Showing papers by "Université catholique de Louvain published in 1997"
TL;DR: A new and simple method to find indicator species and species assemblages characterizing groups of sites, and a new way to present species-site tables, accounting for the hierarchical relationships among species, is proposed.
Abstract: This paper presents a new and simple method to find indicator species and species assemblages characterizing groups of sites The novelty of our approach lies in the way we combine a species relative abundance with its relative frequency of occurrence in the various groups of sites This index is maximum when all individuals of a species are found in a single group of sites and when the species occurs in all sites of that group; it is a symmetric indicator The statistical significance of the species indicator values is evaluated using a randomization procedure Contrary to TWINSPAN, our indicator index for a given species is independent of the other species relative abundances, and there is no need to use pseudospecies The new method identifies indicator species for typologies of species releves obtained by any hierarchical or nonhierarchical classification procedure; its use is independent of the classification method Because indicator species give ecological meaning to groups of sites, this method provides criteria to compare typologies, to identify where to stop dividing clusters into subsets, and to point out the main levels in a hierarchical classification of sites Species can be grouped on the basis of their indicator values for each clustering level, the heterogeneous nature of species assemblages observed in any one site being well preserved Such assemblages are usually a mixture of eurytopic (higher level) and stenotopic species (characteristic of lower level clusters) The species assemblage approach demonstrates the importance of the ''sampled patch size,'' ie, the diversity of sampled ecological combinations, when we compare the frequencies of core and satellite species A new way to present species-site tables, accounting for the hierarchical relationships among species, is proposed A large data set of carabid beetle distributions in open habitats of Belgium is used as a case study to illustrate the new method
7,449 citations
TL;DR: Bacillus subtilis is the best-characterized member of the Gram-positive bacteria, indicating that bacteriophage infection has played an important evolutionary role in horizontal gene transfer, in particular in the propagation of bacterial pathogenesis.
Abstract: Bacillus subtilis is the best-characterized member of the Gram-positive bacteria. Its genome of 4,214,810 base pairs comprises 4,100 protein-coding genes. Of these protein-coding genes, 53% are represented once, while a quarter of the genome corresponds to several gene families that have been greatly expanded by gene duplication, the largest family containing 77 putative ATP-binding transport proteins. In addition, a large proportion of the genetic capacity is devoted to the utilization of a variety of carbon sources, including many plant-derived molecules. The identification of five signal peptidase genes, as well as several genes for components of the secretion apparatus, is important given the capacity of Bacillus strains to secrete large amounts of industrially important enzymes. Many of the genes are involved in the synthesis of secondary metabolites, including antibiotics, that are more typically associated with Streptomyces species. The genome contains at least ten prophages or remnants of prophages, indicating that bacteriophage infection has played an important evolutionary role in horizontal gene transfer, in particular in the propagation of bacterial pathogenesis.
3,753 citations
TL;DR: In this paper, first-order changes of wave functions and density with respect to small atomic displacements or infinitesimal homogeneous electric fields within the density-functional theory are studied.
Abstract: Starting from the knowledge of first-order changes of wave functions and density with respect to small atomic displacements or infinitesimal homogeneous electric fields within the density-functional theory, we write the expressions for the diagonal or mixed second-order derivatives of the total energy with respect to these perturbations: dynamical matrices for different wave vectors, Born effective-charge tensors and electronic dielectric permittivity tensors. Interatomic force constants and the phonon-band structure are then obtained by computing the Fourier transform of dynamical matrices on a regular mesh of wave vectors, with an eventual, separate treatment of the long-range dipole-dipole interaction. The same ingredients also allow one to compute the low-frequency response of the crystal to homogeneous electric fields.
2,378 citations
TL;DR: A deficient activity of the iron-sulphur (Fe-S) cluster-containing subunits of mitochondrial respiratory complexes I, II and III in the endomyocardial biopsy of two unrelated FRDA patients was found to be deficient.
Abstract: Friedreich ataxia (FRDA) is a common autosomal recessive degenerative disease (1/50,000 live births) characterized by a progressive gait and limb ataxia with lack of tendon reflexes in the legs, dysarthria and pyramidal weakness of the inferior limbs(1,2). Hypertrophic cardiomyopathy is observed in most FRDA patients. The gene associated with the disease has been mapped to chromosome 9q13 (ref. 3) and encodes a 210-amino-acid protein, frataxin. FRDA is caused primarily by a GAA repeat expansion within the first intron of the frataxin gene, which accounts for 98% of mutant alleles(4). The function of the protein is unknown, but an increased iron content has been reported in hearts of FRDA patients(5) and the mitochondria of yeast strains carrying a deleted frataxin gene counterpart (YFH1), suggesting that frataxin plays a major role in regulating mitochondrial iron transport(6.7). Here, we report a deficient activity of the iron-sulphur (Fe-S) cluster-containing subunits of mitochondrial respiratory complexes I, II and III in the endomyocardial biopsy of two unrelated FRDA patients. Aconitase, an iron-sulphur protein involved in iron homeostasis, was found to be deficient as well. Moreover, disruption of the YFH1 gene resulted in multiple Fe-S-dependent enzyme deficiencies in yeast. The deficiency of Fe-S-dependent enzyme activities in both FRDA patients and yeast should be related to mitochondrial iron accumulation, especially as Fe-S proteins are remarkably sensitive to free radicals(8). Mutated frataxin triggers aconitase and mitochondrial Fe-S respiratory enzyme deficiency in FRDA, which should therefore be regarded as a mitochondrial disorder.
963 citations
TL;DR: In this article, the changes in density, wave functions, and self-consistent potentials of solids, in response to small atomic displacements or infinitesimal homogeneous electric fields, are considered in the framework of the density-functional theory.
Abstract: The changes in density, wave functions, and self-consistent potentials of solids, in response to small atomic displacements or infinitesimal homogeneous electric fields, are considered in the framework of the density-functional theory. A variational: principle for second-order derivatives of the energy provides a basis for efficient algorithmic approaches to these linear responses, such as the state-by-state conjugate-gradient algorithm presented here in detail. The phase of incommensurate perturbations of periodic systems, that are, like phonons, characterized by some wave vector, can be factorized: the incommensurate problem is mapped on an equivalent one presenting the periodicity of the unperturbed ground state. The singularity of the potential change associated with an homogeneous field is treated by the long-wave method. The efficient implementation of these theoretical ideas using plane waves, separable pseudopotentials, and a nonlinear exchange-correlation core correction is described in detail, as well as other technical issues.
860 citations
TL;DR: The generalized partially linear single-index model (GPLSIM) as discussed by the authors is a nonparametric generalized linear model for regression of a response Y on predictors (X, Z) with conditional mean function based on a linear combination of X, Z, where η 0(·) is an unknown function.
Abstract: The typical generalized linear model for a regression of a response Y on predictors (X, Z) has conditional mean function based on a linear combination of (X, Z). We generalize these models to have a nonparametric component, replacing the linear combination α T 0X + β T 0Z by η0(α T 0X) + β T 0Z, where η0(·) is an unknown function. We call these generalized partially linear single-index models (GPLSIM). The models include the “single-index” models, which have β0 = 0. Using local linear methods, we propose estimates of the unknown parameters (α0, β0) and the unknown function η0(·) and obtain their asymptotic distributions. Examples illustrate the models and the proposed estimation methodology.
794 citations
TL;DR: The Yop virulon enables Yersinia spp.
Abstract: The Yop virulon enables Yersinia spp. (Y. pestis, Y. pseudotuberculosis and Y. enterocolitica) to survive and multiply in the lymphoid tissues of their host. It is an integrated system allowing extracellular bacteria to communicate with the host cell's cytosol by the injection of effector proteins. It is composed of the following four elements. (I) A contact or type III secretion system called Ysc, which is devoted to the secretion of Yop proteins. This secretion apparatus, comprising some 22 proteins recognizes the Yops by a short N-terminal signal that is not cleaved off during secretion. (II) A system designed to deliver bacterial proteins into eukaryotic target cells. This system is made of YopB, YopD and possibly other Yops such as LcrV. (III) A control element (YopN). (IV) A set of effector Yop proteins designed to disarm these cells or disrupt their communications (YopE, YopH, YpkA/YopO, and YopM). The whole virulon is encoded by a 70 kb plasmid designated pYV. Transcription of the genes is controlled both by temperature and by contact with a eukaryotic cell.
590 citations
TL;DR: In this paper, a review of recent approaches to the monitoring and modelling of deforestation and dryland degradation in tropical regions is presented, highlighting the requirement to tailor the investigation method to the specific research question of interest.
Abstract: Transformations in terrestrial ecosystems are increasingly regarded as an important element of global change. Quantitative data on where, when and why land-cover changes take place globally are still incomplete. This article reviews recent approaches to the monitoring and modelling of deforestation and dryland degradation in tropical regions. The review highlights the requirement to tailor the investigation method to the specific research question of interest. Different techniques to monitor land-cover changes at regional scales are analysed. The following modelling scenarios are discussed and illustrated by specific studies: projection of future land-cover changes with descriptive models, explanation of land-cover changes with empirical models, projection of future spatial patterns of changes with spatial statistical models, test of scenarios on future changes in land-cover with dynamic ecosystem models, and design of policy interventions with economic models. The article stresses the needs for a better integration of social science knowledge in land-cover change models and for a comprehensive theory of land-use changes.
589 citations
TL;DR: In this paper, the authors used a broadly familiar and reasonably rich model of fiscal competition in the presence of mobile capital, and established a systematic bias in public spending patterns: starting from the non-cooperative equilibrium, and holding tax rates constant, welfare would be improved by a coordinated reduction in the provision of local public inputs and a corresponding increase in the public provision of public public goods benefiting immobile consumers.
501 citations
TL;DR: It is found that mouse and yeast frataxin homologues contain a potential mitochondrial targeting sequence in their N-terminal domains and that disruption of the yeast gene results in mitochondrial dysfunction.
Abstract: Friedreich's ataxia is due to loss of function mutations in the gene encoding frataxin (FRDA). Frataxin is a protein of unknown function. In situ hybridization analyses revealed that mouse frataxin expression correlates well with the main site of neurodegeneration, but the expression pattern is broader than expected from the pathology of the disease. Frataxin mRNA is predominantly expressed in tissues with a high metabolic rate, including liver, kidney, brown fat and heart. We found that mouse and yeast frataxin homologues contain a potential mitochondrial targeting sequence in their N-terminal domains and that disruption of the yeast gene results in mitochondrial dysfunction. Finally, tagging experiments demonstrate that human frataxin co-localizes with a mitochondrial protein. Friedreich's ataxia is therefore a mitochondrial disease caused by a mutation in the nuclear genome.
465 citations
TL;DR: Study of the yeast ABC proteins provides insight into the physiological function and biochemical mechanisms of their human homologues, such as those involved in cystic fibrosis, adrenoleukodystrophy, Zellweger syndrome, multidrug resistance and the antiviral activity of interferons.
Abstract: The complete sequence of the yeast genome predicts the existence of 29 proteins belonging to the ubiquitous ATP-binding cassette (ABC) superfamily. Using binary comparison, phylogenetic classification and detection of conserved amino acid residues, the yeast ABC proteins have been classified in a total of six clusters, including ten subclusters of distinct predicted topology and presumed distinct function. Study of the yeast ABC proteins provides insight into the physiological function and biochemical mechanisms of their human homologues, such as those involved in cystic fibrosis, adrenoleukodystrophy, Zellweger syndrome, multidrug resistance and the antiviral activity of interferons.
TL;DR: In this article, the correlation between ENSO and Iberian rainfall has increased towards the end of the present century, with strong positive signals spanning over half of the area studied.
Abstract: Analysis of data from seventeen rainfall stations in the Iberian Peninsula, Balearic Islands and Northern Africa has revealed significant El Nino-Southern Oscillation (ENSO) signals in Europe. Both North Atlantic Oscillation (NAO) and Southern Oscillation (SO) exert an influence on Iberian climate, but at different temporal and spatial scales. Though most of the peninsula is under NAO influence in winter, some stations in the eastern region show no connection with this phenomenon. The same is found for ENSO, with a positively correlated region appearing in the eastern part of Spain, while the rest of the peninsula remains insensitive. The correlation between ENSO and Iberian rainfall has increased towards the end of the present century, with strong positive signals spanning over half of the area studied. The percentage of springtime variability due to ENSO has similarly increased, reaching up to 50% in certain areas. We also show how there are outstanding climatic sensors of these phenomena such as Lake Gallocanta, which manifests a positive response to ENSO while appears insensitive to NAO. Common long-term patterns are observed between SOI and an inferred lake level series, suggesting a constant influence of the low-frequency component of ENSO throughout the period considered. Lake drying phases every 14 years reflect the impact of this signal, approximately every four ENSO events.
TL;DR: In this paper, the authors define the core of the game associated with the economy (which specifies the payoff achievable by each possible coalition of players) and also reflect in each case the behavior of the players which are not members of the coalition.
Abstract: When environmental externalities are international — i.e. transfrontier — they most often are multilateral and embody public good characteristics. Improving upon inefficient laissez-faire equilibria requires voluntary cooperation for which the game-theoretic core concept provides optimal outcomes that have interesting properties against free riding. To define the core, however, the characteristic function of the game associated with the economy (which specifies the payoff achievable by each possible coalition of players—here, the countries) must also reflect in each case the behavior of the players which are not members of the coalition. This has been for a long time a disputed issue in the theory of the core of economies with externalities.
TL;DR: It is proposed that PKB is part of the insulin signaling cascade for PFK-2 activation in heart and phosphorylated Ser-466 and Ser-483 in the BH1 isoform, but to different extents.
TL;DR: It is suggested that the colocalization of markers of glycoxidation (pentosidine and CML) with a marker of lipid peroxidation reflects a local oxidative stress in association with the pathogenesis of diabetic glomerular lesions in DN.
Abstract: Advanced glycation end products (AGEs) include a variety of protein adducts whose accumulation alters the structure and function of tissue proteins and stimulates cellular responses. They have been implicated in tissue damage associated with diabetic complications. To assess the possible link between AGE accumulation and the development of diabetic nephropathy (DN), we have examined the immunohistochemical localization of various AGE structures postulated to date, i.e., pentosidine, Nepsilon-(carboxymethyl)lysine (CML), and pyrraline, in diabetic and control kidneys. CML and pentosidine accumulate in the expanded mesangial matrix and thickened glomerular capillary walls of early DN and in nodular lesions and arterial walls of advanced DN, but were absent in control kidneys. By contrast, pyrraline was not found within diabetic glomeruli but was detected in the interstitial connective tissue of both normal and diabetic kidneys. Although the distribution of pyrraline was topographically identical to type III collagen, distribution of pentosidine and CML was not specific for collagen type, suggesting that difference in matrix protein composition per se could not explain heterogeneous AGE localization. Since oxidation is linked closely to the formation of pentosidine and CML, we also immunostained malondialdehyde (MDA), a lipid peroxidation product whose formation is accelerated by oxidative stress, assuming that local oxidative stress may serve as a mechanism of pentosidine and CML accumulation. Consistent with our assumption, diabetic nodular lesions were stained positive for MDA. These findings show that AGE localization in DN varies according to AGE structure, and suggest that the colocalization of markers of glycoxidation (pentosidine and CML) with a marker of lipid peroxidation reflects a local oxidative stress in association with the pathogenesis of diabetic glomerular lesions. Thus, glycoxidation markers may serve as useful biomarkers of oxidative damage in DN.
TL;DR: The neurodegeneration observed in Friedreich's ataxia can be well explained on the basis of a mitochondrial iron overload responsible for an increased production of highly toxic free radicals.
TL;DR: In this paper, the authors use linear programming models to define standardised, aggregate environmental performance indicators for firms, the best practice frontier obtained corresponds to decision making units showing the best environmental behaviour, Results are obtained with data from U.S. fossil fuel-fired electric utilities, starting from four alternative models, among which are three linear programming model that differ in the way they account for undesirable outputs (pollutants) and resources used as inputs.
Abstract: I use linear programming models to define standardised, aggregate environmental performance indicators for firms, The best practice frontier obtained corresponds to decision making units showing the best environmental behaviour, Results are obtained with data from U.S. fossil fuel-fired electric utilities, starting from four alternative models, among which are three linear programming models that differ in the way they account for undesirable outputs (pollutants) and resources used as inputs. The results indicate important discrepancies in the rankings obtained by the four models. Rather than contradictory, these results are interpreted as giving different, complementary kinds of information, that should all be taken into account by public decision-makers.
Anschutz Medical Campus1, University of Lausanne2, Texas Tech University Health Sciences Center3, University of Geneva4, University of Southern California5, Université catholique de Louvain6, University of Tennessee Health Science Center7, Erasmus University Rotterdam8, Albany Medical College9, Hoffmann-La Roche10
TL;DR: A prospectively planned logistic regression analysis to assess treatment effect on 28-day all-cause mortality by means of predicted mortality and serum interleukin 6 levels as continuous covariates demonstrated a significant improvement in outcome for the patients with severe sepsis treated with p55-lgG.
Abstract: Objective. —To evaluate the safety and efficacy of p55 tumor necrosis factor receptor fusion protein, a recombinant chimeric protein of human p55 (type I) tumor necrosis factor receptor (CD120a) extracellular domain and lgG1 sequences (referred to as p55-lgG), in the treatment of patients with severe sepsis or septic shock. Design. —Randomized, prospective, multicenter, double-blind, placebo-controlled clinical trial. Setting. —Forty-four community and university-affiliated hospitals in the United States and Europe. patients. —There were 498 patients enrolled in this clinical trial. Intervention. —Patients prospectively stratified within each site into refractory shock or severe sepsis groups were randomized to receive a single infusion of p55IgG, 0.083 mg/kg, 0.042 mg/kg, or 0.008 mg/kg, or placebo. Patients received standard aggressive medical/surgical care during the 28-day postinfusion period. Outcome Measure. —Twenty-eight—day all-cause mortality. Results. —The distribution of variables describing demographics, organ system dysfunction or failure, infecting microorganisms, predicted mortality, plasma interleukin 6 levels, and plasma tumor necrosis factor α (TNF-α) levels were similar among patients in the p55-lgG and placebo treatment arms. A planned interim analysis was performed after 201 patients were enrolled. Because a statistically nonsignificant trend toward increased mortality was present in patients who had received 0.008 mg/kg, this treatment arm was discontinued, and the study continued with 3 arms. Among all infused patients, there was a statistically nonsignificant trend toward reduced 28-day all-cause mortality in those who received p55-lgG compared with placebo-treated patients (5% reduction, 0.042 mg/kg vs placebo; 15% reduction, 0.083 mg/kg vs placebo;P=.30). However, in patients with severe sepsis and early septic shock (n=247), therapy with p55-lgG, 0.083 mg/kg, was associated with a 36% reduction in 28-day all-cause mortality compared with placebo (P=.07): 20 (23%) of 87 patients died among those treated with p55-lgG, 0.083 mg/kg; 30 (37%) of 82 among those treated with p55-lgG, 0.042 mg/kg; and 28 (36%) of 78 in the placebo group. A prospectively planned logistic regression analysis to assess treatment effect on 28-day all-cause mortality by means of predicted mortality and serum interleukin 6 levels as continuous covariates demonstrated a significant improvement in outcome for the patients with severe sepsis treated with p55-lgG, 0.083 mg/kg, compared with placebo (P=.01). Serious adverse events, including death and the development of new organ system dysfunction, were reported in 65% of patients infused with placebo, with no increased frequency (56%) present in the 2 p55-lgG treatment arms. There were no reports of immediate hypersensitivity reactions caused by p55-lgG. Conclusions. —In this dose-finding study, there was no decrease in mortality between placebo and p55-lgG in all infused patients. In the prospectively defined population of patients with severe sepsis who received p55-lgG, 0.083 mg/kg, there was a trend toward reduced mortality at day 28 that became significant when predicted mortality and plasma interleukin 6 levels were included in a logistic regression analysis.
Washington University in St. Louis1, Max Planck Society2, Université libre de Bruxelles3, German Cancer Research Center4, Goethe University Frankfurt5, Université catholique de Louvain6, University of Liège7, John Radcliffe Hospital8, MediGene9, Vrije Universiteit Brussel10, Katholieke Universiteit Leuven11
TL;DR: No correlation was found between G+C content and gene density along the chromosome, and their variations are random, so accurate verification procedures demonstrate that there are less than two errors per 10,000 base pairs in the published sequence.
Abstract: Here we report the sequence of 569,202 base pairs of Saccharomyces cerevisiae chromosome V. Analysis of the sequence revealed a centromere, two telomeres and 271 open reading frames (ORFs) plus 13 tRNAs and four small nuclear RNAs. There are two Ty1 transposable elements, each of which contains an ORF (included in the count of 271). Of the ORFs, 78 (29%) are new, 81 (30%) have potential homologues in the public databases, and 112 (41%) are previously characterized yeast genes.
TL;DR: The identification of an antigen recognized by autologous cytolytic T lymphocytes on a human squamous cell carcinoma of the oral cavity is reported, encoded by a mutated form of the CASP-8 gene, suggesting that a significant fraction of the point mutations generating a tumor antigen also play a role in the tumoral transformation or progression.
Abstract: Of the antigens recognized on human tumors by autologous cytolytic T lymphocytes, all those defined thus far have been identified on melanoma or renal cell carcinoma. We report here the identification of an antigen recognized by autologous cytolytic T lymphocytes on a human squamous cell carcinoma of the oral cavity. The antigen is encoded by a mutated form of the CASP-8 gene. This gene, also named FLICE or MACH, codes for protease caspase-8, which is required for induction of apoptosis through the Fas receptor and tumor necrosis factor receptor-1. The mutation, which was found in the tumor cells but not in the normal cells of the patient, modifies the stop codon and adds an Alu repeat to the coding region, thereby lengthening the protein by 88 amino acids. The ability of the altered protein to trigger apoptosis appears to be reduced relative to the normal caspase-8. The antigenic peptide is a nonamer presented by HLA-B*3503. The five last amino acids are encoded by the extension of the reading frame caused by the mutation. This, together with previous observations of CDK4 and beta-catenin mutations, suggests that a significant fraction of the point mutations generating a tumor antigen also play a role in the tumoral transformation or progression.
TL;DR: Use of the Von Heijne algorithm allowed the identification of 686 open reading frames (ORFs) in the genome of Saccharomyces cerevisiae that encode proteins with a potential N‐terminal signal sequence for entering the secretory pathway.
Abstract: Use of the Von Heijne algorithm allowed the identification of 686 open reading frames (ORFs) in the genome of Saccharomyces cerevisiae that encode proteins with a potential N-terminal signal sequence for entering the secretory pathway. On further analysis, 51 of these proteins contain a potential glycosyl-phosphatidylinositol (GPI)-attachment signal. Seven additional ORFs were found to belong to this group. Upon examination of the possible GPI-attachment sites, it was found that in yeast the most probable amino acids for GPI-attachment are asparagine and glycine. In yeast, GPI-proteins are found at the cell surface, either attached to the plasma-membrane or as an intrinsic part of the cell wall. It was noted that plasma-membrane GPI-proteins possess a dibasic residue motif just before their predicted GPI-attachment site. Based on this, and on homologies between proteins, families of plasma-membrane and cell wall proteins were assigned, revealing 20 potential plasma-membrane and 38 potential cell wall proteins. For members of three plasma-membrane protein families, a function has been described. On the other hand, most of the cell wall proteins seem to be structural components of the wall: responsive to different growth conditions. The GPI-attachment site of yeast slightly differs from mammalian cells. This might be of use in the development of anti-fungal drugs. (C) 1997 John Wiley & Sons, Ltd.
TL;DR: In this article, the magnetic properties of arrays of submicronic (35 nm-500 nm) Ni and Co wires fabricated by electrodeposition into the cylindrical pores of track-etched polymer membranes are reported.
Abstract: We report on the magnetic properties of arrays of submicronic (35 nm-500 nm) Ni and Co wires fabricated by electrodeposition into the cylindrical pores of track-etched polymer membranes. This work reveals intrinsic differences between the magnetization reversal mechanisms taking place in these two systems. For Ni, the crystal anisotropy is small compared to the shape anisotropy and the magnetization lies along the wire axis. In contrast, the strong crystal anisotropy of Co and the orientation of the crystal easy axis (nearly perpendicular to the wire axis), allows for the appearance of a multidomain magnetization configuration, each domain being oriented partially along the normal to the wire axis. Experimental evidence for the existence of this multidomain configuration has been obtained from resistivity and magnetization measurements. Large scale micromagnetic calculations for Co and Ni wires with high aspect ratios corroborate the strong influence of the crystal anisotropy on the overall properties of Co wires and provide an accurate microscopic description of the nucleation fields and the magnetization reversal mechanism for Ni wires.
TL;DR: In this paper, the authors analyzed both by simulations and measurements the substrate crosstalk performances of various Silicon-On-Insulator (SOI) technologies, and compared them to those of normal bulk CMOS process.
Abstract: This work analyzes both by simulations and measurements the substrate crosstalk performances of various Silicon-On-Insulator (SOI) technologies, and compares them to those of normal bulk CMOS process. The influence of various parameters, such as substrate resistivity, buried oxide thickness and distance between devices, is investigated. The use of capacitive guard rings is proposed, and their effectiveness is demonstrated. A simple RC model has been developed to allow a deep understanding of these phenomena as well as to simplify future studies of more complex systems. The superiority of high-resistivity SIMOX substrates over standard SOI and bulk is finally demonstrated.
TL;DR: In this article, the authors investigate the influence of the nature of the deforestation process on an empirical spatial model of deforestation and test a remote-sensing-based methodology to define the appropriate spatial entities for modelling deforestation, the study area is located in southern Cameroon, and the study included the production and integration in a geographic information system (GIS) of a database of natural and cultural landscape variables.
TL;DR: Because of the architecture of the multimer, YscC appears to represent a novel type of channel‐forming proteins in the bacterial outer membrane.
Abstract: The YscC protein of Yersinia enterocolitica is essential for the secretion of anti-host factors, called Yops, into the extracellular environment. It belongs to a family of outer membrane proteins, collectively designated secretins, that participate in a variety of transport processes. YscC has been shown to exist as a stable oligomeric complex in the outer membrane. The production of the YscC complex is regulated by temperature and is reduced in strains carrying mutations in the yscN-U operon or in the virG gene. The VirG lipoprotein was shown to be required for efficient targeting of the complex to the outer membrane. Electron microscopy revealed that purified YscC complexes form ring-shaped structures of approximately 20 nm with an apparent central pore. Because of the architecture of the multimer, YscC appears to represent a novel type of channel-forming proteins in the bacterial outer membrane.
TL;DR: It is demonstrated that trc-utrophin expression leads to major improvements of the mechanical performance of muscle (that is, force development, mechanical resistance to forced lengthenings and maximal spontaneous activity) and of the maintenance of the intracellular calcium homeostasis.
Abstract: Dystrophin-deficient mice (mdx) expressing a truncated (trc) utrophin transgene show amelioration of the dystrophic phenotype. Here we report a multifunctional study demonstrating that trcutrophin expression leads to major improvements of the mechanical performance of muscle (that is, force development, mechanical resistance to forced lengthenings and maximal spontaneous activity) and of the maintenance of the intracellular calcium homeostasis. These are two essential functions of muscle fibers, known to be impaired in mdx mouse muscles and Duchenne muscular dystrophy (DMD) patients. Our results bring strong support to the hypothesis that muscle wasting in dystrophin-deficient DMD patients could be prevented by upregulation of utrophin.
TL;DR: A computer-aided analysis was carried out of all members of the major facilitator superfamily (MFS), which typically consists of permeases with 12 transmembrane spans, to predict a possible permease function for a total of 119 proteins.
Abstract: On the basis of the complete genome sequence of the budding yeast Saccharomyces cerevisiae, a computer-aided analysis was carried out of all members of the major facilitator superfamily (MFS), which typically consists of permeases with 12 transmembrane spans. Analysis of all 5885 predicted open reading frames identified 186 potential MFS proteins. Binary sequence comparison made it possible to cluster 149 of them into 23 families. Putative permease functions could be assigned to 12 families, the largest including sugar, amino acid, and multidrug transport. Phylogenetic clustering of proteins allowed us to predict a possible permease function for a total of 119 proteins. Multiple sequence alignments were made for all families, and evolutionary trees were constructed for families with at least four members. The latter resulted in the identification of 21 subclusters with presumably tightly related permease function. No functional clues were predicted for a total of 41 clustered or unclustered proteins.
TL;DR: Findings suggest that all three novel genes: ACR1, ACR2 and ACR3 are involved in the arsenical‐resistance phenomenon in S. cerevisiae.
Abstract: A 4.2 kb region from Saccharomyces cerevisiae chromosome XVI was isolated as a yeast fragment conferring resistance to 7 mM-sodium arsenite (NaAsO2), when put on a multicopy plasmid. Homology searches revealed a cluster of three new open reading frames named ACR1, ACR2 and ACR3. The hypothetical projuct of the ACR1 gene is similar to the transcriptional regulatory proteins, encoded by YAP1, and YAP2 genes from S. cerevisiae. Disruption of the ACR1 gene conduces to an arsenite and arsenate hypersensitivity phenotype. The ACR2 gene is indispensable for arsenate but not for arsenite resistance. The hypothetical product of the ACR3 gene shows high similarity to the hypothetical membrane protein encoded by Bacillus subtilis ORF1 of the skin element and weak similarity to the ArsB membrane protein of the Staphylococcus aureus arsenical-resistance operon. Overexpression of the ACR3 gene confers an arsenite- but not an arsenate-resistance phenotype. The presence of ACR3 together with ACR2 on a multicopy plasmid expands the resistance phenotype into arsenate. These findings suggest that all three novel genes: ACR1, ACR2 and ACR3 are involved in the arsenical-resistance phenomenon in S. cerevisiae. (C) 1997 by John Wiley & Sons, Ltd.
01 May 1997
TL;DR: GRAIL is an environment under development to support the KAOS methodology that combines a graphical view, a textual view, an abstract syntax view, and an object base view of specifications.
Abstract: The KAOS methodology provides a language and method for goal-driven requirements elaboration GRAIL is an environment under development to support the KAOS methodology The GRAIL kernel combines a graphical view, a textual view, an abstract syntax view, and an object base view of specifications GRAIL has been used to elicit and specify the requirements of several real, industrial projects