mecanismos envolvidos na osseointegração dos implantes e permite o carregamento da prótese em tempos menores

Characterisation of the muon beams for the Muon Ionisation Cooling Experiment

A novel single-particle technique to measure emittance has been developed and used to characterise seventeen different muon beams for the Muon Ionisation Cooling Experiment (MICE). The muon beams, whose mean momenta vary from 171 to 281 MeV/c, have emittances of approximately 1.2–2.3 π mm-rad horizontally and 0.6–1.0 π mm-rad vertically, a horizontal dispersion of 90–190 mm and momentum spreads of about 25 MeV/c. There is reasonable agreement between the measured parameters of the beams and the results of simulations. The beams are found to meet the requirements of MICE