International statements and definitions of the precautionary principle

The precautionary principle (PP), according to one of its definitions, says that lack of certainty, given the current scientific and technological knowledge, shall not delay effective and proportionate actions to prevent hazards, taking into account cost-benefit considerations. Rather than being a single principle, a variety of statements of the PP are found in international treaties and other documents. Apart from any specific legal force of the documents, countries (e.g., France) have used these statements as a starting point for their own guidance documents and regulations for addressing specific environmental and health issues, for example regulation of genetically modified organisms. Thus, any discussion of the precautionary principle must address a complex legal and regulatory situation. We briefly review different statements of the PP and important commentary, largely from the European Union. We provide references to the original source documents (many of which are found in English on the World Wide Web).     

A three‐dimensional model describing stress‐temperature induced solid phase transformations: solution algorithm and boundary value problems

An always increasing knowledge on material properties as well as a progressively more sophisticated production technology make shape memory alloys (SMA) extremely interesting for the industrial world. At the same time, SMA devices are typically characterized by complex multi‐axial stress states as well as non‐homogeneous and non‐isothermal conditions both in space and time. This aspect suggests the finite element method as a useful tool to help and improve application design and realization. With this aim, we focus on a three‐dimensional macroscopic thermo‐mechanical model able to reproduce the most significant SMA features (Int. J. Numer. Methods Eng. 2002; 55 : 1255–1264), proposing a simple modification of such a model. However, the suggested modification allows the development of a time‐discrete solution algorithm, which is more effective and robust than the one previously discussed in the literature. We verify the computational tool ability to simulate realistic mechanical boundary value problems with prescribed temperature dependence, studying three SMA applications: a spring actuator, a self‐expanding stent, a coupling device for vacuum tightness. The effectiveness of the model to solve thermo‐mechanical coupled problems will be discussed in a forthcoming work. Copyright © 2004 John Wiley & Sons, Ltd.     

Acromioclavicular joint cyst and rotator cuff tear

The role of a depressor factor, atrial natriuretic peptide, in the development of arterial hypertension in adolescents with pubertal hypothalamic syndrome was studied in 52 patients and 13 healthy males aged 13-24 years. The duration of disease was 2-11 years. Radioimmunological methods were used to measure plasma atrial natriuretic peptide, plasma renin activity, and serum aldosterone. Patients with borderline arterial hypertension were found to have a significant reduction in their atrial natriuretic peptide levels, and this correlated directly with the renin-aldosterone system, demonstrating insufficiency of the depressor system in patients with pubertal hypothalamic syndrome and the involvement of atrial natriuretic peptide in the development of arterial hypertension, along with disturbances in the functional relationship between atrial natriuretic peptide and the renin-aldosterone system.     

The effect of cytokines, including IL4, IL7, stem cell factor, insulin-like growth factor on childhood acute lymphoblastic leukemia

We have investigated the effects of some interleukins, such as interleukin (IL) 4, IL7, stem cell factor (SCF) and insulin-like growth factor (IGF-1), known to be involved in human lymphopoiesis, on proliferation, clonal growth and differentiation of cells from two acute lymphoblastic leukemia (ALL) derived pre-B cell lines, that is, Nalm 1, Nalm 6 and purified blasts from 37 childhood ALL. IL4 did not display any promoting activity, an inhibitory effect being observed in two patients. IL7 showed an heterogeneous responsiveness, not related to immunophenotype or cytogenetic features, proliferation and clonal growth being observed in a minority of ALL. In other patients no or even inhibitory effects on proliferation were observed. In one case this inhibition of DNA synthesis was accompanied by maturation of the cells, as demonstrated by the induced expression of surface immunoglobulins (slg); other IL7 treated samples failed to express slg, but showed a decreased expression of terminal deoxynucleotidyl transferase and cALL antigen, suggesting that the cells have a potential of limited maturation by IL7. SCF, known to synergize with IL7 in the most primitive stages of normal B cell development, did not enhance the IL7 response in B cell precursor ALL. Finally IGF-1 failed to induce a proliferative response and clonal growth in BCP ALL either alone or in combination with IL7.     

Interferon-alpha in the idiopathic hypereosinophilic syndrome: consideration of five cases

A consortially developed continuing education series for rural nurses was implemented using videoconferencing technology. This article provides an overview of distance education technologies, the history and goals of the demonstration project at Edinboro University, and the coordination activities and instructional issues faced by the faculty. Participants became acquainted with distance education technology as they developed a process for program development, delivery, evaluation, and for awarding continuing education credits. The project was well received by instructors and students and testified to previous findings in the literature that distance education is a viable delivery system in terms of a teaching tool, learner satisfaction, and cost effectiveness.     

A study on the stability of superconducting YBa2Cu3O7−x phase

The thermal stability of the superconducting phase of nominal composition YBa₂Cu₃O_7–x -sintered pellets has been studied with respect to different temperatures (ranging from 300 to 950° C), time (ranging from 1 to 72 h), oxygen partial pressure (from 4 Pa to 1 atm) and carbon dioxide partial pressure (from 10^–4 Pa to 1 atm). Annealed samples were characterized by X-ray diffraction analysis, optical microscopy, and resistive measurements of the superconductive transition temperature. A stability field of the orthorhombic and tetragonal phases was obtained, showing a region of coexistance. The decomposition of the 1 2 3 phase is found to be strongly influenced by the presence of a small amount of CO₂ (1 p.p.m.) in the sintering atmosphere. A sintering process is proposed to avoid the formation of by-products.     

Liquid-phase hot-pressing and WC-particle reinforcement of SiC-Si composites

The sintering behaviour of SiC-Si and SiC-Si-WC composites hot-pressed via silicon liquid phase has been studied. The results show that the increase of silicon makes the sintered materials densify at lower temperature and the grain growth is restricted due to the effect of the liquid. The strength of SiC-25 vol.% Si samples is higher than the strength obtained for SiC-5 vol.% Si with the same hot-pressing conditions. The addition of WC particles improves relative densities and strengths of SiC-Si ceramics.     

Structural characterization of Ti centres in Ti-silicalite and reaction mechanisms in cyclohexanone ammoximation

The main results obtained by means of many physical methods (IR, Raman, UV-Vis and XAFS spectroscopies) concerning the structure of the Ti centre in titanium silicalite and the reaction intermediates in the ammoximation of cyclohexanone are concisely reviewed.

The Ti is in tetrahedral coordination in vacuo and expands its coordination sphere upon interaction with adsorbates. In the presence of H₂O and H₂O/H₂O₂ solutions one of the SiOTi bridges is hydrolyzed with formation of (SiO)₃L₂TiOH (LH₂O) and (SiO)₃L₂TiOOH species, respectively. When NH₃ is dosed on (SiO)₃L₂TiOOH structures (SiO)₃L₂TiOO⁻NH₄⁺ species are formed. These species are thought to play an important role in the ammoximation reaction. The geometries of the peroxidic species (open or bridged) are discussed also on the basis of ab initio calculations.