Search results for "Formulation"
showing 10 items of 265 documents
The Mathematicians’ Happy Hunting Ground: Einstein’s General Theory of Relativity
2004
There is hardly any doubt that for physics special relativity theory is of much greater consequence than the general theory. The reverse situation prevails with respect to mathematics: there special relativity theory had comparatively little, general relativity theory very considerable, influence, above all upon the development of a general scheme for differential geometry. —Hermann Weyl, “Relativity as a Stimulus to Mathematical Research,” pp. 536–537.
Seeing reality through Einstein's eyes: a teaching proposal for special relativity
2021
The teaching of Special Relativity is still a critical issue not only for students but also for teachers. In this paper, we describe the trial of a learning unit on the Special Relativity topic based on Minkowski's approach through spacetime diagrams, following the results in pedagogical researches in this field. The main innovation of our project consists of a mechanical instrument: it allows to physically and mechanically represent Lorentz’s transformations by hands, exploring the effects of a change of the reference frame. Teachers and students can deal “by eye” with unusual phenomena as the loss of simultaneity, time dilation, length contraction, relativistic addition of velocities and …
Thermoconvective instability and local thermal non-equilibrium in a porous layer with isoflux-isothermal boundary conditions
2014
The effects of lack of local thermal equilibrium between the solid phase and the fluid phase are taken into account for the convective stability analysis of a horizontal porous layer. The layer is bounded by a pair of plane parallel walls which are impermeable and such that the lower wall is subject to a uniform flux heating, while the upper wall is isothermal. The local thermal non-equilibrium is modelled through a two-temperature formulation of the energy exchange between the phases, resulting in a pair of local energy balance equations: one for each phase. Small-amplitude disturbances of the basic rest state are envisaged to test the stability. Then, the standard normal mode procedure is…
Qualità della didattica universitaria e sviluppo della capacità decisionale. Il modello ADVP per garantire i passaggi da L-19 a LM-85bis.
2020
Il presente contributo intende offrire una riflessione sulle competenze attese individuate attraverso la formulazione dei descrittori di Dublino dei CdS in Scienze dell’Educazione (L-19) e Scienze della Formazione Primaria (LM-85bis) istituiti presso l’Ateneo di Palermo e nello stesso tempo proporre un modello per lo sviluppo della maturità professional e necessaria a garantire scelte consapevoli, mature e responsabili. L’analisi condotta ci ha permesso, in una seconda fase di individuare gli obiettivi formativi finali scelti seguendo il modello proposto dalle Linee Guida dell ’Anvur, e di scegliere il modello dell’Activaction du Developpement Vocationnel et Personnel quale strumento per lo…
Finite element method for a nonlocal Timoshenko beam model
2014
A finite element method is presented for a nonlocal Timoshenko beam model recently proposed by the authors. The model relies on the key idea that nonlocal effects consist of long-range volume forces and moments exchanged by non-adjacent beam segments, which contribute to the equilibrium of a beam segment along with the classical local stress resultants. The long-range volume forces/moments are linearly depending on the product of the volumes of the interacting beam segments, and their relative motion measured in terms of the pure beam deformation modes, through appropriate attenuation functions governing the spatial decay of nonlocal effects. In this paper, the beam model is reformulated wi…
Use of the Weibull model to describe inactivation of dry harvested conidia of different Penicillium species by ethanol vapours
2010
Aims: This study aimed at modelling the effect of ethanol vapours, in the range 0·7–7·5 kPa, on the inactivation of dry-harvested conidia of Penicillium chrysogenum, Penicillium digitatum and Penicillium italicum. Methods and Results: Survival curves were modelled by a Weibull model: log (N/N0) = −1/2·303 (t/α)β. The shape parameter β was different from one in all cases, indicating that the classical first-order kinetics approach is the exception rather than the rule. Survival curves exhibited upward concavity (β < 1) with the notable exception of P. chrysogenum at ethanol vapour pressures 0·7 and 1·5 kPa. The scale parameter α (h) varied greatly depending on the ethanol vapour pressure a…
The Asian Taenia and the possibility of cysticercosis
2000
In certain Asian countries, a third form of human Taenia, also known as the Asian Taenia, has been discovered. This Asian Taenia seems to be an intermediate between Taenia solium and T. saginata since in morphological terms it is similar to T. saginata, yet biologically, as it uses the same intermediate host (pigs), it is more akin to T. solium. Taenia solium causes human cysticercosis, while T. saginata does not. It is not known whether the Asian taeniid is able to develop to the larval stage in humans or not. The arguments proposed by those authors who consider it unlikely that the Asian Taenia causes human cysticercosis are: (a) its molecular similarities with T. saginata; (b) the absenc…
Comment on "Epidemiological Survey on Porcine Cysticercosis in Nay Pyi Taw Area, Myanmar".
2015
We have read with interest the paper by Khaing et al. [1], in which first data on Taenia solium cysticercosis in pigs from Myanmar are published. The authors found a porcine cysticercosis prevalence of 23.67% in slaughtered pigs, which, as they mention, indicates the presence of human taeniasis and also the risk of acquiring human cysticercosis and, therefore, neurocysticercosis. The high porcine cysticercosis prevalence detected by the authors means, obviously, that there has to be a high prevalence of human T. solium taeniasis among the inhabitants of Myanmar leading to a high presence of infective eggs in the environment. However, as far as we know, the presence of T. solium taeniasis, a…
Evidence for Transmission of Taenia solium Taeniasis/Cysticercosis in a Rural Area of Northern Rwanda
2021
Cysticercosis is a parasitic infection caused by the metacestode larval stage (cysticercus) of Taenia solium. In humans, cysticercosis may infect the central nervous system and cause neurocysticercosis, which is responsible for over 50,000 deaths per year worldwide and is the major cause of preventable epilepsy cases, especially in low-income countries. Cysticercosis infection is endemic in many less developed countries where poor hygiene conditions and free-range pig management favor their transmission. A cross-sectional study was conducted in 680 children from a rural primary school in Gakenke district (Northern province of Rwanda). Stool samples were collected from participants and analy…
FIA-fluorimetric determination of thiamine.
1990
A flow injection-fluorimetric determination of thiamine is reported. The procedure is based on the oxidation of the analyte with potassium hexacyanoferrate(III) immobilized on an anionic exchange resin; the fluorescence is monitored in aqueous basic solution. Concentrations of the vitamin of 0.1-4 ppm have been determined; the relative standard deviation was 1.8%. The injection rate was 28 samples/h. The influence of other substances and the determination of the drug in a pharmaceutical formulation are also reported.