showing 36 of ~574560 from 574555 documents
Antiasthmatic effects of onions: Inhibition of 5-lipoxygenase and cyclooxygenase in vitro by thiosulfinates and “Cepaenes”
1990
Nine thiosulfinates (TS) and four "Cepaenes" (CS) isolated from onions and/or synthetized by us showed dose dependent (0.25 to 100 microM) marked inhibitory effects on both cyclooxygenase (CA, tested on sheep seminal vesicle microsomes) and 5-lipoxygenase activity (LO, tested on porcine leukocytes). The following rank order of activity was observed: saturated aliphatic TS less than aromatic TS approximately alpha, beta-unsaturated TS less than CS. CS inhibited both CA and LO by more than 75% at 10 and 1 microM concentrations respectively. Most likely, these in vitro effects are responsible for antiinflammatory and antiasthmatic properties of onion extracts observed in vivo, at least in part.
A source of polarized electrons based on photoemission of GaAsP.
1990
Abstract The source described is based on photoemission of electrons from 100-GaAs0.62P0.38 activated to negative electron affinity. It is built to inject a beam of polarized electrons into the 350 MeV linear accelerator in Mainz. It is capable of delivering a mean current of 28 μA spin-polarized longitudinally to a degree of 0.44. The lifetime of the cathode under operational conditions is better than 200 h. The source was successfully run in a parity experiment, in which the analysing power of quasielastic scattering from beryllium for longitudinally polarized electrons was measured.
Search for the t and b' quarks in hadronic decays of the Z0 boson
1990
We present a search for the third generation up type quark t and a possible fourth down type quark b' in hadronic Z0 decays observed in DELPHI at the LEP collider. For any scenario with a decay through the charged current or into a charged Higgs with a mass at least 6 GeV/c2 below the t and 3 GeVc2 below the b' mass, we set a lower limit for the t quark mass at 44.0 GeV/c2 and for the b' mass at 44.5 GeV/c2. For specific scenarios the mass limits are slightly higher, e.g. for charged current decays the limits are 44.5 and 45.0 GeV/c2 respectively, where all limits are given at a 95% confidence level. © 1990.
Sociología y política del socialismo valenciano : 1939-1989
1990
Con frecuencia se dice que el PSOE es una de las instituciones más estables en la historia reciente de España. Desde su fundación, en 1879, los socialistas españoles han visto caer monarquías y repúblicas, han vivido guerras civiles y revoluciones, han sufrido la clandestinidad y la persecución, y han alcanzado los poderes institucionales del Estado, e incluso -recientemente- presidido la Comunidad Europea. Por ello no es extraño que cada vez sean más numerosas las monografías y los libros publicados sobre el socialismo, los socialistas y el PSOE. Últimamente diversas investigaciones sobre el socialismo en las distintas Comunidades Autónomas empiezan a hacer acto de presencia en el panorama…
Didáctica de la presión hidrostática: experiencia de Torricelli
1990
Micellar fluorescence enhancement of carbamate pesticides
1990
Abstract Different studies have been carried out on the interaction of carbamate pesticides, such as carbofuran and carbaryl, with nonionic and anionic surfactants. Micellar fluorescence enhancements (MEF) of 15–20 for carbofuran in the presence of fatty alcohol ethylene oxide condensates, and of 3.7–8.6 in the presence of anionic surfactants at neutral pH have been obtained. Carbaryl does not interact with surfactants, but when it is hydrolysed to 1-naphthol, MEF values of the order of 2 are obtained in the presence of nonylphenol ethylene oxide condensates. The experimental parameters have been optimized in order to obtain maximum fluorescence. The mechanisms involved in the fluorescence …
Polyterritorial Polygyny in the Pied Flycatcher
1990
Publisher Summary The chapter discusses on the evolution of polyterritoriality in Ficedulu hypofeuca species. It estimates the costs and benefits to males and females, and uses the results to evaluate current alternative polygyny models. This chapter also explains that secondary females raise fewer offspring that most likely are of poorer quality than offspring of monogamous and primary females. This is probably not because the secondary females are of lower quality than other females settling at the same time, but because one could not find any differences in age or morphology of simultaneously mated monogamous and secondary females. The main reason is that offspring raised by polygynously…
Conservación de los Ligamentos Cruzados en las Artroplastias Totales de rodilla
1990
L'éducation et l'aide internationale
1990
International audience
Didáctica de las ciencias experimentales y sociales
1990
Trata el texto científico en la enseñanza de la historia con una metodología de aprovechamiento didáctico, lo que supone un planteamiento activo y aprendizaje significativo. Esta utilización de la fuente escrita ayuda no sólo al profesor e investigador, sino también al alumno que le permite avanzar en su formación mediante los conocimientos integrados en el currículo. Las características del texto científico son: actualidad, viabilidad, posibilidades de incógnita y contraste de opiniones. Un esfuerzo que nos permite seguir los pasos del investigador, con nuevas informaciones y un método activo que convierte a los alumnos en indagadores y protagonistas de su propio aprendizaje. Valencia Univ…
Aplicaciones a la Petrología en Arqueología Prehistórica: el estudio del utillaje lítico pulido
1990
ESL ? A New Simulation Language for Economic Models
1990
A new simulation language for modelling economic processes is presented which allows the specification of single decision units and coordinates all their activities. The basic ideas and features of this language will be described and demonstrated through small examples.
Turning exercises into problems: An experimental study with teachers in training
1990
The traditional concept of ‘problem’, as frequently exemplified by the paper‐and‐pencil exercises provided in physics textbooks, is examined and criticized for its lack of a truly scientific approach. The presentation of problems in this way, it is suggested, lies at the root of pupils’ and even teachers’ failure to solve simple exercises successfully. It is proposed that by a process of ‘reflective deconditioning’ it is possible to break down the preconceptions of physics teachers in training and help them to recast familiar situations in such a way that true problem solving is possible. A seminar designed to bring about this sort of change is described. Responses to a series of pre‐ and p…
Ciamexone in endocrine orbitopathy. A randomized double-blind, placebo-controlled study.
1990
Abstract The influence of ciamexone on the activity and course of endocrine orbitopathy was investigated. Fifty-one patients with active orbitopathy classes II-VI were allocated randomly to two groups: over a period of six months, 26 patients received 300 mg/day ciamexone and 25 patients received placebo tablets. In both groups, prednisolone was administered in addition in the first four weeks. Ophthalmological investigations and clinical tests as well as orbit sonography were carried out before as well as one, three and six months after the beginning of therapy. Before and after treatment, computer tomography of the orbit was performed. Symptoms and signs did not show any significant impro…
Molecular materials for electronics: neodymium diphthalocyanine - structure and properties
1990
Friedrich Grimm (1888-1959), patriote allemand et européen convaincu
1990
International audience
Inferencia en modelos dinámicos uniecuacionales con variables integradas
1990
Publicado
El estrato 4 del Filador (Priorato, Tarragona): Un ejemplo de transición Epipaleolítico-Neolítico en el Sur de Cataluña
1990
Régimen jurídico de la Antártida : sus relaciones con las zonas marítimas del Océano Austral
1990
Prof. Merle D'Aubigné (1989) Maestro y amigo de todos los Traumatólogos Españoles
1990
Rheological properties and morphology in LLDPE and PC based blends
1990
Abstract During an interlaboratory project on polymer blends (Technical Working Party-Polymer Blends-VAMAS), the rheological characteristics of some samples of blends of polycarbonate with linear low density polyethylene have been evaluated with the aid of a capillary rheometer. Some morphological observations on the extruded samples have also been performed through SEM and an attempt has been made to correlate the macroscopic and microscopic results.
El medio, un punto de vista del que partir para la enseñanza de las ciencias experimentales en el ciclo superior de la E.G.B: el estudio de la químic…
1990
Osteopoiquilosis.: a propósito de tres casos
1990
Los autores presentan el estudio genealógico, clínico y radiológico de una familia con osteopoiquilosis, haciendo hincapié en el diagnóstico diferencial así como en la importancia de la biopsia en el caso de sospecha de una tumoración ósea. The authors show a genealogic, clinic and radiologic study of one family affected by osteopoikilosis. They emphasiz e the differential diagnosis as well as the importance of biopsy suspecting a bone tumor.
Trace Analysis of Plutonium and Technetium by Resonance Ionization Mass Spectrometry Using an Atomic Beam and a Laser Ion Source
1990
A method for low level detection of plutonium and technetium is described with a detection limit of less than 107 atoms. Plutonium is a very toxic element due to its radioactive decay as well as its chemical behaviour. It was released to the environment in large amounts during the fifties and sixties of his century, principally by nuclear-weapon tests and some accidents. As a result about 0.4 − 4 mBq per gram 239Pu(T1/2 = 24390 y), corresponding to 4 × 108 − 4 × 109 atoms, can be found in the Northern Hemisphere in soil samples.
Review of Some Development of the Hole Drilling Method
1990
This paper contains a survey of some developments of the hole drilling method. It is mainly based on the research work carried out at the University of Palermo in the years from 1978 to 1989. The paper considers the relationship between the relaxed strain and the residual stresses for a rosette with an off-centre hole, the influence of hole eccentricity on the determination of residual stresses and of rosette calibration constants, the sensitivity of strain relaxation.
Speciation of tetraalkyllead compounds by flow injection — atomic absorption spectrophotometry
1990
The on-line demetallation of alkyllead compounds, with iodine, and further emulsification, provides a fast determination of total lead content in liposoluble matrices, such as gasolines. It can be carried out in a double channel manifold, using a magnetically well stirred dilution chamber for the emulsification of the samples, previous to their analysis by flame atomic absorption spectrophotometry. On the other hand, the different behaviour of tetraethyllead (TEL) and tetramethyllead (TML) can be employed for speciation of both compounds in the sample. The effect of the flow injection parameters on the sensitivity and accuracy has been studied and the figures of merit of the proposed method…
Therapieentscheidung beim Gallensteinleiden aus internistischer Sicht
1990
Fur die Therapie des Gallensteinleidens lassen sich folgende Leitlinien festlegen: 1. Gallengangssteine lassen sich in uber 90% der Falle endoskopisch, haufig kombiniert mit mechanischer oder extrakorporaler Stoswellenlithotripsie (ESWL) behandeln. Steine <10 mm im O konnen ohne endoskopische Papillotomie (EPT), grosere Steine nach EPT und Lithotripsie extrahiert werden. Die ESWL ist bei grosen, zu harten oder multiplen Steinen sowie bei atypischer Anatomie indiziert. Patienten mit hohem OP-Risiko werden zunachst nur endoprothetisch versorgt (ca. 2%). Selten (5%) ist bei Gallengangssteinen eine OP notwendig. 2. Symptomatische Blasensteine werden in 80–85% der Falle chirurgisch behandelt. Nu…
Influence of Thymopentin on Antibody Response, and Monocyte and T Cell Function in Hemodialysis Patients Who Fail to Respond to Hepatitis B Vaccinati…
1990
We investigated the influence of thymopentin as an adjuvant for hepatitis B vaccination on in vitro monocyte and T cell function and in vivo antibody response in a prospective, placebo-controlled double-blind trial in 20 low- and nonresponders to hepatitis B vaccination on chronic hemodialysis. 50 mg thymopentin was given subcutaneously twice per week for 3 weeks, followed by 1 intramuscular injection of 40 micrograms HB-Vax and 3 subsequent injections of thymopentin. After 1 month, the patients were boostered with 40 micrograms HB-Vax. There was no significant difference in T cell and monocyte function after administration of thymopentin, as determined in vitro. After 3 months, 3 patients …
Oxygen parameters of blood: Definitions and symbols
1990
Definitions and symbols for relevant parameters of the oxygen status of arterial blood are recommended. The recommendations are as simple as possible, easy to understand, and devoid of misinterpretations and double meanings. The authors propose no new definitions for limited new methods, no combination of symbols and methods, and no association between definition, symbol and commercial name.
“The Great Gatsby and the American Dream”
1990
Conférence présentée à l’Ecole Internationale de l’Accueil Franco-Nordique, Paris
Mechanisms of Autocrine and Paracrine Growth Control in Acute Myelogenous Leukemia
1990
Blast cells of a high proportion of patients with acute myelogenous leukemia (AML) proliferate in response to exogenous hematopoetic growth factors, both in vitro [9, 14, 26, 36, 48, 65] and in vivo [20]. Whereas leukemic colony-forming cells (L-CFCs) from most patients share their growth factor dependence with normal committed myeloid progenitor cells (CFU-GMs), some AML samples autonomously form colonies in agar and are therefore believed to bypass growth factor requirements [17, 42, 72]. Autocrine growth factor production has been identified as one mechanism used by AML blasts to supply various growth-promoting molecules. Moreover nontransformed accessory bone marrow cells have been show…
Neuroleptika: Neue Substanzen — Neue Indikationen
1990
Seit den Untersuchungen von Carlsson u. Lindqvist (1963) weis man, das klinisch wirksame Neuroleptika Dopaminrezeptoren blockieren, und Mitte der 70er Jahre konnte dies erstmals anhand von Rezeptorbindungsstudien direkt nachgewiesen werden (Burt etal. 1975; Seeman etal. 1975). Obwohl man von der antidopaminergen Wirkung der Neuroleptika nicht zwingend auf einen der Schizophrenie zugrundeliegenden Pathomechanismus Ruckschlusse ziehen kann, stellt doch die antipsychotische Wirksamkeit von Dopaminantagonisten eine der wichtigsten Stutzen der mittlerweile weiterentwickelten Dopaminhypothese der Schizophrenie (Crow 1987; McKenna 1987) dar.
Benthic Invertebrates in Relation to Acidity in Finnish Forest Lakes
1990
In order to examine the effects of acidity on abundance and community structure of the benthic invertebrates in forest lakes and to evaluate the applicability of certain benthic animals as early warning indicators of lake acidification, 140 lakes, situated mainly in southern Finland, were studied by quantitative and qualitative sampling methods.
Partial {$*$}-algebras of closable operators. I. The basic theory and the abelian case
1990
This paper, the first of two, is devoted to a systematic study of partial *-algebras of closable operators in a Hilbert space (partial Op*-algebras). After setting up the basic definitions, we describe canonical extensions of partial Op*-algebras by closure and introduce a new bounded commutant, called quasi-weak. We initiate a theory of abelian partial *-algebras. As an application, we analyze thoroughly the partial Op*-algebras generated by a single closed symmetric operator.
Periodicidad y movilidad del comercio: Mercados y ferias valencianos a mediados del siglo XIX
1990
El objetivo de este artículo es analizar la localización y características de los mercados y ferias valencianos de mediados del siglo XIX en función de la teoría económica que explica la periodicidad y movilidad del comercio y la secuencia evolutiva de formación de un comercio estable. El estudio realizado demuestra que existe una estrecha relación entre la organización comercial comarcal y la densidad de población, la estructura de asentamientos y la accesibilidad a las principales corrientes comerciales interregionales, Por otra parte, la localización de las ferias está en función de la existencia de límites entre regiones económicas complementarias, cambios de pendiente y puntos de ruptu…