Are Kaluza-Klein models of the universe chaotic?
; De Rop, Yves ;
in International Journal of Theoretical Physics (1989), 28
The generic behavior of vacuum inhomogeneous and spatially homogeneous Kaluza-Klein models is studied in the vicinity of the cosmological singularity. It is shown that, in space-time dimensions ≥ 11, the ... [more ▼]
The generic behavior of vacuum inhomogeneous and spatially homogeneous Kaluza-Klein models is studied in the vicinity of the cosmological singularity. It is shown that, in space-time dimensions ≥ 11, the generalized Kasner solution, with monotonic power-law behavior of the spatial distances, becomes a general solution of the Einstein vacuum field equations and that, moreover, the chaotic oscillatory behavior disappears. On the other hand, the chaotic oscillatory behavior, absent in diagonal spatially homogeneous cosmological models in space-time dimensions between 5 and 10, can be reestablished when off-diagonal terms are included. [less ▲]Detailed reference viewed: 13 (2 ULg)
Are Magnetic OB Stars More Prone to Mixing? Still an Unsettled Issue
in Astronomical Society of the Pacific Conference Series (2013, January 01)
We review our knowledge of the mixing properties of magnetic OB stars and discuss whether the observational data presently available support, as predicted by some theoretical models, the idea that ... [more ▼]
We review our knowledge of the mixing properties of magnetic OB stars and discuss whether the observational data presently available support, as predicted by some theoretical models, the idea that magnetic phenomena favour the transport of chemical elements. A (likely statistical) relationship between enhanced mixing and the existence of a field has been emerging over the last few years. As discussed in this contribution, however, a clear answer to this question is presently hampered by the lack of large and well-defined samples of magnetic and non-magnetic stars. [less ▲]Detailed reference viewed: 10 (2 ULg)
Are MDRD formulas better than Cockcroft formula for the prediction of glomerular filtration rate in obese patients?
Delanaye, Pierre ; Saint-Remy, Annie ; Rorive, Marcelle et al
in European Renal Association, XLI COngress Lisbon, Abstract book (2004)Detailed reference viewed: 71 (17 ULg)
Are Milk Polyamines Preventive Agents against Food Allergy?
Dandrifosse, Guy ; Peulen, Olivier ; et al
in Proceedings of the Nutrition Society (2000), 59(1), 81-6
Insufficient polyamine intake could play a role in the induction of sensitization to dietary allergens. This proposal is based essentially on investigations made in sucking rats and in children. In ... [more ▼]
Insufficient polyamine intake could play a role in the induction of sensitization to dietary allergens. This proposal is based essentially on investigations made in sucking rats and in children. In sucking rats it has been established that oral administration of spermine can induce all the modifications occurring in the digestive tract at weaning. In the intestine events occur in two phases. The early event consists of desquamation of the epithelium resulting from an activation of apoptosis. The late event appears to involve an hormonal cascade in which adrenocorticotropic hormone, cytokines, bombesin and corticosterone are included. Observations in human subjects show that: (1) the spermine and spermidine concentrations are generally lower in infant formulas than in human breast milk. Mothers seem consistently to have relatively high or relatively low concentrations of spermine and spermidine in their milk. These individual variations may be due to diet, lifestyle or genetic background; (2) the probability of developing allergy can reach 80 % if the mean spermine concentration in the milk is lower than 2 nmol/ml milk. It is approximately 0 % if the mean spermine concentration is higher than 13 nmol/ml milk; (3) preliminary results show that the intestinal permeability to macromolecules differs in premature babies when they are fed on breast milk compared with infant formulas (J Senterre, J Rigo, G Forget, G Dandrifosse and N Romain, unpublished results). This difference does not seem to be present when powdered milk is supplemented with polyamines at the concentration found in breast milk; (4) spermine increases proliferation and differentiation of lymphocytes isolated from the tonsils of children. [less ▲]Detailed reference viewed: 44 (4 ULg)
Are patients with HBV and HCV infection different? Comparison between 2 cohorts of newly diagnosed cases included in prospective registries of the Belgian Association for the Study of the Liver
; ; et al
in Acta Gastro-Enterologica Belgica (2011, March), 74(1), 21Detailed reference viewed: 19 (0 ULg)
Are performance-related characteristics associated with sports injuries in young soccer players?
Frisch, Anne ; ; et al
in 3rd World Conference on Science and Soccer, Ghent, Belgium 14-16 May 2012 (2012, May 15)Detailed reference viewed: 47 (5 ULg)
Are Pituitary tumors more common than previously thought
Scientific conference (2005, June)Detailed reference viewed: 1 (0 ULg)
Are porcine follicle stimulating hormone antibodies associated with decreased superovulatory response in goat ?
Beckers, Jean-François ; ; et al
in Theriogenology (1990), 33(1), 192Detailed reference viewed: 7 (0 ULg)
Are purely formal objects entities or concepts ?
Scientific conference (2009, June 15)
In this paper, our purpose will be to question the ontological nature of the structural - or purely formal - entities which, according to the formalist point of view, are defined within an axiomatic ... [more ▼]
In this paper, our purpose will be to question the ontological nature of the structural - or purely formal - entities which, according to the formalist point of view, are defined within an axiomatic system, rather than described by this system. After a brief reminder of the famous debate between Hilbert and Frege (in a postmail exchange from December the 27th 1899 to January the 6th 1900), as well as of the intuitionistic stance, we will consider Edmund Husserl’s and the early Carnap’s positions. This will lead to a new evaluation of the relations between the notions of “object” and “givenness”, as well as a to a new consideration of the respective contributions of conceptual description and acquaintance in the process of identifying purely formal objects. [less ▲]Detailed reference viewed: 75 (8 ULg)
Are rapid changes in gonadal testosterone release involved in the fast modulation of brain estrogen effects?
Cornil, Charlotte ; ;
in General and Comparative Endocrinology (2009)
Estradiol facilitates the expression of male sexual behavior in Japanese quail within a few minutes. These rapid behavioral effects of estradiol could result from rapid changes in its local production in ... [more ▼]
Estradiol facilitates the expression of male sexual behavior in Japanese quail within a few minutes. These rapid behavioral effects of estradiol could result from rapid changes in its local production in the preoptic area by aromatase, the enzyme converting testosterone into estradiol. Alternatively, aromatase activity may remain constant but fluctuations of local estradiol production could arise from rapid changes in the concentration of the enzymatic substrate, namely testosterone. Rapid increases of circulating testosterone levels have been observed in males of various species following social encounters. Surprisingly, in quail, the interaction with a female seems to result in a decrease in circulating testosterone levels. However, in that study conducted in quail, the samples were collected at intervals longer than the recently observed rapid effects of estradiol on sexual behavior. In the present study we investigated whether plasma testosterone concentrations fluctuate on a shorter time-frame. Eleven male were tested 5 min before and 5, 15 or 30 min after being allowed to have visual access to a female or to copulate with a female for 5 min. Both types of interactions resulted in a significant decline in circulating testosterone levels at latencies as short as 5 min. These data demonstrate that the decrease in testosterone levels is initiated shortly after sexual encounters. Because visual interactions with a female did not result in a rapid increase in testosterone concentrations, these findings rule out the possibility that a rapid rise in circulating testosterone levels participates in the rapid increase in brain estrogen synthesis and its facilitatory effects on copulatory behavior. [less ▲]Detailed reference viewed: 43 (12 ULg)
Are Similar Inflammatory Factors Involved in Strenuous Exercise and Sepsis?
; Deby, Ginette ; et al
in Intensive Care Medicine (1994), 20(8), 602-10
An increasing body of data suggest that strenuous exercise triggers an inflammatory response having some similarity with those occurring in sepsis. Indices of this inflammatory response to exercise (IRE ... [more ▼]
An increasing body of data suggest that strenuous exercise triggers an inflammatory response having some similarity with those occurring in sepsis. Indices of this inflammatory response to exercise (IRE) especially include leukocytosis, release of inflammatory mediators and acute phase reactants, tissue damage, priming of various white blood cell lines, production of free radicals; activation of complement, coagulation and fibrinolytic cascades. Inflammatory responses to strenuous exercise and sepsis could in part be due to the release of endotoxin in blood as common triggering factor, but it seems that tissue damage and/or contact system activation are more important triggering mechanisms in exercising subjects. While the magnitude and duration of cellular and humoral changes associated with IRE are quite different from those observed in sepsis, recent human studies suggested that chronic and/or excessive IRE could have adverse effects. Among the possible consequences of acute and chronic IRE are delayed onset muscular soreness and loss of force, cardiovascular complications, intravascular hemolysis, hypoferraemia and increased susceptibility to infection. [less ▲]Detailed reference viewed: 23 (0 ULg)
Are Simple Calculation Models always on the Safe Side?
in Schaumann, Peter (Ed.) Festschrift Peter Schaumann (2014)
This paper examines the question whether simple calculation models are always on the safe side compared to advanced calculation models. This question is examined for the shadow effect, for the contact ... [more ▼]
This paper examines the question whether simple calculation models are always on the safe side compared to advanced calculation models. This question is examined for the shadow effect, for the contact between steel and concrete in composite steel-concrete floors, for the buckling curves of steel sections and, finally, for the factors κ1 and κ2 applied to the bending resistance of steel beams. [less ▲]Detailed reference viewed: 12 (1 ULg)
Are Skinner's warnings still relevant to current psychology ? Commentary on B.F.Skinner, Methods and theories in the experimental analysis of behavior
in Behavioral and Brain Sciences (1984), 7Detailed reference viewed: 3 (0 ULg)
Are spatial memories strengthened in the human hippocampus during slow wave sleep?
Peigneux, Philippe ; Laureys, Steven ; et al
in Neuron (2004), 44(3), 535-545
In rats, the firing sequences observed in hippocampal ensembles during spatial learning are replayed during subsequent sleep, suggesting a role for posttraining sleep periods in the offline processing of ... [more ▼]
In rats, the firing sequences observed in hippocampal ensembles during spatial learning are replayed during subsequent sleep, suggesting a role for posttraining sleep periods in the offline processing of spatial memories. Here, using regional cerebral blood flow measurements, we show that, in humans, hippocampal areas that are activated during route learning in a virtual town are likewise activated during subsequent slow wave sleep. Most importantly, we found that the amount of hippocampal activity expressed during slow wave sleep positively correlates with the improvement of performance in route retrieval on the next day. These findings suggest that learning-dependent modulation in hippocampal activity during human sleep reflects the offline processing of recent episodic and spatial memory traces, which eventually leads to the plastic changes underlying the subsequent improvement in performance. [less ▲]Detailed reference viewed: 37 (2 ULg)
Are Tangs Morphological Adaptations in View of Hafting? Macro- and microscopic wear analysis on a selection of tanged burins from Maisières-Canal
in Notae Praehistoricae (2002), 114Detailed reference viewed: 9 (4 ULg)
are target dioxin levels in animal feedingstuffs achievable for laboratories in terms of analytical requirements? Results of an interlaboratory study
Eppe, Gauthier ; De Pauw, Edwin
in Organohalogen Compounds (2002)Detailed reference viewed: 8 (0 ULg)
Are the 1999 and 2000 urban floods in Senegal due to exceptional rainfall events?
; Ozer, Pierre
in Demarée, Gaston; De Dapper, Morgan; Alexandre, Jean (Eds.) Tropical Climatology, Meteorology and Hydrology: Climate-related risk analysis and sustainable development in tropical areas. (2004)Detailed reference viewed: 24 (2 ULg)
Are the back educational interventions effective for preventing low back pain
Demoulin, Christophe ; ; et al
in Abstract book of the 8th Interdisciplinary World Congress on Low Back and Pelvic Pain (2013, October)Detailed reference viewed: 7 (0 ULg)