showing 36 of ~574560 from 574555 documents
Noticia preliminar de las excavaciones de la Domus tardía del solar del Romeu (Sagunto)
1994
Glial Swelling and Damage by Arachidonic Acid
1994
Arachidonic acid (AA) is a major constituent of membrane phospholipids in brain tissue. Normally, the free fatty acid is present only in small amounts, but it accumulates under adverse conditions such as ischemia (Kinouchi et al. 1990). The release of free fatty acids involves activation of phospholipases and breakdown of membrane phospholipids. A A in particular is considered to mediate pathological processes. It is a polyunsaturated compound and precursor of prostaglandins, leukotrienes, and oxygen-derived free radicals (Wolfe 1982). In cerebral ischemia concentrations of free AA of up to 0.5mM/kg were found (Kinouchi et al. 1990). But also brain injury and seizures cause increased levels…
A Monte Carlo Simulation of the Stillinger-Weber Model for Si-Ge Alloys
1994
ABSTRACTThe bulk phase behavior of silicon-germanium alloys is investigated by means of a constant pressure Monte Carlo simulation of the Stillinger-Weber potential in the semi-grand-canonical ensemble. At low temperatures, Si and Ge phase separate into a Si-rich phase and a Ge-rich phase. The two-phase region is terminated by a critical point whose nature is investigated thoroughly by the multihistogram method combined with finite size scaling analysis. These results showed that the critical behavior of the alloy belongs to the mean field universality class, presumably due to the elastic degrees of freedom. We have also studied the structural properties of the mixture and found that the li…
Glucose Diffusion Coefficients Determined from Concentration Profiles in Emt6 Tumor Spheroids Incubated in Radioactively Labeled L-Glucose
1994
In order to theoretically assess tissue energetic status, conditions for substance exchange need to be known. One group of parameters important in this context are diffusion coefficients of nutrients and metabolic waste products which may be assessed by incubating spheroids in a medium containing tracer amounts of the radioactively labeled substance in question, for a defined period of time. In previous studies, the overall amount of 14C-labeled substance taken up by the spheroids was measured by scintillation counters (e.g.[1]), or the concentration of 3H-labeled substance in the spheroid center was determined by autoradiography and grain counting (e.g. [4]). From a number of such measurem…
Monte Carlo Simulations of Body Centered Cubic Alloys
1994
We illustrate the use of Monte Carlo simulations in the study of order-disorder phenomena in metallic alloys by presenting detailed work on a fairly realistic lattice model for iron aluminum. The model has been constructed based on recent measurements of effective interaction parameters and includes a description of the magnetism of iron within a Heisenberg Hamiltonian. We show that it reproduces the bulk phase diagram in a qualitatively correct way. Then internal antiphase boundaries and free surfaces in the (100)-direction are studied. An interfacial roughening transition is predicted as well as critical broadening of the profiles as the bulk approaches a second order transition. Nonstoec…
Algebraic Structures of Rough Sets
1994
This paper deals with some algebraic and set-theoretical properties of rough sets. Our considerations are based on the original conception of rough sets formulated by Pawlak [4, 5]. Let U be any fixed non-empty set traditionally called the universe and let R be an equivalence relation on U. The pair A = (U, R) is called the approximation space. We will call the equivalence classes of the relation R the elementary sets. We denote the family of elementary sets by U/R. We assume that the empty set is also an elementary set. Every union of elementary sets will be called a composed set. We denote the family of composed sets by ComR. We can characterize each set X ⊆ U using the composed sets [5].
Fast Solution Precursor Synthesis of the 2223 Phase: the Role of Lead in the Reaction Pathway
1994
ABSTRACTValuable mechanistic information, about the reaction pathway in the formation of the 2223 phase, has been obtained by the use of a solution synthesis route. The presence of lead in the starting mixture has remarkable effects on the nature and stability of the different intermediates: i) the grain size and morphology of Bi2CuO4 is severely changed, ii) calcium carbonate is partially decomposed to yield the calcium plumbate, iii) the 2201 phase results stabilized against the formation of the collapsed phase Bi17Sr16Cu7O49-δ, iv) the melting point of the intermediate 2212 is lowered by about 10 °C. All these effects, due to lead substitution, contribute to promote the formation of the …
La imprenta valenciana de la familia Mey-Huete en el siglo XVI : producción y tipografía
1994
Educación física y desarrollo del currículum : un estudio de casos en investigación colaborativa
1994
Una talla de fines del siglo XVI en la iglesia parroquial de Chulilla
1994
La «Virgen del Rosario» de la iglesia parroquial de Chulilla (Valencia) es una pieza del siglo XVI realizado en madera policromada y dorada, anónima. Esta obra se encuentra en el «Renacimiento Español» con ciertas influencias «romanistas». Se conservan escasas muestras de este tipo de estatuas en la Provincia de Valencia y es necesario que se estudien para contribuir a su divulgación y conservación.
Soft hydrothermal synthesis of new microporous materials based on phosphate-like species
1994
ABSTRACTFactors controlling hydrothermal synthetic procedures are not well understood. A good knowledge of the solution chemistry of precursor species is the best reference for the design of rational procedures. Examples of the predictive character of simple models in order to rationalize complex syntheses are discussed in detail.
La buena letra
1994
Il wagneriano "imperfetto": Richard Strauss e gli Dei di Bayreuth
1994
Il saggio traccia un quadro dei rapporti fra R. Strauss e il mondo di Bayreuth, con particolare riferimento ai rapporti personali ed epistolari con Cosima Wagner.
Didáctica de las ciencias experimentales y sociales
1994
Resumen tomado del autor. Resumen también en inglés Se abordan las características de algunos de los actuales manuales escolares españoles de Ciencias Sociales con el fin de analizar dicha cuestión, en relación tanto con la mayor o menor dimensión europea de los mismos, como de las peculiaridades de su forma de tratamiento. El positivo deseo de superar un tipo de enseñanza de las Ciencias Sociales en la educación obligatoria española, caracterizado anteriormente por su orientación centralista y estatocéntrica, ha abierto una nueva problemática cuyas posibles soluciones no son ni fáciles ni evidentes. La conveniencia cultural, social y política de conocer la propia identidad histórico-social…
Pseudoartrosis de escafoides carpiano tratadas mediante la técnica de Matti-Russe: estudio retrospectivo de 36 casos
1994
Presentamos un estudio retrospectivo de una serie de 36 pacientes con pseudoartrosis de escafoides operados mediante la técnica de Matti-Russe entre 1985 y 1991. Utilizamos injerto córtico esponjoso obtenido del radio (50%), cresta ilíaca (42%) y cúbito (8%) sin diferencias en la incorporación. La tasa de curación fue mayor en las pseudoartrosis medias y distales (80%) que en las de localización proximal (54%). El 80% de los fracasos de curación en la localización media y distal eran pseudoartrosis de más de 30 meses de evolución. Los cambios degenerativos en el carpo de las pseudoartrosis no curadas fueron significativamente mayores (p3 0 months evolution). Carpal degenerative changes were…
Anodic stripping voltammetric determination of heavy metals in solutions containing humic acids
1994
Various simultaneous effects of humic acids on the current and potential of differential pulse anodic stripping peaks of copper, lead, cadmium and zinc in weakly alkaline and acidic (pH 2) solutions have been investigated and interpreted with regard to metal complexation and the adsorption of humic acid on the mercury electrode. The applicability of the standard additions method for metal quantitation and the experimental conditions for UV-photolysis with a high-pressure mercury lamp have been examined in model as well as real water samples.
Salt-regulating hormones in young normotensive obese subjects. Effects of saline load.
1994
To investigate whether the response of salt-regulating hormones to volume expansion is impaired in obese subjects, we assessed the effects of saline load (0.25 mL/kg.min.120 min) in 9 young, healthy, normotensive obese subjects (body mass index, > 30 kg/m2) and in 10 lean control subjects (body mass index, < 25 kg/m2) matched for age, gender, height, and mean blood pressure. Hematocrit, plasma renin activity (PRA), plasma aldosterone (PA), atrial natriuretic factor (ANF), and urinary sodium excretion (UNaV) were evaluated. Saline load increased ANF levels significantly (P < .001) in lean subjects at both 60 and 120 minutes, whereas they decreased in obese subjects. Such decreases b…
Correlation between flavour profiles and aromagrams of Chardonnay Burgundy wines
1994
Osteosíntesis con tornillos de Kadar en las fracturas de cuello femoral
1994
Se estudian retrospectivamente 30 pacientes con fractura de cuello femoral, tipo I y II de Garden, tratadas con osteosíntesis a compresión mediante tornillos de esponjosa tipo Kadar. La edad media de los pacientes fue de 70±19 años, siendo el accidente casual la etiología de todas ellas. Se valoró la calidad de la reducción y de la fijación mediante criterios radiográficos, siendo la reducción óptima en el 93 % de los pacientes y la fijación en el 50%. Como complicaciones hubo 2 desplazamientos precoces de la fractura. No ha habido ninguna pseudoartrosis ni necrosis avascular. Valorando los resultados con arreglo a los criterios de Merle d'Aubigné, hemos obtenidos un 84% de buenos resultado…
Some intriguing items in the history of adsorption
1994
Abstract Clay was already used in antiquity as a drying and bleaching agent, a carrier for paints, and for various medical purposes. Sand was applied for water desalination. Charcoal was recommended as an antidote Based on Lowitz' discovery of the decolorizing effect in 1785, charcoal was used for the purification first of sugar. The patents of Ostrejko in 1900 opened the way for its industrial application. Already in the Bible we find the description of an adsorption experiment. The systematic research began 1773 when Scheele observed the adsorption of air by charcoal using a volumetric apparatus. The first adsorption measuring instruments were hygrometers as described by Nicholas of Cues …
Non-Perturbative Propagators in QCD
1994
Over the last two decades it has become clear that perturbation theory can only give us very limited information about QCD. For example it is not sufficient to describe that most basic of things, the mass spectrum. Although, we may hope one day to gain from the lattice approach numerical confirmation that we have the correct Lagrangian to describe hadronic physics, that day is not at hand. In the meantime it will be argued here, the operator product expansion (OPE) offers us some useful non-perturbative information about the structure of QCD.
Sodium Dodecylsulphate Electrophoresis
1994
Sodium dodecylsulphate (SDS) consists of an aliphatic chain of 12 C atoms to which at one end a sulphate residue is bound. It forms complexes with both the polar and non- polar amino acid residues of proteins irrespective of their sizes and shapes, leaving the primary structure uninfluenced. In electrophoresis SDS is used: a) to separate (enzyme) proteins into their monomeric constituents, b) to estimate the molecular mass of unfolded (and reduced) polypeptides, and c) to keep membrane proteins in a solubilized state.
Results of 200 intracranial stereotactic biopsies
1994
200 stereotactic biopsies were evaluated. The validity of the intraoperative histopathological results were compared with the final diagnosis using conventional embedding and staining techniques. Further comparison between the histology of the biopsy and the post mortem or open operative findings were possible in 41 cases. Discrepancy was found in one case regarding the tumor detection, and in three cases regarding the tumor grading. The mortality in our patients was 1% and the morbidity 3%. Stereotactical biopsy had a low risk even in deep brain regions such as basal ganglia, mesencephalon, and pons. At the same time the high histologic validity makes the CT-guided stereotactical biopsy re…
Le texte à rire : technique du secret et art de l'illusion chez Alphonse Allais
1994
The work of the famous French humorist Alphonse Allais (1854-1905), who wrote mainly short stories and press columns, presents a good subject for literary scholars and semioticians. This study looks at the most characteristic texts of Allais as complex and clever devices specially set up to achieve a humorous effect. Two strategies seem to be particularly important to this end: on the one hand, the sharing and the spreading of information among the protagonists of the text (author, readers, characters); on the other hand, the game of appearances - (trans)forming, (mis)interpreting, discovering and concealing them – in which the protagonists are engaged. One often finds these strategies in h…
Kokkolan monialaisen ammattikorkeakoulun ensimmäinen kokeiluvuosi opiskelijoiden kokemana ja näkemänä
1994
Tämän tutkimuksen tarkoituksena on tukea Kokkolan ammattikorkeakoulussa tapahtuvaa kehittämistyötä selvittämällä opiskelijoiden subjektiivisia odotuksia, koulutuskokemuksia ja mielikuvia ammattikorkeakoulun ensimmäiseltä toimintavuodelta. Tutkimuksen tavoitteena on hahmottaa kuva niistä olosuhteista ja tilasta, jossa Kokkolan ammattikorkeakoulu oli huhtikuussa 1993.
Sui vv. 336-38 del Thyestes di Seneca
1994
I moduli semantici antitetici sui quali si incentra la struttura del dramma costituiscono nella struttura tragica del Thyestes di Seneca e in particolare nel secondo canto corale la proiezione della dell'antitesi furor-mens bona. I vv. 336-38 del secondo coro si costituiscono infatti come elementi significativi nella trama di allusioni e procedimenti antitetici privilegiati da Seneca nell'economia del dramma.
Fraudes alimentarios : Evolución histórica y elementos esenciales del sistema de protección penal
1994
Schematic or taxonomic organisation of the reality and the development of class logic
1994
Abstract The experiment studied the effect of various methods of organising reality (taxonomic vs. schematic) on success in inclusion and logical complementation tasks. Seventy-two nine-year-old children were divided into four groups on the basis of their logical structuring abilities. Using three sets of material (Animals, Plants, Means of Transportation), the subjects performed a sorting task and an evaluation task in which the taxonomic and schematic modes of organising reality were opposed. Contrary to our hypothesis, the ″;logical included' did not exhibit a greater capacity for taxonomic organisation than the “empirical includers” of the same age, either in the sorting or the evaluati…
IS THERE A TWO-STEP FLOW OF AGENDA-SETTING?
1994
Les représentations spatiales de concepts scientifiques : inventaire et diversité
1994
The consultation of twelve journals (French and English language) that deal with science education, for the years 1991 to 1993, allowed us to summarize the use of spatial representations of scientific concepts in didactics research. Two main results were produced from this study : there has not been much work published with spatial representations, and what has been published is very heterogeneous. Analysis of this diversity does not always allow us to understand the authors’ objectives and obliges researchers in didactics to think about the nature and role of spatial representations in the construction of scientific knowledge.
La famille de Bourbon : les mariages des ducs et leurs conséquences politiques
1994
Vivre en prison au XVIIIe siècle. Lettres de Pantaléon Gougis, vigneron chartrain (1758-1762)
1994
Évaluation d'une expérimentation d'activités musicales en Grande Section maternelle
1994
Une évaluation d'une expérimentation d'activités musicales conduite en grande section de maternelle montre que les enfants qui ont bénéficié d'un enseignement musical spécifique (de 2 ou 4 h hebdomadaires) ont réalisé des performances scolaires supérieures à ceux qui étaient scolarisés dans les classes témoins. Ces résultats valent sur les acquis de fin de grande section mais aussi de façon plus convaincante sur les scores en lecture et en mathématiques en fin de cours préparatoire. Au-delà des effets moyens observés, il apparaît que certains élèves, ceux dont les acquis étaient les plus faibles en début de grande section, les élèves étrangers et ceux qui n'ont pas bénéficié d'une scolarisa…
Doux paysages du Doubs
1994
L'eau est partout dans le paysage. Elle intervient comme agent d'érosion : géologues et géomorphologues savent expliquer le rôle prépondérant qu'elle prend dans le façonnement du relief. Elle s'y manifeste aussi comme élément de construction visuelle. Enfin, les sociétés humaines ont conquis les paysages et les ont aménagés pour en faire le support de leurs activités.
La place du quartier canonial dans la ville
1994
J.-C. Picard; International audience