"Exploration des procédés de condensation pour le résumé de texte grâce à l'application des formalismes de la théorie sens-texte"

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Condensation versus air density change as a major cause of airflow: experimental evidence, link to data files and videos

The dominant model of atmospheric circulation posits that hot air rises, creating horizontal winds. A second major driver has recently been proposed by Makarieva and Gorshkov in their biotic pump theory (BPT), which suggests that evapotranspiration from natural closed-canopy forests causes intense condensation, and hence winds from ocean to land. Critics of the BPT argue that air movement to fill the partial vacuum caused by condensation is always isotropic, and therefore causes no net air movement (Bunyard, 2015, hdl:11232/397). This paper explores the physics of water condensation under mild atmospheric conditions, within a purpose-designed square-section 4.8 m-tall closed-system structure. Two enclosed vertical columns are connected at top and bottom by two horizontal tunnels, around which 19.5 m**3 of atmospheric air can circulate freely, allowing rotary airflows in either direction. This air can be cooled and/or warmed by refrigeration pipes and a heating mat, and changes in airflow, temperature, humidity and barometric pressure measured in real time. The study investigates whether the "hot-air-rises" or an implosive condensation model can better explain the results of more than 100 experiments. The data show a highly significant correlation (R2 >0.96, p value <0.001) between observed airflows and partial pressure changes from condensation. While the kinetic energy of the refrigerated air falls short of that required in bringing about observed airflows by a factor of at least 30, less than a tenth of the potential kinetic energy from condensation is shown to be sufficient. The assumption that condensation of water vapour is always isotropic is therefore incorrect. Condensation can be anisotropic, and in the laboratory does cause sustained airflow.

A philosophy in action: Carl Einstein and Die Fabrikation der Fiktionen

Carl Einstein is a not very well known figure within German culture, but his essay Die Fabrikation der Fiktionen remains ignored even among scholars of his work despite containing highly valuable clues to understand the intersection between philosophy and politics that characterizes much of the European thought of the twentieth century. Given this situation, after an initial part where the author’s personality and his latest ideas and actions are taken in account, the article makes a thorough review of Die Fabrikation der Fiktionen by doing firstly a comparison of the different interpretations that it has received until now, and continues by carrying out a new reading of its main ideas –the conflict between Realität and Wirklichkeit or the very concept of Fiktion– and an exercise of contrast between the essay and certain works by contemporary thinkers like Siegfried Kracauer and Paul Nizan.

Scale and ecosystem services: how do observation, management, and analysis shift with scale—lessons from Québec

Ecosystem service assessment and management are shaped by the scale at which they are conducted; however, there has been little systematic investigation of the scales associated with ecosystem service processes, such as production, benefit distribution, and management. We examined how social-ecological spatial scale impacts ecosystem service assessment by comparing how ecosystem service distribution, trade-offs, and bundles shift across spatial scales. We used a case study in Québec, Canada, to analyze the scales of production, consumption, and management of 12 ecosystem services and to analyze how interactions among 7 of these ecosystem services change across 3 scales of observation (1, 9, and 75 km²). We found that ecosystem service patterns and interactions were relatively robust across scales of observation; however, we identified 4 different types of scale mismatches among ecosystem service production, consumption, and management. Based on this analysis, we have proposed 4 aspects of scale that ecosystem service assessments should consider.

Incoherent solitons and condensation processes

We show that coherent phase effects may play a relevant role in the nonlinear propagation of partially incoherent waves, which lead to unexpected processes of condensation, or incoherent soliton generation in instantaneous response nonlinear media. © 2005 OSA.

Off-diagonal ekpyrotic scenarios and equivalence of modified, massive and/or Einstein gravity

Using our anholonomic frame deformation method, we show how generic off-diagonal cosmological solutions depending, in general, on all spacetime coordinates and undergoing a phase of ultra-slow contraction can be constructed in massive gravity. In this paper, there are found and studied new classes of locally anisotropic and (in)homogeneous cosmological metrics with open and closed spatial geometries. The late time acceleration is present due to effective cosmological terms induced by nonlinear off-diagonal interactions and graviton mass. The off-diagonal cosmological metrics and related Stückelberg fields are constructed in explicit form up to nonholonomic frame transforms of the Friedmann–Lamaître–Robertson–Walker (FLRW) coordinates. We show that the solutions include matter, graviton mass and other effective sources modeling nonlinear gravitational and matter fields interactions in modified and/or massive gravity, with polarization of physical constants and deformations of metrics, which may explain certain dark energy and dark matter effects. There are stated and analyzed the conditions when such configurations mimic interesting solutions in general relativity and modifications and recast the general Painlevé–Gullstrand and FLRW metrics. Finally, we elaborate on a reconstruction procedure for a subclass of off-diagonal cosmological solutions which describe cyclic and ekpyrotic universes, with an emphasis on open issues and observable signatures.

Novel insights into mitotic chromosome condensation

The fidelity of mitosis is essential for life, and successful completion of this process relies on drastic changes in chromosome organization at the onset of nuclear division. The mechanisms that govern chromosome compaction at every cell division cycle are still far from full comprehension, yet recent studies provide novel insights into this problem, challenging classical views on mitotic chromosome assembly. Here, we briefly introduce various models for chromosome assembly and known factors involved in the condensation process (e.g. condensin complexes and topoisomerase II). We will then focus on a few selected studies that have recently brought novel insights into the mysterious way chromosomes are condensed during nuclear division.

Conditions for observing IR chemiluminescence and the role of condensation in metal oxidation reactions

Infrared chemiluminescence (IRCL) studies of cw metal oxidation reactions wherein metal atoms entrained in a carrier gas were mixed with an oxidizer by means of a nozzle system are described. One goal of the work was to determine the vibrational distribution of the product molecule produced by the chemical reaction. In order to observe IRCL it was important to operate the system at the appropriate P-T point in the phase diagram of both the metal and metal salt, otherwise rapid condensation quenched any IRCL that was present. If the nucleation rate was greater 1010 3 than ~ cm-sec-I, then only "black body" radiation could be seen from the reaction. Most of the studies were on the Li/I2 system which is unique in that the phase diagrams of Li and LiI in the P-T ranges of interest are almost identical. This property permitted a relatively easy control with respect to condensation and the measurement of IRCL in the 10-28 um range for the excited LiI molecule.

Satisfying the Einstein-Podolsky-Rosen criterion with massive particles

In 1935, Einstein, Podolsky and Rosen (EPR) questioned the completeness of quantum mechanics by devising a quantum state of two massive particles with maximally correlated space and momentum coordinates. The EPR criterion qualifies such continuous-variable entangled states, where a measurement of one subsystem seemingly allows for a prediction of the second subsystem beyond the Heisenberg uncertainty relation. Up to now, continuous-variable EPR correlations have only been created with photons, while the demonstration of such strongly correlated states with massive particles is still outstanding. Here we report on the creation of an EPR-correlated two-mode squeezed state in an ultracold atomic ensemble. The state shows an EPR entanglement parameter of 0.18(3), which is 2.4 s.d. below the threshold 1/4 of the EPR criterion. We also present a full tomographic reconstruction of the underlying many-particle quantum state. The state presents a resource for tests of quantum nonlocality and a wide variety of applications in the field of continuous-variable quantum information and metrology.

Una fórmula de Albert Einstein, trabajo + juego + silencio = éxito : es un merengue 8

Fondo Margaritainés Restrepo

Critical core mass for enriched envelopes: the role of H2O condensation

Context. Within the core accretion scenario of planetary formation, most simulations performed so far always assume the accreting envelope to have a solar composition. From the study of meteorite showers on Earth and numerical simulations, we know that planetesimals must undergo thermal ablation and disruption when crossing a protoplanetary envelope. Thus, once the protoplanet has acquired an atmosphere, not all planetesimals reach the core intact, i.e. the primordial envelope (mainly H and He) gets enriched in volatiles and silicates from the planetesimals. This change of envelope composition during the formation can have a significant effect on the final atmospheric composition and on the formation timescale of giant planets. Aims. We investigate the physical implications of considering the envelope enrichment of protoplanets due to the disruption of icy planetesimals during their way to the core. Particular focus is placed on the effect on the critical core mass for envelopes where condensation of water can occur. Methods. Internal structure models are numerically solved with the implementation of updated opacities for all ranges of metallicities and the software Chemical Equilibrium with Applications to compute the equation of state. This package computes the chemical equilibrium for an arbitrary mixture of gases and allows the condensation of some species, including water. This means that the latent heat of phase transitions is consistently incorporated in the total energy budget. Results. The critical core mass is found to decrease significantly when an enriched envelope composition is considered in the internal structure equations. A particularly strong reduction of the critical core mass is obtained for planets whose envelope metallicity is larger than Z approximate to 0.45 when the outer boundary conditions are suitable for condensation of water to occur in the top layers of the atmosphere. We show that this effect is qualitatively preserved even when the atmosphere is out of chemical equilibrium. Conclusions. Our results indicate that the effect of water condensation in the envelope of protoplanets can severely affect the critical core mass, and should be considered in future studies.

Early and late effects of Ibuprofen on mouse sperm parameters, chromatin condensation, and DNA integrity in mice

Background: There are few studies indicating the detrimental effects of ibuprofen on sperm fertility potential and DNA integrity. Objective: To determine the effects of Ibuprofen on sperm parameters, chromatin condensation and DNA integrity of mice. Materials and Methods: In this experimental study, 36 adult male mice with average weight 37 gr were divided into three groups, including control (group I, n=12), normal dosage of ibuprofen (group II, n=12) and high dosage (group III, n=12). Ibuprofen with different doses was dissolved in daily water of animals. After 35, 70 and 105 days, the cauda epididymis of mice were cut and incubated in Ham’s F10 media. Sperm samples were analyzed for parameters (motility, morphology and count), DNA integrity (SCD test) and chromatin condensation (chromomycin A3 and Aniline blue staining). Results: After 35 days, in addition to above mentioned sperm parameters, all of the treated mice showed statistically significant increase in spermatozoa with immature chromatin (P<0.05). However, after 70 days, the rate of sperm DNA fragmentation assessed by SCD was increased in group II (66.5±0.7) and the percentage of immature spermatozoa (AB+ and CMA3+) was higher in group III (77.5±0.7 and 49.5±6.3 respectively) than other groups. After 105 days, the AB+ spermatozoa were increased in both normal dose and high dose groups. Conclusion: Ibuprofen may cause a significant reduction in sperm parameters and sperm chromatin/DNA integrity in mice. It should be noted that these deleterious effects are dose-dependent and can be seen in early and late stage of drug treatments.

Rapporto tensore su scalare con gravità indotta: analisi dell’approssimazione di slow-roll nei frames di Jordan e Einstein

L’obbiettivo di questa tesi è quello di analizzare le conseguenze della scelta del frame (Jordan o Einstein) nel calcolo delle proprietà degli spettri primordiali generati dall’inflazione ed in particolare dell’osservabile r (rapporto tensore su scalare) al variare del potenziale del campo che genera l’espansione accelerata. Partendo dalla descrizione della teoria dell’inflazione in relatività generale, focalizzando l’attenzione sui motivi che hanno portato all’introduzione di questa teoria, vengono presentate le tecniche di utilizzo comune per lo studio della dinamica omogenea (classica) inflazionaria e di quella disomogenea (quantistica). Una particolare attenzione viene rivolta ai metodi di approssimazione che è necessario adottare per estrarre predizioni analitiche dai modelli inflazionari per poi confrontarle con le osservazioni. Le tecniche introdotte vengono poi applicate ai modelli di inflazione con gravità indotta, ovvero ad una famiglia di modelli con accoppiamento non minimale tra il campo scalare inflatonico e il settore gravitazionale. Si porrà attenzione alle differenze rispetto ai modelli con accoppiamento minimale, e verrà studiata la dinamica in presenza di alcuni potenziali derivanti dalla teoria delle particelle e diffusi in letteratura. Il concetto di “transizione tra il frame di Jordan e il frame di Einstein” viene illustrato e le sue conseguenze nel calcolo approssimato del rapporto tensore su scalare sono discusse. Infine gli schemi di approssimazione proposti vengono analizzati numericamente. Risulterà che per due dei tre potenziali presentati i metodi di approssimazione sono più accurati nel frame di Einstein, mentre per il terzo potenziale i due frames portano a risultati analitici similmente accurati.

A pilot study on the effect of indoor particle sources on indoor particle concentration in residential houses

Characterization of indoor particle sources from 14 residential houses in Brisbane, Australia, was performed. The approximation of PM2.5 and the submicrometre particle number concentrations were measured simultaneously for more than 48 h in the kitchen of all the houses by using a photometer (DustTrak) and a condensation particle counter (CPC), respectively. From the real time indoor particle concentration data and a diary of indoor activities, the indoor particle sources were identified. The study found that among the indoor activities recorded in this study, frying, grilling, stove use, toasting, cooking pizza, smoking, candle vaporizing eucalyptus oil and fan heater use, could elevate the indoor particle number concentration levels by more than five times. The indoor approximation of PM2.5 concentrations could be close to 90 times, 30 times and three times higher than the background levels during grilling, frying and smoking, respectively.