Philosophy of science underpinnings of prototype validation: Popper vs. Quine

Abstract.  In this paper, we aim to provide prototype validation in both custom and packaged software development with a theoretical framework located within the philosophy of science. Towards that end, we consider Popperian and Quinean accounts of scientific knowledge and argue that the theoretical underpinning of prototype validation is Quine's holistic philosophy of science, whose cornerstone principle is that all beliefs are revisable. Specifically, our thesis is that the systems developer and software consumer (user or customer) join forces – not as Popperian falsifiers, who make a decision rule to reject the prototype on account of any divergence, major or minor, from the software consumer's mental model, but – as Quinean revisers, with the objective of fine-tuning the prototype (or the software consumer's mental model) so that the prototype and the software consumer's mental model are congruent with each other. This paper suggests that prototype revisions are belief revisions, and, as such, should be guided – and are guided – by pragmatic norms, such as conservatism, simplicity and generality, and are influenced by social, or sociological, factors as well. Finally, we discuss the relevance, value and pragmatic implications of a Quinean philosophy of science framework for research and practice.     

Evolution over time of the agricultural pollution of waters in an area of Salamanca and Zamora (Spain)

A survey of the herbicides present in surface and groundwaters was conducted in 1999 in an area of the provinces of Salamanca and Zamora (Central-Western Spain) to assess the degree of pollution of the agricultural land and seasonal changes in the presence of herbicide residues. Ten sites were sampled and screened for 17 herbicides commonly used in the area; the compounds were ureas, triazines, amides, and others. A previously optimised method involving solid-phase extraction with polymeric cartridges, followed by HPLC with diode array detection, was used to monitor the herbicides. Of the 17 compounds examined, eight were found: chlorotoluron (41% of total detections), terbutryn (21%), atrazine (14%), linuron (7%), isoproturon and metolachlor (5.5% each), lenacil (4%) and metamitron (2%). Of the detections, 66% corresponded to river water samples (three sites). The herbicides found in groundwaters (seven sites) were: chlorotoluron, atrazine, terbutryn, linuron, and isoproturon, all of which are classified as probable or transient leachers in Europe. The temporal evolution of the herbicide content in river waters shows that the observed pollution is a function of time and is related to the application and use of the herbicides. By contrast, the pollution found in groundwaters was lower than that seen in surface waters, except that due to chlorotoluron, which, additionally, remained almost constant throughout the study period.     

Overcoming the inadequacies or limitations of experimental structures as drug targets by using computational modeling tools and molecular dynamics simulations

X-ray crystallography, NMR spectroscopy, and cryoelectron microscopy stand out as powerful tools that enable us to obtain atomic detail about biomolecules that can be potentially targeted by drugs. This knowledge is essential if virtual screening or structure-based ligand-design methods are going to be used in drug discovery. However, the macromolecule of interest is not always amenable to these types of experiment or, as is often the case, the conformation found experimentally cannot be used directly for docking studies because of significant changes between apo and bound forms. Furthermore, sometimes the desired insight into the binding mechanism cannot be gained because the structure of the ligand-receptor complex, not having been time-resolved, represents the endpoint of the binding process and therefore retains little or no information about the intermediate stages that led to its creation. Molecular dynamics (MD) simulations are routinely applied these days to the study of biomolecular systems with the aims of sampling configuration space more efficiently and getting a better understanding of the factors that determine structural stability and relevant biophysical and biochemical processes such as protein folding, ligand binding, and enzymatic reactions. This field has matured significantly in recent years, and strategies have been devised (for example activated, steered, or targeted MD) that allow the calculated trajectories to be biased in attempts to properly shape a ligand binding pocket or simulate large-scale motions involving one or more protein domains. On the other hand, low-frequency motions can be simulated quite inexpensively by calculation of normal modes which allow the investigation of alternative receptor conformations. Selected examples in which these methods have been applied to several medicinal chemistry and in silico pharmacology endeavors are presented.     

Orange fibre as potential functional ingredient for dry-cured sausages

Dry-cured sausages with orange fibre (juice industry by-products) at five concentrations (0, 5, 10, 15 and 20 g/kg) were prepared and studied. Chemical (residual nitrite level and lipid oxidation) and physico-chemical parameters (colour and pH) were determined during dry-curing stage (4 weeks). Polyphenol composition (extracted with methanol and separated and quantified by HPLC) of each formulation and its evolution during dry-curing were also determined. TBARS values increased in all samples during drying, with lower increase in treatment samples than in control samples. The incorporation of orange fibre into sausages produced a significant decrease in residual nitrite level. The high reactivity of nitrites could allow its reaction with active biocompounds (polyphenols) present in orange fibre. Chromatographic (HPLC) analysis of orange fibre detected numerous peaks, most of them matched with phenolic compounds. The highest peak of this chromatogram was identified as hesperidin. So, hesperidin was selected as the most adequate compound to monitor polyphenols changes in sausages added with orange fibre during processing.     

Quantifying recontamination through factory environments--a review

Recontamination of food products can be the origin of foodborne illnesses and should therefore be included in quantitative microbial risk assessment (MRA) studies. In order to do this, recontamination should be quantified using predictive models. This paper gives an overview of the relevant modelling approaches that are available in the literature to quantify recontamination via factory environment. Different recontamination routes are described: recontamination via air, via processing equipment or via hand contact. Unfortunately, not many available models are directly applicable to the food industry; most models are developed for aquatic or environmental systems. Finally, a general systematic approach is proposed for modelling contamination from surfaces via air, hands or liquid into the product and ranges for the parameters are given.     

Analysis of the colorimetric properties of goniochromatic colors using the MacAdam limits under different light sources

Technological innovation in all areas has led to the appearance in recent years of new metallic and pearlescent materials, yet no exhaustive studies have been conducted to assess their colorimetric capabilities. The chromatic variability of these special-effect pigments may largely be due to the three-dimensional effect of their curved shapes and orientations when they are directionally or diffusely illuminated. Our study examines goniochromatic colors using the optimal colors (MacAdam limits) associated with normal colors (photometric scale of relative spectral reflectance from 0 to 1) under certain conventional illuminants and other light sources. From a database of 91 metallic and interference samples and using a multi-gonio-spectrophotometer, we analyzed samples with lightness values of more than 100 and others with lightness values of less than 100, but with higher chromaticities than optimal colors, which places them beyond the MacAdam limits. Our study thus demonstrates the existence of chromatic perceptions beyond the normal solid color associated with these materials and independent of the light source. The challenge for future research, therefore, is to replicate and render these color appearances in current and future color reproduction technologies for computer graphics.     

Using RFLP-mtDNA for the rapid monitoring of the dominant inoculated yeast strain in industrial wine fermentations

The analysis of restriction fragment length polymorphism of mitochondrial DNA (mtDNA-RFLP) has been applied as a test to monitor the abundance of the starter yeast strain during industrial wine fermentations without previous isolation of yeast colonies. For white wine fermentations, we performed a rapid assay consisting in taking a sample of fermenting must, purifying the DNA from harvested cells, and obtaining the restriction patterns by digestion with the endonuclease HinfI. The same protocol, but adding an overnight cultivation step before DNA purification, was also applied to red wine fermentations. The results were compared with those obtained from the subsequent characterisation of strains, for the same samples, by analysis of the electrophoretic karyotype of isolated yeast colonies. In all cases, when the inoculated strain was dominant within the yeast population, the rapid assay anticipated the result by showing the coincidence between the restriction profiles obtained from both total cells and the inoculated strain. The results were obtained at 11 or 23 h after sampling for white- or red-wine fermentations respectively. This method allows a rapid intervention of the wine-producer if the presence of the inoculated yeasts has suffered a sudden decrease in any phase of the fermentation process.     

Virus inactivation by salt (NaCl) and phosphate supplemented salt in a 3D collagen matrix model for natural sausage casings

Due to possible presence and spread of contagious animal viruses via natural sausage casings the international trade in these food products is subject to veterinary and public health requirements. In order to manage these restrictions we determined the effect of casing preservation on four highly contagious viruses for livestock: foot-and-mouth-disease virus (FMDV), classical swine fever virus (CSFV), swine vesicular disease virus (SVDV) and African swine fever virus (ASFV). We used an in vitro 3D collagen matrix model in which cells, infected with the four different viruses were embedded in a bovine collagen type I gel matrix and treated with either saturated salt (NaCl) or phosphate supplemented saturated salt at four different temperatures (4, 12, 20 and 25 °C) during a period of 30 days. The results showed that all viruses were faster inactivated at higher temperatures, but that stability of the various viruses at 4 °C differed. Inactivation of FMDV in the 3D collagen matrix model showed a clear temperature and treatment effect on the reduction of FMDV titres. At 4 and 12 °C phosphate supplemented salt showed a very strong FMDV inactivation during the first hour of incubation. Salt (NaCl) only had a minor effect on FMDV inactivation. Phosphate supplemented salt treatment increased the effect temperature had on inactivation of CSFV. In contrast, the salt (NaCl) treatment only increased CSFV inactivation at the higher temperatures (20 °C and 25 °C). Also SVDV inactivation was increased by phosphate supplemented salt, but salt (NaCl) treatment only resulted in a significant decrease of SVDV titre at a few time points. The ASFV results showed that both salt (NaCl) and phosphate supplemented salt were capable to inactivate ASFV within 48 h. In contrast to the other viruses (FMDV, CSFV and SVDV), ASFV was the most stable virus even at higher temperatures. The results obtained in this in vitro model underline the efficacy of a combined treatment using phosphate supplemented salt and storage at 20 °C or higher for a period of 30 days. This treatment may therefore be useful in reducing the animal health risks posed by spread of contagious animal viruses by international trade of natural sausage casings.     

INDITEP: The first pre-commercial DSG solar power plant

This paper presents the conceptual design of the first solar power plant using Direct Steam Generation (DSG) in a parabolic-trough solar field. Experience and know-how in the DSG process acquired during the DISS project were applied in designing the solar field of this plant. The 5-MWe plant is composed of a DSG parabolic-trough solar field connected to a superheated steam Rankine power cycle. The solar field produces 410 °C/70-bar superheated steam. Detail engineering of this plant is currently underway within the framework of the INDITEP project, which is promoted by a German-Spanish consortium with the financial support of the European Commission (Contract No. ENK5-CT-2001-00540). The main design objective is to assure high operational flexibility and reliability. This is the reason why a robust superheated steam turbine has been selected, though the efficiency of its power block is modest.