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Showing papers by "University of Seville published in 1995"


Journal ArticleDOI
TL;DR: In this paper, a functional form for the speed-density relationship is presented, which is made up of a nondimensional spacing, the equivalent spacing and a function, the generating function, whose argument is the equivalent space.
Abstract: In this work a functional form for the speed-density relationship is presented This functional form is made up of a nondimensional spacing, the equivalent spacing and of a function, the generating function, whose argument is the equivalent spacing This functional form is derived by means of two different arguments The first argument is based on the set of properties that the volume-speed-density relationships should satisfy The second one arises when applying a dimensional analysis to a generic car-following model Finally, several examples of generating functions are shown

333 citations


Journal ArticleDOI
TL;DR: Respiration in light and respiration in darkness are tightly coupled, with variation in respiration on leaves of an evergreen and a deciduous species accounting for more than 60% of the variation inrespiration in light.
Abstract: Dark respiration in light as well as in dark was estimated for attached leaves of an evergreen (Heteromeles arbutifolia Ait.) and a deciduous (Lepechinia fragans Greene) shrub species using an open gas-exchange system. Dark respiration in light was estimated by the Laisk method. Respiration rates in the dark were always higher than in the light, indicating that light inhibited respiration in both species. The rates of respiration in the dark were higher in the leaves of the deciduous species than in the evergreen species. However, there were no significant differences in respiration rates in light between the species. Thus, the degree of inhibition of respiration by light was greater in the deciduous species (62%) than in the evergreen species (51%). Respiration in both the light and darkness decreased with increasing leaf age. However, because respiration in the light decreased faster with leaf age than respiration in darkness, the degree of inhibition of respiration by light increased with leaf age (from 36% in the youngest leaves to 81% in the mature leaves). This suggests that the rate of dark respiration in the light is related to the rate of biosynthetic processes. Dark respiration in the light decreased with increasing light intensity. Respiration both in the light and in the dark was dependent on leaf temperature. We concluded that respiration in light and respiration in darkness are tightly coupled, with variation in respiration in darkness accounting for more than 60% of the variation in respiration in light. Care must be taken when the relation between respiration in light and respiration in darkness is studied, because the relation varies with species, leaf age, and light intensity.

187 citations


Journal ArticleDOI
TL;DR: The increased expression of glyoxalase-I may be linked to a higher demand for ATP generation and to enhanced glycolysis in salt-stressed plants.
Abstract: A cDNA, GLX1, encoding glyoxalase-I was isolated by differential screening of salt-induced genes in tomato. Glyoxalases-I and-II are ubiquitous enzymes whose functions are not clearly understood. They may serve to detoxify methylglyoxal produced from triosephosphates in all cells. The protein encoded by GLX1 shared 49.4% and 58.5% identity with glyoxalase-I isolated from bacteria and human, respectively. Furthermore, yeast cells expressing GLX1 showed a glyoxalase-I specific activity 20-fold higher than non-transformed cells. Both GLX1 mRNA and glyoxalase-I polypeptide levels increased 2- to 3-fold in roots, stems and leaves of plants treated with either NaCl, mannitol, or abscisic acid. Immunohistochemical localization indicated that glyoxalase-I was expressed in all cell types, with preferential accumulation in phloem sieve elements. This expression pattern was not appreciably altered by salt-stress. We suggest that the increased expression of glyoxalase-I may be linked to a higher demand for ATP generation and to enhanced glycolysis in salt-stressed plants.

174 citations


Journal ArticleDOI
TL;DR: It is suggested that HIV infection can alter the natural course of chronic parenterally acquired hepatitis C, causing an unusually rapid progression to cirrhosis.
Abstract: The aim of the present study was to investigate the possible role of human immunodeficiency virus (HIV) infection in the natural course of chronic hepatitis C. Seventy-six adult patients with chronic parenterally acquired hepatitis C virus (HCV) infection examined from 1989 to 1993 were enrolled; of these 32 (42.1 %) were HIV positive and 44 (57.9 %) were HIV negative. Serum HCV RNA quantitation was carried out by polymerase chain reaction in a well-characterized group (n=20; 11 HIV positive and 9 HIV negative). Distribution of histological findings in liver biopsies from both HIV-infected and noninfected patients was similar. However, within 15 years after initial HCV infection, 8 of 32 (25 %) HIV-positive patients developed cirrhosis, in comparison with only 2 of 31 (6.5 %) patients in the HIV-negative group (p<0.05); similar incidences of cirrhosis were found in both patient groups within 5 and 10 years after HCV infection. Most of the HIV-negative cirrhotic patients (9 of 11) developed cirrhosis in a time interval longer than 15 years. Finally, HCV load was almost ten times higher (1 10-fold dilution) in the HIV-positive group, but this difference did not reach statistical significance in this small study population. These results suggest that HIV infection can alter the natural course of chronic parenterally acquired hepatitis C, causing an unusually rapid progression to cirrhosis.

172 citations


Journal ArticleDOI
TL;DR: In this article, the theory developed in Part I was applied to speed-density curves having the functional form proposed in Part II and the goodness of fit was excellent, except in the case of the left lane detectors.
Abstract: In this part we applied the theory developed in Part I. Some speed-density curves having the functional form proposed in Part I are fitted to traffic data. The goodness of fit is excellent, except in the case of the left lane detectors. A procedure for isolating stationary traffic periods is also explained. This procedure satisfactorily eliminates the dispersion of the individual measurements.

164 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that every system of polynomials satisfying some (2 N + 1)-term recurrence relation can be expressed in terms of orthonormal matrix polynomorphisms for which the coefficients are N × N matrices.

163 citations


Journal ArticleDOI
TL;DR: In this paper, the authors describe the focus group technique, giving details about the methodological process, and include a practical application: the study of teachers' perspectives toward the reform about to be applied in the Spanish educational system.
Abstract: In the past few years, focus group research has been used increasingly in fields different from market research, in which the technique was developed. The application of focus groups in educational research has become particularly useful in evaluation, as an ideal qualitative technique to evaluate viability, to anticipate effects, and to evaluate implementation. This article describes the focus group technique, giving details about the methodological process, and includes a practical application: the study of teachers' perspectives toward the reform about to be applied in the Spanish educational system.

159 citations


Journal ArticleDOI
TL;DR: The evidence that supports the hypothesis of the existence of specific binding sites for melatonin on immune cells, described in human blood lymphocytes and granulocytes, and thymus, spleen, and bursa of Fabricius, is reviewed.
Abstract: This paper reviews the evidence that supports the hypothesis of the existence of specific binding sites for melatonin on immune cells. These binding sites have been described in human blood lymphocytes and granulocytes, and thymus, spleen, and bursa of Fabricius from different rodents and birds. The dissociation constant values of these binding sites are in the 0.1-1 nM range, suggesting that melatonin may play a physiological role in lymphocyte regulation. Moreover, melatonin binding sites appear to be modulated by guanine nucleotides. Therefore, in addition to other mechanisms described for the regulation of immune function by melatonin, a direct mechanism of regulation can be involved via binding of melatonin by immunocompetent cells.

148 citations


Journal ArticleDOI
TL;DR: Upper eyelid position and velocity, and the electromyographic activity of the orbicularis oculi muscle, were recorded bilaterally in alert cats during spontaneous, reflexively evoked, and conditioned eyelid movements, being only a function of stimulus parameters and of the animal's level of alertness.
Abstract: 1. Upper eyelid position and velocity, and the electromyographic (EMG) activity of the orbicularis oculi muscle, were recorded bilaterally in alert cats during spontaneous, reflexively evoked, and conditioned eyelid movements. 2. Spontaneous blinks appeared randomly (0.2-0.5 per min) and consisted of a fast, large downward lid movement followed by a slower up phase. Blinks of smaller amplitude and slower velocity were also observed mainly accompanying behavioral movements, such as during peering and grimacing. 3. Eyelid response to air puffs applied to the cornea and tarsal lid skin consisted of a short-latency (9-16 ms), fast (up to 2,000 degrees/s) downward movement that lasted for 25-30 ms, followed by late, small downward sags that were sometimes still evident after stimulus offset. Blinks outlasted the duration of the stimulus by approximately 150 ms. Blinks elicited by flashes of light or tones showed longer latency (47.3 +/- 6.3 and 53.7 +/- 8.0 ms, mean +/- SD; respectively), smaller amplitude, and a quicker habituation than air-puff-evoked lid responses. 4. For the down phase of the blink, the peak velocity, but not its duration, increased linearly with blink amplitude. Because the rise time of the down phase remained constant, changes in blink amplitude seemed to be the result of increased blink velocity. The down phase of a typical 10 degrees blink was 10 times faster than the up phase of the same blink or than upward and downward lid saccades of the same amplitude. The peak velocity and duration of the up phases of reflex blinks and upward and downward lid saccades increased linearly with lid movement amplitude. 5. The initial down phase of air-puff-evoked blinks decreased in latency, increased in amplitude and peak velocity, and maintained the same rise time for increasing puff pressure. None of these parameters was dependent on puff duration. The duration of the blink also increased linearly with air puff duration. 6. The amplitude of air-puff-evoked blinks was inversely related to lid position, decreasing with further lid positions in the closing direction. In contrast, neither peak nor integrated EMG activity of the orbicularis oculi muscle was affected by lid position, being only a function of stimulus parameters and of the animal's level of alertness. 7. Air puffs > 20 ms and > 1 kg/cm2 evoked two successive bursts (R(ap) 1 and R(ap) 2) in the EMG activity of the orbicularis oculi muscle. Shorter and/or weaker stimuli evoked only the R(ap) 1 response.(ABSTRACT TRUNCATED AT 400 WORDS)

139 citations


Journal ArticleDOI
01 Jan 1995-Genetics
TL;DR: It is proposed that deletions can occur as three types of recombination events: the conservative RAD52-dependent reciprocal exchange and the nonconservative events, one-ended invasion crossover, and single-strand annealing (SSA).
Abstract: We have constructed novel DNA substrates (one inverted and three direct repeats) based on the same 0.6-kb repeat sequence to study deletions and inversions in Saccharomyces cerevisiae. Spontaneous deletions occur six to eight times more frequently than inversions, irrespective of the distance between the repeats. This difference can be explained by the observation that deletion events can be mediated by a recombination mechanism that can initiate within the intervening sequence of the repeats. Spontaneous and double-strand break (DSB)-induced deletions occur as RAD52-dependent and RAD52-independent events. Those deletion events initiated through a DSB in the unique intervening sequence require the Rad1/Rad10 endonuclease only if the break is distantly located from the flanking DNA repeats. We propose that deletions can occur as three types of recombination events: the conservative RAD52-dependent reciprocal exchange and the nonconservative events, one-ended invasion crossover, and single-strand annealing (SSA). We suggest that one-ended invasion is RAD52 dependent, whereas SSA is RAD52 independent. Whereas deletions, like inversions, occur through reciprocal exchange, deletions can also occur through SSA or one-ended invasion. We propose that the contribution of reciprocal exchange and one-ended invasion crossover vs. SSA events to overall spontaneous deletions is a feature specific for each repeat system, determined by the initiation event and the availability of the Rad52 protein. We discuss the role of the Rad1/Rad10 endonuclease on the initial steps of one-ended invasion crossover and SSA as a function of the location of the initiation event relative to the repeats. We also show that the frequency of recombination between repeats is the same independent of their location (whether on circular plasmids, linear minichromosomes, or natural chromosomes) and have similar RAD52 dependence.

130 citations


Journal ArticleDOI
TL;DR: The existence of O2-sensitive, voltage-dependent, Ca2+ channels in vascular smooth muscle that may critically contribute to the local regulation of circulation are demonstrated.
Abstract: We have investigated the modifications of cytosolic [Ca2+] and the activity of Ca2+ channels in freshly dispersed arterial myocytes to test whether lowering O2 tension (PO2) directly influences Ca2+ homeostasis in these cells. Unclamped cells loaded with fura-2 AM exhibit oscillations of cytosolic Ca2+ whose frequency depends on extracellular Ca2+ influx. Switching from a PO2 of 150 to 20 mmHg leads to a reversible attenuation of the Ca2+ oscillations. In voltage-clamped cells, hypoxia reversibly reduces the influx of Ca2+ through voltage-dependent channels, which can account for the inhibition of the Ca2+ oscillations. Low PO2 selectively inhibits L-type Ca2+ channel activity, whereas the current mediated by T-type channels is unaltered by hypoxia. The effect of low PO2 on the L-type channels is markedly voltage dependent, being more apparent with moderate depolarizations. These findings demonstrate the existence of O2-sensitive, voltage-dependent, Ca2+ channels in vascular smooth muscle that may critically contribute to the local regulation of circulation.

Journal ArticleDOI
TL;DR: A gene (chit33) from the mycoparasitic fungus Trichoderma harzianum, coding for a chitinase of 33 kDa, has been isolated and characterized and enzyme characteristics suggest a nutritional, rather than a morphogenetic, role for this chit inase.
Abstract: A gene (chit33) from the mycoparasitic fungus Trichoderma harzianum, coding for a chitinase of 33 kDa, has been isolated and characterized. Partial amino-acid sequences from the purified 33-kDa chitinase were obtained. The amino-terminal peptide sequence was employed to design an oligonucleotide probe and was used as a primer to isolate a 1.2-kb cDNA. The cDNA codes for a protein of 321 amino acids, which includes a putative signal peptide of 19 amino acids. All microsequenced peptides found in this sequence, indicate that this cDNA codes for the 33-kDa chitinase. A high homology (approximately 43% identity) was found with fungal and plant chitinases, including yeast chitinases. However enzyme characteristics suggest a nutritional (saprophytic or mycoparasitic), rather than a morphogenetic, role for this chitinase. The chit33 gene appears as a single copy in the T. harzianum genome, is strongly suppressed by glucose, and de-repressed under starvation conditions as well as in the presence of autoclaved mycelia and/or fungal cell walls. The 33-kDa chitinase seems to be very stable except under starvation conditions. The independent regulation of each of the chitinases in T. harzianum indicates different specific roles.

Journal ArticleDOI
TL;DR: In this paper, the influence of carbon dioxide on the thermal decomposition kinetics of calcium carbonate is studied and it is shown that it is possible to obtain meaningful and reliable kinetic parameters from isothermal and non-isothermal data provided that the pressure correction term is included in the kinetic equation.

Journal ArticleDOI
TL;DR: When mitochondria from laboratory, baker's, and wine yeasts were transferred to baker's and laboratory petite strains, sporulation and four-spore ascus formation frequencies dropped dramatically either to no sporulation at all or to less than 50% in both parameters.
Abstract: Vol. 61, no. 2, p. 635, legend to Fig. 3, line 1: "VS ( )" should read "VS ((symbl))." Legend to Fig. 4, line 3: "DS81-D ( )" should read "DS81-D ((symbl))." [This corrects the article on p. 630 in vol. 61.].

Journal ArticleDOI
TL;DR: The phylogenetic positions of the moderately halophilic bacteria Chromohalobacter marismortui, Volcaniella eurihalina, and Deleya salina were determined by PCR amplification of rRNA genes and direct sequencing and the resulting data were compared with data for other bacteria obtained from 16S rRNA sequence databases.
Abstract: The phylogenetic positions of the moderately halophilic bacteria Chromohalobacter marismortui, Volcaniella eurihalina, and Deleya salina were determined by PCR amplification of rRNA genes and direct sequencing. The resulting data were compared with data for other bacteria obtained from 16S rRNA sequence databases. C. marismortui, V. eurihalina, and D. salina clustered phylogenetically within the gamma subclass of the Proteobacteria and are closely related to other species on the Halomonas-Deleya branch. C. marismortui belongs in the family Halomonadaceae and has the characteristic 16S rRNA signatures defined for this family, including the distinctive cytosine residue at position 486 found in all members of the Halomonadaceae. V. eurihalina is closely related to the type species of the genus Halomonas, Halomonas elongata, and we formally propose that V. eurihalina should be transferred to the genus Halomonas as Halomonas eurihalina comb. nov. The type strain of this species is strain F9-6 (= ATCC 49336). D. salina is not as closely related to other species belonging to the Halomonas-Deleya complex, but is more closely related to Halomonas elongata than to Deleya aquamarina, the type species of the genus Deleya. A polyphasic approach will be necessary to determine the natural taxonomic positions of the species belonging to the genera Halomonas and Deleya, as well as C. marismortui, V. eurihalina, Halovibrio variabilis, and Paracoccus halodenitrificans.

Proceedings ArticleDOI
05 Aug 1995
TL;DR: A new approach is presented that analyzes the stability of a general class of path tracking algorithms taking into account the pure delay in the control loop, one of the most widely used algorithms.
Abstract: This paper presents a new approach that analyzes the stability of a general class of path tracking algorithms taking into account the pure delay in the control loop. The analysis has been done for straight paths and paths of constant curvature. This has sufficient generality since most usual paths can be decomposed in pieces of constant curvature. The method has been applied to the pure pursuit path tracking algorithm, one of the most widely used algorithms. The experiments performed with a computer controlled high mobility multi-purpose wheeled vehicle show good agreement with the theoretical predictions of the proposed method.

Journal ArticleDOI
TL;DR: The presence of high‐ affinity binding sites for melatonin in human circu‐lating T lymphocytes, but not in B lymphocytes shows that CD4+ cells may be the target of melatonin among the human circulating lymphocytes.
Abstract: This paper shows the presence of high-affinity binding sites for melatonin in human circulating T lymphocytes, but not in B lymphocytes. The binding of melatonin to T cells was dependent on time, stable, reversible, saturable, specific, and inversely correlated to the production of melatonin, expressed as the nocturnal 12 h production of its urinary metabolite 6-sulfatoxymelatonin. The affinity of these binding sites (Kd = 0.27 nM) suggests that they may recognize the physiological concentrations of melatonin in serum. Moreover, among the lymphocyte subpopulations studied, binding of melatonin was mostly found in CD4+ cells rather than in CD8+ cells. Results suggest that CD4+ cells may be the target of melatonin among the human circulating lymphocytes.

Journal ArticleDOI
TL;DR: Prospects for cork oak recruitment were examined in a scrub-dominated area with low tree density in southern Spain by sowing acorns experimentally in a variety of sites, and single acorns buried under open or dense scrub experienced the lowest predation and had relatively high emergence rates.

Journal ArticleDOI
TL;DR: In this paper, the authors examined the 10-day response of soil microbial biomass-N to additions of carbon (dextrose) and nitrogen (NH4NO3) to water-amended soils in a factorial experiment in four plant communities of the Chihuahuan desert of New Mexico (U.S.A.).
Abstract: We examined the 10-day response of soil microbial biomass-N to additions of carbon (dextrose) and nitrogen (NH4NO3) to water-amended soils in a factorial experiment in four plant communities of the Chihuahuan desert of New Mexico (U.S.A.). In each site, microbial biomass-N and soil carbohydrates increased and extractable soil N decreased in response to watering alone. Fertilization with N increased microbial biomass-N in grassland soils; whereas, fertilization with C increased microbial biomass-N and decreased extractable N and P in all communities dominated by shrubs, which have invaded large areas of grassland in the Chihuahuan desert during the last 100 years. Our results support the hypothesis that the control of soil microbial biomass shifts from N to C when the ratio of C to N decreases during desertification.

Journal ArticleDOI
TL;DR: This paper presents an application of fuzzy logic control to the distributed collector field of a solar power plant using a special subclass of fuzzy inference systems, the TP and TPE systems, to obtain adequate control signals in the whole range of possible operating conditions.
Abstract: This paper presents an application of fuzzy logic control to the distributed collector field of a solar power plant. The major characteristic of a solar power plant is that the primary energy source, solar radiation, cannot be manipulated. Solar radiation varies throughout the day, causing changes in plant dynamics and strong perturbations in the process. A special subclass of fuzzy inference systems, the TP (triangular partition) and TPE (triangular partition with evenly spaced midpoints) systems, is used to obtain adequate control signals in the whole range of possible operating conditions. The fuzzy logic controller has been tested in the real plant and results obtained are shown. A comparison with other control approaches widely used in the plant is performed using a nonlinear computer model of the field.

Journal ArticleDOI
TL;DR: In this article, the influence of the measurement interval of solar radiation data on the cumulative probability distribution of the clearness index is studied, and a new statistical model is proposed, based on a mixture of two normal distributions, which provides a good fit for the data measured in Seville.

Journal ArticleDOI
01 Nov 1995-Yeast
TL;DR: The polymorphism observed might reflect the enormous variability induced by the ethanol followed by the selection of those mtDNA sequences which make the mitochondria metabolically active under these conditions.
Abstract: Yeast strains which form velum on the surface of Sherry wine during the aging process have been isolated and characterized. According to their metabolic and molecular features most of the yeasts that were isolated belong to different races of Saccharomyces cerevisiae (beticus, cheresiensis, montuliensis and rouxii). Due to the conditions under which these yeasts were isolated, all strains have in common the capacity to develop a film as an adaptive mechanism which allows them to grow and survive in 15.5% vol. ethanol. All strains were prototrophs for amino acids and most vitamins but they gave different responses to the killer factor. However, whereas their physiological features were similar, they showed a great heterogeneity with regards to the nuclear and mitochondrial genome (mtDNA): DNA content per cell was quite variable (1.3 to 2n), electrophoretic karyotypes of nuclear genomes indicated a main pattern with some variations, and polymorphism shown by the mtDNA was very high. Under extreme conditions such as Sherry wine with 15.5% vol. ethanol, no fermentable sugar and an exclusively oxidative metabolism, cells hardly grow and the maintenance of a live population depends on survival and respiration, which in turn depend on the mtDNA. At the same time these environmental conditions are mutagenic for the mtDNA, causing an increase in variation. Thus, the polymorphism observed might reflect the enormous variability induced by the ethanol followed by the selection of those mtDNA sequences which make the mitochondria metabolically active under these conditions.

Journal ArticleDOI
TL;DR: In this article, a non-linear formulation of the second-order terms in the strain-displacement relationship is proposed to represent axial displacement along the deformed (instead of undeformed) axis.
Abstract: In this paper, the equations of motion of flexible multibody systems are derived using a nonlinear formulation which retains the second-order terms in the strain-displacement relationship. The strain energy function used in this investigation leads to the definition of three stiffness matrices and a vector of nonlinear elastic forces. The first matrix is the constant conventional stiffness matrix, the second one is the first-order geometric stiffness matrix ; and the third is a second-order stiffness matrix. It is demonstrated in this investigation that accurate representation of the axial displacement due to the foreshortening effect requires the use of large number or special axial shape functions if the nonlinear stiffness matrices are used. An alternative solution to this problem, however, is to write the equations of motion in terms of the axial coordinate along the deformed (instead of undeformed) axis. The use of this representation yields a constant stiffness matrix even if higher order terms are retained in the strain energy expression. The numerical results presented in this paper demonstrate that the proposed new approach is nearly as computationally efficient as the linear formulation. Furthermore, the proposed formulation takes into consideration the effect of all the geometric elastic nonlinearities on the bending displacement without the need to include high frequency axial modes of vibration.

Journal ArticleDOI
TL;DR: In this paper, the convergence properties of the array of point charges used to simulate the Madelung potential were discussed and large cluster models were used to represent these large clusters by using model potentials and compare the results with those obtained from periodic Hartree-Fock calculations.

Journal ArticleDOI
01 Sep 1995
TL;DR: An adaptive controller for robot manipulators which uses neural networks is presented, based on PD feedback plus a feedforward compensation of full robot dynamics and stability analysis which takes into account neural network learning errors.
Abstract: In this paper, an adaptive controller for robot manipulators which uses neural networks is presented. The proposed control scheme is based on PD feedback plus a feedforward compensation of full robot dynamics. The feedforward signal is obtained by summing up the weighted outputs of a set of fixed multilayer neural nets. The controller is adaptive to robot dynamics and payload uncertainties. A stability analysis which takes into account neural network learning errors is included. Simulation results showing the feasibility and performance of the approach are given. >

Journal ArticleDOI
TL;DR: In the presence of triethylamine, 6,6'-dideoxy-6,6'diisothiocyanato-alpha,alpha'-trehalose underwent intramolecular cyclisation involving HO-4 to give the corresponding bis(cyclic thiocarbamate).

Journal ArticleDOI
TL;DR: In this paper, the influence of processing parameters on the rheology and stability of salad dressing emulsions was analyzed by calculating the relaxation spectra, taking into account the relationship between several structural parameters such as interparticle interactions and droplet size distribution.
Abstract: In order to study the influence that the processing parameters exert on the rheology and stability of salad dressing emulsions, both steady-state shear and oscillatory measurements, as well as droplet size distribution tests were performed. Emulsions containing a mixture of egg yolk and sucrose stearate as emulsifier were prepared using two different emulsification machines, a rotor-stator turbine and a colloidal mill. An increase both in energy input and in the temperature of processing yields higher values of the steady-state viscosity, an increase in emulsion stability and, generally, lower droplet size and lower polydispersity. Furthermore, a plateau region in the loss modulus versus frequency plots appears as the energy input and processing temperature increase. This effect has been analyzed by calculating the relaxation spectra of these emulsions. The results have been discussed taking into account the relationship between several structural parameters, such as interparticle interactions and droplet size distribution, and the rheological response of these emulsions.

Journal ArticleDOI
TL;DR: The demonstration of [125I]MEL binding sites in the spleen, in addition to those described in blood mononuclear cells and thymus, provides evidence to support a direct mechanism of action of melatonin on immune system.

Journal ArticleDOI
TL;DR: The findings are consistent with the hypothesis of lower efficiency of pollination of S flowers by short-tongued insects, resulting in the exclusion of this morph from the hills, and variation in a set of continuous flower traits related to pollination biology was examined.
Abstract: summary Narcissus tazetta shows a genetically-based discrete polymorphism for style length similar to that well known in heterostylous plants. Plants are either short- (S) or long-styled (1). In Israel, marsh populations are dominated by S plants and hill populations by L plants. Populations differ in size, flowering time and duration, flower orientation, inflorescence display, vegetative reproduction, and pollinators. The main visitors to flowers in marshes are hawkmoths, whereas in the hills they are visited by short-tongued insects: solitary bees and hoverflies. The pollination efficiency of these insects was investigated by studying foraging behaviour, visit rate, and pollen deposition on stigmas. Our findings are consistent with the hypothesis of lower efficiency of pollination of S flowers by short-tongued insects, resulting in the exclusion of this morph from the hills. Additionally, we considered the possibility that there might be pollination ecotypes corresponding to the two habitats (marsh and hill) and examined variation in a set of continuous flower traits related to pollination biology. Flower tube length was the only trait showing a distinct difference between the two habitat types. Although the concentration of nectar was not different between habitats, L flowers presented more concentrated nectar than S flowers. Such a difference in nectar concentration may he of adaptive value for the pollination of the L flowers by short-tongued pollinators in the hills.

Journal ArticleDOI
TL;DR: The first genomic and cE)NA clones encoding a β-1,6-endoglucanase gene are described, successfully produced in Saccharomyces cerevisiae upon construction of a transcriptional fusion of the cDNA with a yeast promoter.
Abstract: Hydrolytic enzymes from the filamentous fungus Trichoderma harzianum have been described as critical elements of the mycoparasitic action of Trichoderma against fungal plant pathogens. In this report we describe the first genomic and cE)NA clones encoding a β-1,6-endoglucanase gene. The deduced protein sequence has limited homology with other β-glucanases. Northern experiments show a marked repression of mRNA accumulation by glucose. The protein has been successfully produced in Saccharomyces cerevisiae upon construction of a transcriptional fusion of the cDNA with a yeast promoter. This S. cerevisiae recombinant strain shows a strong lytic action on agar plates containing β-1,6-glucan.