bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelado matemático del efecto del anclaje sobre el sesgo de subconfianza
Authors: Macbeth Guillermo , Razumiejczyk Eugenia
Published: September 2020

Se define el efecto de anclaje como la tendencia del pensamiento humano a la fijación endeterminados fragmentos de información que afectan la toma de decisiones. El sesgo de subconfianza, por su parte, se entiende como la propensión de un agente a subestimar su desempeño objetivo. Si bien se conocen algunos aspectos de la interacción entre ambos efectos, no se dispone de modelos formales que describan tal relación específica. Este estudio presenta: i) un experimento que pone en evidencia el efecto que ejerce el anclaje tanto para reducir, como para amplificar la subconfianza en tareas de decisión geográfica y ii) los fundamentos de un modelo matemático novedoso que permite estudiar con mayor precisión la relación del anclaje con la subconfianza
El análisis microgenético para el estudio del desarrollo moral: consideraciones teóricas y metodológicas
Authors: Barrios Alia , Barbato Silviane , Branco Angela
Published: September 2020

Se parte de la importancia del desarrollo de nueva ideas y metodologías que posibiliten elavance en la interpretación científica del desarrollo moral. La relación entre la ctividad humana, los procesos de comunicación y las cuestiones de moralidad, colocan a los investigadores frente al desafío de desarrollar un abordaje metodológico del desarrollo moral a partir de un enfoque que considere los aspectos cognitivos, afectivos y socioculturales, así como el papel activo de la persona en su proceso de desarrollo. A partir de esas ideas, nuestro objetivo es proponer el análisis microgenético para el estudio del desarrollo moral, tanto desde el punto de vista teórico como metodológico, en el contexto educacional.
Efecto de una plataforma virtual en comprensión de lectura y vocabulario: Una alternativa para mejorar las capacidades lectoras en primaria
Authors: Thorne Cecilia , Morla Kim , Ucelli Paola , Nakano Teresa , Mauchi Beatriz , Landeo Lorena , Vásquez Angie , Huerta Román
Published: September 2020

Frente a los bajos resultados que los niños peruanos obtienen en las pruebas nacionales e internacionales de comprensión de lectura y tomando en consideración el aumento de inversión en tecnología en las instituciones educativas del país, el presente estudio buscó desarrollar y evaluar una herramienta virtual para mejorar la comprensión de lectura. Para ello, se adaptaron las estrategias de comprensión de lectura y ejercicios de vocabulario del entorno virtual ICON y se diseñó la plataforma LEO. Un total de 88 estudiantes de quinto grado de primaria, provenientes de colegios privados de nivel socioeconómico medio-bajo de Lima Metropolitana, participaron en este estudio cuasi-experimental, con un grupo control y un grupo que participó en la intervención digital a lo largo de 12 semanas. Todos los participantes fueron evaluados utilizando pruebas de entrada y salida de comprensión de lectura y vocabulario. Los resultados revelaron que los estudiantes que interactuaron con la plataforma LEO obtuvieron resultados significativamente más altos en la comprensión de textos narrativos y vocabulario luego de finalizada la intervención, respecto a sus puntajes al inicio de la misma y también en comparación con el grupo que no empleó la plataforma.
Validación de una escala de medición del consenso estratégico en equipos pedagógicos
Authors: Puente-Palacios Katia , Puente Tamara
Published: September 2020

Se estudia las evidencias psicométricas de validez de una escala de evaluación del consenso estratégico en equipos pedagógicos. El consenso estratégico es un proceso grupal descrito como la concordancia entre los miembros sobre asuntos estratégicos para el éxito del trabajo. Los participantes fueron 140 profesores de escuelas de Quito (Ecuador). La escala aplicadacuenta con 14 ítems y los análisis estadísticos realizados revelaron una estructura unifactorial que explica 49.72% de la variancia. La confiabilidad interna fue satisfactoria (α = 0.92; r ítem-total = 0.66). Los resultados revelan que la escala constituye una herramienta útil para el diagnóstico del consenso existente entre miembros de equipos pedagógicos y contribuye para la mejor comprensión del fenómeno.
El ajuste instructivo entre estilos de aprendizaje y enseñanza en la universidad
Authors: Ventura Ana Clara
Published: September 2020

Se presenta una revisión de artículos empíricos sobre el ajuste instructivo entre estilos de aprendizaje y estilos de enseñanza en la universidad (2002-2012). Se consultaron las bases dedatos Dialnet, Redalyc, Scielo y Doaj debido a su impacto en el contexto latinoamericano. Los descriptores fueron: “estilos de aprendizaje”, “estilos de enseñanza” y “universidad”. Se identificaron 53 artículos, de los cuales 17 cumplían los criterios de inclusión (artículo:empírico; muestra: universitaria, objeto: ajuste estilos de aprendizaje y de enseñanza, recortetemporal, idioma español). La revisión de la literatura mostró que el ajuste se investiga,entiende y aborda desde dos líneas: (1) la instrucción adaptativa o (2) la estilística. Se discuten los resultados.
Estilo de vida y presencia de síndrome metabólico en estudiantes universitarios. Diferencias por sexo
Authors: Álvarez Gasca María Araceli , Hernández Pozo María del Rocío , Jiménez Martínez Marcela , Durán Díaz Ángel
Published: September 2020

El presente estudio busca analizar la relación entre estilo de vida y el síndrome metabólico en estudiantes universitarios, así como establecer si existen diferencias por sexo. Los participantes fueron 970 estudiantes (67.4% fueron mujeres y 32.6% hombres) seleccionados a partir de un muestreo aleatorio. Se evaluó el Estilo de vida (EV), la Obesidad central y el Síndrome metabólico (SM). Los resultados mostraron SM en 4.63% y obesidad en 36.65%, con mayor frecuencia en las mujeres. El EV predominante fue bueno y mejor en hombres que en mujeres, y la mayor frecuencia del SM fue en el EV malo. La relación entre género, obesidad, y SM fue significativa para la población estudiada. Se encontraron diferencias entre hombres y mujeres.
Naturaleza de las emociones positivas en la evaluación de la Depresión: una nueva visión en psicometría
Authors: Moscoso Manolete S.
Published: September 2020

Los estudios científicos de las emociones han demostrado concluyentemente una robusta relación causal entre eventos estresantes de la vida diaria y la depresión clínica. El marco conceptual del presente estudio toma en consideración los marcos teóricos de Alex Zautra y de Susan Folkman acerca de la coexistencia de emociones positivas y negativas en el proceso de estrés y depresión. El propósito de este estudio es reportar el análisis de ítems y la validez convergente del Inventario Multicultural de la Depresión, Estado-Rasgo (IMUDER). En base a una muestra multicultural, se realizó los análisis psicométricos en base al coeficiente de correlación de Pearson, a fin de determinar la validez convergente. Los resultados de dichos análisis realizados en forma separada para la escala estado y para la escala rasgo, nos indican un elevado nivel de asociación y validez convergente entre las escalas estado y rasgo del IMUDER, dimensiones de distres y eustres, y las pruebas de depresión utilizadas en este estudio. Estos datos indican que el IMUDER es un instrumento psicométrico que presentauna sólida validez convergente y propiedades psicométricas adecuadas.
Validación de la escala de cinismo organizacional: un estudio con trabajadores argentinos
Authors: Salessi Solana , Omar Alicia
Published: September 2020

El objetivo del estudio consistió en validar la Escala de Cinismo Organizacional de Brandespara su empleo con trabajadores argentinos. Se analizó la equivalencia funcional del instrumento. Se administró una versión adaptada a una muestra de 396 empleados, quienes respondieron también una selección de instrumentos para explorar confianza en la organización, compromiso organizacional y satisfacción laboral. El análisis factorial exploratorio mostró una estructura de tres factores que explicaron el 68.8% de la varianza total. El análisis factorial confirmatorio condujo a re-especificar el modelo, eliminando tres ítems. La validez de constructo quedó demostrada en base a los análisis de correlación efectuados. La confiabilidad del instrumento alcanzó niveles satisfactorios. Se puntualizan las debilidades y fortalezas de la investigación realizada. Se sugiere una agenda para futuros estudios.
¡Llegó la hora! Expectativas y experiencias de parto de adolescentes embarazadas
Authors: Centenaro Levandowski Daniela , Marin Angela Helena , Pereira Carolina da Silva , Golembiewski Mendes Marianna
Published: September 2020

Este estudio cualitativo longitudinal investigó las expectativas y experiencias relacionadas con el parto de once adolescentes embarazadas de bajo nivel socioeconómico del Sur de Brasil. Ellas fueron entrevistadas en el segundo trimestre del embarazo y al segundo mes del nacimiento del bebé. El análisis de contenido cualitativo reveló una preferencia por el parto normal (debido a la mayor rapidez de recuperación) y sentimientos de miedo y ansiedad relativos al parto. Sobre la experiencia del parto, se observó un predominio de los partos vaginales y sentimientos de felicidad, así como informes de dolor. Un número reducido de participantes fueron acompañadas por su pareja o figuras femeninas. Se constató tanto correspondencia como ausencia de correspondencia con las expectativas para ese evento. Los resultados indican un escenario similar a lo que se encuentra entre madres adultas.
Validación de una escala de estrés cotidiano en escolares chilenos
Authors: Encina Agurto Yonatan José , Ávila Muñoz Myriam Viviana
Published: September 2020

Se evaluaron las propiedades psicométricas de una escala de estrés cotidiano en el contexto escolar (EECE). Se estudió la estructura factorial y la consistencia interna en una muestra de niños y adolescentes chilenos de la Región del Maule (n = 734) con edades entre 10 y 17 años. La solución factorial de tres factores resultó simple y coherente respecto a las principales dimensiones del contexto escolar que pueden llegar a ser estresantes para los estudiantes: estrés académico, estrés relacional y ambiente escolar inadecuado. Los índices de consisten- cia interna fueron buenos tanto para la escala general como para los tres factores. Además se aprecian diferencias significativas en la percepción de estrés según el sexo (hombre/mujer) y ubicación geográfica (rural/urbano), que son coherentes con lo que señala la literatura.
Estudio del impacto de imágenes ambientales en los aspectos emocionales
Authors: Sánchez Miranda Martha Patricia , Garza González Arturo De la
Published: September 2020

La presente investigación examinó las emociones que desencadenan imágenes de naturaleza y ciudad de forma automática e implícita con la técnica de facilitación afectiva y determinar si el mismo fenómeno que se ha estudiado en experimentos unimodales se repite en la modalidad cruzada. Participaron un total de 57 estudiantes de una universidad pública mexicana, donde se les expuso a imágenes de ambientes naturales y urbanos como facilitadores. Como objetivos se utilizaron palabras con connotación emocional positiva y negativa. Los resultados indican que al igual que en otras investigaciones, existen dos grupos de participantes, en donde no todos poseen emociones positivas hacia la naturaleza. Se discuten los resultados en términos de los mecanismos cognitivos que existen dentro de la técnica.
INVESTIGAÇÃO DE FRAUDES CORPORATIVAS INVESTIGATION OF CORPORATE FRAUD
Authors: Anderson Lopes Petter
Published: September 2020

Este estudo aborda o conceito de investigação e a importância do trabalho do investigador em casos de fraudes e corrupção no ambiente corporativo. A investigação científica tem um papel fundamental na investigação corporativa, bem como as técnicas que serão utilizadas. Traçar um plano, elaborar uma Teoria de Caso e estabelecer etapas de investigação bem definidas, corroboram com um trabalho bem sucedido do investigador profissional. O crime no ambiente corporativo tem níveis de complexidade e sofisticação variados e elevados, portanto, neste cenário cabe uma compreensão maior dos profissionais que trabalham com investigação. Profissionais da área de investigação devem agir de forma autônoma e sigilosa, sendo que no decorrer deste artigo, de forma clara e objetiva, estão definidos os conceitos de investigação e fraudes, bem como as principais etapas que envolvem o trabalho do investigador.
A PROFISSÕES DA SAÚDE E O TRATAMENTO DOS DADOS PESSOAIS: BOAS PRÁTICAS E A CONFORMIDADE
Authors: Joel Brito Lóssio Claudio
Published: September 2020

Diante do transformar de nossa sociedade, novos padrões de segurança e privacidade deverão serem adotados, nesse caso, voltado ao espaço cibernético, onde os dados e as informações são de suma importância para sua existência. Cada vez mais as profissões se misturam com o direito e com a tecnologia, e na área da saúde não é diferente, inclusive quando se trata de lei de proteção de dados, pois essa não é uma tarefa para o TI, advogado, é para o DPO – Data Protection Officer, também conhecido como encarregado de proteção de dados. O profissional poderá alegar o desconhecimento do direito à proteção de dados dos titulares? Ambientes médicos, assim como os profissionais e seus auxiliares deverão com celeridade buscar aprimorar seus processos de segurança da informação e Compliance para que a proteção de dados seja garantida, visto que a privacidade é um Direito Fundamental. O aprimoramento não está relacionado exclusivamente a seara dos técnicos de informática, mas aos funcionários, aos profissionais da saúde, aos ambientes de saúde tanto públicos quanto privados, também não apenas na área digital, mas também no ambiente físico.
The Divide among the Millennial Generation: Historical and Empirical Justifications. (Part one)
Authors: Radaev Vadim V.
Published: September 2020

This article is about developing a sociological approach towards generational cohort analysis. The previously examined generation of millennials is divided into two age cohorts. A specific group of so-called “3S” millennials (“smartphones”, “social media”, “slump in the economy”) is distinguished. This younger generation entered their period of adulthood starting in the year of 2008, which was marked by continuous economic recession and a broad dissemination of new technologies and digital consumer services. Data was gathered from the annual Russian Longitudinal Monitoring Survey (RLMS–HSE) for the years 1994–2018. The obtained results show a divide within the millennial generation, measured by a multiplicity of social indicators along with the preservation of many inter-generational differences. In part one of the paper published in this issue of the journal, we reveal that the younger “3S” generation of millennials has been dealing with new digital technologies since their early adolescent years. They are better educated, have more educated parents, and often postpone important decisions like marriage, first pregnancy, having children, employment in the labor market. Many intra- and intergenerational differences remain stable during the observation period when controlling for age and other standard variables.
[Rev.] On book publication: Popov N.P. Rossiya — Amerika: “Pryamaya svyaz”. Vospominaniya Amerikanista i Sovetologa. [Russia — America: “Direct Connection”: Memoirs of an Americanist and Sovietologist.] Moscow: KnigIzdat publ., 2020
Authors: Doktorov Boris Z.
Published: September 2020

The book is constructed in the form of an interview of the famous Soviet/Russian sociologist and americanist doctor of sciences N.P. Popov with doctor of sciences B.Z. Doktorov, who developed the genre of scientific memoirs and conducted over a hundred interviews with Russian and American sociologists. The paper covers three main topics. Like any biography, this is a personal story of the author — his youth in the post-war years, the path to the profession of a journalist and sociologist, the worldview of the “sixties”. Journalism leads the author, as well as many American pollsters, to the study of public opinion, at first American, continued at the Institute of US and Canadian Studies. He like no other is closely acquainted with the work of leading American pollsters: George Gallup, Louis Harris, Warren Mitofsky, Mervin Field and other gurus. The study of American polling technology and public opinion on socio-political problems and electoral orientations of the population were used by the author in further work at Soviet and Russian centers for the study of public opinion, first of all – at the All-Union center for the study of public opinion (VTSIOM), created in 1988, where he was offered a job by Tatyana Zaslavskaya and Boris Grushin. They also recommended him later as head of the sociological department of the presidential administration right before the 1996 election. The book includes a number of articles by the author on Russian and American public opinion in different years.
The psychological impact of COVID-19 on staff and patients in a psychiatric intensive care setting
Authors: Harries Bethan , Skelton Luke , Blake Lucy , Pugh Ria , Butler Margaret , Bolade Adenike , Rathouse Robert , Sethi Faisil
Published: September 2020

This article is part of a series exploring how the COVID-19 pandemic affected, and continues to affect, a psychiatric intensive care unit (PICU) in London, UK. The series so far has focused primarily on the systems, processes and practical challenges of managing acutely disturbed patients
in the inpatient setting with the added complexity of COVID-19 infection. This article outlines the psychological impact on staff and patients on a PICU during this time.
Apresentação do dossiê
Authors: Garcia Tânia da Costa
Published: September 2020

Música e política, temática ainda pouco visitada por historiadores e cientistas sociais que se debruçam sobre o século XX, laboratório dessa profícua combinação entre tecnologias comunicacionais, ebulição cultural, política de massas e utopias de esquerda.
Ambições e vocações cruzadas
Authors: Schmiedecke Natália Ayo
Published: September 2020

Dialogando com o tema machadiano da ambição e vocação em música, o presente texto enfoca as relações estabelecidas entre músicos populares e músicos de conservatório no interior do movimento da Nova Canção Chilena. Elegendo a cantata popular Santa María de Iquique (1970) – composta por Luis Advis e interpretada pelo conjunto Quilapayún – como representativa da articulação entre elementos historicamente concebidos como pertencentes a âmbitos separados (erudito, popular e folclórico; arte e política), buscaremos demonstrar que as opções estéticas e temáticas que caracterizam a obra dialogam intimamente com seu contexto político de produção, marcado pela perspectiva do advento de um governo de esquerda e pela intenção de utilizar o meio artístico como lugar de combate.
Abílio Manoel e a ola latinoamericana no Brasil dos anos de 1970
Authors: Garcia Tânia da Costa
Published: September 2020

A trajetória artística do cantor, compositor, produtor musical e radialista Abílio Manoel, falecido em 2010, confunde-se com o turbilhão de acontecimentos políticos que dominaram o Brasil entre o final dos anos de 1960 e a obscura década de 1970, cujos ventos trouxeram para cá a Nova Canção latino-americana. Iniciando sua carreira como compositor e cantor romântico, o caráter engajado de seu trabalho, foco desse artigo, manifesta-se em meados dos anos de 1970: data de 1972 o seu Lp América Morena; e, a partir de 1978 até 1982, produz e veicula o programa América do Sol na rádio Bandeirantes. O presente artigo, no rastro da carreira artística de Abílio Manoel, examina o lugar e os sentidos atribuídos à música popular latino-americana no Brasil, sobretudo a Nova Canção, durante a ditadura militar.
Functional ARCH and GARCH Models: A Yule-Walker Approach
Authors: Kühnert Sebastian
Published: September 2020

Conditional heteroskedastic financial time series are commonly modelled by (G)ARCH processes. ARCH(1) and GARCH were recently established in C[0,1] and L^2[0,1]. This article provides sufficient conditions for the existence of strictly stationary solutions, weak dependence and finite moments of (G)ARCH processes for any order in C[0,1] and L^p[0,1]. It deduces explicit asymptotic upper bounds of estimation errors for the shift term, the complete (G)ARCH operators and the projections of ARCH operators on finite-dimensional subspaces. The operator estimaton is based on Yule-Walker equations, and estimating the GARCH operators also involves a result estimating operators in invertible linear processes being valid beyond the scope of (G)ARCH. Moreover, our results regarding (G)ARCH can be transferred to functional AR(MA).
Nucleic Acid and Immunological Diagnostics for SARS-CoV-2: Processes, Platforms and Pitfalls
Authors: Premraj Avinash , Aleyas Abi George , Nautiyal Binita , Rasool Thaha Jamal
Published: September 2020

Accurate diagnosis at an early stage of infection is essential for the successful management of any contagious disease. The COVID-19, caused by the SARS-CoV-2 virus is a pandemic that has affected 214 countries affecting more than 30.8 million people causing 0.957 million deaths as of third week of September, 2020. The primary diagnosis of the infection is done either by the molecular technique of RT-qPCR by detecting portions of the RNA of the viral genome or through immunodiagnostic tests by detecting the viral proteins or the antibodies produced by the host. As the demand for the test increased rapidly many naive manufacturers entered the market with novel kits and more and more laboratories also entered the diagnostic arena making the test result more error-prone. There are serious debates globally and regionally on the sensitivity and specificity of these tests and about the overall accuracy and reliability of the tests for decision making on control strategies. The significance of the test is also complexed by the presence of asymptomatic carriers, re-occurrence of infection in cured patients as well as by the varied incubation periods of the infection and shifting of the viral location in the host tissues. In this paper, we review the techniques available for SARS-CoV-2 diagnosis and probable factors that can reduce the sensitivity and specificity of the different test methods currently in vogue. We also provide a check-list of factors to be taken care to avoid fallacious practices to reduce false positive and false negative results by the clinical laboratories
Cell Membrane Rupture: A Novel Test Reveals Significant Variations Among Different Brands of Tissue Culture Flasks
Authors: Tchao Ruy
Published: September 2020

Unanticipated errors in scientific research data can be attributed to the unwarranted assumption of uniformity in the polystyrene surface that is ubiquitously used in tissue culture flasks and dishes. We have shown that when adherent cells are subjected to fluid shear force, equivalent to rinsing the culture with a balanced salt solution, cells on some areas of the polystyrene surface will immediately rupture while still adherent on the surface. This heterogeneity on the polystyrene surface can cause unexpected variability in experimental results and in replicating experiments among labs. In this paper a novel quantitative method is described to measure the degree of heterogeneity on the polystyrene surface of tissue culture flasks. The results show significant variation among several brands of tissue culture flasks as well as large variability within the production lot of a manufacturer. The assay method involves loading the cells with a fluorescent marker that is released upon membrane rupture. Cell membrane rupture also causes the loss of marker proteins used in Westernblots. This novel assay method can be used to monitor the batch consistency and the manufacturing process of flasks and dishes. It may also be used to test new biomaterials.
Distorções Regionais na Distribuição do Fpm: Um Estudo Aplicando Conjuntos Fuzzy em Municípios de Minas Gerais
Authors: Castro Kleber Pacheco de , Lima Ana Carolina da Cruz
Published: September 2020

O FPM é uma transferência incondicional e redistributiva recebida pelos municípios e oriunda da União. Seus critérios de rateio de recursos apresentam inconsistências que geram uma distribuição pouco equânime dos recursos do fundo. Usando o instrumental matemático da lógica fuzzy, este artigo verificou a relação entre a distribuição do FPM e o nível de necessidade fiscal dos municípios de Minas Gerais entre 2000 e 2010. Constatou-se que a maior parte dos municípios recebe recursos aquém do necessário e que este problema tende a ser maior nas cidades mais populosas. Os resultados corroboram outras evidências em torno da divisão distorcida do FPM e reforçam a necessidade de revisão de seus critérios.
Análise de variáveis para mensuração da eficiência do gasto público por função de governo
Authors: Ribeiro Siqueira Leonardo , Gomes de Souza Weslei , Araújo Sousa Farias Rafael , De Souza Bermejo Paulo Henrique
Published: September 2020

Nas últimas décadas, diversos países implementaram políticas com vistas a obter eficiência nos gastos públicos. Esse tema também tem sido objeto de estudo da academia. Foi observado que geralmente as publicações realizam a mensuração da eficiência de setores específicos, evitando uma análise ampla. Para essa mensuração, a seleção de variáveis é uma etapa relevante. O objetivo desta pesquisa é identificar as variáveis mais utilizadas para mensurar a eficiência do gasto. Para tal, foi conduzida uma revisão bibliográfica sistemática, utilizando os métodos Proknow-C e Análise de Conteúdo, que ao final do processo identificou 82 artigos. Nesses trabalhos foram identificados 225 inputs e 365 outputs. Os de maior recorrência foram consolidadas quadros-resumo. Entre os achados, destaca-se a ausência de padrões na escolha de inputs e outputs e a falta de arcabouço teórico para fundamentar a utilização delas, o que pode comprometer a confiabilidade dos estudos.
Consórcios Intermunicipais para o Desenvolvimento: Determinantes da Cooperação entre os Municípios Baianos
Authors: Doin Tatiana Aparecida Ferreira , Lopes Laerson Morais Silva , Afonso Adelzira Souza , Rigo Ariádne Scalfoni
Published: September 2020

O presente artigo se propõe a identificar quais as características econômicas, fiscais, demográficas e geográficas dos municípios baianos influenciam a formação de consórcios intermunicipais de desenvolvimento. A fundamentação teórica do estudo baseou-se na Teoria da Ação Coletiva Institucional, importante lente adotada na literatura para a análise dos fatores que condicionam a propensão à cooperação intergovernamental. Quanto ao método, o estudo é descritivo e exploratório, com abordagem quantitativa, que utilizou bases de dados secundárias para analisar, pela estatística inferencial e o modelo de regressão logística, os dados coletados dos 417 municípios baianos. Os resultados evidenciaram três características correlacionadas, ou seja, que influenciam a formação de consórcios intermunicipais de desenvolvimento: maior receita tributária, maior porte (população) e municípios inseridos em aglomeração urbana. Sugere-se que estudos futuros analisem a economia de escala decorrente desses acordos e avaliem a influência da orientação política na cooperação intermunicipal.
Characteristics of sweeteners used in foods and their effects on human health
Authors: Antonik Natalia , Janda Katarzyna , Jakubczyk Karolina
Published: September 2020

Foodstuffs containing large amounts of sucrose, which is rapidly absorbed by the human body, cause a marked increase in blood glucose levels; for some people, especially those with diabetes, this is undesirable. Therefore, efforts were undertaken to produce food with a reduced calorie content, but maintaining a sweet taste. Additionally, food producers were interested in cutting costs by replacing sugar with a cheaper alternative. Saccharin, one of the first synthetic sweeteners, was discovered in the USA in the 2nd half of the 19th century. Subsequently, other sugar substitutes were developed: synthetic (e.g. aspartame or acesulfame K), semi-synthetic (xylitol, mannitol), or polyols.

The latter were used during the First and Second World War to increase the calorific content of the available food. Nowadays, the advancing obesity epidemic has resulted in the increasing popularity of synthetic and semi-synthetic sweeteners. However, from the beginning of their existence there have been controversies regarding their safety and impact on health. There have been many studies on individual sweeteners, specifying any adverse or side effects. Therefore, the aim of this paper is to summarizes the characteristics of the most popular sweeteners and their effects on human health.
A Comprehensive Study of Unconventional Reservoirs: The Case of Rechitskoe Field Sediments of Rock Units I-III
Authors: Kudryashov Alexey , Povzhik Peter
Published: September 2020

Due to the deterioration of petroleum resources in the Republic of Belarus, unconventional reservoirs, which contain hydrocarbons in "shale-like" low-permeable rocks, which include Domanic deposits, become increasingly important. These rocks containing hydrocarbons are both producing oil and at the same time they are not reservoirs in the traditional sense (Varlamov A. I. et al., 2017). The most common technology for developing unconventional reservoirs is drilling horizontal wells with multi-stage hydraulic fracturing. The technological efficiency of drilling such wells will primarily depend on getting into the so - called "sweet spots" - places characterized by the best petrophysical, pyrolytic and geomechanical properties. This ultimately determines the need for a comprehensive study of hydrocarbon deposits in unconventional reservoirs.

This article describes the workflow for studying unconventional reservoirs of one of the fields of the Pripyat trough of the Republic of Belarus. Studying these reservoirs was a challenge because due to geological and surface conditions no seismic data was available. The first well logging results showed the absence of significant rock anisotropy detected by standard methods of acoustic logging. This caused difficulties in determining the direction of drilling horizontal wells. There were also insufficient results of core studies of wells, including fully geochemical and geomechanical studies.

Carrying out a comprehensive study of promising formations and confirming their oil bearing capacity required making a comprehensive program presented below, which outlined the types of studies that would provide necessary information about lithological, petrophysical, pyrolytic, and geomechanical characteristics of unconventional reservoirs of the field under study.

Core studies performed within the integrated study confirmed that the studied sediments are source rocks. At the same time, according to the results of pyrolytic research, it was found that the rocks contain both in-situ hydrocarbons, and the ones which migrated from the underlying formations.

The set of geophysical studies carried out on the legacy wells, including logging, hydraulic fracturing and surface seismic monitoring, allowed determining the direction of maximum stress, which eventually allowed determining the direction of drilling horizontal wells.

The set of studies described in this article can be used in the study of other unconventional deposits of the Pripyat trough, belonging to the Domanic type.
The Effects of Crude Oil Gravity and Composition on EOR Surfactants Selection and Performance
Authors: Al-Anazi Amer , Abdelgawad Khaled , Alsofi Abdulkarim , Kaidar Ziyad
Published: September 2020

Surfactant applicability for enhanced oil recovery (EOR) is conventionally characterized by their efficiency in reducing oil/water interfacial tension (IFT). A suitable surfactant for one crude oil might not be suitable for another in terms of lowering IFT. Therefore, formulations should be revisited for particular cases, especially with changes in crude oil API gravity. In this work, we investigate the performance of various EOR surfactants and their behaviors with different crude oil samples from super light to extra heavy.

EOR surfactants of different classes showed a suitable compatibility in high salinity brines and at high temperatures. The gravities of tested crude oil samples ranged from 8 to 37° API. Crude oil properties were validated using viscometer and density meter. The experimental work focused on IFT measurement and critical micelle concentrations (CMC). IFTs were measured using a spinning drop tensiometer at a fixed concentration and CMCs were determined using a Du Noüy ring type tensiometer.

CMCs of the amphoteric and nano-encapsulated-ionic surfactants were found very low compared to that of cationic and nonionic surfactants. Both amphoteric and nano-encapsulated-ionic surfactants demonstrated superior results across all benchtop studies. They have exhibited a better temperature stability with low- and high-salinity brines. Both showed low IFT values around 0.02 mN/m for light crude oil. Those IFT values remained the lowest compared to other surfactants with heavier crude oil samples but gradually increased to 0.18 mN/m for the heaviest crude. In terms of IFT equilibration, the amphoteric and nano-encapsulated-ionic surfactants resulted in IFT values that gradually increased with the increase of oil viscosity. This was quite opposite for the cationic quaternary ammonium and anionic alfa olefin sulfonate surfactants. The different behavior of surfactants with crude oils of varying compositions indicate the distinctive reaction of each surfactant with a specific crude oil.

The results highlight the effects of crude oil gravity and composition on surfactant ability to result in a low IFT. Coupled with CMC measurements at elevated temperatures, a good insight can be established for evaluating the performance and potential of a surfactant for EOR application.
Selection of Effective Solvents – Universal Modification of Presently Available Enhanced Oil Recovery Methods and Oil Production Stimulation Processes
Authors: Litvin Aleksandr Tarasovich , Terentiyev Aleksey Alekseyevich , Gornov Denis Anatolevich , Kozhin Vladimir Nikolaevich , Pchela Konstantin Vasiliyevich , Kireyev Ivan Ivanovich , Demin Sergei Valeriyevich , Nikitin Aleksandr Valeriyevich , Roschin Pavel Valeriyevich
Published: September 2020

The paper presents various modified technologies to enhance oil production and to stimulate the inflow of high-viscosity oil, based on a combination of the traditional approach and the use of solvents.

The results of laboratory experiments to study the effects of 29 solvents reagents on high-viscosity oil samples from 5 different objects are presented. Based on the analysis of the obtained laboratory data, basic recommendations are formulated to increase the efficiency of extraction of high-viscosity oil using solvents.

In order to determine the potential for modifying oil recovery enhancement and well stimulation methods by adding solvents to their process, a comparative hydrodynamic modeling of 3 treatment options for the bottom-hole zone and subsequent assessment of their economic effect were carried out.
The Application of Drilling Fluid System Based on Salt-Saturated Direct Emulsion in Construction of Wells on Yurubcheno-Tokhomskoye Field
Authors: Tikhonov Evgeny Vladimirovich , Korsunov Evgeny Ivanovich , Kovshov Nikolay Leonidovich , Semenikhin Igor Petrovich , Gassan Alexander Alexandrovich , Pogorelova Svetlana Petrovna , Kharitonov Andrey Borisovich , Zagrivny Fyodor Alexandrovich , Lemeshov Sergey Alexandrovich , Ganiev Denis Fakilevich
Published: September 2020

One of main drilling challenges in the Yurubcheno-Tokhomskoye field is fluid losses. In particular, the requirement of a drilling fluid with minimal mud weight to minimize risks associated with fluid losses when drilling overbalanced, enabling drilling through salt intervals. Historically, the technical column interval has been drilled using generic OBM using local crude oil. However, such fluids carried significant health and safety risks associated with low flashpoints.

Invert emulsion fluids, based on local crude oil as the continuous phase, are characterized by flashpoints of 6-8 °C, which does not address the safety concerns. Alternatively, a drilling fluid, designed based on a salt-saturated, continuous phase, direct emulsion, with up to 30 % local crude oil (as the internal phase) to achieve a mud weight 1.10 SG is characterized by a flash point higher than 100 °C. A flash point >100 C enables significant minimization of these health and safety risks.

As well as improving the fluid flashpoint and avoiding related incidents, direct emulsion fluids can be formulated to present high long-term stability, a stable rheology profile, and superior filtration control.

Five 245 mm casing intervals were drilled to date using the direct emulsion and successfully set at targeted TDs. The solutions applied have assisted to achieve following KPIs:

15% less mud volume due to lower volume lost into the formation. 45% less crude oil used due to significantly lower oil content in the fluid. 15% less losses into the formation presumably due to low Pumps on ECD achieved. 50% less time associated with lost circulations.

These achievements resulted in a three-day reduction in the time of the interval construction (average of five wells drilled) compared to similar intervals drilled using generic invert emulsions.

This paper discusses the development and selection of a new, economical, safe, and efficient drilling fluid, for 245 mm casing intervals in the Yurubcheno-Tokhomskoye field. Supporting laboratory test results, fluid performance achieved, lessons learned and recommendations for further system optimization of the drilling fluid and drilling practices, are presented for consideration.

The positive KPIs and superior mud performance achieved enable expanding the use of the direct emulsion on the field and recommend its application to other fields in the area.
Positive Experience Using Foam Cementing Technology for Production Casing Cementing in the Volga-Ural Field
Authors: Fomenkov Aleksey , Pinigin Ilya , Velikiy Daniil , Denisov Ivan
Published: September 2020

The largest discovery of oil and gas in recent years is situated in the Volga-Ural field in Orenburg Oblast. The field was discovered in 2005. The development target is the Devonian Dkt formation which is an aggregate of ancient strata in the Earth's crust that were formed during the Devonian Period of the Paleozoic Era. The Devonian System is divided into a Lower, Middle and Upper series. It consists of alternating layers of sandstone-claystones and siltstones, which have low permeability. Hydraulic fracturing is required to obtain hydrocarbon inflow from this type of rock.

The well design employed in the Volga-Ural field incorporates five casing strings and the main challenge while drilling wells in this field is lost circulation. This ranges from partial fluid loss to no returns and has a significant impact on the cementation of the 178/146 mm production casing. Lost circulation has resulted in a failure to achieve the targeted top of cement, annular pressure, annular crossflows and a poor cement bond with both the casing and formation. Prior to 2015, a stage cementing collar (SCC) technique was used to cement the production casing without losses. However, this cementing technique often resulted in poor zonal isolation resulting in water flows between zones. Additionally, after well completion, poor cement bonding to both the casing string and producing formation created a pathway for annular flow of the formation fluids. These challenges called for an alternate solution. This paper presents how foamed cementing technology was used to solve the challenges in isolation of the sandstones and the subsequent improvement of the cementing bond quality. The foam cementing technique was tested in the Volga-Ural field at the end of 2015 and in early 2016 and became the standard solution for cementing the 178/146 mm production.
Construction of Horizontal Wells on the Salmanovskoye Field: Challenges Encountered, Decisions and Measures Taken to Ensure Trouble-Free Drilling
Authors: Kabanov Alexander Viktorovich , Matsera Aleksander Mikhailovich , Galimkhanov Aydar Ramilevich , Rudenko Sergey Ivanovich , Tikhonov Evgeny Vladimirovich , Kharitonov Andrey Borisovich , Kruchenko Dmitry Viktorovich , Sokovnin Sergey Anatolyevich , Sidorov Dmitry Nikolaevich
Published: September 2020

Several wells have been drilled recently by Arctic LNG 2 at the Salmanovskoye (Utrenneye) field. Horizontal drilling at this field is challenging because of an inclination angle up to 52° in the intermediate section, drilled with a 311.2 mm bit. Drilling of large (311.2 mm) intermediate sections with significant vertical offset is not common for this area. The production wellbore section was drilled at an angle of 86°. Solutions suggested for complex wellbore sections drilling, included the use of oil based mud.

Multiple tests were conducted in order to select the best drilling fluids formulation and an action plan was developed to maintain stability of the wellbore and to optimize wellbore cleaning.

Nevertheless, multiple issues were encountered during the first well drilling, which resulted in a significant extension of the construction period. Lessons learned during the first well were studied thoroughly and included into risk assessments made for drilling of subsequent wells. This contributed to the overall success of drilling these wells and to the significant reduction of their construction periods.

Drilling practices and fluids properties were optimized as follows:

The whole volume of mud was mixed as required for intermediate section drilling. Dedicated software was used for the continuous modeling of wellbore cleaning efficiency and drilling parameters were adjusted promptly in accordance with the modelling results. HPHT filtration rate was reduced to 2 ml/30 min in challenging wellbore sections. The decision tree was revised as required for the efficient response in case of lost circulation.

Newly prepared OBM, combined with the developed and optimized action plan, contributed to the incident-free drilling of complex wells at the Salmanovskoye field.

Located remotely, requirements for proper logistical solutions was vital for success. This is discussed in details below.

With the success of these messures, it is expected that these practices will be implemented at two other fields on the Gydan peninsula and in other areas where traditional drilling practices may be ineffective due to challenging lithology, geological conditions and logistics and HSE risks
New Tailored Spacer System Helps Reduce Lost Circulation and Enhances Cement Bonding during Multistage Cementing Operations in Fractured Formations in Kyumbinskoe Field, Eastern Siberia
Authors: Tcibulskii Mikhail , Massie Iain , Agapiou Kyriacos , Trofimenko Ivan , Lodin Alexey , Khohryakov Vladimir
Published: September 2020

Lost circulation (LC) is commonly encountered in drilling and cementing operations and can significantly contribute to non-productive time (NPT). An operator in the Kyumbinskoe Field faced this challenge in a fractured production section of the formation, and conventional LC solutions had been ineffective at achieving strict regulatory top of cement (TOC) requirements and satisfactory cement bonding. This paper describes a tailored spacer fluid system engineered to effectively and efficiently prevent LC to meet the job requirements. The tailored spacer system includes additives that perform synergistically to help prevent LC in permeable and fractured formations and enables rheological hierarchy to facilitate effective mud displacement. The spacer was designed to meet operational parameters for cementing a production casing string in two stages through the use of a multi-stage tool and was subjected to thorough verification through lab testing and computer simulations to ensure job requirements could be met. The tailored spacer system was used in three trial jobs to assess its ability to minimize losses in a permeable and fractured formation with a history of LC with the ultimate goal to achieve planned TOC and improve cement bond quality as verified by Cement Bond Logs (CBL’s).

Use of this tailored spacer system helped to minimize losses experienced on all three wells. CBL results were also significantly improved with an average of 70% of the cemented interval being classified as "good bond" on wells cemented without the tailored spacer system to 88% on the three wells where it was used. Barrier dependability with the new spacer system was improved through achieving strict regulatory requirements for TOC on two out of three wells and improved cement evaluation results, which is a critical requirement of well construction that allows for maximizing production over the life of the well.
New Opportunities for Multistage Stimulation Design - Frac Sleeves Activated by Single-Sized Dissolvable Balls
Authors: Vikulin Nikita Anatolievich , Rusakov Valeriy Arkadyevich , Aliyev Abdulali Akifovich , Mityaev Oleg Igorevich
Published: September 2020

This article includes review of evolution of multistage fracturing completions for conventional oil reserves in continental Russia and focuses on attempts of the LLC "RN-Yuganskneftegaz", the one of the largest operator company in Russia, to solve the challenge of well life extension by implementing new completion technologies allowing reliable means of re-fracturing on the well after several years of service as well as the means to isolate gas or water break-through.

A comparative analysis of different types of multistage fracturing completions was performed by LLC "RN-Yuganskneftegaz" with the aim to select the most suitable technology to address the above-mentioned goals without sacrifice of time required to drill, complete and stimulate the well.

As the result of the analysis the technology of the frac valves activated by single-sized dissolvable balls was selected as a most appropriate. The successful field trial on 2 wells is described in this paper.