Search results for "Roca"

Metals and Organochlorine Compounds in Fish from Latvian Lakes

1998

Organochlorines and metals have high toxicity and worldwide distribution in the aquatic environment. They are known to accumulate in sediments. In mollusks and fishes, they are bioconcentrated, even when released in minute quantities into the environment. This is important, as these chemicals have an adverse impact on species diversity, and accumulate in humans when seafood is consumed (Jaffar et al. 1988; Ruiter 1995). The nature and extent of accumulation and impact of persistent xenobiotics in water bodies depend on their sources; i.e. whether they are from industry, agricultural activities, transboundary transport with air masses (Sharif et al. 1993), geochemically determined elevated c…

Effect of an Acaricide on the Reproduction and Survival of Daphnia magna

1999

Daphnia magna feeding behavior after exposure to tetradifon and recovery from intoxication.

1999

Abstract The feeding behavior of the cladocera Daphnia magna subjected to a short-term exposure to the acaricide tetradifon (4-chlorophenyl 2,4,5-trichlorophenyl sulfone) was studied. The experiments were performed using the unicellular algae Nannochloris oculata at a density of 5×10 5 cells/ml as food for the organisms. In a first experiment, three generations (F0, F1, and F3) of the daphnids were exposed to sublethal levels of tetradifon (0.1, 0.18, 0.22, and 0.44 mg/l) and the effect of the toxicant on filtration and ingestion rates was determined. Rates of filtration and ingestion of D. magna declined in the three generations studied with increasing toxicant concentrations; however, tox…

Population dynamics in Daphnia magna as modified by chronic tetradifon stress.

2000

Two Daphnia magna offsprings (animals from the first and third brood) whose parentals (F0-generation) were exposed during 21 days to different tetradifon (4-chlorophenyl 2,4,5-trichlophenyl sulfone) concentrations, were transferred to a pesticide free medium during 21 days (recovery period). The algae Nannochloris oculata (5 x 10(5) cells/mL) was used as food. In this recovery study, survival, growth and reproduction (mean total young per female, mean brood size, onset of reproduction and mean number broods per female) were assessed as individual parameters and the intrinsic rate of natural increase (r) as population parameter, for F1 generation (1st and 3rd broods). Reproduction was still …

A new lattice action for studying topological charge

1996

We propose a new lattice action for non-abelian gauge theories, which will reduce short-range lattice artifacts in the computation of the topological susceptibility. The standard Wilson action is replaced by the Wilson action of a gauge covariant interpolation of the original fields to a finer lattice. If the latter is fine enough, the action of all configurations with non-zero topological charge will satisfy the continuum bound. As a simpler example we consider the $O(3)$ $\sigma$-model in two dimensions, where a numerical analysis of discretized continuum instantons indicates that a finer lattice with half the lattice spacing of the original is enough to satisfy the continuum bound.

Instrucción en estrategias de comprensión lectora mediante enseñanza recíproca: efectos del agrupamiento de los estudiantes

2013

The aim of this study was to compare the effects of two grouping formats on the reading comprehension. Reading comprehension Instruction used reciprocal teaching (RT) that is an instructional procedure to teach students cognitive strategies that might lead to improved reading comprehension. A sample of 43 students in the fourth year of primary education was selected: 18 children were instructed in regular classroom (GG), 8 were instructed in small group (PG), while the remaining 17 made up the comparison group (GC). Two types of comprehension measures were used: tasks of specific effects (getting the main idea, comprehension-monitoring test) and transfer effect measures (standardized test, …

Prospective comparison of cardiopulmonary events during minilaparoscopy and colonoscopy under conscious sedation.

2005

BACKGROUND AND STUDY AIMS Cardiorespiratory parameters were examined throughout diagnostic minilaparoscopy procedures. The same parameters were analyzed during colonoscopy, and the data were compared. PATIENTS AND METHODS Sixty-five consecutive unselected patients undergoing minilaparoscopy (group 1: ASA I, n = 34; group 2: ASA II/III, n = 31) and 61 consecutive unselected patients undergoing colonoscopy (group 3: ASA I, n = 31; group 4: ASA II/III, n = 30) were included. Oxygen saturation (Sao (2)), heart rate (HR) and mean arterial pressure (RRm) were measured continuously, and 12-lead electrocardiography (ECG) recordings were made at specific times during each procedure. RESULTS Minor di…

Spatially chaotic configurations and functional equations with rescaling

1996

The functional equation is associated with the appearance of spatially chaotic structures in amorphous (glassy) materials. Continuous compactly supported solutions of the above equation are of special interest. We shall show that there are no such solutions for , whereas such a solution exists for almost all . The words `for almost all q' in the previous sentence cannot be omitted. There are exceptional values of q in the interval for which there are no integrable solutions. For example, , which is the reciprocal of the `golden ratio' is such an exceptional value. More generally, if is any Pisot - Vijayaraghavan number, or any Salem number, then is an exceptional value.

Lifelong Learning: international injunctions and university practices

2001

JEAN-PIERRE JALLADE & JOSE´-GINE´S MORAIntroductionThe aim of this article is to elucidate whether the international discourse onlifelong learning (LLL) had any influence on what universities are doing in thisfield. International trends will be examined on the basis of OECD, UNESCO,EU and Council of Europe policy documents. University practice will be based onan enquiry carried out in 28 universities in seven European countries in 1999–2000 in the framework of the project Lifelong Learning and the University,sponsored by the EU/DG 12.Between the international policy discourse and university practice stands thenational layer of policy-making, giving rise to two interesting issues: first, don…

Reciprocal vs nonreciprocal trade agreements: Which have been best to promote exports?

2019

The Doha Development Agenda recognizes the central role that international trade can play in the promotion of economic development. In fact, the increase of exports from developing countries to developed nations' markets has been considered a key element for developing countries to realize the potential benefits of globalization. Over the last decades, developed countries have provided preferential access to their markets to developing countries through nonreciprocal trade agreements. Moreover, developing countries have also participated in reciprocal trade agreements. This paper re-examines comparatively the effect of both kinds of trade agreements on exports from developing countries but …