Arago (1810): the first experimental result against the ether

95 years before Special Relativity was born, Arago attempted to detect the absolute motion of the Earth by measuring the deflection of starlight passing through a prism fixed to the Earth. The null result of this experiment gave rise to the Fresnel's hypothesis of an ether partly dragged by a moving substance. In the context of Einstein's Relativity, the sole frame which is privileged in Arago's experiment is the proper frame of the prism, and the null result only says that Snell's law is valid in that frame. We revisit the history of this premature first evidence against the ether theory and calculate the Fresnel's dragging coefficient by applying the Huygens' construction in the frame of the prism. We expose the dissimilar treatment received by the ray and the wave front as an unavoidable consequence of the classical notions of space and time.Comment: 16 pages. To appear in European Journal of Physic

Evaluating the admission of graduates of information technology courses on brazilian regional labor market: A study in campi of cities of interior

A política de expansão das universidades brasileiras para o interior foi uma tendência nos últimos anos. O presente artigo apresenta os resultados de uma investigação que avaliou o processo de inserção laboral de egressos dos cursos da área de Tecnologia da Informação (TI) dos campi de interior da Universidade Federal do Ceará (UFC). Foram identificadas as facilidades e dificuldades que os 102 egressos respondentes (68,9% do universo) encontraram ante o mundo do trabalho, revelando uma dificuldade para a inserção laboral nos mercados regionais. A principal contribuição do trabalho foi a análise da estreita relação entre universidade, qualificação profissional, mercado de trabalho e desenvolvimento regionalThe expansion of Brazilian universities policy for the interior has been a trend in recent years. This paper presents the results of a study that evaluated the job placement of graduates from Information Technology (IT) undergraduate courses of the Federal University of Ceará (UFC), Brazil. We identified which facilities and difficulties that 102 graduates surveyed (68.9% of the universe) met at the labor world and our results indicated the difficulty of labor insertion in regional markets. This research sought to contribute to the analysis of the close relationship between university, vocational training, labor market and regional developmen

Mechanics of Micro-Architected Lattice Structures

Honeybees construct nests that consist of tessellated hexagonal prismatic structures. The bees develop a linear succession of tetrapod structures that serve as the nest’s foundation in the initial stage of construction. This natural hexagonal lattice structure has been the epitome of extensive aerospace applications. And, has particularly been widely used on aircraft control surfaces as they provide an ideal set of mechanical properties; minimal density and ability to withstand high magnitudes of compressive and shear force. This paper analyses this hexagonal lattice configuration using theoretical analysis and simulations. It first analyses the lattice structure by breaking it down into three individual components somewhat resembling the constructional stages in which the nests are developed: cantilever beam, unit cell which is initially the tetrapod structure, and the complete system of the lattice itself. In further chapters, refined geometries, namely stepped and quadratic lattice of the honeycomb, are then analysed with the objective of enhancing its strength to weight ratio, this is again analysed through the same bottom-up approach and procedure. Two approaches are implemented in the enhancement procedure. The obtained numerical results are then reviewed through simulations using multiple computer-aided software, Solidworks and ANSYS where the mechanical properties are established and compared

Optical chirality without optical activity: How surface plasmons give a twist to light

Light interacts differently with left and right handed three dimensional chiral objects, like helices, and this leads to the phenomenon known as optical activity. Here, by applying a polarization tomography, we show experimentally, for the first time in the visible domain, that chirality has a different optical manifestation for twisted planar nanostructured metallic objects acting as isolated chiral metaobjects. Our analysis demonstrate how surface plasmons, which are lossy bidimensional electromagnetic waves propagating on top of the structure, can delocalize light information in the just precise way for giving rise to this subtle effect.Comment: Opt. Express 16, 12559 (2008

Reduction of the ATPase inhibitory factor 1 (IF1) leads to visual impairment in vertebrates

In vertebrates, mitochondria are tightly preserved energy producing organelles, which sustain nervous system development and function. The understanding of proteins that regulate their homoeostasis in complex animals is therefore critical and doing so via means of systemic analysis pivotal to inform pathophysiological conditions associated with mitochondrial deficiency. With the goal to decipher the role of the ATPase inhibitory factor 1 (IF1) in brain development, we employed the zebrafish as elected model reporting that the Atpif1a−/− zebrafish mutant, pinotage (pnttq209), which lacks one of the two IF1 paralogous, exhibits visual impairment alongside increased apoptotic bodies and neuroinflammation in both brain and retina. This associates with increased processing of the dynamin-like GTPase optic atrophy 1 (OPA1), whose ablation is a direct cause of inherited optic atrophy. Defects in vision associated with the processing of OPA1 are specular in Atpif1−/− mice thus confirming a regulatory axis, which interlinks IF1 and OPA1 in the definition of mitochondrial fitness and specialised brain functions. This study unveils a functional relay between IF1 and OPA1 in central nervous system besides representing an example of how the zebrafish model could be harnessed to infer the activity of mitochondrial proteins during development

Electrical circuit simulation

Treballs Finals de Grau de Matemàtiques, Facultat de Matemàtiques, Universitat de Barcelona, Any: 2020, Director: Antoni Benseny[en] Given an electrical circuit, formed by wires, nodes, batteries and resistors, the main goal of this work is to solve this electrical circuit. This means finding the electric current in each wire. The graph theory and its use in computer science through data structures, like trees, and hierarchical traversing algorithms, like the Breadth-first search algorithm, will be used to solve the problem. The first part of the project will intend to solve an electrical circuit using C++, the main algorithms used have been described in this paper. The second part of the project will simulate an electrical circuit using graphics and control libraries allowing to interact with the electrical circuit

Biotechnology applied to aromatic plants for the controlled production of bioactive compounds

Salvia sensu lato includes more than about 9000 species and is considered one of the largest taxa of the Lamiaceae (Will et al., 2015). For a long time, Salvia species were known for a wide variety of medicinal used in folk medicine for the relief of pain, protecting the body against oxidative stress, free radical damages, angiogenesis, inflammation, bacterial and virus infection, etc\u2026 (Hamidpour et al., 2014). In vitro cultures have been considered as an alternative agricultural processes for producing secondary metabolites (Y. Kim et al., 2002). The research activity of this PhD project was aimed to the application of in vitro biotechnology techniques applied to aromatic plants for the production of bioactive compounds. The selected plants are species of Salvia showing an important antibacterial activity. The investigation study was carried out on S. corrugata and S. tingitana. Salvia corrugata Vahl. is an ornamental plant that grown easily along the Mediterranean coast. The aerial part is rich in terpenoid compounds like the diterpene quinones fruticuline A and demethylfruticuline A that present high antibacterial activity. Protocols of tissue culture and genetic transformation were set up with the aim to obtain in vitro shoot and hairy root biomass to grown in controlled condition for metabolite extraction. Two strains of Agrobacterium rhizogenes (wild type ATCC 15834 and hypervirulent LBA9402) were tested for their ability to induce hairy root on wounded leaves. The best response (75 %) was achieved by infection with ATCC 15834 about thirty days after the infection onto the hormone-free MS basal solid medium. Two hairy-root lines from ATCC 15834 treatment and one from LBA 9402 treatment were established. Transformation of selected clones was confirmed by polymerase chain reaction analysis of bacterial rolC and virC1 genes. The growth evaluation in TIS RITA\uae bioreactor put in evidence the best cultural conditions for the biomass production; the clone SCO-HR-FA8 had the best increase on Murashige and Skoog (1962) and \ubd Woody plant medium (Lloyd et al., 1980) salt compositions in comparison to other tested media. 30 mg/L was the best sucrose concentration that guaranteed the highest biomass production. The growth curve of HR lie SCO-HR-FA8 was elaborated and then, three classes of elicitors and their combination were tested: a heavy metal ions (Ag+), the yeast extract and plant response-signaling compound (methyl jasmonate MJ). Among them, Ag+ and yeast extract (YE) at high concentration were most effective to stimulate the biomass production. The scale up of the biomass was performed using the bioreactor RITA\uae. The methanolic extracts of the biomass (16.8 g) was fractionated by Si gel MPLC to obtain 16 fractions. The methanolic extract and the semi-purified fractions were tested against several multidrug resistant clinical strains of various bacterial species: Staphylococci and Enterococci and E. coli. The total extract was poorly effective while the semi purified fractions displayed variable potency with MIC values ranging from 8 to >128 \u3bcg/mL and from 4 to >128 \u3bcg/mL respectively against the Staphylococci and Enterococci strains considered. Our results suggest that the application of biotechnology approach on S. corrugata, it is possible to induce hairy roots from leaf, optimize the condition to increase the production of biomass, scale-up using TIS bioreactor and produce secondary metabolites with antibacterial activity. The study carried out on S. tingitana aimed to develop an in vitro culture protocol to produce different plant tissues and investigate the antibacterial activity of the extract. The callus formation from sterilized leaves was evaluated on MS medium added with different PGRs in presence of ascorbic acid in light or in dark conditions. The result showed the importance of the presence 2,4-D and darkness for callus development. The high development percentage (94.4 %) was achieved by combining KIN and 2,4-D at the concentration of 0.5:0.5 or 1:1 mg/L respectively. The optimization of the medium for the callus growth was determined evaluating the type and concentration of cytokinin and auxin in dark. The suitable condition for callus proliferation was MS medium supplemented with 2,4-D 4.52 \u3bcM, KIN 2,32 \u3bcM and 10 mg /L of ascorbic acid. The elicitation with MJ or light intensity was investigated. The methanolic extract and fractions obtained by MPLC were inactive against Staphylococci species and E. coli. The fractions 11 and 12 displayed an antibacterial activity only against E. faecalis and E. faecium with MIC values ranging from 32 to 64\u3bcg/mL. In S. tingitana, a successful protocol for callus production was established; this in vitro culture system can be used as good method to obtain medicinally-useful secondary compounds from S. tingitana