2,616 research outputs found
Thermal Analysis of Carbon Nanofiber Reinforced Isotactic Polypropylene
Isotactic Polypropylene (IPP) is a commonly known thermoplastic that has unique properties include being light weight, high performance, impact strength, tensile strength, elongation, and high temperature properties. The use of vapor grown carbon nanofiber (VGCNF) reinforcements on polypropylene has shown to produce high specific modulus, strength, electrical and thermal properties on specimens. Thermogravimetric (TGA) investigations on the thermal degradation of isotactic polypropylene – vapor grown carbon nanofibers composites in nitrogen were reported. The mass evolution as a function of temperature is a single sigmoid for both polypropylene and polypropylene loaded with VGCNF. The inflection temperature of these sigmoids increases as the concentration of VGCNF is increased. The width of the degradation process narrows as the concentration of VGCNF is increased due to a better homogenization of the local temperature provided by the high thermal conductivity of carbon nanofibers. TGA analysis data indicates the formation of polymer – VGCNF interface
Assessing Long-Term Coral Coverage at East and West Flower Garden Banks
Coral reefs provide critical habitat for diverse benthic communities; however, more than 10% of existing reefs have been lost as a result of natural and anthropogenic stressors. While there has been a decline in reefs around the world, East and West Flower Garden Banks (FGBs), part of Flower Garden Banks National Marine Sanctuary (FGBNMS), have maintained \u3e 50% live coral cover for over 27 years as revealed by the FGBNMS long-term monitoring (LTM) program. In the 1980’s, the LTM program at East and West FGBs was developed in response to the expansion of oil and gas exploration, anchoring, and fishing impacts to assess coral and reef-associated benthic organism health. As part of the LTM program, repetitive photostations were established in 1989 to detect and evaluate long-term changes and changes within the benthic community at East and West FGB. However, the assertion of maintenance of over 50% live coral coverage has been questioned because of changes in LTM methods used for image acquisition and data analysis throughout the study period. To address this concern, I used a standardized methodology to reanalyze repetitive photostation data and found a significant increase in repetitive photostation coral coverage at West FGB from 1989 to 2017 (P = 4.3154 e–05) and no significant change at East FGB (P = 0.36783). This is in contrast to the recorded declines at other coral reefs in the Gulf of Mexico region
Falling upwards
There exists a group of people known as the Winged who live in a city called Colonia, nestled in the mountains and by a high stone wall. The humans don\u27t know about them, but the Winged were actually once humans themselves. The Winged life seems utopian. They don\u27t age or get sick, they live in utter peace with each other, and they are free to do whatever they want with their lives. The only requirement their unofficial leader, Scio, mandates is that they task more humans by turning them into Winged. At one hundred and twenty years old, Anagnorisis is one of the older Winged living in Colonia. When he decides to seek out his final task without permission from Scio, he sets into motion events that will change the course of the Winged\u27s history forever. A new Winged by the name of Revelation will unexpectedly and violently turn against them. Revelation is cold, unstable, and merciless, picking them off one by one in the name of unspoken revenge. The passive Anagnorisis will have to decide whether or not to step in to save his people. But once he discovers the truth about the Winged, he may not want to
Water Uptake, Water Relations, Tree Growth, and Root Distribution under Herbaceous Competition
There are numerous situations where trees are grown together with herbaceous plants. In these situations there will be some degree of competition between their root zones, depending on the water content of the soils and crop and tree root distribution . Two studies were conducted : the first with maple (Acer platanoides) grown in turf grass, and the second with willow (Salix matsudana) grown in more deeply rooted barley . The objectives of this study were to quantify the effect of herbaceous competition of potential tree water stress under irrigation and when the soil is allowed to dry-down . Soil water uptake was measured in both studies to 1.2 m depth and outwards to 1.2-2.10 m away from the tree . In the maple-turf grass study, water content was measured in a single line away from the tree , while four lines covering a quadrant of the surface area were measured in willow . Water relations stomatal conductance and water potential, and tree growth were also monitored in both studies. Water uptake in turf plots was statistically different from mulch plots by depth and distance during three seasons. Water uptake was greatest at 0-60 cm depth in the turf treatments compared with mulch treatments. Soil water in mulched plots decreased slowly during the growing season. There were no statistical differences between bare soil and barley competition water uptake after soil surface water was depleted.
There were marked differences in tree root characteristics as a result of competition from turf or barley roots. The root systems of maples in the mulch and willow in bare soil extended laterally and fine roots were evident. Tree roots extended deeper and fine root were reduced under competition from turf and barley. Trees growing with turf and barley had fewer roots in the top 0.3 m soil surface while trees in mulch and bare soil had more and greater diameter roots at the same depth. Early in the season, when water content is high, root competition for water was not evident, and late in the season after turf roots and barley had depleted the soil water, trees exhibited more negative predawn leaf water potential and less stomatal conductance in response to water stress during a soil dry-down period. Tree growth was measured periodically during 1994, 1995, and 1996. Leaf area and stem growth comparisons showed a significant increase in size as a result of the absence of competition in both species, with mulch and bare soil treatments. Leaf area in mulched trees was twice that in turf treatments. In summary, we found that competition resulted in deeper tree root growth and less top growth in the presence of herbaceous competitors
The Relationship Between Rumination of COVID-19 and Anxiety Levels
The COVID-19 pandemic has caused an increase in psychological distress among individuals around the world (Saddik et al., 2021) (Ting et al., 2021.) Rumination is a factor in increased distress caused by the pandemic. Rumination about COVID-19 may be related to the contraction and transmission of the virus. Previous literature suggests that rumination about COVID-19 increases anxiety symptoms (Jamieson, D., et al, 2021.) However, it is unknown whether time thinking about COVID-19 impacts this relationship uniquely and directly as well.
A sample of 225 undergraduate psychology students completed an online survey in April 2020 evaluating rumination, time spent thinking about COVID-19, and symptoms of anxiety. Rumination was assessed using the rumination subscale of the Regulation of Emotion Systems Survey (RESS). Anxiety symptom severity over the past 2 weeks was measured using the seven-item Generalized Anxiety Disorder (GAD-7) questionnaire.
A linear regression analysis tested the relationship between rumination, time thinking about COVID-19 and anxiety. Results indicated that both rumination, B = .44, p \u3c .001, and time spent thinking about COVID-19, B = 1.05, p = .001, predicted the severity of anxiety symptoms. Our results suggest that the tendency to ruminate and time spent thinking about COVID-19 are related to increased anxiety symptoms. Understanding how COVID-19 impacts the psychological mind can aid in targeting this issue in therapy. The current study suggests that limiting one’s time thinking about COVID-19 may reduce anxiety. Remaining self-aware of the relationships between rumination and negative feelings about COVID-19 may improve one’s quality of life during the COVID-19 pandemic
Walmart en áreas periurbanas de la ciudad de Toluca, México: efectos sociales, económicos y territoriales
Este estudio, a través de entrevistas aplicadas a los residentes, gerentes, clientes e interpretación cartográfica, caracteriza los efectos sociales, económicos y territoriales que dos tiendas de Walmart (Adolfo López Mateos y Alfredo del Mazo) generan en áreas periurbanas de la ciudad de Toluca. La penetración comercial determina la reducción de los costos de localización periférica, la formación de un mercado de lugar de alcance regional, y la organización y uso de la tecnologÃa que mantiene las ventajas competitivas. En esta lógica, la intensidad de uso del territorio muestra la multiplicidad de agentes productivos, actividades económicas, asentamientos humanos y elementos culturales, que identifican la aglomeración comercial como determinante del hecho urbano. No obstante que las externalidades fortalecen las ventajas comparativas del lugar, y los entrevistados las califican positivamente, los efectos negativos plantean el incremento de la vulnerabilidad social y económica local, y la degradación urbana.Este estudio, a través de entrevistas aplicadas a los residentes, gerentes, clientes e interpretación cartográfica, caracteriza los efectos sociales, económicos y territoriales que dos tiendas de Walmart (Adolfo López Mateos y Alfredo del Mazo) generan en áreas periurbanas de la ciudad de Toluca. La penetración comercial determina la reducción de los costos de localización periférica, la formación de un mercado de lugar de alcance regional, y la organización y uso de la tecnologÃa que mantiene las ventajas competitivas. En esta lógica, la intensidad de uso del territorio muestra la multiplicidad de agentes productivos, actividades económicas, asentamientos humanos y elementos culturales, que identifican la aglomeración comercial como determinante del hecho urbano. No obstante que las externalidades fortalecen las ventajas comparativas del lugar, y los entrevistados las califican positivamente, los efectos negativos plantean el incremento de la vulnerabilidad social y económica local, y la degradación urbana
Vers un modèle de développement et d'identités professionnelles agricoles globalisés: Dynamiques d’innovation autour du semis direct en Argentine et en France
Cet article éclaire par une analyse croisée des dynamiques de développement du semis direct (SD) en Argentine et en France, la globalisation des systèmes d’innovation et des identités professionnelles agricoles autour des productions de grandes cultures. Il montre les proximités entre les dispositifs liés au développement de cette technologie dans les deux pays, en soulignant l’engagement des multinationales agrochimiques et semencières auprès des agriculteurs et d’organisations de lobbying. Les identités professionnelles des agriculteurs concernés présentent également de profondes similitudes, témoignant d’un sentiment d’appartenance à une définition commune du métier d’agriculteur basée notamment sur la connaissance du fonctionnement des sols et l’objectif partagé de leur conservation .Fil: Hernandez, Valeria Alicia. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentin
Vers un modèle de développement et d'identités professionnelles agricoles globalisés: Dynamiques d’innovation autour du semis direct en Argentine et en France
Cet article éclaire par une analyse croisée des dynamiques de développement du semis direct (SD) en Argentine et en France, la globalisation des systèmes d’innovation et des identités professionnelles agricoles autour des productions de grandes cultures. Il montre les proximités entre les dispositifs liés au développement de cette technologie dans les deux pays, en soulignant l’engagement des multinationales agrochimiques et semencières auprès des agriculteurs et d’organisations de lobbying. Les identités professionnelles des agriculteurs concernés présentent également de profondes similitudes, témoignant d’un sentiment d’appartenance à une définition commune du métier d’agriculteur basée notamment sur la connaissance du fonctionnement des sols et l’objectif partagé de leur conservation .Fil: Hernandez, Valeria Alicia. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentin
Agricultural supplies market, companies and innovations: from product to consumer
En este artÃculo se analiza el cambio ocurrido en el mercado argentino de agroinsumos a partirde la introducción de un nuevo sistema de comercialización de las innovaciones tecnológicasrecientes (biotecnologÃas y tecnologÃas de la información y la comunicación) por parte de empresas transnacionales dominantes. En base a una investigación antropológica multisituada, seaborda el caso de la empresa SemGen y se restituye el proceso de reorganización de su canal dedistribución. Se señalan los efectos que este proceso tuvo, tanto en el modo de circulación desus productos como en el de relacionamiento entre los actores del sistema. En la conclusión sediscute la capacidad de control que adquirieron las empresas transnacionales sobre el mercado,y el rol del Estado como su garante y regulador.This paper analyses agroindustrial supplies market changes due to the introduction of a new commercialization system for recent technological innovations (biotechnologies and communications and information technology) created by dominant transnational enterprises. Basing on a multi situated anthropological approach, this research addresses the case of SemGen Company and the reorganization process of their distribution channels. We show the effects of those changes, both on the products circulation mode and on the relationships among the actors in the system. In the conclusion we discuss the capacity of control that transnational enterprises gained over the market and the State’s role as it’s guarantor/regulator.Fil: Hernandez, Valeria Alicia. Universidad Nacional de San MartÃn; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentin
A Deep Learning Approach for Robust Detection of Bots in Twitter Using Transformers
© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksDuring the last decades, the volume of multimedia content posted in social networks has grown exponentially and such information is immediately propagated and consumed by a significant number of users. In this scenario, the disruption of fake news providers and bot accounts for spreading propaganda information as well as sensitive content throughout the network has fostered applied researh to automatically measure the reliability of social networks accounts via Artificial Intelligence (AI). In this paper, we present a multilingual approach for addressing the bot identification task in Twitter via Deep learning (DL) approaches to support end-users when checking the credibility of a certain Twitter account. To do so, several experiments were conducted using state-of-the-art Multilingual Language Models to generate an encoding of the text-based features of the user account that are later on concatenated with the rest of the metadata to build a potential input vector on top of a Dense Network denoted as Bot-DenseNet. Consequently, this paper assesses the language constraint from previous studies where the encoding of the user account only considered either the metadatainformation or the metadata information together with some basic semantic text features. Moreover, the Bot-DenseNet produces a low-dimensional representation of the user account which can be used for any application within the Information Retrieval (IR) framewor
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