304 research outputs found
Intra-cavity generation of superpositions of Laguerre-Gaussian beams
No full textNaidoo, D. Ait-Ameur, K. Brunel, M. Forbes, A. Spring Meeting of the German-Physical-Society 2011 Dresden, GERMANY German Phys Soc SiIn this paper we demonstrate experimentally the intra-cavity generation of a coherent superposition of Laguerre-Gaussian modes of zero radial order but opposite azimuthal order. The superposition is created with a simple intra-cavity stop that creates equal losses for the two azimuthal modes, and we show that by adjustment of the stop we can produce modes up to azimuthal order 8. The fact that we have a coherent superposition rather than an incoherent superposition is verified by intensity measurements, propagation measurements and a decomposition of the field by an inner product executed on a phase-only spatial light modulator. Such fields have relevance in quantum information and optical trapping
Chemical composition of the essential oils of the berries of Juniperus oxycedrus L. ssp rufescens (L.K.) and Juniperus oxycedrus L. ssp. macrocarpa (S.&m.) Ball. and their antioxidant activities
No full textThis study is outlined to probe the chemical composition of essential oil and in vitro antioxidant activity of Juniperus oxycedrus ssp. macrocarpa (S. & m.) Ball. and Juniperus oxycedrus L. ssp. rufescens (L. K.) berries, collected from four sites, according to their maturity phase. The chemical composition of the hydrodistilled essential oil was analysed by GC-MS. Forty-eight compounds were identified, accounting for approximately 79.8-98.9% of the oil. The main constituents were alpha-pinene, germacrene D, myrcene, abietadiene and cis-calamenene, their mean percentage vary according to their phenological stage. The antioxidant activity of the samples was determined by the ABTS and DPPH radical scavenging activities. Hawaria essential oil extracted from mature berries showed the highest antioxidant capacity
Study of some parameters influence on a Saharian building balance sheet
No full textThis work has undertaken a study of the influence of some parameters on the energy balance of a premise located in an arid area. The objective of this study is to calculate the heat of a South facing office record, and study the influence of various parameters such as: glazing, insulation, orientation, building materials and occupants. The system is composed of a desktop represented by its design, and external surrounding climatic condition of Bechar city
Gluten-free diet and gut microbiome
Get PDFAs the only effective therapy against diagnosed celiac disease (CD), the gluten-free diet (GFD) has inevitable repercussion on the gut microbiome composition and functionality. Being the cause or the consequence of the disease, an altered homeostasis of the gut microbiome usually affects CD patients at diagnosis. After describing the main features of this altered physiological condition, this review defines the main nutritional aspects of the GFD and elucidates how this diet regimen does not fully restore the optimal gut microbiome composition and functionality. Unbalanced ratios between beneficial and potentially harmful bacteria are frequently present in fecal materials, biopsy specimens and saliva, used as ecological model systems to observe CD. Metabolome analyses also show how an altered microbiome synthesize different metabolite with respect to healthy conditions. The review concludes illustrating the current supplementations (biotics family), which fortify the GFD with the aim of restoring the homeostasis of the gut microbiome
Thirty years of knowledge on sourdough fermentation. A systematic review
No full textBackground: Sourdough is one of the oldest examples of natural starters, mostly used for making fermented baked goods as an alternative to baker's yeast and chemical leavening. Almost 30 years of research have accumulated showing its performance. Time is mature to elaborate collectively these data and to draw conclusions, which would represent milestones for scientists, industries and consumers. Scope and approach: With the scope of highlighting its microbiological, biochemical, technological and nutritional potential, we used “sourdough” as the only keyword and the PRISMA flow diagram to retrieve, select and systematically review 1230 peer reviewed research articles from four databases (Google Scholar, Scopus, PubMed and ScienceDirect). Key findings and conclusions: The literature states that sourdough baked goods underwent characterization in almost 50 countries and all continents, mainly dealing with salty (breads and substitutes) and sweet products. Converging data defined optimal use conditions, most common microbiological and biochemical characteristics, criteria for selecting and re-using starters, and versatility of sourdough for making baked goods with a relevant number of flour species/varieties and agro-food by-products. Because of the unique microbial composition and functionality, sourdough has claimed as an irreplaceable starter for improving the sensory, rheology and shelf life attributes of baked goods. The most recent literature showed how the sourdough fermentation mainly increased mineral bioavailability, enabled fortification with dietary fibers, lowered glycemic index, improved protein digestibility and decreased the content of anti-nutritional factors. This knowledge is solid for delivering to industries and consumers, and to face new research challenges starting from a consolidated state of the art
A Voice of the French Suburbs: “Wesh wesh, qu’est-ce qui se passe?” and “Bled Number One” by Rabah Ameur-Zaïmeche
No full textAutorka analizuje dyptyk filmowy francuskiego reżysera o algierskich korzeniach Rabaha Ameur-Zaïmeche’a: Wesh wesh, qu’est-ce qui se passe? (2001) i Bled Number One (2006). W filmach tych twórca zastanawia się nad sytuacją społeczną, ekonomiczną i prawną, a także kondycją psychologiczną i uwarunkowaniami kulturowymi tysięcy imigrantów z Afryki Północnej oraz ich potomków zamieszkujących francuskie przedmieścia. Filmy poświęcone tym zagadnieniom powstają we Francji od dekad i stanowią przedmiot zainteresowania wielu badaczy zachodnich, jednak w Polsce wciąż nie poświęca się im należnej uwagi. Autorka dokonuje analizy składników świata przedstawionego w obu produkcjach przede wszystkim przez odniesienie ich do rzeczywistości pozafilmowej, w której poszukuje zakorzenienia fabuły i uzasadnienia jej poszczególnych elementów. Koncentruje się też na indywidualnym, paradokumentalnym stylu reżysera i stosowanych przez niego rozwiązaniach formalnych, demonstrując, w jaki sposób podkreślają one wymowę obu dzieł i jak ściśle są jej podporządkowane.The author analyzes a film diptych by the French-Algerian director Rabah Ameur-Zaïmeche: Wesh wesh, qu’est-ce qui se passe? (2001) and Bled Number One (2006). The diptych explores the social, economic, and legal situation of thousands of North African immigrants and their descendants living in the French banlieues. Films devoted to these issues have been created in France for decades and have become an object of interest for many Western scholars, but in Poland they still have not received sufficient attention. In this article, the author analyzes the components of the world depicted in both films, primarily by relating them to the real world. She considers the elements of the diegesis as reflecting the real (social, economic etc.) phenomena. She also focuses on the director’s individual, paradocumentary style and formal solutions, showing how they emphasize the meaning of both films
Subset selection and the cone of factor-width- k matrices
No full textInternational audienceWe study the cone of factor-width-k matrices, where the factor width of a positive semidefinite matrix is defined as the smallest number k allowing it to be expressed as a sum of positive semidefinite matrices that are non-zero only on a single k* k principal sub-matrix. Two hierarchies of approximations are proposed for this cone. Some theoretical bounds to assess the quality of the new approximations are derived. We also use these approximations to build convex conic relaxations for the subset selection problem where one has to minimize under the constraint that x has at most k non-zero components. Several numerical experiments are performed showing that some of these relaxations provide a good compromise between tightness and computational complexity and rank well compared to perspective-type relaxations
On the K-divisibility constant for some special finite-dimensional Banach couples
No full textAbstractWe prove new estimates of the K-divisibility constants for some special Banach couples. In particular, we prove that the K-divisibility constant for a couple of the form (U⊕V,U) where U and V are non-trivial Hilbert spaces equals 2/3. We also prove estimates for the K-divisibility constant of the two-dimensional version of the couple (L2,L∞), proving in particular that this couple is not exactly K-divisible. There are also several auxiliary results, including some estimates for relative Calderón constants for finite-dimensional couples
The k-Separator Problem
No full textInternational audienceGiven a vertex-weighted undirected graph G = (V, E,w) and a positive integer k, we consider the k-separator problem: it consists in finding a minimum-weight subset of vertices whose removal leads to a graph where the size of each connected component is less than or equal to k. We show that this problem can be solved in polynomial time for some graph classes: for cycles and trees by a dynamic programming approach and by using a peculiar graph transformation coupled with recent results from the literature for mK2-free, (G1,G2, G3, P6)-free, interval-filament, asteroidal triple-free, weakly chordal, interval and circular-arc graphs. Approximation algorithms are also presented
Characterisation of a horizontal axis wind turbine’s tip and root vortices
Get PDFThe vortical near wake of a model horizontal
axis wind turbine has been investigated experimentally in a
water channel. The objective of this work is to study vortex
interaction and stability of the helical vortex filaments
within a horizontal axis wind turbine wake. The experimental model is a geometrically scaled version of the
Tjæreborg wind turbine, which existed in western Denmark
in the late 1980s. Here, the turbine was tested in both the
upwind and downwind configurations. Qualitative flow
visualisations using hydrogen bubble, particle streakline
and planar laser-induced fluorescence techniques were
combined with quantitative data measurements taken using
planar particle image velocimetry. Vortices were identified
using velocity gradient tensor invariants. Parameters that
describe the helical vortex wake, such as the helicoidal
pitch, and vortex circulation, were determined for three tip
speed ratios. Particular attention is given here to the root
vortex, which has been investigated minimally to date.
Signatures of the coherent tip vortices are seen throughout
the measurement domain; however, the signature of the
root vortex is only evident much closer to the rotor plane,
irrespective of the turbine configuration. It is postulated
that the root vortex diffuses rapidly due to the effects of the
turbine support geometries
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