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Search Results: 1 - 10 of 3579 matches for " Alexandra Gruss "
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Two Coregulated Efflux Transporters Modulate Intracellular Heme and Protoporphyrin IX Availability in Streptococcus agalactiae
Annabelle Fernandez ,Delphine Lechardeur,Aurélie Derré-Bobillot,Elisabeth Couvé,Philippe Gaudu,Alexandra Gruss
PLOS Pathogens , 2010, DOI: 10.1371/journal.ppat.1000860
Abstract: Streptococcus agalactiae is a major neonatal pathogen whose infectious route involves septicemia. This pathogen does not synthesize heme, but scavenges it from blood to activate a respiration metabolism, which increases bacterial cell density and is required for full virulence. Factors that regulate heme pools in S. agalactiae are unknown. Here we report that one main strategy of heme and protoporphyrin IX (PPIX) homeostasis in S. agalactiae is based on a regulated system of efflux using two newly characterized operons, gbs1753 gbs1752 (called pefA pefB), and gbs1402 gbs1401 gbs1400 (called pefR pefC pefD), where pef stands for ‘porphyrin-regulated efflux’. In vitro and in vivo data show that PefR, a MarR-superfamily protein, is a repressor of both operons. Heme or PPIX both alleviate PefR-mediated repression. We show that bacteria inactivated for both Pef efflux systems display accrued sensitivity to these porphyrins, and give evidence that they accumulate intracellularly. The ΔpefR mutant, in which both pef operons are up-regulated, is defective for heme-dependent respiration, and attenuated for virulence. We conclude that this new efflux regulon controls intracellular heme and PPIX availability in S. agalactiae, and is needed for its capacity to undergo respiration metabolism, and to infect the host.
Konservative Therapie der Stuhlinkontinenz
Gruss HJ
Journal für Urologie und Urogyn?kologie , 2004,
Black Holes in Ho?ava Gravity with Higher Derivative Magnetic Terms
Eyal Gruss
Physics , 2010, DOI: 10.1088/0264-9381/28/8/085007
Abstract: We consider Horava gravity coupled to Maxwell and higher derivative magnetic terms. We construct static spherically symmetric black hole solutions in the low-energy approximation. We calculate the horizon locations and temperatures in the near-extremal limit, for asymptotically flat and (anti-)de Sitter spaces. We also construct a detailed balanced version of the theory, for which we find projectable and non-projectable, non-perturbative solutions.
A Suggestion for a Teleological Interpretation of Quantum Mechanics
Eyal Gruss
Physics , 2000,
Abstract: We suggest solving the measurement problem by postulating the existence of a special future final boundary condition for the universe. Although this is an extension of the way boundary conditions are usually chosen (in terrestrial laboratories), it is our only deviation from standard quantum mechanics. Using two state vectors, or the "two-state", to describe completely the state of systems of interest, we analyze ideal and "weak" measurements, and show the consistency of our scheme. If the final state of a measuring device is assigned to be one of the possible outcomes of the measurement, an effective reduction is observed after an ideal measurement process. For final conditions chosen with an appropriate distribution, the predictions of standard quantum mechanics may be reconstructed, thus eliminating probability from the description of any single measurement. The interpretation attained, the Teleological Interpretation, is an ontological one; it is local and deterministic. Other special assumptions in the choice of the final boundary condition may explain certain unaccounted for phenomena, or even supply a mechanism for essential free will. In this context we believe that a new conception of time should be adopted.
Identification of DNA Motifs Implicated in Maintenance of Bacterial Core Genomes by Predictive Modeling
David Halpern,Hélène Chiapello,Sophie Schbath,Stéphane Robin,Christelle Hennequet-Antier,Alexandra Gruss,Meriem El Karoui
PLOS Genetics , 2007, DOI: 10.1371/journal.pgen.0030153
Abstract: Bacterial biodiversity at the species level, in terms of gene acquisition or loss, is so immense that it raises the question of how essential chromosomal regions are spared from uncontrolled rearrangements. Protection of the genome likely depends on specific DNA motifs that impose limits on the regions that undergo recombination. Although most such motifs remain unidentified, they are theoretically predictable based on their genomic distribution properties. We examined the distribution of the “crossover hotspot instigator,” or Chi, in Escherichia coli, and found that its exceptional distribution is restricted to the core genome common to three strains. We then formulated a set of criteria that were incorporated in a statistical model to search core genomes for motifs potentially involved in genome stability in other species. Our strategy led us to identify and biologically validate two distinct heptamers that possess Chi properties, one in Staphylococcus aureus, and the other in several streptococci. This strategy paves the way for wide-scale discovery of other important functional noncoding motifs that distinguish core genomes from the strain-variable regions.
Alterations of Amino Acids and Monoamine Metabolism in Male Fmr1 Knockout Mice: A Putative Animal Model of the Human Fragile X Mental Retardation Syndrome
Michael Gruss,Katharina Braun
Neural Plasticity , 2001, DOI: 10.1155/np.2001.285
Abstract: The Fragile X syndrome, a common form of mental retardation in humans, is caused by silencing the fragile X mental retardation (FMR1) geneleading to the absence of the encoded fragile X mental retardation protein 1 (FMRP). We describe morphological and behavioral abnormalities for both affected humans and Fmr1 knockout mice, a putative animal model for the human Fragile X syndrome. The aim of the present study was to identify possible neurochemical abnormalities in Fmr1 knockout mice, with particular focus on neurotransmission. Significant region-specific differences: of basal neurotransmitter and metabolite levels were found between wildtype and Fmr1 knockout animals, predominantly in juveniles (post-natal days 28 to 31). Adults (postnatal days 209 to 221) showed only few abnormalities as compared with the wildtype. In juvenile knockout mice, aspartate and taurine were especially increased in cortical regions, striatum, hippocampus, cerebellum, and brainstem. In addition, juveniles showed an altered balance between excitatory and inhibitory amino acids in the caudal cortex, hippocampus, and brainstem. We detected very few differences in monoamine turnover in both age stages. The results presented here provide the first evidence that lack of FMRP expression in FMRP knockout mice is accompanied by age-dependent, region-specific alterations in neurotransmission.
La pintura mural hispano-musulmana. Tradición o innovación?
Rallo Gruss, Carmen
Al-Qantara : Revista de Estudios Arabes , 2003,
Abstract: It is generally thought that in Western Europe and at the end of the medieval period, tempera paint with oil as a medium was applied to dry plaster walls because the Roman technique for painting on wet plaster (al fresco) had been forgotten. Texts such as the Libro dell'Arte by Cennino Cennini discuss the recovery of the fresco technique by some of the founding painters of the Italian Renaissance, such as Giotto. From Renaissance Italy, it is argued, the technique expanded to the rest of Europe. However, in medieval Hispanic monuments with Islamic iconography there is evidence of painted fresco decoration dated prior to the fifteenth century. This paper studies the sources of this technical tradition by analysing examples of Iberian, Roman, Islamic, Mudéjar and Morisco mural painting. El convencimiento de que a finales de la Edad Media las paredes eran decoradas con pintura al seco, realizada con temple, más o menos graso, olvidando la técnica de pintura al fresco utilizada habitualmente por los romanos, es algo admitido para toda la Europa Occidental. Textos como el Libro dell′Arte de Cennino Cennini nos hablan de su recuperación por los iniciadores del Renacimiento italiano como el Giotto; desde allí se expandirá la técnica a todos los países europeos. Sin embargo, en los monumentos hispanos con iconografía de tradición islámica se siguen realizando decoraciones al fresco hasta el siglo XV. En busca de explicaciones a esta excepción, en este artículo se buscan las fuentes de esa tradición técnica, analizando ejemplos de pintura mural ibera, romana, islámica y de lo morisco o mudéjar. El estudio se centra en los materiales utilizados, incluso con analítica de laboratorio, en paralelo con los motivos estilísticos que se encuentran en cada época.
Facial Expression Reactions to Feedback in a Human-Computer Interaction—Does Gender Matter?  [PDF]
Stefanie Rukavina, Sascha Gruss, Holger Hoffmann, Harald C. Traue
Psychology (PSYCH) , 2016, DOI: 10.4236/psych.2016.73038

The present study investigated facial expressions as reactions to positive and negative feedback during a human-computer interaction. Thirty subjects interacted in natural language with a computer system while conducting a mental task, which was designed in the style of a Wizard of Oz scenario. During six different experimental sequences from a well-known memory paradigm (“Concentration”), the wizard produced different feedback as a manipulative tactic to alter the users’ reactions, e.g., praising the subject was assumed to exert a positive influence on the subjects’ moods. To analyze the impact of various feedback on the emotional reaction, facial expressions from all subjects were coded with the Facial Expression Coding System (FACES). In general, the outcomes yielded more negative facial expressions in response to positive feedback as compared with negative feedback. Furthermore, a gender difference was evident: women showed significantly more negative facial expressions in response to praise (“Your performance is improving”) than men. The study and results show that when considering future companion technologies, it is important to carefully investigate users’ reactions to feedback, since paradoxical reactions may ensue.

Elderly People Benefit More from Positive Feedback Based on Their Reactions in the Form of Facial Expressions during Human-Computer Interaction  [PDF]
Stefanie Rukavina, Sascha Gruss, Holger Hoffmann, Harald C. Traue
Psychology (PSYCH) , 2016, DOI: 10.4236/psych.2016.79124
Abstract: In this brief report, we present the results of our investigation into the impact of age on reactions in the form of facial expressions to positive and negative feedback during human-computer interaction. In total, 30 subjects were analyzed after a video-recorded mental task in the style of a Wizard of Oz scenario. All subjects and their facial reactions were coded using the Facial Expression Coding System (FACES). To summarize briefly, we can conclude from our facial expression analysis that compared with their younger counterparts, elderly people show significantly lower levels of negative expression in response to positive feedback from the technical system (“Your performance is improving!”). This result indicates that elderly people seem to benefit more from praise during interaction than younger people, which is significant for the design of future companion technologies.
Modeling Spatial Opportunity Structures and Youths’ Transitions from School to Training  [PDF]
Alexandra Wicht, Alexandra Nonnenmacher
Open Journal of Statistics (OJS) , 2017, DOI: 10.4236/ojs.2017.76071
Abstract: This paper examines the significance of spatial externalities for youths’ school-to-training transitions in Germany. For this purpose, it is necessary to address the methodological question of how an individual’s spatial context has to be operationalized with respect to both its extent and the problem of spatial autocorrelation. Our analyses show that the “zone of influence” comprises of the whole of Germany, not only close-by districts, and that these effects differ between structurally weak and strong regions. Consequently, assuming that only close proximity affects individual outcomes may disregard relevant contextual influences, and for spatial models that require an a priori definition of the weights for spatial units, it may be erroneous to make a decision based on this assumption. Concerning spatial autocorrelation, we found that neglecting local spatial autocorrelation at the context level causes considerable bias to the estimates, especially for districts that are close to the home district.
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