bluuebunny/crossref_metadata_2025 huggingface dataset:
El aprendizaje en familias agricultoras a través de la estrategia de la escuela de campo
Authors:   Comisión Nacional para el Desarrollo y Vida sin Drogas- DEVIDA, Mendoza Vela Ana Luisa
Published: February 2021

El presente estudio se realizó con el objetivo de analizar el problema del aprendizaje en adultos. Para ello se tomó la experiencia de un grupo de agricultores quienes experimentaron el ciclo de aprendizaje de Kolb bajo la dirección de un grupo de docentes, quienes a través de su labor buscaron generar una producción agrícola sostenible en la zona. Los sujetos participantes pertenecen a una zona rural del Alto Huallaga (Perú). Metodológicamente, se procedió al análisis sistemático de la propuesta del ciclo de aprendizaje y luego se complementó con la entrevista semiestructurada con el fin de profundizar en los hallazgos documentales. Los resultados muestran que el equipo de docentes está conformado por profesionales de las ciencias agrarias que no fueron preparados eficientemente para aplicar la Escuela de Campo como estrategia de enseñanza-aprendizaje para adultos. El Sistema Nacional de Evaluaci´on Acreditación y Certificación (Sineace) ha elaborado un programa de certificación para Facilitadores de Escuela de Campo, cuyo proceso debe ser difundido, debido que a partir de estos resultados se propone una obligada certificación por parte de los profesionales de las ciencias agrarias, dedicados a ser docentes de Escuelas de Campo, con el objetivo de asegurar una correcta aplicación del ciclo de aprendizaje y por ende una formación de calidad en cada uno de los agricultores y agricultoras a fin de redundar en el mejoramiento de la productividad de sus cultivos y crianzas.
Halaman Depan Chart Datum Vol 6 No 1 2020
Authors: Subandriyo Joko
Published: February 2021

Halaman Depan Chart Datum Vol 6 No 1 2020
Molotov Cocktails to Mass Marches: Strategic Nonviolence, Symbolic Violence, and the Mobilizing Effect of Riots
Authors: Case Benjamin
Published: February 2021

What effects do violent protests have on social movement mobilizations? In recent decades, the field of nonviolence studies has popularized a strategic nonviolence framework to understand activist tactics. This framework is problematic in two ways. First, dominant theories argue that violent protest actions demobilize nonviolent protest. However, there is less empirical support for this claim than often assumed. Current quantitative findings on the demobilizing effects of violent protest rely on a false dichotomy between violence and nonviolence that obscures the effects of low-level violent actions. Through statistical analysis of protest trends in the US over 72 years, I show that riots have an overall mobilizing impact on nonviolent protests. Second, the strategic nonviolence framing encourages an instrumental view of tactics that is prone to miss the symbolic and emotional aspects of different types of actions. Through qualitative interviews with participants in the black bloc tactic, I explore the experiential effects of the riot, and find that rioting can have deeply empowering emotional impacts on participants, with lasting effects that sustain activists’ political engagement. In combination, these results demonstrate that low-level violent actions interact with movements in more dynamic ways than dominant theories have understood. [Article copies available for a fee from The Transformative Studies Institute. E-mail address: journal@transformativestudies.org Website: http://www.transformativestudies.org ©2021 by The Transformative Studies Institute. All rights reserved.]
All Art is with the Crowd or the Police
Authors: Schultz Heath
Published: February 2021

Partisan in tone, “All art is with the crowd or the police” draws clear battle lines. This piece of experimental writing collages texts from anti-capitalist activists, corporate news, critical theorists, poets, and press releases to form a quasi-unified voice “from the crowd” that works toward a position against representation. This hybridized voice is juxtaposed with excerpts from a police manual on riot control. The crowd contradicts itself as it grapples with what is possible to produce in struggle; the authoritarian voice of the police outlines methods for containment. Meandering through various events—the blockade, the protest march, the occupation—the conflicted voice weaves together conversations about art, gentrification, violence, whiteness, representation, community, and capitalism. [Article copies available for a fee from The Transformative Studies Institute. E-mail address: journal@transformativestudies.org Website: http://www.transformativestudies.org ©2021 by The Transformative Studies Institute. All rights reserved.] KEYWORDS: Gentrification, Riot, Whiteness, Police, Anarchism.
Riotous Epistemology: Open Referentiality and Reconfigured Temporalities in AK Thompson’s Black Bloc, White Riot
Authors: Carley Robert
Published: February 2021

This paper suggests that AK Thompson’s text be viewed through the twin lenses of what I describe as “open referentiality” and “reconfigured temporalities” in order to broadly understand the pedagogical and epistemological contributions of his work. I argue that Thompson’s work, at the pedagogical level, provides several reference points through which readers are invited to consider how theories, concepts, and the traditions that they are embedded in can be reinterpreted in the context of contemporary forms of social struggle, protest, demonstrations, and direct action. I connect the pedagogical aspects of Thompson’s work to their epistemological underpinnings arguing that Thompson’s work produces a phenomenology of thought and action that, taken in consort with his pedagogical invitation to reconsider aspects of radical and critical traditions, provides a riot in the epistemological frameworks that settle or partition (radical and critical) traditions of thought. I explore this idea by discussing how Black Bloc White Riot provided a means for me to rethink the contributions of Antonio Gramsci to contemporary social movement studies. [Article copies available for a fee from The Transformative Studies Institute. E-mail address: journal@transformativestudies.org Website: http://www.transformativestudies.org ©2021 by The Transformative Studies Institute. All rights reserved.] KEYWORDS: AK Thompson, Black Bloc White Riot, Critical Theory, Radical Theory, Direct Action, Antonio Gramsci.
Identification of Methyl Isocyanate and Other Complex Organic Molecules in a Hot Molecular Core, G31.41+0.31
Authors: Gorai Prasanta , Das Ankan , Shimonishi Takashi , Sahu Dipen , Mondal Suman Kumar , Bhat Bratati , Chakrabarti Sandip K.
Published: February 2021

G31.41+0.31 is a well known chemically rich hot molecular core (HMC). Using Band 3 observations from the Atacama Large Millimeter Array (ALMA), we have analyzed the chemical and physical properties of the source. We have identified methyl isocyanate (CH3NCO), a precursor of prebiotic molecules, toward the source. In addition to this, we have reported the presence of complex organic molecules (COMs) like methanol (CH3OH), methanethiol (CH3SH), and methyl formate (CH3OCHO). Additionally, we have used transitions from molecules like HCN, H13CO+, and SiO to trace the presence of infall and outflow signatures around the star-forming region. For the COMs, we have estimated the column densities and kinetic temperatures, assuming molecular excitation under local thermodynamic equilibrium (LTE) conditions. From the estimated kinetic temperatures of certain COMs, we found that multiple temperature components may be present in the HMC environment. Comparing the obtained molecular column densities between the existing observational results around other HMCs, it seems that the COMs are favorably produced in the hot core environment (∼100 K or higher). Though the spectral emissions toward G31.41+0.31 are not fully resolved, we find that CH3NCO and other COMs are possibly formed on grain/ice phase and populate the gas environment similar to other hot cores like Sgr B2, Orion KL, and G10.47+0.03.
Reheating after an Inflationary Universe from a Perfect Fluid and Its Comparison with Observational Data
Authors: Mirtalebian F. S. , Nozari Kourosh , Azizi Tahereh
Published: February 2021

We present the reheating constraints on an inflationary universe induced by perfect fluid models. Starting with the descriptions for the observables of the scalar field inflationary models in the reconstructed methods, we outline the procedure of perfect fluid inflationary models through these methods to calculate the inflationary observables and reheating. We show that the reheating e-folds number N

re
and the reheating final temperature T

re
are bound depending on the finite range of reasonable values of

. By restricting the equation-of-state parameter in the reheating stage,

, more stringent constraints can be derived for the model’s parameter space of perfect fluid. These constraints correspond to viable values of the scalar spectral index n

s
and tensor-to-scalar ratio r, released by Planck2018 observational data.
Stellar Feedback on the Earliest Stage of Massive Star Formation
Authors: Nayak O. , Meixner M. , Okada Y. , Lee M. Y. , Chevance M. , Buchbender C. , Fukui Y. , Onishi T. , Parikka A. , Stutzki J.
Published: February 2021

We report SOFIA/GREAT observations of high-J CO lines and [C ii] observations of the super star cluster candidate H72.97-69.39 in the Large Magellanic Cloud (LMC), which is in its very early formation stage. We use our observations to determine if shocks are heating the gas or if photon-dominated regions (PDRs) are being heated by local far-UV radiation. We use a PDR model and a shock model to determine whether the CO and [C ii] lines arise from PDRs or shocks. We can reproduce the observed high-J CO and [C ii] emission with a clumpy PDR model with the following properties: a density of 104.7 cm−3, a mass of 104
M
⊙, and UV radiation of 103.5 in units of Draine field. Comparison with the ALMA beam-filling factor suggests a higher density within the uncertainty of the fit. We find the lower-limit [C ii]/total infrared (TIR) ratio (ϵ) traced by [C ii]/TIR to be 0.026%, lower than other known young star-forming regions in the LMC. Our shock models may explain the CO (16−15) and CO (11−10) emission lines with shock velocity of 8–11 km s−1, pre-shock density of 104–105 cm−3, and G
UV = 0 in units of Draine field. However, the [C ii] line emission cannot be explained by a shock model, thus it is originating in a different gas component. Observations of [O i] 63 μm predicted to be 1.1 × 10−13 W m−2 by PDR models and 7.8 × 10−15 W m−2 by shock models will help distinguish between the PDR and shock scenarios.
Sunspot Simulations: Penumbra Formation and the Fluting Instability
Authors: Panja Mayukh , Cameron Robert H. , Solanki Sami K.
Published: February 2021

The fluting instability has been suggested as the driver of the subsurface structure of sunspot flux tubes. We conducted a series of numerical experiments where we used flux tubes with different initial curvatures to study the effect of the fluting instability on the subsurface structure of spots. We used the MURaM code, which has previously been used to simulate complete sunspots, to first compute four sunspots in the slab geometry and then two complete circular spots of opposite polarities. We find that the curvature of a flux tube indeed determines the degree of fluting the flux tube will undergo—the more curved a flux tube is, the more fluted it becomes. In addition, sunspots with strong curvature have strong horizontal fields at the surface and therefore readily form penumbral filaments. The fluted sunspots eventually break up from below, with lightbridges appearing at the surface several hours after fluting commences.
Markov Chain Monte Carlo Predictions of Neutron-rich Lanthanide Properties as a Probe of r-process Dynamics
Authors: Vassh Nicole , McLaughlin Gail C. , Mumpower Matthew R. , Surman Rebecca
Published: February 2021

Lanthanide element signatures are key to understanding many astrophysical observables, from merger kilonova light curves to stellar and solar abundances. To learn about the lanthanide element synthesis that enriched our solar system, we apply the statistical method of Markov Chain Monte Carlo to examine the nuclear masses capable of forming the r-process rare-earth abundance peak. We describe the physical constraints we implement with this statistical approach and demonstrate the use of the parallel chains method to explore the multidimensional parameter space. We apply our procedure to three moderately neutron-rich astrophysical outflows with distinct types of r-process dynamics. We show that the mass solutions found are dependent on outflow conditions and are related to the r-process path. We describe in detail the mechanism behind peak formation in each case. We then compare our mass predictions for neutron-rich neodymium and samarium isotopes to the latest experimental data from the CPT at CARIBU. We find our mass predictions given outflows that undergo an extended (n,γ)⇄(γ,n) equilibrium to be those most compatible with both observational solar abundances and neutron-rich mass measurements.
Bounds on Velocity-dependent Dark Matter–Proton Scattering from Milky Way Satellite Abundance
Authors: Maamari Karime , Gluscevic Vera , Boddy Kimberly K. , Nadler Ethan O. , Wechsler Risa H.
Published: February 2021

We use the latest measurements of the Milky Way satellite population from the Dark Energy Survey and Pan-STARRS1 to infer the most stringent astrophysical bound to date on velocity-dependent interactions between dark matter particles and protons. We model the momentum-transfer cross section as a power law of the relative particle velocity v with a free normalizing amplitude, σ
MT = σ
0
v

n
, to broadly capture the interactions arising within the nonrelativistic effective theory of dark matter–proton scattering. The scattering leads to a momentum and heat transfer between the baryon and dark matter fluids in the early universe, ultimately erasing structure on small physical scales and reducing the abundance of low-mass halos that host dwarf galaxies today. From the consistency of observations with the cold collisionless dark matter paradigm, using a new method that relies on the most robust predictions of the linear perturbation theory, we infer an upper limit on σ
0 of 1.4 × 10−23, 2.1 × 10−19, and 1.0 × 10−12 cm2, for interaction models with n = 2, 4, and 6, respectively, for a dark matter particle mass of 10 MeV. These results improve observational limits on dark matter–proton scattering by orders of magnitude and thus provide an important guide for viable sub-GeV dark matter candidates.
Use of Handheld Versus Standard Ultrasound Devices in Ultrasound Rotation at the Emergency Department
Authors: Ienghong Kamonwon , Jumroenketpratheep Kotchakorn , Tiamkao Somsak , Apiratwarakul Korakot
Published: February 2021

BACKGROUND: Recently, handheld ultrasound equipment has come to replace standard machines in the training of emergency medicine residents. However, there have been few studies examining how this change has affected medical education.
AIM: We aimed to compare standard and handheld ultrasound machines as educational tools in the emergency medicine residency program.
METHODS: A cross-sectional survey of 17 emergency medicine residents at Srinagarind Hospital emergency department were trained to use point-of-care ultrasound and provided with handheld ultrasound devices during their 2-week ultrasound rotations, which took place between July 2019 and May 2020. Participants were given a 25-question survey comparing their learning experiences with standard versus handheld ultrasound machines. Data were analyzed using an independent sample t-test, and p < 0.05 was considered statistically significant.
RESULTS: The response rate was 100%. At the baseline survey, most participants rated their learning experience as greater than 4 out of 5 with both ultrasound devices. They rated the learning experience with the handheld device as being more enjoyable and accessible but not to a statistically significant extent. There were also no significant differences in participants’ ratings of image quality or the ease of obtaining images. However, they rated the handheld device as being more useful and convenient (p < 0.001 and 0.034, respectively).
CONCLUSIONS: The handheld ultrasound machine is useful in the training of emergency medicine residents. Further studies should be conducted to evaluate residents’ competency in using these devices.
Brachial Plexus Injury: Recent Diagnosis and Management
Authors: Sumarwoto Tito , Suroto Heri , Mahyudin Ferdiansyah , Utomo Dwikora Novembri , Hadinoto Seti Aji , Abdulhamid Muhammad , Utomo Pamudji , Romaniyanto Romaniyanto , Prijosedjati R. Andhi , Rhatomy Sholahuddin
Published: February 2021

Brachial plexus injury is known to be one of the most serious upper limb injuries, causes paralysis of the upper limbs and changes in activity of daily living, with the consequence disruption of activity of daily living, socio-economic problems, depression, and hopelessness. Management must be done properly. The evaluation and examination consist of detailed anamnesis on chronological events, complete physical examination, imaging studies, and electrophysiology study. Management can be done nonsurgically and surgically. Knowledge of the history of injury, timing of surgery, priority in restoring function, and managing patient expectations are important concepts in treating patient with brachial plexus injury. Timing is a very important thing. The results of these interventions vary depending on several parameters. Recognizing the basic principles of managing brachial plexus injuries is indispensable for all clinicians who treat these injuries.
Corticosteroid Therapy for Brain Tumor Patients with Adrenal Insufficiency
Authors: Immadoel Haq Irwan Barlian , Aprianto Dirga Rachmad , Susilo Rahadian Indarto , Wahyuhadi Joni
Published: February 2021

The use of corticosteroids in cases of brain tumors has become common to reduce brain edema. However, the use can cause adrenal insufficiency (AI) if used long-term and in large doses and with rapid withdrawal. In cases of pituitary macroadenoma that has undergone surgery, AI may also occur. AI also affects the treatment of brain tumor patients. Hence, AI is an important problem in brain tumors because almost all patients with brain tumors receive corticosteroids at some point in the course of their disease. The management is similar to another AI with focus of hydrocortisone treatment. The adjustment of hydrocortisone dosage in patients whom undergo brain surgery is similar with another major surgery, whether the adjustment for pituitary adenoma patients whom undergo excision is more complicated and careful due to the high risk and incidence of AI in these patients.
Effect of Different Remineralizing Agents on White Spot Lesions
Authors: Alagha Ebaa , Samy Amira Mohammad
Published: February 2021

AIM: This study evaluated the impact of two remineralizing agents containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and tricalcium phosphate (TCP) on white spot lesions.
MATERIALS AND METHODS: A total of 90 freshly extracted upper premolars were divided in three equal groups (30 each): Group A: Control group, Group B: Varnish containing CPP-ACP, and Group C: Varnish containing TCP. The teeth were subjected to Diagnodent test after inducing white spot lesions to assess any surface changes present on the teeth. The readings were repeated post-demineralization and post-remineralization.
RESULTS: Statistically significant difference was present in the mean values between the tested groups. CPP-ACP group recorded higher mean value at demineralization when compared to TCP group. Statistically significant difference (p < 0.00`01) was present between the baseline and the demineralization values. CPP-ACP group presented higher remineralization results when compared to TCP group. T-test proved a significant difference between the tested groups.
CONCLUSION: CPP-ACP containing varnish had higher remineralizing effect when compared to TCP containing varnish.
CLINICAL SIGNIFICANCE: Recently, the focus of restorative dentistry has been directed toward a conservative approach. Prevention and non-restorative treatment of initial enamel caries is the main concern. Remineralization procedures are the most preferred way of regeneration of lost tooth structure.
Molecular identification and larval morphology of spionid polychaetes (Annelida, Spionidae) from northeastern Japan
Authors: Abe Hirokazu , Sato‐Okoshi Waka
Published: February 2021

Planktonic larvae of spionid polychaetes are among the most common and abundant group in coastal meroplankton worldwide. The present study reports the morphology of spionid larvae collected mainly from coastal waters of northeastern Japan that were identified by the comparison of adult and larval 18S and 16S rRNA gene sequences. The molecular analysis effectively discriminated the species. Adult sequences of 48 species from 14 genera (AonidesClaparède, 1864;BoccardiaCarazzi, 1893;BoccardiellaBlake & Kudenov, 1978;DipolydoraVerrill, 1881;LaoniceMalmgren, 1867;MalacocerosQuatrefages, 1843;ParaprionospioCaullery, 1914;PolydoraBosc, 1802;PrionospioMalmgren, 1867;PseudopolydoraCzerniavsky, 1881;RhynchospioHartman, 1936;ScolelepisBlainville, 1828;SpioFabricius, 1785;SpiophanesGrube, 1860) and larval sequences of 41 species from 14 genera (Aonides;Boccardia;Boccardiella;Dipolydora;Laonice;Paraprionospio;PoecilochaetusClaparède in Ehlers, 1875;Polydora;Prionospio;Pseudopolydora;Rhynchospio;Scolelepis;Spio;Spiophanes) of spionid polychaetes were obtained; sequences of 27 of these species matched between adults and larvae. Morphology of the larvae was generally species‐specific, and larvae from the same genus mostly shared morphological features, with some exceptions. Color and number of eyes, overall body shape, and type and arrangement of pigmentation are the most obvious differences between genera or species. The morphological information on spionid larvae provided in this study contributes to species or genus level larval identification of this taxon in the studied area. Identification keys to genera and species of planktonic spionid larvae in northeastern Japan are provided. The preliminary results of the molecular phylogeny of the family Spionidae using 18S and 16S rRNA gene regions are also provided.
Description of Hemienchytraeus wuhanensis sp. nov. (Annelida, Clitellata, Enchytraeidae) from central China, with comments on species records of Hemienchytraeus from China
Authors: Chen Juanjuan , Schmelz Rüdiger M. , Xie Zhicai
Published: February 2021

Hemienchytraeus wuhanensissp. nov. is described from hardwood forest soil in Wuhan, China. This moderately sized enchytraeid species of 6–9 mm body length is characterized by: (1) an oesophageal appendage with tertiary branches, (2) three pairs of secondary pharyngeal gland lobes in V, VI, VII, (3) five pairs preclitellar nephridia, from 5/6 to 9/10, (4) dorsal vessel originating in clitellar segments, (5) a girdle-shaped clitellum, (6) a relatively small male reproductive apparatus without seminal vesicle, and (7) spermathecae that extend to VI–VII. DNA barcodes of paratype specimens of the new species are provided. Previous species records of Hemienchytraeus from China are critically discussed.
Escritura creativa y neurociencia cognitiva
Authors: Vázquez-Medel Manuel A. , Mora Francisco , Acedo García Antonio
Published: February 2021

El desarrollo de la neurociencia ha permitido, en las últimas décadas, espectaculares avances en torno al mejor conocimiento de diferentes prácticas humanas desde las bases neurofisiológicas del funcionamiento cerebral. A pesar de que aún nos encontramos en la «prehistoria» del descifrado funcional del más complejo órgano que conocemos en el universo, es un momento adecuado para hacer un balance operativo, desterrando algunas falsedades y aprovechando algunos datos consolidados para su aplicación a la enseñanza y a la praxis de la escritura creativa.
De manera sintética, abordaremos algunas claves sobre la creatividad en general, para centrarnos en la creatividad verbal estética, tanto en su expresión oral como a través de los cambios cerebrales que se operan en el proceso de aprendizaje de la lectura. Reflexionaremos acerca de la complejidad de nuestras representaciones mentales vinculadas, por ejemplo, con el discurso poético verbal, ofreceremos algunas indicaciones sobre la importancia de la escritura como potenciador de nuestra reserva cognitiva, destacando algunas orientaciones prácticas para potenciar la creatividad en la experiencia de esa misma escritura. Insistiremos en la importancia de la emoción y la atención, así como en la interconexión entre inteligencia racional e inteligencia emocional en los ámbitos de la escritura y la lectura. Finalizaremos con un análisis de las nuevas prácticas de lectura y escritura desarrolladas en el tercer entorno (cibersociedad), nuevas narrativas construidas en el nuevo paradigma tecnológico que han posibilitado nuevos ámbitos creativos para la escritura, insistiendo en los conceptos de ‘transmedialidad’, ‘literacidad digital’, ‘hipertextualidad’, ‘multimodalidad’ y su incidencia en nuestra actividad cerebral.
Aportaciones de la retórica a la escritura creativa en cuanto disciplina docente universitaria: una propuesta
Authors: Mora-Fandos José Manuel , Schreiber-Di Cesare Christelle
Published: February 2021

Escritura creativa es un término que apela a diversas posibilidades educativas y formativas a través del medio de la escritura. Para su realización concreta recurre a recursos y orientaciones procedentes de diversos saberes y disciplinas. Nuestra propuesta es acotar uno de estos significados de la escritura creativa y presentar su relación con la retórica, disciplina que puede aportar elementos significativos a los fines formativos de la escritura creativa, tal como la hemos acotado. Para esta acotación del significado narraremos primero brevemente la historia de su constitución, y a continuación su finalidad como realidad formativa. Sobre la base de esta finalidad delimitaremos a grandes rasgos la disciplina de la retórica y presentaremos sus posibles aportaciones a la escritura creativa.
Ciencia y naturaleza en Goethe: apuntes sobre la epistemología natural goetheana a partir de La metamorfosis de las plantas
Authors: Lavernia Kilian
Published: February 2021

El artículo reactualiza y defiende la potencialidad filosófica de La metamorfosis de las plantas (1791), de Johann Wolfgang Goethe. A partir de la reflexión sobre sus claves conceptuales se desplegarán, a continuación, otros momentos de talante epistemológico relativos a su reflexión sobre la naturaleza, entre otros: la morfología como teoría de la forma, su comprensión de la ciencia como experiencia viva de los fenómenos y su reivindicación de la metamorfosis del científico.
Factores epistemológicos y contextuales en la genealogía de la teoría de la fotografía en la segunda mitad del siglo XX
Authors: Mira Pastor Enric
Published: February 2021

El giro crítico del arte conceptual en los años sesenta, la subsiguiente aparición de estrategias de hibridación y escenificación a finales de los setenta y, en paralelo, la institucionalización de la fotografía con su entrada al museo y el surgimiento de un pujante mercado fotográfico, constituyen el caldo de cultivo en el que se gesta la demanda de la teoría de la fotografía como disciplina con identidad epistemológica propia. Esta demanda se hizo explícita a través de las iniciativas llevadas a cabo por Rosalind Krauss y Annette Michelson en el número 5 de la revista October en 1978, por Alan Trachtenberg en Classic Essays on Photography en 1980 y de modo más categórico por Victor Burgin en Thinking Photography en 1982. El presente artículo analiza los argumentos y posiciones intelectuales sobre la necesidad de articular un discurso teórico sobre fotografía, así como los aspectos epistemológicos y sociales asociados a la idea de teoría subyacente en cada una de las propuestas. Por último, se realiza una breve aproximación al ámbito teórico español a través de la publicación en 1984 del libro Estética fotográfica y en 1997 de El beso de Judas, ambos de Joan Fontcuberta.
Conception d'un e-portfolio pour les langues : réflexions autour d'une évolution didactique et techno-pédagogique
Authors: Othman Sophie
Published: February 2021

Dans cet article, nous décrivons ce qui nous a paru particulièrement intéressant dans la démarche de conception d'un e-portfolio en montrant la méthodologie de travail et quelques exemples. Ce travail permettra d'identifier les traits saillants d'un e-portfolio intégré dans un environnement numérique pour l'enseignement-apprentissage des langues. Nous proposons également quelques lignes directrices et des points-clés qui nous semblent à prendre en compte par les concepteurs souhaitant concevoir et mettre en place un projet de e-portfolio pour les langues.
Casimir Perier
Authors: Bourset Madeleine
Published: February 2021

Héritier d’une dynastie bourgeoise du Dauphiné, Casimir Perier (1777-1832) est l’une des personnalités éminentes du premier xixe siècle français. Membre de la Haute Banque parisienne, Régent de la Banque de France et chef d’entreprise, il fut un pionnier de la modernisation de l’économie nationale. Il mit son autorité, son énergie et son sens des responsabilités au service d’une activité politique commencée sous la Restauration, dans les rangs de l’opposition libérale. Ministre de Louis-Philippe, il donna la pleine mesure de ses qualités d’homme d’Etat en se plaçant délibérément au-dessus des partis et en adoptant une politique d’indépendance nationale. Par l’ampleur de son action marquée du sceau de sa vive intelligence, Casimir Perier prend un relief particulier dans la France des Notables.
Art et État sous la IIIe République
Authors: Genet-Delacroix Marie-Claude
Published: February 2021

L’État, en la personne de son souverain, a depuis toujours entretenu avec l’art un rapport privilégié. L’histoire de l’art qui traite des artistes et de leurs œuvres et l’histoire qui exalte la gloire du Prince se rencontrent aisément autour des Princes-mécènes qui ont encouragé les arts et honoré les artistes. Mais quand le Prince est devenu l’Etat républicain, depuis 1875 donc, tout devient beaucoup plus complexe. Comment définir un style, juger l’action, ou évaluer le rayonnement d’un « Prince » collectif, anonyme et changeant ? L’État républicain se veut respectueux de la liberté de création (intellectuelle, artistique), des goûts et des opinions de tout un chacun : peut-il avoir une politique de l’art, voire une esthétique qui inspire son mécénat ? Au-delà des simplifications habituelles sur « l’art officiel » et l’oppression des artistes d’avant-garde, Marie-Claude Genet-Delacroix montre que la gestion du patrimoine, la politique éducative en matière d’art, le soutien de la création s’intégrent dans un véritable système des Beaux-Arts qui, loin d’être un supplément d’âme accessoire, joue un rôle capital dans le triomphe et la pérennisation du modèle républicain français, libéral et démocratique.
Solving Interval Type-2 Fuzzy Reliability-Redundancy Allocation Systems With Efficient PSO Algorithm
Authors: Ashraf Zubair , Hasan Md. Gulzarul , Khan Mohd Shoaib
Published: February 2021

A new type-2 fuzzy reliability-redundancy allocation problem (IT2FRRAP) is introduced in this study, which maximizes system reliability underneath the type-2 fuzzy uncertainty. Throughout the design process, estimation of system parameters with type-2 fuzzy sets is very rational, as many experts may have varying views on the numerous risks involved with the multi-state framework. The authors consider fuzzy membership functions of interval type-2 to fuzzy set to reflect the reliability of the sub-system. By using the extension theory, they evaluate the total system reliability as per respective configurations (i.e., series, parallel, non-parallel, and bridge). They developed a novel solution method focused on particle swarm optimization to address the IT2FRRAP. They carried out the computational simulations on various numerical databases to show the gravity of the proposed formulations. To compare its productiveness, a detailed analysis of the proposed solution was made with the genetic algorithm (GA).
Effect of Nano Dispersant Additions to the Electrodes for Aluminum Electrolysis
Authors: Akhtar Shahid , Larsen Sten Yngve
Published: February 2021

Over the next half decade, significant changes expected in global carbon structures, carbon products and applications. Technological advances that improve the structure-property relationship of advanced carbon materials and breakthrough in manufacturing processes resulting in lower cost, leads to availability of carbon nano materials for applications in the metallurgical industry with a reference to electrodes for the metallurgical industry.In the current work we synthesized pitch-based C/C nano composite lab scale electrodes, partially replacing petroleum coke with nanofibers, by using a ball milling dispersion and high energy milling technique. The effect of different processing variables including the amount of binder and dispersants as well as mixing conditions is investigated. Low vacuum -SEM analyses of green pitch and dispersant samples show the pitch coating on dispersants. Field emission gun (FEG)-SEM is used to analyse dispersants, baked pitch/dispersant system as well baked electrodes. Transmission electron microscope (TEM) is applied to investigate in detail the primary structure of the dispersants, as well as the fiber/matrix interface and the alignment of binder with the fibres in graphitized and un-graphitized electrodes.
Effect of Polymer Matrix in Polymer/trGO Nano-Composite for EMI Shielding Application in Microwave and Infrared Region
Authors: Zubair Khadija , Shakir Muhammad Fayzan
Published: February 2021

Thermally reduced graphene oxide (trGO) was successfully prepared and confirmed by XRD then dispersed in polystyrene (PS) and Acrylonitrile-Butadiene-Styrene (ABS) polymers and evaluated for EMI shielding in microwave and infrared (IR) region. Thickness of prepared polymer/trGO composite films were 200-250 micron. It was observed that trGO has more compatibility with PS then ABS and dispersed more easily and uniformly in PS than ABS. This effect was also observed in IR shielding as ABS+15trGO have 3% transmission and PS+1% trGO have 1.5% transmission. Maximum 29 dB and 25 dB shielding effectiveness was measured by vector network analyzer (VNA) in microwave region (9-18 GHz) of PS+2% trGO and ABS+2% trGo composite respectively. These results clearly indicating that trGO is more compatible with PS than ABS and form more stable and mature interconnected network structure in PS at lower concentrations.
Evolution of Fatigue Crack Growth Phenomena in Friction Stir Welded AA2xxx Alloys
Authors: Muhammad Wali , Hussain Wilayat , Zaigham Hamid , Zubair Nouman
Published: February 2021

Aluminum 2xxx alloys have been one of the primary materials for the structural applications of aerospace and transportation industry because of their performance, manufacturing and reliable inspection techniques. Welding is very important in the manufacturing process of structural parts and is now known as the most vital process in the manufacturing route. A relatively new process of joining of materials is friction stir welding process, which was invented by The Welding Institute (TWI) in the UK in 1991. The friction stir welding is mainly employed in aerospace, marine and transportation fields that have high safety requirements. The failure by fatigue is the dominant failure mode for structural weld joints. Since fatigue failure of parts accounts for 50 to 90% of all failures, it is of great significance to understand the fatigue properties of friction stir welded joints. The aim of this overview is to summarize the current research on fatigue crack growth behavior of friction stir welded AA2xxx alloys and critical attention is payed to the damage tolerance performance of friction stir welded aluminum joints that can be affected by welding process parameters, residual stress, stress ratio, environment and post weld treatments.
Decipher Ultrasonic Signals from Defects in Thick Aluminum Extrusions to Identify Type and Origin of Defects
Authors: Batool Lubaba , Nawaz Zukhruf , Jahangir Irsa , Abbasi Zeeshan , Tauqir Anjum
Published: February 2021

Manufacturing of thick seamless pipes of age-hardenable aluminum alloys are a specialized technology since their application is limited to specific hi-tech areas. Quality criteria for their inspection are propriety items of the very few production facilities that develop these criteria in-house. Present study relates ultrasonic signals reflecting back from non-continuities in the thickness of seamless pipes with their microstructural features. Detailed study of defects leads to the source of their formation and will ultimately help to systematically control them. Signals from ultrasonic testing trace defects as UT waves reflect back from discontinuities in the material. Defective sections of seamless pipes were cut with precision to reveal the defects. The sectioned surfaces were subjected to metallographic preparation and revealed defects were studied using Optical and Field Emission Scanning Electron Microscopes (FESEM). Defects are grouped based on the shape of UT signals as well as the defect morphology as revealed by microscopic studies. Most of the observed cracks are found to grow in the direction of extrusion. Energy Dispersive Spectroscopy (EDS) analysis was conducted to determine the composition of inclusions in the vicinity of the defects. Data from elemental analysis is used to identify the potential sources. The study recommends measures to control the defects and improve the yield.
Effect of Deposition Time and Heat Treatment on Structural and Mechanical Properties of Ni3Al Coating Deposited by Air Plasma Spraying on Tool Steel
Authors: Zaman Sabah , Mehmood Khalid , Abbas Shabbar , Rauf Mudassir , Khan Shaheed
Published: February 2021

This study focuses on the effect of deposition time and heat treatment on Ni3Al coatings with respect to mechanical and microstructural properties of the material. Air plasma spraying technique was employed to deposit Ni3Al on hot work tool steel samples for different deposition times i.e. 15-45 seconds. The coated samples were then heat treated at 900 °C for 20 to 100 hours at an interval of 20 hours each. The characterization tools such as X-Ray diffraction (XRD), optical and scanning electron microscopy (SEM) were used to study the homogeneity, phases formed and structure of coatings. All the coatings showed lamellar structure with distinctive boundaries along with the presence of some porosity and oxide particles. The XRD analysis of as prepared samples showed characteristic peaks of Ni3Al whereas of heat treated samples revealed NiO formation that increased with increasing heat treatment time. Micro-hardness and wear resistance measurements of the coated layer showed that they were increasing with the deposition time due to formation of more thick and dense layers. Formation of NiO, due to heat treatment imparted greater hardness and wear resistance to the coating. Moreover, the SEM study of heat-treated samples showed presences of alumina and spinel phases which were confirmed by energy dispersive spectroscopic analysis.
Effect of Ni3Al Coating on Vibration Suppression of Beams of Various Thicknesses
Authors: Nadeem Shoaib , Saeed Hasan Aftab , Aziz Imran , Mehmood Khalid
Published: February 2021

High cycle fatigue (HCF) caused by the vibratory stresses is the main cause of failure in many machine components, e.g. aircraft engine and gas turbine components, which has caused loss of many lives and billions of dollars. To avoid these kind of failures, vibratory stresses should be attenuated to an acceptable level, especially at resonant frequencies. A lot of previous studies have shown that thin coatings of different materials significantly reduced these vibratory stresses by adding extra damping to the system. These include viscoelastic materials, plasma graded coatings, piezoelectric materials, and magneto-mechanical damping material coatings, but some of these had applicability and performance issues. Among these thin coatings, magneto-mechanical materials are very effective in reducing these vibratory stresses significantly.In this study, the effect of different beam structure thicknesses under same magneto-mechanical coating of 0.2mm was studied. For this purpose, Ni3Al was applied as magneto-mechanical coating. The natural frequencies, damping ratios and displacements of beams were calculated before and after applying magneto-mechanical coatings using forced response analysis and hammer tests. The results indicated a sharp change in vibration characteristics i.e. natural frequency, damping ratio and beam deflections, of all the beams used. The results showed that the magneto-mechanical coatings were more effective when applied to thin structures as compared to thick structures, because thin structures have higher strains, which enabled magneto-mechanical coatings to dissipate larger amounts of energy of applied loadings, because performance of these coatings is strain dependent.
Improving the Corrosion Resistance of API X56 and API X70 Pipeline Steels by Hot Dip Aluminization
Authors: Karim Muhammad Ramzan Abdul , Daniel Sanam , Ul Haq Ehsan , Ahmad Akhlaq , Khan Khurram Imran , Raza Syed Abbas
Published: February 2021

The external surface of the pipeline steels can be protected from corrosion by cathodic protection and a suitable coating system. But to protect the internal surface of steel pipelines from corrosion is always a challenge. In the current study, a protective aluminum coating was applied on the internal surface of steel pipeline grades API X56 and API X70 by hot dip aluminization process to minimize the cost of inhibitors. The steel substrates were dipped in the hot aluminum bath, whose temperature was maintained at 720 °C, for three different dipping times (5, 7.5 and 10 minutes) and then permitted to cool to room temperature. The coated specimens were characterized in terms of their structure and composition by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM micrographs analysis reveal that the hot dip aluminized specimens gave an unwavering and well adherent interface which is essential for corrosion resistance of the substrates. The corrosion behavior was evaluated by weight loss method in case of sweet corrosion (in 1.0 % NaCl + CO2 environment) and, by electrochemical potentiodynamic polarization tests for marine corrosion (in 3.5% NaCl environment). The sweet corrosion rates showed severe material loss (14.17 mpy for API X56 and 6.6 mpy in case of API X70) of uncoated samples as compared to the aluminized samples which showed no corrosion at all even after one week due to the passive layer of Al2O3. Whereas the marine corrosion of aluminized specimens was also reduced to 0.11 mpy (coated specimens) from 0.57 mpy (uncoated specimens).
Microsecond Laser Texturing of an Aerospace Grade Aluminum Alloy to Synthesize Superhydrophobic, Anti-Water Clogging Surfaces
Authors: Naeem Aneeqa , Butt Esham , Khawaja Hamza , Nadeem Irfan , Akhter Rehan , Tauqir Anjum
Published: February 2021

Traditionally superhydrophobic surfaces are prepared by applying liquid repellant organic coatings or nano-based coatings. These superhydrophobic coatings are prone to wear and can be easily damaged by abrasion and cleaning. Recently researchers are switching interest to more efficient and promising technology of pulse laser texturing for engineering sub-micron topographies to have superhydrophobic surfaces. In this research, the micro-second Laser Pulses are used to feature sub-micron textures on titanium nitride coated aluminum and polished aluminum surfaces in order to achieve the water contact angle greater than 150°. Titanium nitride coated aluminum surface with scan line separation of 50 µm shows superior hydrophobicity having a water contact angle of 156º. These superhydrophobic aluminum surfaces have applications for anti-water clogging and anti-corrosion use.
Optimization of Pulsed Fiber Laser Texturing for Solid Lubricant Deposition on a Ti/TiN Coated Aerospace Alloy
Authors: Nadeem Irfan , Akhter Rehan , Akhtar Shazeen , Tauqir Anjum
Published: February 2021

AA2219 is a superior performance Al-base alloy which promises toughness, strength and creep resistance which allows the deposition of titanium nitride (TiN) coating at 200 °C. The present research addresses the issue of poor wear properties of the alloy, using state of the art technologies, to deposit hard and adherent thin TiN layer followed by laser surface texturing. The thickness of sub-micron size coating is determined by appropriate modification of the existing mathematical model and composite microhardness values. Laser energy density of 20.8 J/cm2 and 4 repeated pulses is optimized to produce regular size and shape of micro-holes on TiN-coated samples. Epoxy-based MoS2 lubricant is deposited on laser textured samples to produce ultra-low friction surfaces. The micro-holes act as a micro-reservoir of MoS2 solid lubricant. Field emission scanning electron microscope and optical profilometer were used to estimate the topology, shape, size, and depth of micro-holes. The cross-sectional view shows the successful impregnation of epoxy-based MoS2 due to the chemisorption of functional groups with an Al oxide surface.
Strip Size Optimization for Spiral Type Actuator Coil Used in Electromagnetic Flat Sheet Forming Experiment
Authors: Akbar Shakeel , Aleem Muhammad Adeel , Pirandad Faisal , Zillohu Ahnaf Usman , Awan Muhammad Saifullah , Haider Ali , Farooque Muhammad
Published: February 2021

Flat spiral coil for electromagnetic forming system has been modelled in FEMM 4.2 software. Copper strip was chosen as material for designing the actuator coil. Relationship between height to width ratio (S-factor) of the copper strip and coil’s performance has been studied. Magnetic field intensities, eddy currents and Lorentz force were calculated for the coils that were designed using six different 'S-factor' values (0.65, 0.75, 1.05, 1.25, 1.54 and 1.75), keeping the cross-sectional area of strip same. Results obtained through simulation suggest that actuator coil with S-factor ~ 1 shows optimum forming performance as it exerts maximum Lorentz force (84 kN) on work piece. The same coils was fabricated and used for electromagnetic sheet forming experiments. Aluminum 6061 sheets of thickness 1.5 mm have been formed using different voltage levels of capacitor bank. Smooth forming profiles were obtained with dome heights 28, 35 and 40 mm in work piece at 800, 1150 and 1250 V respectively.