bluuebunny/crossref_metadata_2025 huggingface dataset:
Les représentations de la créativité en arts appliqués d’élèves de lycée professionnel
Authors: Roy Emeline
Published: September 2023

Selon le dernier rapport de l’OCDE, la créativité est l’une des compétences du 21ᵉ siècle. En France, au lycée professionnel, elle est spécifiquement travaillée dans la discipline arts appliqués et cultures artistiques. Cette capacité à avoir une idée ou à réaliser une production innovante et adaptée au contexte est marquée par des changements identitaires à l’adolescence. Cette étude s'attache à répondre à la problématique suivante : Comment les élèves de lycée professionnel perçoivent-ils la créativité et comment cette perception évolue-t-elle au cours de leur formation ? Deux hypothèses sont avancées, la première suggère que les élèves préparant un diplôme dans le secteur industriel développent une vision pragmatique de la créativité comparée à celle des élèves du secteur tertiaire ; la seconde postule une évolution progressive de la représentation de la créativité au cours de leur formation. Cette étude approfondit la compréhension de ces représentations en interrogeant des élèves de diverses filières à travers une méthodologie mixte, combinant enquêtes quantitatives (N=596) et entretiens directifs (N=40). Les résultats font état d’une évocation forte entre l’enseignement d’arts appliqués et la créativité. La représentation de la créativité s’affinerait durant la scolarité, passant d’une activité manuelle et personnelle conduisant à une réalisation originale à un processus de création d’artéfact basé sur l’imagination.
A novel nonsense mutation in BBS4 gene identified in a Chinese family with Bardet-Biedl syndrome
Authors: Li Qian , Zhang Yongpeng , Jia Liyun , Peng Xiaoyan
Published: September 2023

Background

Bardet-Biedl syndrome (BBS) is a genetically heterogeneous disease, and information about BBS in Chinese populations is very limited. The purpose of the present study was to determine the genetic cause of BBS in a Chinese Han family.

Methods

Clinical data were recorded for the 4-year-old female proband and the available family members. The proband was screened for mutation by Sanger sequencing for a total of 142 exons of the 12 BBS-causing genes (BBS1-BBS12). The variants detected in the proband were further confirmed in the other family members.

Results

We identified a novel homozygous nonsense mutation (c.70A>T, p.K24X) in theBBS4gene exon 2 in the proband. Such mutant allele was predicted to cause a premature truncation in the N-terminal of the BBS4 protein, and probably induced the nonsense-mediated decay ofBBS4messenger RNAs. The proband's parents and brother were heterozygous for the nonsense mutant allele. It was absent in 50 Chinese control subjects. An additional rare heterozygous missense single nucleotide polymorphism (SNP) named rs200718870 inBBS10gene was also detected in the proband, her father and her brother. Some manifestations of the proband including atypical retinitis pigmentosa, choroidal sclerosis, high myopia, and early onset of obesity might be associated with this mutation inBBS4gene. The proband's father also reported surgical removal of an extra finger during childhood.

Conclusions

The present study described a novel nonsense mutation inBBS4gene in a Chinese family. This homozygous mutation was predicted to completely abolish the synthesis of the BBS4 protein. We also detected a rare heterozygous missense SNP inBBS10gene in the family, but did not find sufficient evidence to support the triallelic inheritance.
Left atrial appendage morphology in patients with atrial fibrillation in China: implications for stroke risk assessment from a single center study
Authors: Kong Bin , Liu Yu , Hu He , Wang Lei , Fan Yang , Mei Yang , Liu Wanli , Liao Jiafen , Liu Dan , Xing Dong , Huang He
Published: September 2023

Background

The left atrial appendage (LAA) is thought to be the main source of thrombi in patients with atrial fibrillation (AF). The purpose of this study was to describe the LAA orifice diameter, LAA length, and morphologic type of the LAA in Chinese patients with AF as well as to evaluate whether these LAA parameters are associated with a history of stroke in patients with AF from a single center in China.

Methods

The study population consisted of 219 consecutive patients with drug-refractory, symptomatic paroxysmal, or persistent AF scheduled to undergo radiofrequency catheter ablation in our single center. All patients underwent extensive clinical assessment and multidetector computed tomography to fully explore the anatomy of the LAA.

Results

Of the 219 patients who underwent catheter ablation procedures, chicken wing LAA morphology was found in 114 patients (52.2%), windsock in 52 (23.9%), cauliflower in 29 (13.0%), and cactus in 24 (10.9%). Compared with the windsock LAA morphology, cactus had a larger left atrial diameter ((42.40±3.68) and (37.91±4.32) mm, P=0.005) and LAA orifice diameter ((27.38±3.70) and (24.14±3.58) mm, P=0.048). The LAA length was significantly larger in the chicken wing morphology than in the windsock ((37.50±6.74) and (31.33±3.92) mm, P=0.015) and cauliflower morphologies ((37.50±6.74) and (31.33±3.92) mm, P=0.015). According to their medical records, 26 patients (11.9%) had suffered a prior stroke. Compared with patients who had no history of stroke, the prior-stroke patients were older (62.04±8.07 and 58.24±9.24, P=0.047) and there were fewer patients with chicken wing (23.1% and 59.1%, P=0.001) and more patients with cauliflower (26.9% and 9.8%, P=0.046). Multivariate Logistic regression analysis demonstrated that age (odds ratio (OR) 1.26; 95% confidence interval (CI) 1.08–1.47; P=0.003), non-chicken wing morphology (OR 5.82; 95% CI 1.61–21.03; P=0.007), and LAA orifice diameter (OR 1.25; 95% CI 1.05–1.49; P=0.014) were independent predictors of stroke after adjusting for all parameters that emerged as potential confounders with univariate analysis.

Conclusion

LAA analysis can potentially be used to inform guidance on the implication for stroke risk assessment.
Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid
Authors: Sokolov Vladislav A , Golushko Andrei A , Boyarskaya Irina A , Vasilyev Aleksander V
Published: September 2023

Trichloromethyl-substituted enones (1-aryl-4,4,4-trichlorobut-2-en-1-ones, ArCOCH=CHCCl3, CCl3-enones) undergo intramolecular transformation into 3-trichloromethylindan-1-ones (CCl3-indanones) in Brønsted superacid CF3SO3H (triflic acid, TfOH) at 80 °C within 2–10 h in yields up to 92%. Protonation of the carbonyl oxygen of the starting CCl3-enones by TfOH affords the key reactive intermediates, the O-protonated forms ArC(=OH+)CH=CHCCl3, which are then cyclized into the target CCl3-indanones. These cations have been studied experimentally by means of NMR spectroscopy in TfOH and theoretically by DFT calculations. Under the same superacidic conditions in TfOH, CCl3-hydroxy ketones (1-aryl-4,4,4-trichloro-3-hydroxybutan-1-ones; ArCOCH2CH(OH)CCl3) undergo dehydration to the corresponding CCl3-enones, which are further cyclized into CCl3-indanones. The yields of CCl3-indanones starting from CCl3-hydroxy ketones are up to 86% in TfOH at 80 °C within 3–18 h.
Fast Globally Optimal Catalog Matching using MIQCP
Authors: Feitelberg Jacob , Basu Amitabh , Budavári Tamás
Published: September 2023

We propose a novel exact method to solve the probabilistic catalog matching problem faster than previously possible. Our new approach uses mixed integer programming and introduces quadratic constraints to shrink the problem by multiple orders of magnitude. We also provide a method to use a feasible solution to dramatically speed up our algorithm. This gain in performance is dependent on how close to optimal the feasible solution is. Also, we are able to provide good solutions by stopping our mixed integer programming solver early. Using simulated catalogs, we empirically show that our new mixed integer program with quadratic constraints is able to be set up and solved much faster than previous large linear formulations. We also demonstrate our new approach on real-world data from the Hubble Source Catalog. This paper is accompanied by publicly available software to demonstrate the proposed method.
Rapidly Evolving Transients in Archival ZTF Public Alerts
Authors: Li 李 Wenxiong 文雄 , Arcavi Iair , Nakar Ehud , Filippenko Alexei V. , Brink Thomas G. , Zheng WeiKang , Yang 杨 Yi 轶 , Lam Marco C. , Keinan Ido , Brennan Seán J. , Shitrit Noi
Published: September 2023

We search the archival Zwicky Transient Facility public survey for rapidly evolving transient (RET) candidates based on well-defined criteria between 2018 May and 2021 December. The search yielded 19 bona fide RET candidates, corresponding to a discovery rate of ∼5.2 events per year. Even with a Galactic latitude cut of 20°, eight of the 19 events (∼42%) are Galactic, including one with a light-curve shape closely resembling that of the GW170817 kilonova (KN). An additional event is a nova in M31. Four out of the 19 events (∼21%) are confirmed extragalactic RETs (one confirmed here for the first time) and the origin of six additional events cannot be determined. We did not find any extragalactic events resembling the GW170817 KN, from which we obtain an upper limit on the volumetric rate of GW170817-like KNe of R ≤ 2400 Gpc−3 yr−1 (95% confidence). These results can be used for quantifying contaminants to RET searches in transient alert streams, specifically when searching for KNe independently of gravitational-wave and gamma-ray-burst triggers.
Metal Abundances of Intermediate-redshift Active Galactic Nuclei: Evidence for a Population of Lower-metallicity Seyfert 2 Galaxies at z = 0.3–0.4
Authors: Carr David J. , Salzer John J. , Gronwall Caryl , Williams Anna L.
Published: September 2023

We derive oxygen abundances for two samples of Seyfert 2 (Sy2) active galactic nuclei (AGNs) selected from the KPNO International Spectroscopic Survey (KISS). The two samples from KISS include 17 intermediate-redshift (0.29 ≤ z ≤ 0.42) Sy2s detected via their [O iii] lines, and 35 low-redshift (z ≤ 0.1), Hα-detected Sy2s. The primary goal of this work is to explore whether the metallicity distribution of these two samples changes with redshift. To determine the oxygen abundances of the KISS galaxies, we use Cloudy to create a large number of photoionization model grids by varying the temperature of the accretion disk, the ratio of X-ray to UV continuum light, the ionization parameter, the hydrogen density, and the metallicity of the narrow-line region clouds. We link the results of these models to the observed [O iii]/Hβ and [N ii]/Hα emission-line ratios of the KISS sample on a Baldwin–Philips–Terlevich diagram, interpolating across the model grids to derive metallicity. The two redshift samples overlap substantially in terms of derived metal abundances, but we find that some of the intermediate-redshift Sy2s possess lower abundances than their local universe counterparts. Our analysis provides evidence for modest levels of chemical evolution (0.18 ± 0.06 dex) over 3–4 Gyr of look-back time. We compare our results to other AGN abundance derivation methods from the literature.
Observations of Magnetospheric Solar Wind Charge Exchange
Authors: Ringuette R. , Kuntz K. D. , Koutroumpa D. , Kaaret P. , LaRocca D. , Richardson J.
Published: September 2023

The study of solar wind charge exchange (SWCX) emission is vital to both the X-ray astrophysics and heliophysics communities. SWCX emission contaminates all astrophysical observations in X-rays regardless of the direction. Ignoring this contribution to X-ray spectra can lead to erroneous conclusions regarding the astrophysical plasmas along the line of sight owing to the similar spectral distributions of SWCX and several common types of more distant astrophysical plasmas. Since its discovery, the literature has distinguished between diffuse SWCX emission resulting from solar wind–neutral interactions within Earth’s magnetosphere, called magnetospheric SWCX, and similar interactions occurring more generally throughout the heliosphere, called heliospheric SWCX. Here we build on previous work validating a modeling method for the heliospheric SWCX contribution in X-ray spectra obtained with a medium-resolution CubeSat instrument named HaloSat at low ecliptic latitudes. We now apply this model to a specially designed set of extended observations with the same instrument and successfully separate the spectral contributions of the astrophysical background and the heliospheric SWCX from the remaining contributions. Specifically, we find significant excess emission for four observations in the O vii emission line not explained by other sources, possibly indicative of magnetospheric SWCX. We discuss these results in comparison with simulation results publicly available through the Community Coordinated Modeling Center. We also report an absorbed high-temperature component in 2 of the 12 fields of view analyzed.
Grids of Wolf–Rayet Stars Using MESA with the k − ω Model: From 25 to 120 M
⊙ at Z = 0.02
Authors: Li 李 Zhi 志 , Li 李 Yan 焱
Published: September 2023

To explore overshoot mixing and rotational mixing beyond the convective core during the core He-burning phase in massive stars, we computed a grid of stellar models, both rotating and nonrotating, with the k − ω model at Z = 0.02, covering a mass range of 25–120 M
⊙. The rotating models start with a rotation rate of v
ini/v
crit = 0.4 at the zero-age main sequence, and the evolution is computed until the end of the central carbon-burning phase. Models with the k − ω model provide larger convective cores and a broadening of the main-sequence width. The diffusive-overshoot models with f
ov = 0.027 are, on average, closer to the k − ω models for massive stars at Z = 0.02, particularly for the stars with masses greater than 40 M
⊙. The final masses of the Wolf–Rayet (WR) stars range from 9.5–17.5 M
⊙ and 10–23 M
⊙ for the rotating and nonrotating models, respectively. In the rotating models, the C/N ratio decreases slowly below 0.1 outside the convective core, resulting in a flatter element transition region. In addition, the lifetimes of the WNC phase are 1–4 × 104 yr, which is about 1 order of magnitude longer than that in the nonrotating models. The masses of the WNC stars are dominated by internal mixing processes and the maximum masses of the He-burning convective cores during the core He-burning phase are in the range of 15–35 M
⊙. The expected WNC/WR ratios are 0.059 and 0.004 for the rotating and nonrotating models, respectively.
Influence of Heliobond on Microtensile Bond Strength of a New BIS-GMA Free Versus BIS-GMA Containing Composite Resin Restoration
Authors: Elsebaey Labib , Dowidar Weam , Alahmed Bader , Elmarakby Ahmed Mohamed
Published: September 2023

AIM: The main objective of this study was to assess the micro-tensile bond strength (µTBS) of a free bisphenol-a-diglycidyl-ether-dimethacrylate (Bis-GMA) resin composite restorative material compared to a Bis-GMA-containing resin composite following the application of a hydrophobic coating (heliobond).
MATERIALS AND METHODS: A flat occlusal dentin surface was exposed in a total of eighty extracted teeth that were removed for periodontal reasons. Teeth were divided into two main equal groups according to the type of applied filling materials: BIS-GMA-free versus BIS-GMA-containing resin composite (n = 40). Each main group was subdivided into two equal subgroups (n = 20) according to the application of Heliobond (hydrophobic resin coating). Heliobond has been applied after adhesive application and before resin composite application. The first group was restored by a Free Bis-GMA Resin Composite (Admira, Voco, Germany); the second group was restored by a Bis- GMA-containing resin composite (Grandio, Voco, Germany). Each tested restorative material was applied and cured according to the manufacturer’s instructions.
RESULTS: Regardless of different composite and adhesive types, there was a statistically significant difference (p < 0.05) among all subgroups.  Specimens with Heliobond recorded a higher µTBS mean value (30.46 ± 6.7 megapaskal [MPa]) than groups without Heliobond, which recorded µTBS mean value (23.95 ± 9.02 MPa).
CONCLUSION: Application of an extra hydrophobic layer coating (Heliobond) has improved the performance of the µTBS of the adhesive systems utilized with the new BIS-GMA-free versus BIS-GMA-containing composite resin
An illustrated atlas of the vertebral morphology of extant non-caenophidian snakes, with special emphasis on the cloacal and caudal portions of the column
Authors: Szyndlar Zbigniew , Georgalis Georgios L.
Published: September 2023

Abstract

We here present a thorough documentation of the vertebral morphology and intracolumnar variation across non-caenophidian snakes. Our studied sample of multiple individuals covers a large number of genera (67) and species (120), pertaining to almost all extant non-caenophidian families. Detailed figuring of multiple vertebrae across the trunk, cloacal, and caudal series for many different individuals / taxa documents the intracolumnar, intraspecific, and interspecific variation. An emphasis is given in the trunk-to-caudal transition and the pattern of the subcentral structures in that region of the column. Extant non-caenophidian snakes show an astonishing diversity of vertebral morphologies. Diagnostic vertebral features for extant families and many genera are given, though admittedly vertebral distinction among genera in certain groups remains a difficult task. A massive compilation of vertebral counts for 270 species, pertaining to 78 different genera (i.e., almost all known valid genera) and encompassing all extant non-caenophidian families, is provided based on our observations as well as an extensive literature overview. More particularly, for many taxa, detailed vertebral counts are explicitly given for the trunk, cloacal, and caudal portions of the column. Extant non-caenophidian snakes witness an extremely wide range of counts of vertebrae, ranging from 115 up to 546. A discussion on the diagnostic taxonomic utility and potential phylogenetic value of certain vertebral structures is provided. Comparisons of the subcentral structures of the cloacal and caudal vertebral series are also made with caenophidian lineages. We anticipate that this illustrative guide will set the stage for more vertebral descriptions in herpetological works but will also be of significant aid for taxonomic identifications in ophidian palaeontology and archaeozoology.
La puissance des céréales
Authors: Stanziani Alessandro
Published: September 2023

Tous les empires dans l’histoire ont pu faire ce constat : la puissance n’est pas seulement une question d’armement, mais aussi de contrôle des céréales. Elles ont constitué, jusqu’à l’essor de la consommation de viande, le carburant du travail humain. Cet article permet une charnière bienvenue entre histoire et actualité (« pénurie » et déstabilisation des marchés mondiaux des céréales avec la guerre d’Ukraine). Il retrace l’histoire longue des marchés des céréales dans le monde, les successions des politiques visant leur contrôle (stockage, contrôle des prix, blocage des approvisionnements) ou donnant libre cours à la spéculation, les effets de ces cycles sur les famines et les guerres. Ce qui spécifie le « nouveau capitalisme agraire » contemporain depuis les années 1980, c’est la spéculation totalement dérégulée sur les céréales : marchés virtuels, futures , accaparement des terres, contrôle du vivant et monopoles des semences, entrée de nouveaux acteurs comme banques, fonds de pension, hedge funds . L’auteur propose en conclusion quelques options politiques pour lutter contre cette hégémonie.
Trois interrogations sur les activités d’élevage
Authors: Larrère Raphaël
Published: September 2023

Les activités d’élevage sont depuis des décennies fortement remises en cause pour leurs effets sur l’environnement et la concurrence qu’elles exercent sur l’accès à la terre, de grandes surfaces étant dans le monde dédiées à l’alimentation animale (maïs, soja). L’auteur montre les ambivalences des problématiques d’élevage en discutant trois questions. L’élevage représente-t-il un handicap pour nourrir le monde ? L’élevage contribue-t-il à l’érosion de la biodiversité ? L’élevage nuit-il à la santé ? En relativisant et contextualisant ces trois assertions, l’auteur désigne les méfaits de l’élevage industriel et plaide pour une démarche d’agro-écologie associant élevage et cultures. Mais il exprime ses craintes quant à la poursuite de la tendance actuelle.
L’agriculture rêve-t-elle de moutons électriques ?
Authors: Oui Jeanne
Published: September 2023

Face aux pollutions environnementales causées par les pratiques productivistes, le modèle de l’« agriculture de précision » s’est développé depuis les années 1990 : des capteurs, des satellites, des GPS et des algorithmes permettraient de diminuer les dégâts écologiques causés par les activités de production. Au-delà des pratiques sur les exploitations, « agriculture digitale », «  smartfarming  » et autres « AgTech » sont devenus des termes quotidiens pour les organismes et les politiques agricoles. L’article propose de s’interroger sur l’argumentaire environnemental entourant ces outils numériques et leur développement, en mettant en avant les enjeux politiques, techniques et commerciaux inhérents à ce déploiement.
La lutte pour l’usage des terres à Notre-Dame-des-Landes
Authors: De Roo Priscilla
Published: September 2023

Au-delà d’une bataille écologique tenace pour l’abandon du projet d’aéroport, le bocage de Notre-Dame des Landes a constitué un terrain d’expérimentation pour transformer l’occupation militante en droit pérenne d’usage des terres. Les « zadistes » se sont battus pour devenir agriculteurs et exploiter collectivement la terre au service d’une agriculture « écolo et non Monsanto ». Ils ont parié sur le fait de mener une bataille sur le droit face à l’administration et, en échange de fiches de projets, ont obtenu des baux ruraux individuels de neuf ans, comme les paysans résistants et les paysans cumulards, qui exploitaient les terres avant la préemption. Le rêve éveillé est devenu réalité, même si l’un des principes de base initiaux, « la terre en commun », a subi des altérations.
Subsistance
Authors: Pruvost Geneviève
Published: September 2023

Le « féminisme de la subsistance », à l’intersection du féminisme, de l’écologie et de l’anticapitalisme, a été remis en lumière par des théoricien·nes et activistes du Nord et du Sud dans les années 2010. L’étude des sociétés paysannes montre que l’accomplissement par les femmes des tâches vitales pour le groupe a été sous-estimé et leur confère puissance, sacralité et autonomie, en particulier pour assurer l’égale répartition des biens de subsistance. Face aux critiques dénonçant cet essentialisme, l’auteure propose un « écoféminisme vernaculaire » qui s’appuie sur les pratiques concrètes des femmes intégrant agriculture, artisanat, travaux de mécanique et de maçonnerie, agirs familiaux. Car, sous sa forme moderne, le travail domestique est doublement aliéné : non seulement, il n’est pas rémunéré, mais il est coupé de ses potentialités productives de subsistance pour se cantonner à la consommation et au care . Les écoféministes de la subsistance veulent s’opposer aux vocations « naturelles » des femmes et imaginer des perspectives : se réapproprier et partager collectivement des fonctions nourricières de base dans un monde où s’impose de façon accélérée l’aménagement agro-industriel de la planète.
Le mouvement des académies solidaires en Turquie
Authors: Bakırezer Güven
Published: September 2023

Cet article est un récit analytique basé sur des témoignages primaires concernant le Mouvement des Académies Solidaires qui a émergé à la suite des purges des Académiciens de la Paix en Turquie. Il examine le Mouvement sous l’angle de la signification et de la possibilité d’une subjectivité académique révolutionnaire, montre son originalité académique et organisationnelle, et analyse son déclin face aux problèmes auxquels il est confronté. Les Académies Solidaires, en tant qu’initiatives radicales qui transcendent la légalité existante, ont créé des environnements de connaissance et d’apprentissage en commun, mais elles ont régressé parce qu’elles n’ont pas pu transformer cette expérience en un projet capable de résoudre les problèmes d’organisation interne et de relation avec l’environnement social.
La montagne, le tournesol et le potager
Authors: Hervé Louise , Maillet Clovis
Published: September 2023

Gleïzès, philosophe proche des Méditateurs et des dormeuses, avait écrit une épopée pionnière du mouvement végétarien se déroulant sur la Montagne noire dans le Sud-Ouest de la France. Ce livre en main, Louise Hervé et Clovis Maillet ont été à la rencontre des maraîchers et des végétarien·nes de la région en 2023, au lendemain d’une grande manifestation contre la construction de l’autoroute Toulouse-Castres. Leur cri de ralliement était : « Moins de bitume, plus de légumes ».
Formes de coordination professionnelle et coopération interpersonnelle en maison d’assistantes maternelles
Authors: Garnier Pascale , Bouve Catherine , Janner-Raimondi Martine
Published: September 2023

Instituées en 2010, les maisons d’assistantes maternelles (Mam) permettent à des professionnelles de se regrouper pour accueillir des jeunes enfants (0-3 ans) dans un local distinct de leur domicile. Ces lieux représentent des formes d’hybridation entre des accueils individuels et collectifs. Cet article vise à les analyser en lien avec les modalités d’organisation du travail en Mam, en distinguant la coordination entre assistantes maternelles, fondée sur une division fonctionnelle du travail, de leur collaboration, s’appuyant sur leurs relations interpersonnelles. L’enquête empirique, réalisée en 2020-2021 dans six Mam aux caractéristiques très contrastées, comprend notamment un travail d’observation in situ , des entretiens individuels avec toutes les professionnelles des Mam et avec des acteurs de leur environnement local. L’analyse des différentes tâches des assistantes maternelles rend compte de la singularité de chaque Mam, parce qu’elle révèle la manière dont ces deux logiques de coordination et de collaboration se confortent ou s’opposent, modelées par les trajectoires des assistantes maternelles et leurs modalités d’accompagnement local.
Fourth power mean values of one kind special Kloosterman's sum
Authors: Rui Li , Bag Nilanjan
Published: September 2023

The main purpose of this article is using the analytic methods and properties of classical Gauss sums to study the calculating problem of fourth power mean values of one kind special Kloosterman's sum, and give a sharp asymptotic formula for it. At the same time, the paper also provides a new and effective method for the study of related power mean value problems.
On a class of weakly Landsberg metrics composed by a Riemannian metric and a conformal 1-form
Authors: Dong Fangmin , Li Benling
Published: September 2023

Without the quadratic restriction, there are many non-Riemannian geometric quantities in Finsler geometry. Among these geometric quantities, Berwald curvature, Landsberg curvature and mean Landsberg curvature are related directly to the famous "unicorn problem" in Finsler geometry. In this paper, Finsler metrics with vanishing weakly Landsberg curvature (i.e., weakly Landsberg metrics) are studied. For the general $ (\alpha, \beta) $-metrics, which are composed by a Riemannian metric $ \alpha $ and a 1-form $ \beta $, we found that if the expression of the metric function doesn't depend on the dimension $ n $, then any weakly Landsberg $ (\alpha, \beta) $-metric with a conformal 1-form must be a Landsberg metric. In the two-dimensional case, the weakly Landsberg case is equivalent to the Landsberg case. Further, we classified two-dimensional Berwald general $ (\alpha, \beta) $-metrics with a conformal 1-form.
New algorithms for solving nonlinear mixed integral equations
Authors: Matoog R. T. , Abdou M. A. , Abdel-Aty M. A.
Published: September 2023

In this article, the existence and unique solution of the nonlinear Volterra-Fredholm integral equation (NVFIE) of the second kind is discussed. We also prove the solvability of the second kind of the NVFIE using the Banach fixed point theorem. Using quadrature method, the NVFIE leads to a system of nonlinear Fredholm integral equations (NFIEs). The existence and unique numerical solution of this system is discussed. Then, the modified Taylor's method was applied to transform the system of NFIEs into nonlinear algebraic systems (NAS). The existence and uniqueness of the nonlinear algebraic system's solution are discussed using Banach's fixed point theorem. Also, the stability of the modified error is presented. Some numerical examples are performed to show the efficiency and simplicity of the presented method, and all results are obtained using Wolfram Mathematica 11.
Gold and the global financial cycle
Authors: Salisu Afees A. , Gupta Rangan , Ntyikwe Siphesihle , Demirer Riza
Published: September 2023

We examine the potential of gold and other precious metals as safe havens during negative market shocks caused by the Global Financial Cycle (GFCy). We analyze a vast global vector autoregressive (GVAR) model that includes developing and emerging market countries for a total of 33 countries, from 1979:Q2 to 2019:Q4. This approach allows us to account for individual country peculiarities while also considering the transmission of global shocks. We found that during financial market distress caused by a negative GFCy shock, gold, silver and platinum all serve as hedges. Interestingly, our results suggest that silver and platinum are better hedges than gold, offering greater positive returns in response to negative GFCy shocks, especially in recent years. Overall, our findings support the benefits of investing in precious metals, as they can help investors mitigate losses resulting from global financial shocks. While the metals vary in their hedging ability, platinum and silver offer even greater protection than gold.
Multiple class shares and double voting rights: Literature review and research prospects
Authors: Bruslerie Hubert de La
Published: September 2023

Dual class shares and multiple voting rights have increasingly developed despite formal reference to the “one share–one vote” principle. This contradictory situation is analyzed within a survey of the academic literature to understand the reasons why shareholding structures with equal rights and unequal rights between shareholders may coexist in firm ownership. The financial literature is screened through the key concept of dual class shares. This concept has both theoretical and empirical consequences and needs to be analyzed in a dynamic framework referring to the firm economic life cycle. The steps of firm development sometimes need a concentration of economic power and control by some shareholders, particularly after an initial public offering, and sometimes should be based on equal treatment between shareholders. We conclude in favor of an evolutionary approach toward legal contractual rules. We identify seven avenues for future research.
Offre de services et niveau d’activité des plateformes d’equity crowdfunding
Authors: BOUAISS Karima , GIRARD-GUERRAUD Carine , ZOUKOUA Éric-Alain
Published: September 2023

Cet article propose une étude de l’offre de services sur le niveau d’activité des 57 plateformes, qui constituent l’ensemble du marché français actuel de l’equity crowdfunding. Tous les services offerts par ces plateformes sont pertinents car ils contribuent à renforcer le niveau d’activité aussi bien en nombre de campagnes qu’en montants levés. Ces services permettent d’émettre un signal vers la communauté de la plateforme et aident à réduire les asymétries d’information, aussi bien en termes de sélection adverse des entrepreneurs (due diligence et e-vote) et des investisseurs potentiels (co-investissement avec des BAs et VCs, ticket d’entrée), que d’aléa moral au travers de mécanismes de gouvernance permettant d’administrer les participations des actionnaires (holding et pacte d’actionnaires).
Service offering and level of activity of equity crowdfunding platforms
Authors: BOUAISS Karima , GIRARD-GUERRAUD Carine , ZOUKOUA Éric-Alain
Published: September 2023

This article sets out to study the link between the services offered and the level of activity of the 57 platforms, which currently constitute the entire French equity crowdfunding market. All the services offered by these platforms are considered relevant since they contribute to increasing the level of activity in terms of both the number of campaigns and the amounts raised. These services send a signal to the platform’s community and help reduce not only information asymmetries in terms of the adverse selection of entrepreneurs (due diligence and e-voting) and potential investors (co-investment with BAs and VCs, entry ticket), but also moral hazard through governance mechanisms to manage shareholders (holding company and shareholders’ agreement).
Le tourisme réflexif en montagne à l’heure de l’Anthropocène : discussion autour du projet de réhabilitation du Montenvers, Chamonix
Authors: Salim Emmanuel , Girault Camille , Nesur Kalpana
Published: September 2023

L’entrée dans l’Anthropocène, défini comme l’ère dans laquelle les activités humaines deviennent des forces à même d’influencer le climat et l’environnement à l’échelle planétaire, induit de nombreuses questions pour le tourisme. S’ils ne sont pas les seuls, les sites touristiques glaciaires, et les pratiques afférentes, se transforment avec leur environnement. Ces transformations posent la question de l’influence du changement climatique sur les motivations des acteurs touristiques et permettent d’envisager plus spécifiquement l’avènement d’un tourisme réflexif. Entendu comme une prise de conscience par les touristes eux-mêmes des enjeux – ici, environnementaux – soulevés par les modes de vie actuels, le tourisme réflexif permet plus largement d’aborder les contradictions auxquelles sont confrontées les sociétés dans le cadre des défis de la transition écologique. À travers l’analyse de la mise en œuvre du projet de réhabilitation de l’un des sites glaciaires les plus connus de France, le Montenvers et sa Mer de Glace, cet article entend interroger les logiques du développement touristique d’un tel site tout en soulignant ses contradictions. Les entretiens menés avec les parties prenantes du site et du projet montrent une tension claire entre une logique de durabilité menant au tourisme réflexif et une logique économique d’investissement et de quête de rentabilité. Au-delà de ce cas d’étude, ce travail questionne plus généralement la figure du tourisme comme symbole des contradictions sociétales entre discours et pratiques à l’heure de l’Anthropocène.
Understanding the Developments in the Business Perspective of Cloud Computing
Authors: Parekh Harsh , Cheng Huai-Tzu , Schwarz Andrew
Published: September 2023

Research on cloud computing (CC) has gained a lot of momentum owing to its massive adoption. It has moved beyond the exploration of inherent capabilities to understand its disruptiveness and transformative value. In this vein, the authors conducted a comparative literature review of 101 articles to better understand the developments from previous reviews. This article serves as a replication study to evaluate the growth of the business perspective of CC. The authors identify 126 factors guiding the characteristics, adoption, governance, and business impact of the cloud. Further, they employ a rigorous analysis that situates our review at the intersection of these factors and applies a multidimensional scaling technique. The developed matrix (a) helps to clarify the current state of research, (b) identifies research gaps, and (c) identifies potential further research avenues. Unlike previous reviews, this developed multidimensional view of each article uncovers numerous perspectives that can guide future research.
Pesquisas com os cotidianos
Authors: Toja Noale , Machado Marcelo , Alves Nilda
Published: September 2023

A corrente de pesquisa que foi nomeada como ‘pesquisas nos/dos/com os cotidianos’ começou a ser articulada, no Brasil, há trinta anos. O artigo comenta o que foi este começo e a preocupação com a organização metodológica que se teve já que estava sendo criado algo novo no país. Conta-se aqui, uma história possível desse início. Indica as bases teóricas iniciais que foram trazidas de Certeau e Deleuze, embora, em seguida, múltiplos grupos foram se organizando, em diversas universidades brasileiras, em torno de temáticas diversas e contando com a inclusão de outros autores europeus e latino-americanos, tais como: Maturana, Lefebvre, Mafesoli, Boaventura de Sousa Santos entre muitos. Indica-se, por fim, as questões epistemológico-teórico-metodológicas mais recentes dos grupos. Lembramos, então: os movimentos necessários às pesquisas com os cotidianos; as inúmeras redes educativas que formamos e nas quais nos formamos; a importância dos intercessores para a formação do pensamento; a virtualidade na formação dos possíveis acontecimentos curriculares; uma compreensão diversa para a ideia de repetição, como ‘espaçotempo’ de mudanças; as conversas como lócus central dos processos de pesquisa; a necessidade das relações com as artes para as pesquisas dessa corrente o que nos leva à compreensão da presença de todos os sentidos em nossos cotidianos, ações e pensamentos; a compreensão de que os atos pedagógicos trazem sempre à cena dimensões éticas, estéticas, políticas e poéticas.
A pesquisa arquivística e o gesto problematizador em Foucault
Authors: Munhoz Angélica Vier , Ribeiro Inauã Weirich
Published: September 2023

Michel Foucault utilizou diversas ferramentas analíticas em suas pesquisas, mas um gesto investigativo esteve presente em todo o seu percurso arqueogenealógico: a problematização. Considerando esta noção, este texto tem como objetivo arquivar alguns gestos problematizadores de Michel Foucault na obra A hermenêutica do sujeito (2010a), a qual reúne suas aulas ministradas no Collège de France no período 1981-1982. O arquivamento deu-se pela leitura sistemática das aulas deste curso, a fim de identificar todos os problemas postos por Michel Foucault. Os problemas foram suspendidos como enunciados, como elementos do arquivo, sendo possível observar seu funcionamento ao longo das aulas. Cada problema foi localizado na obra a partir dos seguintes marcadores: página do livro, hora (1A ou 2A), data da aula (dia/mês/ano). Os problemas abordados por Foucault no decorrer do curso e rastreados no conjunto da obra foram arquivados em quatro categorias: a) problema disparador da investigação; b) problemas de ordem histórico-procedimental; c) problemas lançados ao presente; d) problemas lançados ao arquivo. O gesto investigativo-problematizador de Michel Foucault, atrelado à pesquisa arquivística, pode ser tomado como uma maneira de investigar em que a forma do problema se coloca em jogo ao longo de todo o processo de pensamento. A problematização foucaultiana não se dá apenas pelo problema disparador, que se modifica ao longo da investigação, mas também pela localização de problemas lançados ao próprio arquivo. Este texto pode funcionar como um arquivo das problematizações do curso A hermenêutica do sujeito, de Michel Foucault (2010a), um apoio de leitura para outras investigações.
Review on Friction Stir Welding of Dissimilar Metals
Authors: Thamizhmanii S. , Ravikumar E. , Senthilkumar J.S. , Karpagaraj A.
Published: September 2023

Friction stir welding (FSW) is a solid–state joining process that is increasingly being used in various industrial applications due to its numerous advantages over conventional welding techniques. FSW uses a non-consumable rotating tool to generate frictional heat and plasticize the material in the joint, resulting in a defect-free, high-quality bond between two pieces of metal without the need for any filler material or shielding gas. The process is particularly well-suited for welding lightweight and high-strength materials, such as aluminium, magnesium and titanium and is known for its ability to produce joints with superior mechanical properties, including high fatigue strength and improved corrosion resistance. This paper addresses the need for future development in Friction Stir Welding.
Machine Learning (ML) Based Prediction of Defects in Extrusion-Type Additively Manufactured Parts
Authors: Regalla Srinivasa Prakash , Kaushal Apoorva , Khetan Sarvesh
Published: September 2023

Additive manufacturing (AM) is gradually occupying a unique place as a viable industrial manufacturing technology for parts with complex geometry and difficult-to-machine materials. The capability of AM to apply to such parts in various sectors of industry, including automotive, aerospace, and medical devices, stems from the layer-by-layer building process and manufacturing directly from computer-aided design (CAD) models. All AM processes share a common set of steps and characteristics but are distinct in the type and form of raw material, energy source, and supply to the target location to build the layers. Based on these differences, the AM processes have been classified into different types: material extrusion-based processes, powder bed fusion (PBF) processes, direct energy deposition (DED) processes, and photo-polymerization processes. All the AM processes induce certain defects in the parts, making the final mechanical properties inferior. A capability to edict the mechanical properties of the parts by identifying defects in layers can help in designing parts and planning for AM to reduce those defects. The present work investigates the feasibility of applying a machine learning (ML) based technique to identify typical AM defects. The idea of transfer learning of a pre-trained network, namely, AlexNet, with a limited-size dataset of defect images generated from the layer images has been studied. A novel yet simple and effective experimental setup has been devised to capture high-resolution images of the layers of the part in a fused deposition modeling (FDM) machine. From these layer images, a total two hundred defect images have been captured and converted into an input image dataset for transfer learning. After suitable modification of the pre-trained network, the training and validation gave an accuracy of about 62%. Two different techniques of hyper-parameter tuning were then conducted, through which the accuracy of training improved to more than 95%. Based on the success achieved, further possible tracks of future research have been suggested.
Development Advances in Liquid Rocket Engines Turbopump: A Review
Authors: Singhal Rahul , Toppo Clevin , Roy Pratap , Biswakarma Rupak , Sahu Sristy , Kalita Ujjal
Published: September 2023

In the recent century, rocket engine development has witnessed a vast number of technological advances made in the field. Rocket engines have been very crucial technological equipment for the human race to space. With the change in technology and requirement, the turbopump system has been crucial for the development of the rocket engine. This article provides insight into a technological improvement over the last century and gives a brief note of some of the crucial engines in humankind's history. This research highlights the roadmap to understanding the different categories of turbopump systems within liquid propulsion rocket engines and lays out a comparative study of the different turbopump configurations. This article will help researchers in understanding and appraising the works with their existing results. Further, this article will help newcomers and different researchers in getting an overview of turbopump and the various existing works performed on it and related to this field over the years.
Numerical Investigation of Tool Stirring Speed in Friction Stir Processing of AA7075 Using Smoothed-Particle Hydrodynamics
Authors: Kathiravan Dinish Mutu , Marode Roshan Vijay , Pedapati Srinivasa Rao , Lemma Tamiru Alemu
Published: September 2023

Friction Stir Process (FSP) is considered one of the most convenient, effective, and environmental friendly manufacturing processes. In these processes, a tool involves a pin that blends the material around it and a shoulder that creates frictional heat. On the other hand, the pin mixes the soft material to refine the grain structure. This paper aims to investigate a thermal model using Altair to numerically simulate the temperature distribution profiles of 7075 Aluminum Alloy material using FSP. Using a novel technique called Smoothed-Particle Hydrodynamics (SPH), we extracted the temperature distribution in the Stir Zone (SZ) for 900 RPM, 1200 RPM, and 1500 RPM Tool Rotational Speed (TRS) with constant Tool Traverse Speed (TTS). The temperature results obtained are incremental with increasing TRS. As a result, the temperature achieved from 900 RPM to 1500 RPM has increased by 21.20%. In addition, the obtained temperature is almost 50% of the melting point. The material flow on both Advancing Side (AS) and Retreating Side (RS) shows the thorough material mixing. The SPH technique helps to investigate the proper material flow modeling by dividing the AS and RS nodes and it was observed that they have thoroughly been mixed near the FSP tool pin.
Formability Analysis of Stretch and Shrink Flanging by Single Point Incremental Forming Based on Stresses
Authors: Fernández José Andrés López , Borrego Puche Marcos , Centeno Báez Gabriel , Vallellano Carpoforo
Published: September 2023

Flanges are commonly used in aircrafts to provide stiffness and support for the assembly Incremental Sheet Forming (ISF) processes have been approached to produce both stretch and shrink flanges as a low-cost alternative in the fabrication of a small number of parts and prototypes. This work analyzes stretch and shrink flanges of AA2024-T3 sheet with different geometries manufactured by Single Point Incremental Forming (SPIF). The numerical simulation using Finite Elements of the flanges allows evaluating the stress in successful and failed flanges. On the one hand, the formability of stretch flanges is usually evaluated in terms of principal strains within the Forming Limit Diagram (FLD). However, this approach does not seem to capture all the physics to explain the enhancement in formability observed in SPIF over the conventional forming. A formability analysis is performed in the field of stress triaxiality versus equivalent plastic strain, discussing the differences between successful and fractured specimens. On the other hand, for shrink flanging, the appearance of wrinkles is analyzed in terms of the compressive stresses along the flange during the incremental forming. This allows to determine a critical limit stress of winkling to predict the failure in practice for a given geometry and forming condition.
Conceptual Study of Ornithopter for Better Future Performance and Application
Authors: Akash P. , Mansoori Mohammad Faizan , Mazumder Saikat , Bhardwaj Shubham , Biswas Tanmoy , Chavhan Harikrishna , Thakur Amit Kumar
Published: September 2023

An ornithopter is a power-driven aircraft that utilizes a flapping mechanism. This paper summarized the research and development carried on Unmanned Aerial Vehicle (UAV) till date and reclaims the efficiency on ornithopter namely the flapping frequency, Reynold number, kinematics, transmission system and flapping mechanisms. The present investigation explores the design of a biologically inspired flying Unmanned Aerial Vehicle. For its execution, varied of analyses of flight mechanics, stability, and the control of flapping motion. The theoretical techniques involved in the construction of an ornithopter have investigation for surveillance, military application, spy work, and rescue operations. Additionally, the material used for construction of ornithopter is also discussed. The benefits of the flapping mechanism for are not limited. This paper also reviews the research and development done on the previous UAVs and from small birds to large birds. In this paper the experimental analysis has been done on the ANSYS Fluent on a semi elliptical wing design with a wingspan of 0.25m which delivered the output of how the wind flow and pressure can affect the efficiency of a flapping wing according to the varying angle of attack. This concluded the selection of a material with low stiffness.