Showing papers by "University of Lisbon published in 1991"

Coffin-Siris syndrome.

Abstract: In 1970 Coffin and Siris described three unrelated female children with severe mental and developmental retardation, sparse scalp hair, and coarse appearing facies with bushy eyebrows, a wide mouth, and thick lips. There were, in addition, lax joints and brachydactyly of the fifth digits of both hands and feet with absence of the nails and terminal phalanges.' To our knowledge, there have been 31 cases of this condition reported and these are reviewed in the present paper with the addition of two new cases.

A High-Temperature Transient Hot-Wire Thermal Conductivity Apparatus for Fluids.

Abstract: A new apparatus for measuring both the thermal conductivity and thermal diffusivity of fluids at temperatures from 220 to 775 K at pressures to 70 MPa is described. The instrument is based on the step-power-forced transient hot-wire technique. Two hot wires are arranged in different arms of a Wheatstone bridge such that the response of the shorter compensating wire is subtracted from the response of the primary wire. Both hot wires are 12.7 µm diameter platinum wire and are simultaneously used as electrical heat sources and as resistance thermometers. A microcomputer controls bridge nulling, applies the power pulse, monitors the bridge response, and stores the results. Performance of the instrument was verified with measurements on liquid toluene as well as argon and nitrogen gas. In particular, new data for the thermal conductivity of liquid toluene near the saturation line, between 298 and 550 K, are presented. These new data can be used to illustrate the importance of radiative heat transfer in transient hot-wire measurements. Thermal conductivity data for liquid toluene, which are corrected for radiation, are reported. The precision of the thermal conductivity data is ± 0.3% and the accuracy is about ±1%. The accuracy of the thermal diffusivity data is about ± 5%. From the measured thermal conductivity and thermal diffusivity, we can calculate the specific heat, Cp , of the fluid, provided that the density is measured, or available through an equation of state.

A well-posed problem for the exterior Stokes equations in two and three dimensions

Abstract: This paper treats the Stokes problem in exterior Lipschitz-continuous domains of ℝ2 and ℝ3. Using the weighted Sobolev spaces of Hanouzet (in ℝ3) and Giroire (in ℝ2), we establish the inf-sup condition between the velocity and pressure spaces. This fundamental result shows that the variational Stokes problem is well-posed in those spaces. In the last paragraph, we obtain additional regularity of the solution when the data are smoother.

The thermal conductivity and heat capacity of fluid nitrogen

Abstract: This paper presents new absolute measurements of the thermal conductivity and the thermal diffusivity of nitrogen made with a transient hot wire instrument. The instrument measures the thermal conductivity with an uncertainty less than ±1% and the thermal diffusivity with an uncertainty of ±5% except at the fluid critical point. The data cover the region from 80 to 300KK pressures to 70 MPa. The data consist of 8 supercritical isotherms, 3 vapor isotherms, and 4 liquid isotherms. A surface fit is developed for our nitrogen thermal conductivity data from 80 to 300 K at pressures to 70 MPa. The data are compared with a recent theory for the first density coefficient of thermal conductivity and a new mode-coupling theory for the thermal conductivity critical enhancement. These data illustrate that it is necessary to study a fluid over a wide range of temperatures and densities in order to characterize the thermal conductivity surface. Isobaric heat capacity results were determined from the simultaneously measured values of thermal conductivity and thermal diffusivity, using the density calculated from an equation of state. The heat capacities obtained by this technique are compared to the heat capacities predicted by a recent equation of state developed specifically for nitrogen.

Contact sensitization to 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one (MCI/MI). A European multicentre study.

Abstract: The frequency of positive reactions to 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one (MCI/MI) were studied at 22 European contact dermatitis clinics over a period of 1 year. A total of 4713 patients participated. All the patients were patch tested with nickel sulphate, formaldehyde, paraben-mix, and MCI/MI. 19.4% of the patients had positive patch tests to nickel, making this the most common allergen. 3% of the patients reacted to 100 ppm MCI/MI, while 2.6% reacted to formaldehyde and 1.1% to parabens. There was great variation in the frequency of MCI/MI sensitivity among the 22 centres. MCI/MI contact allergy was most common among women and in patients with facial dermatitis, while it was rarely seen in patients with dermatitis on the lower legs. There were no fluctuations in the number of positive patch tests to MCI/MI on a monthly basis when the results from all centres were combined. 117 of the 141 MCI/MI sensitized patients included in the study were retested. 88% had positive patch tests when retested. 101 of the MCI/MI-sensitive patients participated in a double-blind, placebo-controlled product use test. This test showed that 31% of the MCI/MI-sensitive patients had a positive reaction to a MCI/MI-preserved product. Only a few patients reacted to a control product. It is concluded that the preservative MCI/MI is an important new contact allergen.

Acute effects of maternal cigarette smoking on fetal heart rate and fetal body movements felt by the mother.

Abstract: Acute effects of maternal cigarette smoking on fetal heart rate (FHR) and fetal body movements felt by the mother (FM) were studied in 51 pregnant volunteers. Thirty four were chronic smokers (6 or more cigarettes per day, with an average of 14 cigarettes/day) and 17 were sporadic smokers (1 to 5 cigarettes per day, with an averaged of 3 cigarettes/day). In both groups the number of FM, fetal reactivity and short-term FHR variability decreased significantly in the 20 minutes following cigarette smoking; a sustained FHR rise of 10 or more beats/min was also found after the cigarette in more than 50% of the cases in the 2 groups. No statistically significant differences were found among the 2 groups when the post-cigarette data were compared. We conclude that maternal cigarette smoking produces important acute effects upon FM and FHR regardless the average daily number of cigarettes smoked by the mother.

Lattice Site of Iron in LiNbO3(Fe3+) by the PIXE/Channelling Technique

Abstract: The lattice location of Fe in LiNbO3 single crystals has been investigated by PIXE-channelling techniques. For the first time, it has unambiguously shown that Fe (mostly as Fe3+) lies at or near the Li-site, although a small fraction sitting at the Nb or intrinsic vacant sites cannot be ruled out.

Thermal conductivity surface of argon: A fresh analysis

Abstract: This paper presents a fresh analysis of the thermal conductivity surface of argon at temperatures between 100 and 325 K with pressures up to 70 MPa. The new analysis is justified for several reasons. First, we discovered an error in the compression-work correction, which is applied when calculating thermal conductivity and thermal diffusivity obtained with the transient hot-wire technique. The effect of the error is limited to low densities, i.e., for argon below 5 mol·L−1. The error in question centers on the volume of fluid exposed to compression work. Once corrected, the low-density data agree very well with the available theory for both dilute-gas thermal conductivity and the first density coefficient of thermal conductivity. Further, the corrected low-density data, if used in conjunction with our previously reported data for the liquid and supercritical dense-gas phases, allow us to represent the thermal conductivity in the critical region with a recently developed mode-coupling theory. Thus the new surface incorporates theoretically based expressions for the dilute-gas thermal conductivity, the first density coefficient, and the critical enhancement. The new surface exhibits a significant reduction in overall error compared to our previous surface which was entirely empirical. The uncertainty in the new thermal conductivity surface is ±2.2% at the 95% confidence level.

Characteristics of the acoustic signals in nine species of cicadas (homoptera, cicadidae)

Abstract: Detailed descriptions of the acoustic signals of European cicadas are available only for a few species. In this paper the acoustic signals and biomechanics of the timbals in nine species of cicadas from Portugal have been examined. Those species are Cicada barbara lusitanica (Boulard, 1982), C. orni (Linnaeus, 1758), Tettigetta argentata (Olivier, 1790), T. atra (Gomez-Menor, 1957), T. estrellae (Boulard, 1982), T.josei (Boulard, 1982), Tibicina quadrisignata (Hagen, 1855), Tympanistalna gastrica (Stal, 1854), and one unidentified species of Tettigetta. A qualitative and quantitative description of the sound is given in the time domain and the frequency domain. An acoustic male-to-male interaction signal that ceases the courtship was identified in C. barbara lusitanica. Some evolutionary aspects related to the biomechanics of the timbals and to the sounds produced are discussed.

Normal and diffusely abnormal myocardium in humans: functional and metabolic characterization with P-31 MR spectroscopy and cine MR imaging.

Abstract: The current study tested the concept that cine magnetic resonance (MR) imaging and phosphorus-31 MR spectroscopy might be used to provide a comprehensive evaluation of the functional and metabolic status of the myocardium in humans. Thirteen patients with congestive cardiomyopathy and eight healthy volunteers were imaged at 1.5 T with the one-dimensional chemical shift imaging technique for localization of P-31 MR spectroscopy and an electrocardiographically referenced gradient refocused sequence for imaging of the heart. Prominent peaks in the PDE and PME regions were observed in cardiomyopathic patients, but only the former peak was measured. The PCr/beta-ATP peak ratio was not significantly lower in cardiomyopathic patients compared with healthy subjects (1.51 +/- 0.08 vs 1.54 +/- 0.04). The ratios of PDE/PCr (0.80 +/- 0.07 vs 0.54 +/- 0.10) (P less than or equal to .01) and PDE/beta-ATP (1.19 +/- 0.10 vs 0.84 +/- 0.08) (P less than or equal to .05) were significantly higher in patients with dilated cardiomyopathy compared with healthy volunteers. Left ventricular systolic wall thickening was significantly lower and left ventricular peak and end-systolic wall stress and mass were significantly higher in cardiomyopathic patients compared with healthy volunteers. Thus, localized, gated P-31 MR spectroscopy combined with cine MR imaging allowed identification of both abnormal myocardial phosphate metabolism and abnormal ventricular function. While this study suggests that increased myocardial PDEs may be a marker for abnormal myocardium, the sensitivity and specificity of this marker need to be further evaluated.

Longitudinal comparative study on the influence of computers on reporting of clinical data.

Abstract: The impact of the clinical database system SISCOPE on medical services was evaluated and objective data compiled on the quality of information recording and reporting using a fully structured data entry system compared to traditional free text reporting. 1565 upper endoscopy reports produced with SISCOPE over a period of 12 months were assessed for completeness and compared to 152 and 208 free text reports done 4 months before and 1 month after the study period, respectively. Data on four common gastrointestinal findings (esophageal varices, ulcers, polyps and tumors) were evaluated. Physicians' compliance with the new system was good, as reflected by a constant level of quality of reporting over time, although a very slight decline in the ratio of computer generated reports to the total number of examinations was noted. Structured reports had an 18% missing data rate and contained 60% more relevant information than free text reports, which had a 48% missing data rate. No educational effect of the system was seen as missing data rates returned to pre-computerization levels just one month after the end of the study. It is concluded that menu-driven structured data entry systems result in production of far superior reports as compared to free text systems, probably due to their reminder effect.

Excitation of the nitro group in nitromethane by electron transfer

Abstract: In this paper we report on complementary measurements on ion‐pair formation in collisions between K atoms and CH3NO2 molecules. The experiments were performed in a c.m. energy range from 20 up to 300 eV. Double differential cross sections were obtained by measuring the K+ ion yield as a function of the scatter angle and as a function of the post‐collision laboratory energy. On the other hand, relative total partial cross sections for the formation of CH3NO−2, NO−2, and O− were measured in the same energy range. The experimental results lead to the conclusion that in this energy range electron transfer takes place to three ionic states of CH3NO−2, a dominantly repulsive 2A1 state and two 2B1 states with relatively deep potential wells.

Tumor-associated trypsin inhibitor (TATI) in patients with colorectal carcinoma. A critical comparison with CEA.

Abstract: We have evaluated the clinical utility of tumor-associated trypsin inhibitor (TATI) in colorectal cancer and compared it with carcinoembryonic antigen (CEA), the classical marker for this disease. We measured the serum levels of these markers in 53 patients with colorectal carcinoma before and after surgery. CEA was found to have greater sensitivity than TATI in this disease. The TATI concentrations did not correlate as well as CEA with the presence or absence of metastasis and with the the course of the disease after surgery. The use of TATI together with CEA for detection or follow up of colorectal cancer does not seem to be useful because a significant increase of positivity is not obtained as compared with determination of CEA alone.

Tectonic framework of the Azores Triple Junction

Abstract: The lack of accurate and detailed magnetic information has, in the past, limited the development of well constrained models for the plate tectonic evolution of the Azores Triple Junction. An aeromagnetic survey, made possible by the existing airport facilities, has long been desired as it can provide high quality magnetic data, whose homogeneity and coherency is far better than those provided by classic marine surveys. The results presented in this paper concern only a part of the Aeromagnetic Survey conducted by the Portuguese Instituto Nacional de Meteorologia e Geofisica and already allow an improved definition of the basic tectonic boundaries at the central part of the Azores plateau.

Radiative Heat Transfer in Transient Hot-Wire Measurements of Thermal Conductivity

Abstract: New measurements of the thermal conductivity of liquid toluene between 300 and 550 K have been used to study the importance of radiative heat transfer when using the transient hot-wire technique. The experimental data were used to obtain the radiation correction to the hot-wire temperature rises. Radiationcorrected values of thermal conductivity are reported. This study shows that the transient hot-wire method is much less affected by radiation than steady-state techniques.

The phytoestrogens present in de-ethanolized bourbon are biologically active: a preliminary study in a postmenopausal woman.

Abstract: Bourbon and some other alcoholic beverages have been shown to contain phytoestrogens which, as a result of an excessive intake and alcohol associated liver disease, have been suggested as contributing to the feminization of chronic alcoholic men. To evaluate this hypothesis directly, de-ethanolized bourbon was prepared and orally administered to a single postmenopausal woman. Serum or plasma levels of luteinizing hormone, follicle stimulating hormone, sex steroid binding globulin, high density lipoprotein cholesterol, and estradiol were monitored before, during, and after administration of the de-ethanolized bourbon at a dose equivalent to 4 ounces of bourbon for 20 days. The changes observed for each parameter during the injection of the bourbon extract are consistent with the presence of a biologically active estrogenic substance being present in the bourbon extract. These observations provide the first direct evidence in man for the presence of a biologically active estrogenic substance(s) in bourbon.

Fluid interfacial phenomena

Abstract: We review the thermodynamic and structural behaviour of interfaces between two coexisting phases in 3d. In particular we look at (i) surface and interfacial phase transitions (including critical phenomena) and (ii) systems in confined geometry. These concepts are illustrated using results for the surface phase diagram of systems with orientational degrees of freedom which were obtained using a variety of theoretical methods: mean-field, cluster variational and Monte Carlo computer simulation.

Cu and Zn uptake by Halimione portulacoides (L. ) Aellen. A long-term accumulation experiment

Abstract: Coastal areas and plant species colonizing salt-marshes are often exposed to a large diversity of pollutants, with emphasis on heavy metals. The important role of marsh vegetation in the accumulation of metals has been shown. Halimione portulacoides is one of the most representative halophytes of the salt-marshes of the river Sado estuary. In order to study the uptake and pattern of accumulation of Cu and Zn by the roots, stems and leaves of Halimione, plants were cultivated in vitro and treated daily with solutions containing 5, 25 and 50ppm Cu (as CuCl{sub 2}) and 50, 100 and 150ppm Zn (as ZnCl{sub 2}).

The effect of storage and thermocycling on the shear bond strength of three dentinal adhesives.

Abstract: The purpose of this investigation was to evaluate the effects of time of storage and thermocycling on the shear bond strength of three dentinal adhesives. The shear bond strength of Mirage Bond was significantly greater than that of Scotchbond 2, which was significantly greater than that of Scotchbond Dual Cure (P less than or equal to .05). Thermocycling significantly lowered the shear bond strength of Scotchbond Dual Cure and Scotchbond 2, but not that of Mirage Bond (P less than or equal to .05). Time of storage did not affect the shear bond strength of the other adhesives, but Mirage Bond had a significantly greater shear bond strength after 1 month of storage (P less than or equal to .05). Scanning electron microscopic observations showed that the fracture patterns were all at the smear layer-adhesive interface for Scotchbond Dual Cure, the majority of the fractures were at the primer-adhesive interface for Scotchbond 2, and most of the fractures were cohesive in the bonding agent for Mirage Bond.

Plant regeneration from protoplasts of long-term callus cultures of Actinidia deliciosa var. deliciosa cv. Hayword (Kiwifruit).

Abstract: Plant regeneration of Actinidia deliciosa var. deliciosa cv. Hayword was obtained from protoplasts isolated from petiole derived long-term callus cultures. Protoplasts were cultured in liquid medium over agarose gelled medium. Regenerated green callus, plated on solid medium, could develop shoots that rooted spontaneously in hormone-less medium. The plants obtained are growing fast in soil and present a normal phenotype.

Are bacteria the third partner of the Azolla-Anabaena symbiosis?

Abstract: The development of the prokaryotic colony in Azolla filiculoides indicates that Anabaena azollae is maintained through the life cycle of the fern and present in the leaves and megasporocarps. The same biological pattern is applied to the bacteria that are also present in these structures and seems to follow a development pattern identical to the cyanobacteria and probably can be considered the third partner of this symbiotic association.

Kinetic study of the reduction mechanism for Desulfovibrio gigas cytochrome c3.

Abstract: The kinetic aspects of the reduction process in cytochrome c3 from Desulfovibrio gigas have been investigated over a wide range of pH values ranging between pH 5.8 and pH 9.8. The data have been analyzed in the framework of an I2H4 interaction network coupled to a proton-linked equilibrium between two tertiary structures (Cornish-Bowden, A. & Koshland, D.E. Jr (1970) J. Biol. Chem. 245, 6241-6250). The kinetic rate constants for the reduction of the four hemes for the two tertiary conformations have been characterized in the framework of the thermodynamic network obtained from the equilibrium analysis (Coletta, M., Catarino, T., LeGall, J.J. & Xavier, A.V. (1991) Eur. J. Biochem. 202, 1101-1106). The intrinsic reduction rate constants determined by reaction with sodium dithionite for two hemes (namely heme 4 and heme 1) are significantly faster than those for the other two heme residues. In view of the equilibrium redox properties, heme 4 (with the fastest reduction rate) may then work as the kinetic electron-capturing site for the electrons from sodium dithionite. The transfer to hemes 2 and 3 then occurs by virtue of their free-energy levels at equilibrium. At our experimental conditions, there is also transfer of electrons to hemes 2 and 3 from heme 1, which is reduced at a slower rate than heme 4, thus contributing to the biphasic kinetics observed for the overall process. The kinetic parameters obtained are discussed in terms of the mechanism proposed for the coupling between the electron and proton transfer, as induced by the heme/heme cooperativity network.

Nitrate reduction in seedlings of carob (Ceratonia siliqua L.)

Abstract: summary The distribution of nitrate reduction in young carob plants (Ceratonia siliqua L. cv. Mulata) was studied. Plants (three months old) were grown in aerated nutrient solutions under greenhouse conditions. Reduction of nitrate was estimated both in the leaves and in the roots by: (a) accumulation of nitrite in vitro, (b) accumulation of nitrite in vivo and (c) disappearance of nitrate in vivo. Disappearance of nitrate in vivo offered the closest estimation of the rate of nitrate reduction. Leaves consistently showed rates of nitrate reduction lower than those in roots, regardless of assay method. Lowering root temperature had no marked effect on the distribution of nitrate reductase activity in the plant; increasing nitrate concentration in the shoot, however, markedly increased leaf nitrate reduction. The relatively low level of nitrate reductase in leaves appears to be caused mainly by a limitation of nitrate transport from root to shoot. Nitrate reduction takes place in both the root and the shoot of young carob plants with the shoot accounting for approximately 20% of total nitrate reduction in the plant.

Lattice site of trivalent impurities in Mg-doped lithium niobate crystals

Abstract: The lattice site of trivalent impurities (lutetium, neodymium and indium) was determined in magnesium-doped LiNbO3 crystals by Rutherford backscattering and proton-induced X-ray emission channelling experiments. It was shown that lutetium and indium substitute mainly for lithium ions, while most of the neodymium ions occupy structural vacancy positions. It cannot be excluded, however, that a fraction of the impurities may replace niobium sites. In all of the three crystals an IR absorption band was detected which is attributed to OH− stretching vibrations in M3+ (niobium site)-OH−Mg2+ (lithium site) complex defects.