Is There an Absolute Scale for Speed?

Except for the speed of photons in vacuum, all speeds are relative. Could we develop an absolute scale for speed in which relative values for speed may be arbitrarily positioned and compared in absolute terms? The currently accepted definition for the meter as the distance covered by photons in vacuum during 1/299,792,458 s, and the view that the greater a material particle is accelerated towards c, the greater time dilation and length contraction will be, suggest that anything disturbing one of the four spacetime dimensions may affect the other three as well. One hypothetical experiment, one real experiment performed in the 1970s, and one experiment from a different field of science are discussed to propose that both time and velocity are only partially relative. In the first experiment, person A is standing still on the Earth’s surface, and person B is onboard a train passing by person A at the constant speed of 60 km/h (as measured by person B on the train’s speedometer). Persons A and B define two distinct inertial frames of reference, which correspond to two different spacetime conditions and which are therefore characterized by comparatively different lengths of the meter and durations of the second, as predicted by the Lorentz factor. Therefore, if person B onboard the train measures the train’s speed relative to person A as 60 km/h, a simple calculation will show that person A will perceive the train passing by at 59.99999999999981455834 km/h. If we consider the speed of photons in vacuum (c = 299,792,458 m/s) as a universal reference, and if we consider that the greater a material particle is accelerated towards c, the greater time dilation and length contraction will be, then person C, occupying an independent, distinct inertial frame of reference, will be unable to determine persons A and B’s absolute speeds, but may infer which one is moving at a speed closer to c by comparing, with his own meter and second, the durations of the second and the lengths of the meter experienced by persons A and B. The relativity of time may not be complete due to the bias that derives from the limit imposed on spacetime by c and the Lorentz factor, causing relativity to be partial. The second and third experiments further help understand this partiality.

Suicide among Physicians and Methodological Similarities of MEDLINE/PubMED and BVS/BIREME Open Access Bibliographic Databases: A Systematic Review with Metanalysis

Background: Suicide among physicians is a serious public health issue, with an extremely complex and multifactorial behavior. Aim: The aim of this study was to use the theme “Suicide among Physicians” to exemplify the analysis of methodological similarities between the scientific content available at MEDLINE and BVS databases, as scientific research tools. Methods: This is a systematic review with metanalysis. The following combinations of keywords were used for data search in the referred databases: “suicide” AND “physicians” AND “public heath”. Results: Three hundred and thirteen publications were identified, but only 16 studies were chosen. Great association was found between MEDLINE and BVS databases and the Odds Ratio regarding the theme: “Suicide among physicians”. Conclusions: Considering the similarities found in the utilization of the two analyzed databases, it was possible to identify that suicide among physicians is associated with the exercise of an important professional role in the society and in the workplace. With regard to scientific information, the p-value-obtained value (<0.05) seems to be statistically significant for the association between the suggested theme and the methodological similarities of the scientific information available in the analyzed databases. Thus, these open-access research tools are considered scientific reliable tools.

An Application of the Taguchi Method (Robust Design) to Environmental Engineering: Evaluating Advanced Oxidative Processes in Polyester-Resin Wastewater Treatment

This paper presents the Taguchi Method, a statistical design modelling for experiments applied in environmental engineering. This method was applied to optimize the treatment conditions of polyester-resin effluent by means of Advanced Oxidative Processes (AOPs) using chemical oxygen demand (COD) as response parameter. The influence of each independent parameter including respective interactions was evaluated by Taguchi Method, which allowed determining the most statistically significant variables and conditions to best fit the process. Results showed that Taguchi Method is a very useful tool for environmental engineering field and possible simplifications of analysis and calculations through commercially available software.

Brown Algae <i>Himantothallus grandifolius</i>(Desmarestiales, Phaeophyceae) Suppresses Proliferation and Promotes Apoptosis-Mediated Cell Death in Tumor Cells

Marine algae have been used as food since ancient times and today are consumed as a regular part of the diet. In this study, we hypothesized that H. grandifolius phlorotannins-enriched extract exerts cytotoxic selective effects against tumor cell lines promoting cell death trough apoptosis mechanisms. The aim of the present study is to characterize chemically and investigate the selective cytotoxic effect of the H. grandifolius extract on epithelial tumour cell lines (A375, A549, Hep-2, HeLa) compared to non-malignant cell line (Hek-293), and evaluate possible molecular mechanisms involved in the programmed cell death pathway. High-resolution directly-infusion mass spectrometry (HR-DIMS) analysis with electrospray ionization (ESI) was performed in positive and negative mode. Cytotoxicity was evaluated through colorimetric assay and morphological alterations were observed in giemsa stained cells after extract treatment. Apoptosis was further evaluated by annexin V staining. Spectra showed peaks m/z between 370 and 430 and molecular formula was defined upon isotopic ratio. Extract showed selectivity to the non-tumor line with enhanced cytotoxicity in tumor cells according to the concentration and exposure time. After 72 h treatment, the HeLa strain was more susceptible to the extract, followed by lines Hep2, A375 and A549. Morphological changes by giemsa were observed after increased doses of extracts and staining for annexin V showed majority of tumor cells at early stages of the apoptotic process. Here, selective anti-tumor activity of extract taken from the alga H. grandifolius was able to suppress proliferation and promote apoptosis-mediated cell death with induction of initial stages of apoptosis in different cell lines.

A Reference Model for the Analysis and Comparison of MDE Approaches for Web-Application Development

The emerging Model-Driven Engineering (MDE) paradigm advocates the use of models as first-class citizens in the software development process, while artifacts such as documentation and source-code can be quickly produced from those models by using automated transformations. Even though many MDE-oriented approaches, languages and tools have been developed in the recent past, there is no standard that concretely defines a specific sequence of steps to obtain a functional software system from a model. Thus, the existing approaches present numerous differences among themselves, because each one handles the problems inherent to software development in its own way. This paper presents and discusses a reference model for the comparative study of current MDE approaches in the scope of web-application development. This reference model focuses on relevant aspects such as modeling language scope (domain, business-logic, user-interface), usage of patterns, separation of concerns, model transformations, tool support, and deployment details like web-platform independence and traditional programming required. The ultimate goal of this paper is to determine the aspects that will be of greater importance in future web-oriented MDE languages.