Axiomatization and Models of Scientific Theories

In this paper we discuss two approaches to the axiomatization of scien- tific theories in the context of the so called semantic approach, according to which (roughly) a theory can be seen as a class of models. The two approaches are associated respectively to Suppes’ and to da Costa and Chuaqui’s works. We argue that theories can be developed both in a way more akin to the usual mathematical practice (Suppes), in an informal set theoretical environment, writing the set theoretical predicate in the language of set theory itself or, more rigorously (da Costa and Chuaqui), by employing formal languages that help us in writing the postulates to define a class of structures. Both approaches are called internal, for we work within a mathematical framework, here taken to be first-order ZFC. We contrast these approaches with an external one, here discussed briefly. We argue that each one has its strong and weak points, whose discussion is relevant for the philosophical foundations of science

Biochemical parameters for Piaractus mesopotamicus, Colossoma macropomum (Characidae) and hybrid tambacu (P. mesopotamicus X C. macropomum).

Estudaram-se os valores de glicose plasmática, proteína total sérica e íons séricos (cálcio, potássio, magnésio, sódio e cloreto) em jovens de Colossomoma macropomum Cuvier 1818, Piaractus mesopotamicus Holmberg 1887 e híbrido tambacu (P. mesopotamicus x C. macropomum), mantidos em cultivo intensivo. As concentrações plasmáticas de glicose no híbrido tambacu foram maiores que em P. mesopotamicus e C. macropomum. Os níveis de proteínas totais em P. mesopotamicus foram maiores em C. macropomum e híbrido tambacu. O C. macropomum apresentou maior concentração de sódio e cloreto, ao passo que o P. mesopotamicus mostrou maior concentração de potássio e magnésio. Porém, os níveis de cálcio mostraram-se similares nas três espécies estudadas. O híbrido tambacu apresentou os menores níveis de proteínas totais e níveis intermediários de potássio, sódio, magnésio e cloreto quando comparado ao P. mesopotamicus e C. macropomum. Foram estabelecidos valores basais para peixes sadios criados em cativeiro, os quais poderão ser usados em estudos de comparação futura em populações selvagens de P. mesopotamicus e C. macropomum

Measuring the Charged Particle Multiplicity with ALICE

The charged particle multiplicity distribution is one of the first measurements that ALICE will be able to perform. The knowledge of this basic property at a new energy is needed to configure Monte Carlo generators correctly with the aim of understanding the background of other, especially rare, processes including new physics. It allows to study the scaling behaviour and to verify model predictions. The unfolding of the measurement is a non-trivial task due to the finite precision and acceptance of the detector. Solutions are based on chi2 minimization or iteratively using Bayes' theorem. Both approaches to unfold the spectrum are presented. Furthermore, the capabilities of the SPD fast OR trigger are shown that enable physics at very high multiplicities.Comment: Proceedings of poster presentation at Quark Matter 2008, 20th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions in Jaipur, India; to be published in Indian Journal of Physics; 4 pages, 4 figure

Rapid determination of food quality using steady state free precession sequences in TD-NMR spectroscopy.

bitstream/item/180768/1/Rapid-determination-of-food-quality-using-steady-state-free-precession-sequences-in-TD-NMR-spectroscopy..pd

Axiomatization and Models of Scientific Theories

In this paper we discuss two approaches to the axiomatization of scien- tific theories in the context of the so called semantic approach, according to which (roughly) a theory can be seen as a class of models. The two approaches are associated respectively to Suppes’ and to da Costa and Chuaqui’s works. We argue that theories can be developed both in a way more akin to the usual mathematical practice (Suppes), in an informal set theoretical environment, writing the set theoretical predicate in the language of set theory itself or, more rigorously (da Costa and Chuaqui), by employing formal languages that help us in writing the postulates to define a class of structures. Both approaches are called internal, for we work within a mathematical framework, here taken to be first-order ZFC. We contrast these approaches with an external one, here discussed briefly. We argue that each one has its strong and weak points, whose discussion is relevant for the philosophical foundations of science

Using multifractal analysis of ultra-weak photon emission from germinating wheat seedlings to differentiate between two grades of intoxication with potassium dichromate

Abstract. The aim of the present study was to test whether the multifractal properties of ultra-weak photon emission (UPE) from germinating wheat seedlings (Triticum aestivum) change when the seedlings are treated with different concentrations of the toxin potassium dichromate (PD). To this end, UPE was measured (50 seedlings in one Petri dish, duration: approx. 16.6–28 h) from samples of three groups: (i) control (group C, N = 9), (ii) treated with 25 ppm of PD (group G25, N = 32), and (iii) treated with 150 ppm of PD (group G150, N = 23). For the multifractal analysis, the following steps where performed: (i) each UPE time series was trimmed to a final length of 1000 min; (ii) each UPE time series was filtered, linear detrended and normalized; (iii) the multifractal spectrum (f(α)) was calculated for every UPE time series using the backward multifractal detrended moving average (MFDMA) method; (iv) each multifractal spectrum was characterized by calculating the mode (αmode) of the spectrum and the degree of multifractality (Δα); (v) for every UPE time series its mean, skewness and kurtosis were also calculated; finally (vi) all obtained parameters where analyzed to determine their ability to differentiate between the three groups. This was based on Fisher’s discriminant ratio (FDR), which was calculated for each parameter combination. Additionally, a non-parametric test was used to test whether the parameter values are significantly different or not. The analysis showed that when comparing all the three groups, FDR had the highest values for the multifractal parameters (αmode, Δα). Furthermore, the differences in these parameters between the groups were statistically significant (p < 0.05). The classical parameters (mean, skewness and kurtosis) had lower FDR values than the multifractal parameters in all cases and showed no significant difference between the groups (except for the skewness between group C and G150). In conclusion, multifractal analysis enables changes in UPE time series to be detected even when they are hidden for normal linear signal analysis methods. The analysis of changes in the multifractal properties might be a basis to design a classification system enabling the intoxication of cell cultures to be quantified based on UPE measurements

Seleção de clones de copa de seringueira resistentes ao mal das folhas.

A fim de selecionar novos materiais genéticos para novos cultivos o trabalho teve por objetivos estimar os parâmetros genéticos de clones de copas de seringueira resistentes ao M. ulei nas condições edafoclimáticas da Amazônia Tropical Úmida, durante seis anos de produção em análise conjunta

Determinação da atividade peroxidásica em cultivares de feijão-caupi (Vigna unguiculata) tratados com ácido salicílico.

Apesar de sua aparente passividade, as plantas reagem quando submetidas a situações adversas, tais como, o ataque de fungos, bactérias, vírus, nematóides, insetos e também sob estresse abiótico, como por exemplo, variações de temperatura, ausência de água ou tratamento com agentes químicos. Dentre o arsenal de defesa utilizado pelas plantas estão o reforço da parede celular (lignificação) e a indução de PR-Proteínas. A peroxidase (POX) é uma enzima associada com este processo, sendo, portanto, associada ao mecanismo de resposta de defesa. No presente trabalho avaliou-se a POX em duas cultivares de feijão-caupi (?Mulato? e ?Gurguéia?), visando a promover um maior entendimento do mecanismo de defesa desta importante cultura, procurando verificar a participação desta enzima neste processo. Folhas primárias das duas cultivares foram tratadas com ácido salicílico 10 mM no 10° dia após o plantio. As folhas foram coletadas com 1, 2, 3, 4, 6 e 9 dias após o tratamento, sendo o extrato total utilizado na determinação de proteínas e atividade POX. O teor de proteínas nas cultivares testadas não mostrou diferença significativa após o tratamento. A atividade POX foi induzida após o tratamento em ambas as cultivares, com pico de atividade 9 dias após o tratamento. A cultivar ?Gurguéia? (109,65 UA/gF) apresentou maior nível de atividade POX quando comparada com a cultivar ?Mulato? (88,00 UA/gF). Estes resultados sugerem a participação da POX no mecanismo de defesa do feijão-caupi.bitstream/item/24666/1/bpd41-feijao-caupi.pd