Landbouw, landbouwwetenschap en samenleving. Filosofische opstellen.

Deze bundel bedoelt een bijdrage te zijn van de vakgroep Wijsbegeerte van de Landbouwuniversiteit aan de discussie over landbouw, landbouwwetenschap en samenleving. De 8 opstellen gaan onder meer over de betekenis van de klassieke landbouwwetenschap, de opgang van een geintegreerde systeembenadering in de landbouwwetenschap, een commentaar op het NRLO-rapport van 1986 over de taakopvattingen van het sociaal-wetenschappelijk onderzoek m.b.t. het landbouwbeleid, een aantal crisissituaties in de landbouw en de landbouwwetenschap, en de morele zijde in de omgang mens-die

Empirical laws, regularity and necessity

In this book I have tried to develop an analysis of the concept of an empirical law, an analysis that differs in many ways from the alternative analyse's found in contemporary literature dealing with the subject.1 am referring especially to two well-known views, viz. the regularity and necessity views, which have given rise to many interesting papers and books within the philosophy of science.In developing my own views, it very soon became clear to me that the mere restatement of these alternative views, followed by a discussion of their defects and an explanation of my own view, would not suffice to show what 1 regard as basically unsound in these views.If we seriously consider the well-known difficulties facing the regularity view, we have to consider the possibility that the time has arrived to stop our attempts to solve, by means of patch-work additions, the fundamental problem of empirical laws within the traditional context of logical positivist doctrines.I have tried to find a solution which is based on a different philosophical context, the main incentive being that the discouraging results of the customary attempts to solve the problem might have been the outcome of the fundamental philosophical setting within which the problem had been formulated and within which everyone looked for a solution. The problem of empirical laws is not a problem existing by its own rights - it is shaped by an underlying point of view or theoretical framework.For this reason I have started with a brief sketch of the logical positivist context. However, I want to stress the fact that my intention was not to offer an historical exposition, but an exposition which becomes meaningful when related to the subsequent arguments concerning empirical laws.The notion of direct or theory-free observation has been taken as the fundamental characteristic of the logical positivist point of view. This view has been further characterised by means of five theses, among which is the thesis that observational terms are isolated or theory-independent units of extensional meaning. These terms are then supposed to be the starting-points of meaning and the end-points of confirmation, and these very characteristics mark the privileged position such terms have in a logical positivist philosophy.The post-positivist view, on the other hand, is characterised by the opposing notion of theory-loaded observation. This notion leads to other conclusions which radically oppose some of the theses of logical positivism. The notion of theory- loaded observation itself, although often clearly stated, has not yet been systematically elucidated, and I have made an attempt to do this in ch. I after my sketch of the logical positivist context. This seemed to me to be necessary in order to make my post-positivist point of view as clear as possible, before tackling the problem of empirical law itself.I have paid special attention to the lawlikeness of concepts and their confirmation and falsification.These epistemological issues are followed by a separate examination of Goodman's riddle in ch. II, because it lies somewhere between the lawlikeness of concepts and the lawlikeness of laws. If Goodman's riddle is taken as a serious problem, as I think it should, it is primarily a problem of concept or theory formation and not a problem of induction.In ch. III the regularity view has been examined and the well-known difficulties related to such a view are considered, assuming the knowledge gained in ch. I. This has led to some interesting results, especially in connection with the analysis of counterfactuals and the confirmation of 'normal' singular conditionals, to which I return in the last chapter.Three different views of the necessity view are briefly stated and investigated in ch. IV. RESCHER'S view is, I think, close to mine, which has been developed in ch. V. However, there are fundamental epistemological differences between our views.In the last chapter I have given my own analysis of the concept of an empirical law, which should not be taken as a synthesis of a regularity and a necessity view, but as opposed to both. It is, as far as particulars may count, the result of an analysis of the concepts 'regularity' and 'necessity'. I have tried to argue that the greatest shortcoming of the regularity view lies in the fact that the proponents of such a view have not been really concerned with the concept of 'regularity' itself. They usually take this concept to be intuitively clear enough to serve as basis for their analysis. Their attacks upon the necessity view are based on the reproach that 'necessity' is a very obscure concept, and that it should, therefore, be avoided in the philosophy of science. We could, however, reproach them in a similar way, since the concept of 'regularity' is anything but clear.One may say that an empirical law formulates a 'regularity in nature', but we can only do justice to the function a law has in science, if we are ready to view this regularity as a necessary connection, which does not exist in an observer-independent reality, but in a theoretically co-constituted empirical world.This investigation does not pretend to answer all questions concerning empirical laws. It should, therefore, not be regarded as complete, but neither should the arguments and suggestions be regarded as completely free from ambiguity.Much remains to be done in order to offer a generally acceptable theory and better understanding

Estimating the Costs and the Disease Burden Associated With Campylobacter Infections and Sequelae in the Netherlands

Campylobacter infections pose an important public health problem in the Netherlands. Approximately 79,000 persons per year are estimated to experience symptoms of acute gastroenteritis. Further annually some 1400 ReA cases, 60 GBS cases and 11 IBD cases are associated with a previous Campylobacter infection. Using a stochastic simulation model the disease burden and the cost-of-illness of Campylobacter infections and its sequelae were estimated. Estimates of the Campylobacter-associated disease burden and costs-of-illness were 1185 DALYs (90% C.I. 693 - 1845 DALYs) per year and some 21 million E (90% C.I. 10 - 38 million E) per year respectively.Campylobacter, sequelae, cost-of-illness, disease burden, Netherlands, Food Consumption/Nutrition/Food Safety,

Predicting phase equilibria in polydisperse systems

Many materials containing colloids or polymers are polydisperse: They comprise particles with properties (such as particle diameter, charge, or polymer chain length) that depend continuously on one or several parameters. This review focusses on the theoretical prediction of phase equilibria in polydisperse systems; the presence of an effectively infinite number of distinguishable particle species makes this a highly nontrivial task. I first describe qualitatively some of the novel features of polydisperse phase behaviour, and outline a theoretical framework within which they can be explored. Current techniques for predicting polydisperse phase equilibria are then reviewed. I also discuss applications to some simple model systems including homopolymers and random copolymers, spherical colloids and colloid-polymer mixtures, and liquid crystals formed from rod- and plate-like colloidal particles; the results surveyed give an idea of the rich phenomenology of polydisperse phase behaviour. Extensions to the study of polydispersity effects on interfacial behaviour and phase separation kinetics are outlined briefly.Comment: 48 pages, invited topical review for Journal of Physics: Condensed Matter; uses Institute of Physics style file iopart.cls (included

Low-temperature specific heat and thermal conductivity of glycerol

We have measured the thermal conductivity of glassy glycerol between 1.5 K and 100 K, as well as the specific heat of both glassy and crystalline phases of glycerol between 0.5 K and 25 K. We discuss both low-temperature properties of this typical molecular glass in terms of the soft-potential model. Our finding of an excellent agreement between its predictions and experimental data for these two independent measurements constitutes a robust proof of the capabilities of the soft-potential model to account for the low-temperature properties of glasses in a wide temperature range.Comment: 4 pages, 3 figures. To be published in Phys. Rev. B (2002

Risk factors associated with Campylobacter jejuni infections in Curacao, Netherlands Antilles

A steady increase in the incidence of Guillain-Barre syndrome (GBS) with a seasonal preponderance, almost exclusively related to Campylobacter jejuni, and a rise in the incidence of laboratory-confirmed Campylobacter enteritis have been reported from Curacao, Netherlands Antilles. We therefore investigated possible risk factors associated with diarrhea due to epidemic C. jejuni. Typing by pulsed-field gel electrophoresis identified four epidemic clones which accounted for almost 60% of the infections. One hundred six cases were included in a case-control study. Infections with epidemic clones were more frequently observed in specific districts in Willemstad, the capital of Curacao. One of these clones caused infections during the rainy season only and was associated with the presence of a deep well around the house. Two out of three GBS-related C. jejuni isolates belonged to an epidemic clone. The observations presented point toward water as a possible source of Campylobacter infections

Guillain-Barré syndrome: a century of progress

In 1916, Guillain, Barré and Strohl reported on two cases of acute flaccid paralysis with high cerebrospinal fluid protein levels and normal cell counts — novel findings that identified the disease we now know as Guillain–Barré syndrome (GBS). 100 years on, we have made great progress with the clinical and pathological characterization of GBS. Early clinicopathological and animal studies indicated that GBS was an immune-mediated demyelinating disorder, and that severe GBS could result in secondary axonal injury; the current treatments of plasma exchange and intravenous immunoglobulin, which were developed in the 1980s, are based on this premise. Subsequent work has, however, shown that primary axonal injury can be the underlying disease. The association of Campylobacter jejuni strains has led to confirmation that anti-ganglioside antibodies are pathogenic and that axonal GBS involves an antibody and complement-mediated disruption of nodes of Ranvier, neuromuscular junctions and other neuronal and glial membranes. Now, ongoing clinical trials of the complement inhibitor eculizumab are the first targeted immunotherapy in GBS

Epidemiology of childhood Guillan-Barre syndrome in the north west of Iran

<p>Abstract</p> <p>Background and aims</p> <p>This study was carried out to investigate the incidence, annual time trend and some epidemiological and clinical features of Guillain-Barre syndrome in children in the north west of Iran.</p> <p>Materials and methods</p> <p>In this population-based cross sectional research, epidemiological and clinical features of 143 cases with Guillain-Barre syndrome between 2001 and 2006 were studied. The setting of the study was Tabriz Children Medical Centre, the major University-Hospital located in Tabriz city of the East Azarbaijan province covering whole region. Data collected included age, gender, chronological information, preceding events, functional grade of motor deficit.</p> <p>Results</p> <p>The mean age (standard deviation) of subjects was 5.4 (3.6) years. The male/female ratio was 1.3. The average annual incidence rate was 2.27 per 100 000 population of 15 years children (CI95%: 1.9–2.6). The majority of cases occurred in March, July and November and the highest proportion of the syndrome was observed in winter (29 percent, P > 0.10).</p> <p>Conclusion</p> <p>The results indicated that an unexpected high incidence of Guillain-Barre syndrome has occurred in 2003 in the region. We concluded that a monitoring and surveillance system for Guillain-Barre syndrome is essential to set up in this region.</p