Showing papers by "Autonomous University of Barcelona published in 1986"
TL;DR: New mechanisms for understanding neutrino masses in superstring models that contain E/sub 6/-singlet zero-mass fields after compactification are proposed and it is shown that the low-energy gauge group of these models can be phenomenologically acceptable.
Abstract: We propose new mechanisms for understanding neutrino masses in superstring models that contain ${\mathrm{E}}_{6}$-singlet zero-mass fields after compactification. We show that the low-energy gauge group of these models can be phenomenologically acceptable. We then comment on \ensuremath{\Delta}B=1 and \ensuremath{\Delta}B=2 baryon-number-violating processes in these models.
1,182 citations
TL;DR: In this paper, a detailed mapping of the South Pyrenean zone in the eastern Spanish Pyrenees is presented, showing that a great number of Alpine thrusts affect the basement and the cover.
158 citations
TL;DR: In this article, the red crystalline alkenyl species Ru(CO)Cl(RCHR′)(PPh 3 ) 2 (R = H, R′ = C 3 H 7, Ph; R = R′= Ph), which can be regarded as resulting from elimination of one phosphine molecule and insertion of the alkyne into the RuH bond, was characterized by elemental analysis and 1 H NMR and IR spectroscopy.
151 citations
TL;DR: It is concluded that antagonistic relationships such as primary consumption, predation, and scavenging had already evolved in microbial ecosystems prior to the appearance of eukaryotes.
Abstract: Two kinds of predatory bacteria have been observed and characterized by light and electron microscopy in samples from freshwater sulfurous lakes in northeastern Spain The first bacterium, named Vampirococcus, is Gram-negative and ovoidal (06 micrometer wide) An anaerobic epibiont, it adheres to the surface of phototrophic bacteria (Chromatium spp) by specific attachment structures and, as it grows and divides by fission, destroys its prey An important in situ predatory role can be inferred for Vampirococcus from direct counts in natural samples The second bacterium, named Daptobacter, is a Gram-negative, facultatively anaerobic straight rod (05 x 15 micrometers) with a single polar flagellum, which collides, penetrates, and grows inside the cytoplasm of its prey (several genera of Chromatiaceae) Considering also the well-known case of Bdellovibrio, a Gram-negative, aerobic curved rod that penetrates and divides in the periplasmic space of many chemotrophic Gram-negative bacteria, there are three types of predatory prokaryotes presently known (epibiotic, cytoplasmic, and periplasmic) Thus, we conclude that antagonistic relationships such as primary consumption, predation, and scavenging had already evolved in microbial ecosystems prior to the appearance of eukaryotes Furthermore, because they represent methods by which prokaryotes can penetrate other prokaryotes in the absence of phagocytosis, these associations can be considered preadaptation for the origin of intracellular organelles
147 citations
TL;DR: The results indicate that corticosterone, glucose, and serum lipid responses were not sensitive indices of the emotional arousal elicited by brief stress stimuli and were not related to the intensity of stress.
123 citations
TL;DR: Low cell wall elasticity seems to be an important causes of the low water stress tolerance in Cd-toxic plants.
123 citations
TL;DR: The prognostic significance of 20 clinical and histologic parameters was evaluated in a series of 416 laryngeal carcinomas treated between 1969 and 1981 and 5 of those parameters were found to influence survival independently.
Abstract: The prognostic significance of 20 clinical and histologic parameters was evaluated in a series of 416 laryngeal carcinomas treated between 1969 and 1981 at the Hospital de Santa Cruz y San Pablo, Barcelona, Spain. Clinical follow-up ranged from 2 to 13 years. The variables considered were: age, smoking habits, previous laryngeal disease, duration of clinical symptoms, motility of vocal cords, interval between diagnosis and treatment, postoperative infection, topographic location of the tumor, previous tracheostomy, ulceration, tumor size, resection margins, histologic grading, patterns of growth, types of invasion, mitotic index, depth of invasion, positive lymph nodes, T categories and N categories. Fourteen parameters were found to be significantly related to survival. After a multifactorial study using Cox's life table regression model, 5 of those 14 parameters were found to influence survival independently. The five variables ordered according to prognostic significance were: (1) positive lymph nodes, (2) T categories, (3) histologic grading, (4) ulceration, and (5) location.
98 citations
TL;DR: The influence of acid concentration was studied and the kinetics of the acid-catalyzed hydrolysis has been modeled suggesting a two-consecutive reactions mechanism, useful to explain the different behavior of the concentration of the two main sugars produced.
Abstract: Wheat straw has been hydrolized with sulfuric acid at 34 and 90 degrees C. The treatment at 90 degrees C yields complete solubilization of hemicellulose to xylose and arabinose without significant amounts of furfural. The influence of acid concentration was studied and the kinetics of the acid-catalyzed hydrolysis has been modeled suggesting a two-consecutive reactions mechanism. This model is useful to explain the different behavior of the concentration of the two main sugars produced. The enhanced cellulose accessibility to enzymatic attack is also reported. 26 references.
95 citations
01 Oct 1986
TL;DR: In this article, a semi-analytical theory for the halo orbits in the Restricted Three Bodies Problem (RTBP) is presented, which is valid and amenable to computation to any order.
Abstract: Techniques for computing and controlling a halo orbit are considered in this paper. It presents a semi-analytical theory for the halo orbits in the Restricted Three Bodies Problem (RTBP), that is valid and amenable to computation to any order. Results are presented up to order 11. The Floquet modes of the monodromy matrix are used to define a local optimal control procedure through the concepts of projection and gain functions.
86 citations
TL;DR: Improvements in the established conditions for the formation and storage of amino acid dabsyl derivatives and the use of new reversed-phase columns allow the chromatographic analysis in 25 min of all the proteinogenic amino acids in well resolved peaks of homogenous and highly reproducible size.
83 citations
Journal Article•
TL;DR: The Sensation Seeking Scale-Eorm: V (SSS) desarrollada by Zuckerman and cols. as mentioned in this paper is a version of the SSSS.
Abstract: Resumen es: Por necesidades de investigacion habiamos traducido al espanol y utilizado la Sensation Seeking Scale-Eorm: V (SSS) desarrollada por Zuckerman y cols.,...
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TL;DR: In this article, a re-examination of the gaussian effective potential (GOP) indicates the existence of a stable, non-trivial form of (λφ4)3+1 with positive, infinitesimal λB.
TL;DR: The phase diagram of the ternary subsystem Ge-GeTe-Sb 2 Te 3 -Sb was investigated using differential thermal analysis, differential scanning calorimetry, thermogravimetry powder X-ray diffraction and metallographic techniques as mentioned in this paper.
TL;DR: The course of 66 pregnancies was studied in 48 women with primary glomerular diseases; in all cases diagnoses were established by biopsy before pregnancy, and the incidence of hypertension, proteinuria, and renal failure was similar in the two groups.
TL;DR: Most of the rat ocular ADH is localized in the cornea where it could play a significant role in the detoxication of the alcohols of a broad range of structures.
TL;DR: The genetic basis of hybrid sterility has been investigated in backcross segmental hybrids between two sibling species, Drosophila buzzatii and D. serido, and asynapsis of homologous bands in hybrid polytene chromosomes has been used to identify the D. buzzatti genome.
Abstract: The genetic basis of hybrid sterility has been investigated in backcross segmental hybrids between two sibling species, Drosophila buzzatii and D. serido. Asynapsis of homologous bands in hybrid polytene chromosomes has been used to identify the D. serido chromosome segments introgressed into the D. buzzatti genome. All the investigated chromosomes contain male sterility factors. For autosomes, sterility is produced when an introgressed D. serido chromosome segment, or combination of segments, reaches a minimum size. On the other hand, any introgressed X chromosome segment from D. serido, irrespective of its size, produces either male hybrid sterility or inviability.
Journal Article•
TL;DR: The results show that the urinary excretion of DTPA is a simple test that measures accurately the degree of activity of inflammatory bowel disease, and detects intestinal permeability abnormalities even in clinical remission.
TL;DR: The results indicate strong directional selection for larval viability acting on the second‐chromosome karyotypes and also suggest selective differences in fecundity and longevity, and heterotic selection cannot be ruled out for other fitness components such as male mating success.
Abstract: The pattern of selection acting in nature on the chromosomal polymorphism of the cactophilic species Drosophila buzzatii was investigated by comparing inversion and karyotypic frequencies through four different life-cycle stages: adult males, eggs, third-instar larvae, and immature adults. All population samples were obtained in June 1981 at an old Opuntia ficus-indica plantation near Carboneras, Spain. The analysis rests on several assumptions which are explicitly set forth and discussed. The results, if these assumptions prove true, indicate strong directional selection for larval viability acting on the second-chromosome karyotypes and also suggest selective differences in fecundity and longevity. Heterotic selection, however, cannot be ruled out for other fitness components such as male mating success. This kind of selection could be operating on the fourth-chromosome polymorphism as well. Some gene arrangements showed significant and opposite changes in frequency at different parts of the life cycle, thus demonstrating endocyclic selection.
TL;DR: In roots Cd-toxicity increased ABA levels, while in plants treated with higher Cd concentrations no increase in ABA content in response to wilting was observed, and Cd at high concentrations is suggested to decrease water stress resistance by inhibition of the hydroactive stomata response.
TL;DR: Hexavalent chromium compounds, but not trivalent, are proficient agents of induction of the SOS system and can produce indirect mutagenesis in Escherichia coli.
Abstract: The induction of several SOS genes of Escherichia coli such as recA, umuC, and sfiA by hexavalent (K/sub 2/Cr/sub 2/O/sub 7/, K/sub 2/CrO/sub 4/, and CrO/sub 3/) and trivalent (CrCl/sub 3/, Cr(NO/sub 3/)/sub 3/, and (CH/sub 3/COO)/sub 3/Cr) compounds of chromium was studied. Induction was measured as ..beta..-galactosidase activity, using lacZ gene fusions under the control region of different SOS genes. The hexavalent chromium forms induced the genes responsible for massive synthesis of RecA protein, error-prone repair, and inhibition of cell division. On the other hand, the trivalent chromium compounds were unable to induce any of the SOS genes tested. Individual assay of hexavalent chromium compounds showed that K/sub 2/Cr/sub 2/O/sub 7/ was a stronger inducing agent of those three SOS genes tested than K/sub 2/CrO/sub 4/, which, in turn, was stronger than CrO/sub 3/. All this data led to the conclusion that hexavalent chromium compounds, but not trivalent, are proficient agents of induction of the SOS system and can produce indirect mutagenesis in Escherichia coli.
TL;DR: In this article, a possible solution of the solar neutrino problem is that electron neutrinos decay in transit from the sun, and the phenomenological consequences of this hypothesis are discussed for the experiments with detectors of 2 H, 40 Ar, 71 Ga, 98 Mo, and electron-neutrino scattering.
TL;DR: The activity of adenosine deaminase was significantly higher in the tuberculous cases than for the other three groups and significantlyHigher in pleural effusions of lymphomatous origin than in the neoplastic and miscellaneous groups.
TL;DR: In this article, the contribution to stellar energy loss is considered that would result if finite-range baryonic and/or leptonic forces exist, and upper limits on their strength are placed on their strengths.
TL;DR: The concentrations of glucose 6-P achieved upon incubation of hepatocytes with glucose plus mannoheptulose, an inhibitor of glucokinase and hexokinase, were lower than those found when the incubation was carried out with glucose alone.
TL;DR: HD‐Ag was found more often in the patients studied during the first 2 wk of illness, and anti‐HD of the IgM class was the only marker in one patient.
Abstract: Sixty-three intravenous drug addicts with HBsAg positive hepatitis were studied to evaluate the diagnostic usefulness of hepatitis delta virus (HDV) markers for diagnosis of acute HDV infection. Patients were tested for HBsAg, anti-HBc-IgM, and anti-HD-IgM by radioimmunoassay (RIA), and for hepatitis delta antigen (HD-Ag) by a commercial enzyme-linked immunoassay (ELISA). At least two serum samples at a mean interval of 4 wk were examined from each patient. HDV markers were found in 41 cases. In the first serum sample (obtained within 1-5 wk after onset of illness) HD-Ag was found in 32 cases and was the only HDV marker in 22; in the remaining 10 cases, HD-Ag was found along with total anti-HD, and in 6 of them anti-HD-IgM was also detected. Five additional patients were only positive for total anti-HD, and anti-HD of the IgM class was the only marker in one patient. HD-Ag was found more often in the patients studied during the first 2 wk of illness. In the second serum sample, HD-Ag was never the only marker detected, seven patients were still positive, and in all of them anti-HD was also present. Thirty patients were only positive for anti-HD. Seroconversion from HD-Ag to anti-HD occurred in 20 of 22 (91%) patients. The results suggest that HD-Ag determination by ELISA in the initial serum sample, during the first 2 wk of illness, may be the most sensitive test for the diagnosis of acute delta infection, and that seroconversion to anti-HD usually occurs after the sixth week of illness.
TL;DR: It is suggested that if aminoglycoside therapy is employed, these antibiotics must be administered both intravenously and directly into CNS.
Abstract: In order to evaluate the clinical aspects of gram-negative bacillary meningitis (GNBM) we reviewed the charts of 20 adult patients with the discharge diagnosis of meningitis caused by gram-negative bacilli (bacteriologically proved) seen between 1973 and 1984. Nine patients had post-neurosurgical (post-NS) GNBM and 11 patients spontaneous (S) GNBM; the mean age of the former was 42 ± 16 years and of the latter 56±14 years (p>0.05). The overall mortality rate was 50% (33% in the post-NS group and 64% in the S group). The glucose levels in CSF were significantly lower in the patients who died. Patients treated with combined aminoglycoside therapy presented a lower mortality rate than those treated with intravenous aminoglycoside only (25% versus 70%). We suggest that if aminoglycoside therapy is employed, these antibiotics must be administered both intravenously and directly into CNS.
TL;DR: It is shown that the sex ratio and the incidence of aneuploidy are similar, irrespective of the fertilization system used, and male and female gametes have the same levels ofAneuploids.
Abstract: A comparison of the first cleavage-stage chromosome complements of 1022 in vivo fertilized mouse embryos and 1033 in vitro fertilized mouse embryos is reported. The chromosome analysis of first-cleavage embryos allows us to study directly the chromosome complement of the sperm and oocyte that contribute to the embryo, since both chromosome clusters remain separate when an antimitotic agent is used to prevent syngamy. In this paper we show that the sex ratio and the incidence of aneuploidy are similar, irrespective of the fertilization system used. Male and female gametes have the same levels of aneuploidy. Triploidy is more frequent in the in vitro fertilized embryos and the difference can be ascribed to a higher incidence of polyspermy and diploid spermatozoa.
TL;DR: Cells considered to be migratory in the cerebral cortex of adult lizards are ultrastructurally of two types; cells with spongy chromatin show an increase in cytoplasmic organelles and progressive chromatin condensation as they travel from the ependymal layer to the granular layer.
Abstract: Cells considered to be migratory in the cerebral cortex of adult lizards are ultrastructurally of two types. Nuclei in the first type have highly dispersed chromatin, creating a spongy appearance, whereas in the second type the chromatin is irregularly clumped. Both types of cells are closely associated with processes of radial ependymal glia cells, which perhaps orient their migratory pathways. Cells with spongy chromatin show an increase in cytoplasmic organelles and progressive chromatin condensation as they travel from the ependymal layer to the granular layer. Possibly these cells account for the neuronal increase that takes place in the granular layer during postnatal life. Cells with chromatin clumps are very scarce; ultrastructurally they resemble immature reptilian astroglia cells.
TL;DR: In this article, the authors used amperometric detection after separation in a diffusion cell with a teflon membrane to detect sulphur dioxide in wines. But the results showed that at 25°C, the calibration graph showed two linear ranges, between 0.06 and 6 mg l −1 and 12 and 110 ml l − 1, with a detection limit of 0.03 mg l−1.
TL;DR: Enhanced renal prostaglandin synthesis in cirrhosis, inversely related to PRA and aldosterone, may be dependent on volume status; and preserved renal function in these patients is associated with the ability to synthesize prostacyclin and PGE2.
Abstract: Urinary prostaglandin excretion was studied in 42 patients with liver cirrhosis and in nine control subjects on restricted sodium intake and on bed rest. Creatinine clearance (CCr), sodium excretion (UNaV), plasma renin activity (PRA) and plasma aldosterone were also evaluated. Patients without ascites and ascitic patients without renal failure showed increased urinary excretion of immunoreactive 6-ketoprostaglandin F1 alpha (i6-keto-PGF1 alpha), prostaglandin E2 (iPGE2) and thromboxane B2 (iTXB2) when compared with controls, while immunoreactive PGF2a (iPGF2 alpha) levels did not differ from those in the control group. Patients with functional renal failure (FRF) presented a significant reduction of vasodilator prostaglandins but urinary excretion of iTXB2 was higher than in controls. On the whole, cirrhotic patients with higher urinary excretion of prostaglandins had normal or nearly normal PRA and aldosterone levels. i6-keto-PGF1 alpha and iPGE2 inversely correlated with PRA and aldosterone. The relationship between i6-ketoPGF alpha alpha and CCr was found to be highly significant in cirrhotic patients but not in the control group. On the other hand, iPGE2 significantly correlated with UNaV and with the fractional excretion of sodium (FENa). We concluded that: (a) enhanced renal prostaglandin synthesis in cirrhosis, inversely related to PRA and aldosterone, may be dependent on volume status; and (b) preserved renal function in these patients is associated with the ability to synthesize prostacyclin and PGE2.