The passage of a spin-1/2neutral particle through a region of uniform magnetic field and the corresponding precession mechanism is analyzed from the viewpoint of scattering theory, with particular consideration of the role of the field boundaries.

We characterize strict Mittag-Leffler modules in terms of free realizations of positive primitive formulas, and rings over which projectives are trivial in terms of various notions of separability of strict Mittag-Leffler modules. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The occurrence of hiccoughs (hiccups) is very widespread and yet their neuronal origin and physiological significance are still unresolved. Several hypotheses have been proposed. Here we consider a phylogenetic perspective, starting from the concept that the ventilatory central pattern generator of lower vertebrates provides the base upon which central pattern generators of higher vertebrates develop. Hiccoughs are characterized by glottal closure during inspiration and by early development in relation to lung ventilation. They are inhibited when the concentration of inhaled CO2 (...) is increased and they can be abolished by the drug baclofen (an agonist of the GABAB receptor). These properties are shared by ventilatory motor patterns of lower vertebrates, leading to the hypothesis that hiccough is the expression of archaic motor patterns and particularly the motor pattern of gill ventilation in bimodal breathers such as most frogs. A circuit that can generate hiccoughs may persist in mammals because it has permitted the development of pattern generators for other useful functions of the pharynx and chest wall muscles, such as suckling or eupneic breathing. BioEssays 25:182–188, 2003. © 2003 Wiley Periodicals, Inc. (shrink)

Dogmatic Metaphysics and Tschirnhaus's M ethodology MARTIN SCHONFELD ACCORDING TO STANDARD COMMENTARIES, Tschirnhaus's main work, Medicina mentis, ~ supposedly furnished the methodological basis for the Leibnizian-Wolffian metaphysics. ~ Christian Wolff and his disciples, at any rate, preferred to think so. Wolff taught classes on Tschirnhaus and claimed that he had developed his own tenets on the basis of Tschirnhaus's ideas; Johann Christoph Gottsched praised the Medicina mentis as the basic methodology of the Wolffian enlightenment.3 Mirroring these views, W. Wundt and (...) H. J. de Vleeschauwer saw in Tschirnhaus the inventor of the "geometric method" adopted by the School Philosophers.4 According to M. ' Medicina Mentis, sive Tentamen genuinae Logicae, in qua disseritur de Methodo detegendi incoKaitas veritates, Amsterdam, 1687. Second and revised edition, Medicina Mentis, sive Artis inveniendi Praecepta generalia, Leipzig, 1695. ~For example, cf. Wilhelm Windelband, Geschichte der Philosophie, 3~o-33 and 356; Friedrich Ueberweg, Grundriss der Geschichte der Philosophie, III: ~95-97, 3 x~ 34o-43; A. Robert Caponigri, A History of Western Philosophy (Notre Dame/London: University of Notre Dame.. (shrink)

L'axe principal de ce texte du philosophe polonais Emil Lask (1875-1915) est la critique de la philosophie de la valeur et la théorie de la connaissance. Son exposé est l'une des révisions du kantisme les plus radicales du début du XXe siècle.

If one starts from de Broglie's basic relativistic assumptions, i.e., that all particles have an intrinsic real internal vibration in their rest frame, i.e., hv 0 =m 0 c 2 ; that when they are at any one point in space-time the phase of this vibration cannot depend on the choice of the reference frame, then, one can show (following Mackinnon (1) ) that there exists a nondispersive wave packet of de Broglie's waves which can be assimilated to the nonlinear (...) soliton wave U 0 introduced by him in his double solution model of wave mechanics. (2) Since de Broglie's linear pilot waves can be considered to be real waves propagating as collective motions on a covariant subquantum chaotic “aether,” (3) these new solition waves can be considered as describing the particle's immediate neighborhood, i.e., the aether's reaction to the particle's motion in the stochastic interpretation of quantum mechanics. The existence of such a physical aether (which provides a perfectly causal interpretation of the action-a-distance implied by the Einstein-Podolsky-Rosen experiments) can now be proved by establishing the reality of de Broglie's waves in realizable experiments. (shrink)

Intracellular pH (pHi) regulation is a homeostatic function of all cells. Additionally, the plasma membrane‐based transporters controlling pHi are involved in growth factor activation, cell proliferation and salt transport – all processes active in early embryos. pHi regulation in the early embryos of many species exhibits unique features: in mouse preimplantation embryos, mechanisms for correcting excess acid apparently are inactive, while excess base is removed by the mechanism common in differentiated cells. Additionally, unlike differentiated cells, mouse preimplantation embryos are highly (...) permeable to H+ until the blastocyst stage, where the epithelial cells surrounding the embryo are impermeable. In several non‐mammalian species, of which the best‐studied is sea urchin, cytoplasmic alkalinization at fertilization is necessary for development of the embryo, and elevated pHi must be maintained during early development. Thus, pHi regulatory mechanisms appear to be important for early embryo development in many species. (shrink)

Lead (Pb) contamination of the environment is an important human health problem. Children are vulnerable to Pb toxicity; it causes damage to the central nervous system and, in some extreme cases, can cause death. Lead is widespread, especially in the urban environment, and is present in the atmosphere, soil, water and food. Pb tends to accumulate in surface soil because of its low solubility, mobility, and relative freedom from microbial degradation of this element in the soil. Lead is present in (...) soil as a result to weathering and other pedogenic processes acting on the soil parent material; or from pollution arising caused by the anthropogenic activities; such as mining, smelting and waste disposal; or through the adoption of the unsafe and unethical agricultural practices such as using of sewage sludge, and waste water in production of vegetable crops or cultivation of vegetables near highways and industry regions. Lead concentrations are generally higher in the leafy vegetables than the other vegetables. Factors affecting lead uptake included its concentration in the soil, soil pH, soil type, organic matter content, plant species, and unsafe agriculture practices. Generally, as Pb concentration increased; dry matter yields of roots, stems and leaves as well as total yield decreased. The mechanism of growth inhibition by lead involve: a decrease in number of dividing cells, a reduction on chlorophyll synthesis, induced water stress to plants, and decreased NO 3 - uptake, reduced nitrate and nitrite reductase activity, a direct effect of lead on protein synthesis, a decrease on the uptake and concentration of nutrients in plants. The strategies to minimize Pb hazard can be represented in: (a) Phytoremediation, through natural plants are able to bio-accumulate Pb in their above–ground parts, which are then harvested for removal such as, using Indian Mustard (Brassica juncea), Ragweed (Ambrosia artemisiifolia), Hemp Dogbane (Apocynum cannabium), or Poplar trees, which sequester lead in its biomass. (b) Good and ethical agricultural practices such as cultivation of vegetables crops as far from busy streets or highways and industry regions as well as nonuse of sewage sludge and waste water in cultivated soils. (c) Increasing the absorptive capacity of the soil by adding organic matter and humic acid. (d) Growing vegetable crops and cultivars with a low potential to accumulate lead, especially in soils exposed to atmospheric pollution. (e) Washing of leafy vegetables by water containing 1 % vinegar or peeling roots, tubers, and some fruits of vegetables before consumption may be an important factor in reducing the lead concentration. (shrink)