Extended Birkhoff's Theorem in the f(T) Gravity

The f(T) theory, a generally modified teleparallel gravity, has been proposed as an alternative gravity model to account for the dark energy phenomena. Following our previous work [Xin-he Meng and Ying-bin Wang, EPJC(2011), arXiv:1107.0629v1], we prove that the Birkhoff's theorem holds in a more general context, specifically with the off diagonal tetrad case, in this communication letter. Then, we discuss respectively the results of the external vacuum and internal gravitational field in the f(T) gravity framework, as well as the extended meaning of this theorem. We also investigate the validity of the Birkhoff's theorem in the frame of f(T) gravity via conformal transformation by regarding the Brans-Dicke-like scalar as effective matter, and study the equivalence between both Einstein frame and Jordan frame.Comment: 7 pages, 1 figure, submitted to EPJ-C. arXiv admin note: substantial text overlap with arXiv:1107.062

Mobilise-D insights to estimate real-world walking speed in multiple conditions with a wearable device

This study aimed to validate a wearable device’s walking speed estimation pipeline, considering complexity, speed, and walking bout duration. The goal was to provide recommendations on the use of wearable devices for real-world mobility analysis. Participants with Parkinson’s Disease, Multiple Sclerosis, Proximal Femoral Fracture, Chronic Obstructive Pulmonary Disease, Congestive Heart Failure, and healthy older adults (n = 97) were monitored in the laboratory and the real-world (2.5 h), using a lower back wearable device. Two walking speed estimation pipelines were validated across 4408/1298 (2.5 h/laboratory) detected walking bouts, compared to 4620/1365 bouts detected by a multi-sensor reference system. In the laboratory, the mean absolute error (MAE) and mean relative error (MRE) for walking speed estimation ranged from 0.06 to 0.12 m/s and − 2.1 to 14.4%, with ICCs (Intraclass correlation coefficients) between good (0.79) and excellent (0.91). Real-world MAE ranged from 0.09 to 0.13, MARE from 1.3 to 22.7%, with ICCs indicating moderate (0.57) to good (0.88) agreement. Lower errors were observed for cohorts without major gait impairments, less complex tasks, and longer walking bouts. The analytical pipelines demonstrated moderate to good accuracy in estimating walking speed. Accuracy depended on confounding factors, emphasizing the need for robust technical validation before clinical application. Trial registration: ISRCTN – 12246987

Automatic Covert Channel Analysis of a Multilevel Secure Component

The NRL Pump protocol defines a multilevel secure component whose goal is to minimize leaks of information from high level systems to lower level systems, without degrading average time performances

Especializações em psicologia: subsídios para uma discussão necessária

O presente trabalho discute criticamente a proposição de áreas de especialização profissional para a psicologia. Com o propósito de oferecer um quadro conceitual que possa orientar a discussão subseqüente, algumas categorias heurísticas de análise são tentativamente propostas e algumas das propostas formais e/ou informais de especialização são discutidas à luz dessas categorias. O autor considera que a ausência de uma demonstração inequívoca e epistemologicamente sólida do caráter específico e da utilidade daquelas especializações, aliada aos riscos que uma fragmentação prematura pode trazer para a profissão, indica a conveniência de se adiar o reconhecimento formal e oficial dessas propostas

Postconditioning of sevoflurane and propofol is associated with mitochondrial permeability transition pore*

Background: Sevoflurane and propofol are effective cardioprotective anaesthetic agents, though the cardioprotection of propofol has not been shown in humans. Their roles and underlying mechanisms in anesthetic postconditioning are unclear. Mitochondrial permeability transition pore (MPTP) opening is a major cause of ischemia-reperfusion injury. Here we investigated sevoflurane- and propofol-induced postconditioning and their relationship with MPTP. Methods: Isolated perfused rat hearts were exposed to 40 min of ischemia followed by 1 h of reperfusion. During the first 15 min of reperfusion, hearts were treated with either control buffer (CTRL group) or buffer containing 20 µmol/L atractyloside (ATR group), 3% (v/v) sevoflurane (SPC group), 50 µmol/L propofol (PPC group), or the combination of atractyloside with respective anesthetics (SPC+ATR and PPC+ATR groups). Infarct size was determined by dividing the total necrotic area of the left ventricle by the total left ventricular slice area (percent necrotic area). Results: Hearts treated with sevoflurane or propofol showed significantly better recovery of coronary flow, end-diastolic pressures, left ventricular developed pressure and derivatives compared with controls. Sevoflurane resulted in more protective alteration of hemodynamics at most time point of reperfusion than propofol. These improvements were paralleled with the reduction of lactate dehydrogenase release and the decrease of infarct size (SPC vs CTRL: (17.48±2.70)% vs (48.47±6.03)%, P<0.05; PPC vs CTRL: (35.60±2.10)% vs (48.47±6.03)%, P<0.05). SPC group had less infarct size than PPC group (SPC vs PPC: (17.48±2.70)% vs (35.60±2.10)%, P<0.05). Atractyloside coadministration attenuated or completely blocked the cardioprotective effect of postconditioning of sevoflurane and propofol. Conclusion: Postconditioning of sevoflurane and propofol has cardioprotective effect against ischemia-reperfusion injury of heart, which is associated with inhibition of MPTP opening. Compared to propofol, sevoflurane provides superior protection of functional recovery and infarct size

Empirical pseudopotential and full-Brillouin-zone k*p electronic structure of CdTe, HgTe and HgCdTe

Two alternative approximations of the electronic structure of CdTe and HgTe are proposed, both suited to the needs of accuracy and numerical efficiency of full-band carrier transport simulation: a local empirical pseudopotential (EPM) parametrization including relativistic corrections, and an original full- Brillouin-zone (FBZ) k.p model using two expansion points (C and W). The EPM and k.p band structures closely match the available experimental and ab initio information, complemented with the results of new density functional theory (DFT)-local density approximation (LDA) calculations, for the conduction and valence bands relevant in transport phenomena. The EPM description of the binary compounds, featuring transferable Te pseudopotentials, is the basis for a computation of the electronic structure of the ternary alloy HgCdTe in the framework of disorder-corrected virtual crystal approximation. The composition dependence of energy gaps, effective masses, and high-frequency dielectric constants are discussed and compared with available experimental data, and the novel FBZ approach is applied to the case of x = 0.