Very recently a new inversion method has been developped to analyze the intergalactic medium seen in absorption in quasar spectra (the so-called Lyman-alpha forest). This method is applied to recover ...the temperature of the gas and the underlying density field. Using constraints from the Lyman-beta forest, it is possible to recover this field up to over-densities delta=10. By inverting the HI and CIV absorptions together it has been shown that the CIV/HI ratio varies through the profile of strong lines, beeing larger in the wings. The method can be applied to reconstruct the 3D density field from multiple lines of sight and is shown to give good results up to mean separations of 3 arcmin. Results from a survey of QSO pairs performed with HST/STIS and VLT/UVES-FORS are summarized.
Colombi et al. 1999 (paper I) investigated the counts-in-cells statistics and their respective errors in the \(\tau\)CDM Virgo Hubble Volume simulation. This extremely large \(N\)-body experiment ...also allows a numerical investigation of the {\em cosmic distribution function}, \(\Upsilon(\tA)\) itself for the first time. For a statistic \(A\), \(\Upsilon(\tA)\) is the probability density of measuring the value \(\tA\) in a finite galaxy catalog. \(\Upsilon\) was evaluated for the distribution of counts-in-cells, \(P_N\), the factorial moments, \(F_k\), and the cumulants, \(\xiav\) and \(S_N\)'s, using the same subsamples as paper I. While paper I concentrated on the first two moments of \(\Upsilon\), i.e. the mean, the cosmic error and the cross-correlations, here the function \(\Upsilon\) is studied in its full generality, including a preliminary analysis of joint distributions \(\Upsilon(\tA,\tB)\). The most significant, and reassuring result for the analyses of future galaxy data is that the cosmic distribution function is nearly Gaussian provided its variance is small. A good practical criterion for the relative cosmic error is that \(\Delta A/A \la 0.2\). This means that for accurate measurements, the theory of the cosmic errors, presented by Szapudi & Colombi (1996) and Szapudi, Colombi & Bernardeau (1999), and confirmed empirically by paper I, is sufficient for a full statistical description and thus for a maximum likelihood rating of models. As the cosmic error increases, the cosmic distribution function \(\Upsilon\) becomes increasingly skewed and is well described by a generalization of the lognormal distribution. The cosmic skewness is introduced as an additional free parameter. (...more in paper...)
Counts-in-cells are measured in the \(\tau\)CDM Virgo Hubble Volume simulation. This large N-body experiment has 10^9 particles in a cubic box of size 2000 h^{-1} Mpc. The unprecedented combination ...of size and resolution allows for the first time a realistic numerical analysis of the cosmic errors and cosmic correlations of statistics related to counts-in-cells measurements, such as the probability distribution function P_N itself, its factorial moments F_k and the related cumulants \(\xiav\) and S_N's. These statistics are extracted from the whole simulation cube, as well as from 4096 sub-cubes of size 125 h^{-1}Mpc, each representing a virtual random realization of the local universe. The measurements and their scatter over the sub-volumes are compared to the theoretical predictions of Colombi, Bouchet & Schaeffer (1995) for P_0, and of Szapudi & Colombi (1996, SC) and Szapudi, Colombi & Bernardeau (1999a, SCB) for the factorial moments and the cumulants. The general behavior of experimental variance and cross-correlations as functions of scale and order is well described by theoretical predictions, with a few percent accuracy in the weakly non-linear regime for the cosmic error on factorial moments. (... more in paper >...)
Abstract
The METAFORET experiment was designed to demonstrate that complex wave physics phenomena classically observed at the meso- and micro-scales in acoustics and in optics also apply at the ...geophysics scale. In particular, the experiment shows that a dense forest of trees can behave as a locally resonant metamaterial for seismic surface waves. The dense arrangement of trees anchored into the ground creates anomalous dispersion curves for surface waves, which highlight a large frequency band-gap around one resonant frequency of the trees, at ∼45 Hz. This demonstration is carried out through the deployment of a dense seismic array of ∼1000 autonomous geophones providing seismic recordings under vibrating source excitation at the transition between an open field and a forest. Additional geophysical equipment was deployed (e.g. ground-penetrating radar, velocimeters on trees) to provide essential complementary measurements. Insights and interpretations on the observed seismic wavefield, including the attenuation length, the intensity ratio between the field and the forest and the surface wave polarization, are validated with 2D numerical simulations of trees over a layered halfspace.
This study addressed the scarcity of NH3 measurements in urban Europe and the diverse monitoring protocols, hindering direct data comparison. Sixty-nine datasets from Finland, France, Italy, Spain, ...and the UK across various site types, including industrial (IND, 8), traffic (TR, 12), urban (UB, 22), suburban (SUB, 12), and regional background (RB, 15), are analyzed to this study. Among these, 26 sites provided 5, or more, years of data for time series analysis. Despite varied protocols, necessitating future harmonization, the average NH3 concentration across sites reached 8.0 ± 8.9 μg/m3. Excluding farming/agricultural hotspots (FAHs), IND and TR sites had the highest concentrations (4.7 ± 3.2 and 4.5 ± 1.0 μg/m3), followed by UB, SUB, and RB sites (3.3 ± 1.5, 2.7 ± 1.3, and 1.0 ± 0.3 μg/m3, respectively) indicating that industrial, traffic, and other urban sources were primary contributors to NH3 outside FAH regions. When referring exclusively to the FAHs, concentrations ranged from 10.0 ± 2.3 to 15.6 ± 17.2 μg/m3, with the highest concentrations being reached in RB sites close to the farming and agricultural sources, and that, on average for FAHs there is a decreasing NH3 concentration gradient towards the city. Time trends showed that over half of the sites (18/26) observed statistically significant trends. Approximately 50 % of UB and TR sites showed a decreasing trend, while 30 % an increasing one. Meta-analysis revealed a small insignificant decreasing trend for non-FAH RB sites. In FAHs, there was a significant upward trend at a rate of 3.510.45,6.57%/yr. Seasonal patterns of NH3 concentrations varied, with urban areas experiencing fluctuations influenced by surrounding emissions, particularly in FAHs. Diel variation showed differing patterns at urban monitoring sites, all with higher daytime concentrations, but with variations in peak times depending on major emission sources and meteorological patterns. These results offer valuable insights into the spatio-temporal patterns of gas-phase NH3 concentrations in urban Europe, contributing to future efforts in benchmarking NH3 pollution control in urban areas.
Si le roi savait Briatte, François; Bruno, Isabelle; Carnino, Guillaume ...
Tracés (Lyons, France),
12/2018
18
Journal Article
Recenzirano
Odprti dostop
The artisanal publishing of a journal of the humanities and social sciences is a matter of particular intellectual and professional commitment. While the demands for a certain professionalisation ...– bureaucratic, normalizing, and disillusioning – of editorial teams and committees are increasing in intensity, the members of Zilsel are joyfully attached to the most elementary norms of the scientific ethos in their publishing work. Craft on form, experimentations on the contents and controlled improvisations, combined with a certain conception of research and its dissemination, thus constitute the desirable horizon for an editorial adventure on a crest line – academic and iconoclastic, demanding and gladly disturbing.
Les physiciens des ondes élaborent des modèles théoriques et numériques pour un contrôle accru de la lumière dans des matériaux structurés à l’échelle nanométrique et s’en inspirent pour contrôler ...les ondes mécaniques de Rayleigh dans des sols structurés à l’échelle métrique, avec des trous dans un sol ou des arbres en surface savamment agencés. Un transfert de paradigme s’opère entre les métamatériaux électromagnétiques pour la photonique et les métamatériaux sismiques pour le génie civil.
Si le roi savait Briatte, François; Bruno, Isabelle; Carnino, Guillaume ...
Tracés (Lyons, France),
05/2019, Letnik:
18
Journal Article
Recenzirano
Odprti dostop
Éditer une revue de sciences humaines et sociales artisanale relève d’un engagement intellectuel et professionnel particulier. Alors que les injonctions à une certaine professionnalisation ...– bureaucratique, normalisatrice, tue-l’amour de la science – des équipes et comités de rédaction redoublent d’intensité, les membres de Zilsel se retrouvent dans une pratique éditoriale joyeusement attachée aux normes les plus élémentaires de l’ethos scientifique. Le bricolage sur la forme, les expérimentations de fond et les improvisations contrôlées, unies à une certaine conception de la recherche et de sa mise en partage, constituent ainsi l’horizon désirable d’une aventure éditoriale sur une ligne de crête – académique et iconoclaste, exigeante et volontiers perturbatrice.
Faire revue Albert, Anaïs; Béja, Alice; Briatte, François ...
Tracés (Lyons, France),
2018
Journal Article
Recenzirano
Odprti dostop
En considérant les chaînes du travail éditorial, les temporalités et les conditions sociales de production comme la place des différent-e-s actrices et acteurs dans l’élaboration des revues ...scientifiques, ce numéro hors-série de Tracés veut réfléchir aux effets du format revue sur la production et la réception du savoir en sciences humaines et sociales. Il invite des études réflexives par des membres de différentes revues, jeunes ou plus installées, ainsi que des analyses transverses intéressant plus généralement les revues. Dans « Faire revue », trois dimensions essentielles sont analysées. Une première perspective définit la revue comme un lieu de pouvoir, où le statut professionnel et le profil sociologique de ses membres, le rôle attribué à chacun-e, ainsi que les thèmes abordés ou les modalités de traitement des articles interrogent en son cœur les rapports entre pouvoir et savoir scientifique. La deuxième dimension est celle des conditions de travail et de l’économie des revues. Quels sont leurs financements et les choix stratégiques qui bien souvent en dépendent ? Pourquoi une revue passe-t-elle au tout numérique tandis qu’une autre fait le choix du papier et d’un travail graphique soigné ? La question de l’accès libre est-elle purement financière ? Quels effets produisent les environnements électroniques de publication sur les métiers de la chaîne éditoriale ? Nous intéresse ici l’incidence de ces dimensions sur les conditions matérielles de production de la revue. Enfin, celle-ci est pensée pour être lue. Interroger la réception, réelle et souhaitée, les écarts ou mises à l’écart, permet de comprendre aussi comment s’oriente la production du savoir à travers des cas singuliers. Considering the chains of editorial work, the temporalities and social conditions of production, the place assigned to every male and female participant in the publishing process, this special issue of Tracés aims to reflect on the effects of the “academic journal” format on the production and reception of knowledge in the humanities and social sciences. The issue invites studies by members of individual journals, both new and old, as well as scholars reflecting on transversal topics interesting journals. In “Academic journals in the making” three essential dimensions are epitomized. Academic journals may be considered as places of power, where the professional status and sociological profile of its members, their assigned role, but also the topics addressed or else the selecting or commissioning of articles crucially put to question the relationship between power and scientific knowledge. The second dimension is the economics of journals, including working conditions. How are journals funded and what the consequences on their strategic choices? Why does one journal go all-digital while another chooses hard copy print and careful design? Is open access publishing a pure financial matter? What are the effects of digital environments on the professions and practices of publishing chains? This issue analyses the impact of these dimensions on the production of journals and the material conditions that make them possible. Finally, a journal is designed to be read. Questioning the reception, real and desired, through specific cases, also makes it possible to understand how the production of knowledge is directed.
El uso de estrategias de soporte respiratorio no invasivo (NIRS) ha demostrado disminuir el consumo de recursos asociados al requerimiento de unidad de cuidados intensivos y estancia hospitalaria en ...los pacientes pediátricos con insuficiencia respiratoria aguda, sin embargo, se considera importante identificar su frecuencia de uso en el paciente pediátrico con SARS-CoV-2 y su relación con la estancia hospitalaria. Objetivo: Identificar la frecuencia de uso de las estrategias de soporte respiratorio no invasivas (NIRS) en pacientes pediátricos con SARS-CoV-2. Material y métodos: Revisión de alcance en tono a cuál es la frecuencia de uso de las NIRS en SARS-CoV-2 pediátrico entre enero del 2020 a septiembre del 2021. La búsqueda se ejecutó en las bases de datos Cochrane Library, PubMed, Scopus y los buscadores bibliográficos Science Direct y Oxford.
PDF
