Torsion and gravitation: A new view

According to the teleparallel equivalent of general relativity, curvature and torsion are two equivalent ways of describing the same gravitational field. Though equivalent, they act differently: curvature yields a geometric description, in which the concept of gravitational force is absent whereas torsion acts as a true gravitational force, quite similar to the Lorentz force of electrodynamics. As a consequence, the right-hand side of a spinless-particle equation of motion (which would represent a gravitational force) is always zero in the geometric description, but not in the teleparallel case. This means that the gravitational coupling prescription can be minimal only in the geometric case. Relying on this property, a new gravitational coupling prescription in the presence of curvature and torsion is proposed. It is constructed in such a way to preserve the equivalence between curvature and torsion, and its basic property is to be equivalent to the usual coupling prescription of general relativity. According to this view, no new physics is connected with torsion, which is just an alternative to curvature in the description of gravitation. An application of this formulation to the equations of motion of both a spinless and a spinning particle is discussed.

Alternative interpretations of some earliest ediacaran fossils from China

In a letter to Nature (February, 2011), Xunlai Yuan and collaborators recorded carbon compression fossils from black shales of the Lantian Formation (Ediacaran), southern Anhui Province, South China. The new fossils, described under five morphological types (Types A to E), exhibit degrees of morphological differentiation suggesting that they were multicellular eukaryotes. Some of the Lantian macrofossils were interpreted as algae, but others are of unknown affinities. For reasons noted in this discussion, Type A fossils attracted our particular attention, and we suggest an alternative interpretation of their affinities. According to our view, some of them (at least those with three faces and no globose holdfast at their base) may represent conulariid cnidarians or close medusozoan relatives. The undistorted organism probably was a three-sided cone in life. We believe that our suggested alternative interpretations of the anatomy and affinities of the fossils in question can be useful in guiding future research on the oldest currently known fossil assemblage of multicellular organisms. Copyright © 2012.

Acetone as a greener alternative to acetonitrile in liquid chromatographic fingerprinting

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Intravenous procedural sedation: an alternative in the treatment of patients with intellectual disability

Conscious sedation has become established as an important alternative to general anesthesia (GA) in dental treatment of patients with intellectual disability (ID). Aim: to investigate dental patients undergoing sedation using a mean dose of 0.6 mg/kg intravenous midazolam and the adverse events of sedation in patients with ID. Methods: This study analyzed the records of 163 dental patients with ID aged between 2 and 76 years who had undergone conscious intravenous sedation (CIV) using a mean dose of 0.61 mg/kg of midazolam at Araçatuba Dental School, São Paulo State University, Brazil. The efficacy and complications induced by CIV were evaluated in each subject. Results: CIV was effective for dental treatment in 80% of the cases. A total of 626 dental procedures were performed. The mean treatment time was 33.9 minutes. There was statistically significant difference (p<0.05) between absence and presence of adverse reactions. Adverse reactions were observed in 21.47% of the cases. Conclusions: The results of this study showed that CIV is a useful method for dental treatment of patients with ID and these patients can need higher doses of sedative to reach an adequate level of sedation.