bluuebunny/crossref_metadata_2025 huggingface dataset:
Executing Unconventional Coiled Tubing Sand Plugs for Multistage Fracturing Operations in HP/HT Wells
Authors: Singh Ishaan , Saraf Aman , Pathak Akash Ramesh , Bandyopadhyay Bholanath , Dehingia Madhurjya , Wijoseno Danny Aryo , Sharma Lovely , Gondalia Ravi Ramniklal , Jha Amay Kumar , Joshi Vaibhav , Shaik Moulali , Rao Dasari Papa
Published: April 2020

Coiled tubing (CT) sand plug operations associated with multistage fracturing operations in high-pressure/high-temperature (HP/HT) wells are very challenging, in part because of the small number of such jobs that have been performed worldwide. The wells in "A" field in India have HP/HT formations, with a bottomhole temperature (BHT) of 310°F and a reservoir pressure of 9,000 psi. Although millable bridge plugs are preferred industry-wide, this case illustrates how sand plugs become a suitable alternate solution for multistage stimulation to address space limitations, equipment and completion restrictions, and small tubing sizes, even in challenging downhole conditions. This study provides solutions to operational challenges of low injectivity and completion restrictions, which preclude bullheading and use of conventional bridge plugs. Simulations were sensitized to identify the best solutions for sand settling time, HP/HT conditions, pumping rates, CT speeds, and cleanouts where calcite or scale deposits on sand hinder bottomhole assembly (BHA) penetration.

Best practices are given for sand plug operations in challenging HP/HT environments; those best practices can be applied as a reference to design, prepare, and safely perform CT sand plug jobs in such conditions around the world. To address operational challenges in the cases presented here, the first three stages were bullheaded and the last two (a total 325-m sand plug) were placed using CT. Wireline was run to verify CT sand plug tag at ×200-m measured depth (MD). After the successful refracturing job, the 340-m sand plug was cleaned out, followed by acid spotting and squeeze using CT to rejuvenate the lowest zone. Strict application of the recommendations prevented the occurrence of operational contingencies, such as stuck CT, sand bridging, and settling of sand in surface equipment.
Prelude FLNG Towing, Station-Keeping and Mooring Hook-Up
Authors: Jones Ashley Michael , Clergue Simon , Pedlow Philip Jonathan , Holyst Cyril , Artus Victor , Buck Andrew , Wake Damian , Keij Willem
Published: April 2020

Prelude FLNG ("Prelude"), the largest offshore floating facility ever built, was constructed in Geoje, South Korea, requiring a 3,200nm ocean tow to its installation location 475km north northeast of Broome, Western Australia. A team of station keeping vessels then took control of Prelude to accurately hold her in position above the pre-laid moorings for mooring hook-up operations.

Planning and executing the tow, station keeping and mooring hook-up operations for mega floaters in remote locations requires precise planning, bespoke solutions to unprecedented challenges, comprehensive testing over a prolonged period and a global team with a diverse skill set. Overcoming key challenges required extensive engineering coupled with state-of-the-art vessel simulations, a bespoke mooring handling system, and full-scale winch wire testing. The result was a safe, successful and efficient operation demonstrating the industry's ability to execute the unprecedented challenges of projects in the search for economic development of remote and challenging reservoirs.
Early Kick Detection from Downhole Measurements: A Novel Method for Reducing the Frequency and Magnitude of Loss-of-Well-Control Events
Authors: Tost Brian Christopher , Rose Kelly , Carney Janine , Aminzadeh Fred , Suhag Anuj
Published: April 2020

Loss-of-well-control (LOWC) events are generally defined as uncontrolled flow of formation or other fluids to either the surface or another subsurface formation. Such events are also known as blowouts. Blowouts can result in the loss of human life, catastrophic damage to ecosystems, and substantial economic losses. Many blowouts start with a "kick event", where the formation pore pressure becomes greater than the wellbore pressure, causing formation fluid to flow into the wellbore and combine with the drilling fluid (i.e., mud). Detecting a kick as early as possible is key to preventing a blowout. Conventional kick detection methods (e.g., monitoring mud pit returns, monitoring wellbore liquid levels) are usually time-consuming, resulting in delays during which the kick may grow in intensity and efforts required to re-establish well control may become more extensive. Some, more sophisticated kick detection techniques use instrumentation that can be costly. In this paper, an alternative, lower-cost, early kick detection method is proposed.

Here a kick detection method is proposed that uses measurements from the instrumentation deployed on the drillstring to provide real-time information on the wellbore. Specifically, bulk density, acoustic (compressional wave) velocity, and electrical resisitivity are considered for use as detection parameters. These fluid mixture (combined formation and drilling fluid) properties as a function of kick fluid volume are estimated. Theoretically, these parameters are found to be sufficiently responsive to be used for kick detection. However, additional work is needed to determine how these parameters respond in experimental or field conditions.
Fully Integrated Subsea Sulfate Removal and Low Salinity Plant for IOR and EOR
Authors: Hegdal Torbjørn , Haruna Samuel , Sveberg Knut
Published: April 2020

The world's first full-scale subsea plant for production of sulphate free or low salinity water for IOR and EOR purposes has been designed, procured, constructed, and commissioned. This has been achieved with the involvement and support of an original equipment manufacturer, the Norwegian Research Council, and several offshore oilfield operators. The full-scale subsea treatment plant has undergone qualification in accordance with API 17N, and this paper shares key design aspects of the plan, operational experience, and the water quality results achieved.

Subsea seawater treatment for water injection has several inherent advantages compared to topside treatment. One significant aspect is the increased flexibility afforded to reservoir engineers in improving effective reservoir management by providing the opportunity to implement any desired water injection capacity, anywhere and anytime. In addition, the ability to provide 'tailor made' water for injection into oil reservoirs is seen as a game changing opportunity for offshore oilfield production companies wishing to produce more, produce faster, and produce cheaper.

The process advantages of the seawater treatment plant being on the seabed allows for a design that is simplified compared to a corresponding topside plant. This system design is explained in the paper and how it translates into improved reliability and availability. The all electric design also has the capabilities to be installed, moved, and reused on the seabed with minimum impact on topside infrastructure.

This paper provides information that has not been presented before about the novel subsea seawater treatment process. It shares commissioning and operational knowledge gained during a six month test period and includes water quality results achieved at progressive points through the treatment plant. The ability to operate a water treatment plant on the seabed necessitates instrumentation and control that provides good condition monitoring of equipment and the ability to check and control water quality. The novel methods that have been employed and tested on this treatment plant are discussed.

The treatment plant has been fully tested and is now available to clients for installation and operation on an offshore field. Lessons learnt are shared along with showing how the treatment design can be used to provide high-quality water on a wide range of field applications at any stage of a field's lifetime.

There are several aspects of the design that reduce the health, safety and environment (HSE) impact of water injection in general, including; lower power consumption (reducing carbon footprint) and no (or significantly reduced) liquid chemical requirement; hence, lower handling exposure for operators.
Decisions, Decisions – FLNG Technology Options for Pretreatment, Liquefaction and Driver Selection
Authors: Tierling Kenneth Shane
Published: April 2020

Floating LNG (FLNG) technologies are being deployed to monetize mid-sized offshore gas reservoirs, avoiding constructing a sub-sea gas pipeline to a land-based LNG facility and export jetty. Containing the processing to an oceanic environment also reduces the impact on indigenous peoples as well as terrestrial flora and fauna. FLNG facilities also have the potential of serving multiple offshore fields over the life of the facility, thereby reducing the minimum size field that can be economically monetized.

Three major decisions for FLNG topsides are pretreatment, liquefaction and driver technology selections, with major impacts on safety, weight, space, maintainability and sensitivity to motion. A fourth decision is selection of a new build hull or LNG carrier revamp. The take-away from this work is an understanding of the tradeoffs inherent in these selections, supporting tailoring an FLNG facility to business constraints.

Cryogenic processing requires pretreatment for removal of water and carbon dioxide to prevent solids formation. The use of brazed or welded aluminum equipment, common in cryogenic processing, also requires the removal of mercury. Candidate pretreatment technologies will be covered with an emphasis on the advantages and drawbacks regarding weight, space, and sensitivity to both tilt and motion.

Offshore liquefaction technologies are often novel and have few or no offshore references. The available offshore liquefaction technologies and Licensors will be presented. Because of the diversity of liquefaction technologies, the technologies will be grouped by refrigerant, and then these liquefaction categorizations will be compared with an emphasis on safety, scale, weight, and sensitivity to motion and efficiency.

Application of mechanical drives for centrifugal compressors in an offshore environment is well-practiced. Given this maturity, types of technologies will be compared on power ratings, availability, maintainability, flexibility and weight, without referring to individual suppliers.
The Application and Comparative Study of Calcined Clay and Nanoclay Mixed Cement Slurries at HPHT Conditions
Authors: Murtaza Mobeen , Rahman Mohammad Kalimur , Al Majed Abdulaziz Abdulla
Published: April 2020

In oil and gas wells construction, the cement sheath in the annulus between casing and formation plays a critical role throughout the producing life of the oil and gas well. Under elevated conditions of temperature and pressure, set cement changes its physical, chemical and mechanical properties. Sometimes these changes can lead to strength retrogression of cement. Recently, it was found that calcined clay (CC) and nanoclay (NC) significantly improve the hardened cement matrix properties as both materials have pozzolanic properties. Both additives have characteristics such as acid and sulfate resistance, low heat of hydration, low density, low permeability and the formed phases with the higher thermal endurance.

In this study, cement mixes with different percentages (1% & 2%) by weight of cement (BWOC) of calcined clay and nanoclay were investigated and compared with Class G cement slurry. Rheology, fluid loss and compressive strength properties of all cement slurries were measured.Rheological properties were measured at 50°C temperature and atmospheric pressure. The fluid loss test was conducted at 50°C and 1000 psi pressure. The uniaxial compressive strength (UCS) test was conducted for cement samples cured at 121°C temperature and 3000 psi pressure conditions for 24 hours and 5 days in HPHT curing chamber. Microstructural investigations were conducted using SEM analysis of cured samples.

It was observed that addition of nanoclay and calcined clay in Class G cement enhanced the rheological properties of cement slurries. The plastic viscosity increased with an increase in percentages of both additives. Higher values of yield point and plastic viscosity were obtained for calcined clay. In case fluid loss, a reduction in fluid loss was noticed for nanoclay. There was no appreciable change in fluid loss with the addition of calcined clay in mixes. Calcined clay-based cement slurries resulted in robust structure and sustained high compressive strength after exposure to high temperature high-pressure conditions. The nanoclay-based mixesgave higher strength compared to Class G cement slurry but lower than calcined clay. The compositional analysis showed that calcined clay gave low calcium/silica ratio and strong bonded structure.

This study will pave a way for researchers to study further the application of calcined clay in oil and gas cementing and its long-term durability.
A Robotic System Development for Rigless Light Intervention
Authors: Figliuolo Saulo Queiroz , Beal Valter Estevão , Rodamilans Guilherme Bulhosa , Almeida Danilo Araujo , Heredia Laerte Girola , Almeida Cleber Ribeiro , Igino Wellington Passos , Santos Hugo Francisco Lisboa
Published: April 2020

A major concern in offshore production is the well intervention cost and the time taken to perform the operations. These issues relate to the need for a rig or a similar unit to perform those operations. This paper presents the current stage of the development of an autonomous robot for rigless well interventions. The robot enters the well through the Christmas Tree using a special tool. This proposal will allow significant cost reduction by avoiding the need for a rig to do light workover operations in offshore locations. This strategy reduces intervention time since a simpler unit may deploy the robot. Examples of operation performed by the robot are production logging, gas lift valve replacement, sliding sleeve opening and closing and plug insertion or removal. A Simplified Robot allowed evaluating the technical feasibility of this proposal, both theoretically and experimentally. This Simplified Robot allowed evaluating the Traction System, the Energy Storage, and the Positioning Algorithm. After that, the design of the Real Robot started. This system will be modular and adjustable according to the needed operation.
Appomattox Mooring System Lessons Learned
Authors: Liagre Pierre F. , Ang Zhili , Wibner Christopher G. , Aragh Sina H.
Published: April 2020

This paper presents a multitude of lessons learned during the 5 years spent on the design, manufacturing and delivery of the on- and off-vessel mooring components for the Appomattox semi-submersible.

Appomattox is Shell's newest and largest deepwater oil & gas production asset in the Gulf of Mexico (GoM). It was successfully moored about 260 kilometers Southeast of New Orleans, in June 2018 using a 16-point chain-polyester-chain mooring system. It was the culmination of the work done by a dedicated team of Shell civil-marine engineers, mooring equipment suppliers and an offshore installation contractor. Shortly after completion of mooring lines hook-up operations, the polyester ropes were pre-stretched, and the FPS was moved into position for the start of the Steel Catenary Riser (SCR) system installation. Appomattox started production in May 2019. The mooring equipment has so far been performing as expected.

The delivery of Appomattox mooring components was particularly challenging due to an unusually large number of stringent constraints including: 40-year design life, first application of fairleads with underwater chain stoppers in the GoM to mitigate out-of-plane chain link bending fatigue, polyester rope properties fine-tuned to ensure that installation and in-service requirements are met, stringent inspection oversight to enforce project-specific requirements, Thermal Spray Aluminum (TSA) on portions of the platform chains and novel chain handling equipment and method for mooring lines hook-up operations, just to mention a few. The design of the overall system and management of the mooring equipment vendors was performed using mostly in-house resources.

The paper starts with some general information about the Appomattox development. The three subsequent sections present the mooring system, the delivery team and the overall timeline. The lessons are then organized in sections by mooring component types (on-vessel, polyester ropes, chains, and various connectors). Some reflections on how stakeholders influenced certain characteristics of the mooring components are disseminated throughout the paper. The paper also includes some observations about how the equipment performed in the field even though the lessons learned about the commissioning and offshore installation are left for a separate future paper.
Effect of Best-Estimate Clay P-Y Curves on Performance of Offshore Structures
Authors: Wu Fu , Chen Ching-Hsiang , Litton Richard W.
Published: April 2020

Fixed offshore platform pile foundation design and assessment in the Gulf of Mexico (GOM) has been based on API RP 2A [1] and current (2014) API/ISO RP 2GEO 1st edition [2] recommendations. Over the years, post-hurricane observations of the platform performance in the GOM have shown that these standards tend to underestimate soil lateral stiffness and capacity. Research work has been carried out for years to understand this conservatism and define the best-estimate soil lateral reaction for pile foundation design. These efforts culminated in a proposed draft of API/ISO RP 2GEO 2nd edition, which re-defines the clay soil lateral reaction formulations (p-y curves) for piles under monotonic, cyclic, and fatigue loads.

This paper summarizes a study performed to determine the effect of the new clay soil p-y curves on the structural responses of offshore platforms. In this study, three (3) featured fixed offshore platforms in the GOM were selected as representative structures for structural analysis and comparison. The selected platforms are actual platforms in operation in the GOM. The predicted platform responses from analyses were directly compared with measured and observed platform performance in field, including platform damage in hurricanes.

Analysis results demonstrate that structural models using the soil reaction formulations of the proposed 2GEO 2nd edition (draft), in combination with the best-estimate soil profiles interpreted based on the standard direct simple shear (DSS) tests, adequately predicted the platform responses observed in field.

The clay soil p-y reaction formulations (monotonic, cyclic, and fatigue) proposed for the update of 2GEO, as included in Appendix A, show significant improvement over the formulations in older editions of 2GEO and RP 2A, and are endorsed and recommended for pile foundation design and assessment.

Complete documentation of the study can be found in [3].
Dual Refrigerant LNG Liquefaction Cycle for Offshore FLNG and Its Pilot Plant
Authors: Park Hyunki , Kim Minki , Kim Chulwoo , Kim Hyobin , Lee Kihwan , Kim Mungyu , Lee Donghun
Published: April 2020

The purpose of this paper is to explain the developed dual refrigerant LNG liquefaction cycle for offshore FLNG, the outputs from detailed engineering of its pilot plant, the results of dynamic engineering studies including dynamic simulation with dynamic model/DCS (Distributed Control System) integration, and the current status of its pilot plant.

Compared with the current existing conventional gas expansion cycle, the developed dual refrigerant LNG liquefaction cycle is composed of three different levels of expansion in order to improve the system efficiency which is expressed in terms of kW/(ton/day). There are two stages in the methane (CH4) expansion loop, which are classified warm and cold loop. The warm loop is in charge of the pre-cooling zone and the cold loop is responsible for the main liquefaction zone. The nitrogen (N2) loop is a single stage and is used for sub-cooling of liquefied natural gas. This configuration allows the developed liquefaction cycle to be optimized by closely matching methane (CH4) and nitrogen (N2) warming curve with the natural gas cooling curve. As a result, the thermodynamic inefficiencies are minimized and the power requirements are accordingly reduced when compared to the current existing conventional gas expansion cycle.

Process simulation, which is based on models, is a key activity in process engineering covering the whole life cycle of a process. Therefore, having a good knowledge of the modelling background is compulsory for getting reliable results. Dynamic engineering studies have been carried out in order to achieve the three (3) main objectives (i.e., Process validation, DCS validation, Operator training) because it helps to validate process, establish experts and best practices among operators, enhancing understanding.

The detailed design engineering for 1/42 small scaled pilot plant had been carried out during around one (1) year after completing concept design of the proposed liquefaction cycle. The major outputs from the detailed engineering are HMB (Heat & Material Balance), P&IDs (Piping & Instrumentation Diagrams), 3-D Model, HAZOP (HAZard and Operability) & close-out report, control logics, distributed control system and so on.
Power at Sea: Use of Wave Energy Converters for Powering Offshore Oil and Gas Operations
Authors: Lesemann Arvid Reenst
Published: April 2020

New innovative services and goods based on artificial intelligence, next-generation robotics, autonomy, digitization, and electrification are taking root in the ocean economy. More typical competitive forces, such as value enhancement and safety improvement, are also present, as suppliers constantly strive to improve their competitive positioning. Concurrently, the Oil and Gas sector is experiencing mounting pressure to decrease its operational carbon emissions, forcing efforts to reduce or eliminate liquid fuel consumption offshore.

Companies in the ocean economy are having to react to this combination of macro- and micro-level drivers and innovate at an ever more rapid pace. However, before many of these new capabilities can be implemented, new, clean, reliable power sources are needed, especially as liquid fuel grows increasingly out of favor. For many of these loads—both old and new and ranging from watts to megawatts—wave energy systems provide the best solution for remote power generation. As such, research, development and demonstration activities are underway to prove wave energy's ability to provide reliable, consistent energy supplies for certain offshore Oil and Gas activities, paving the way for near term commercialization. This paper outlines these drivers, competitive reaction to them, and why and how wave energy can be a preferable choice for power at sea.
Elucidating the pathogenic and biomarker potentials of FOXG1 in glioblastoma
Authors: A. Richard Seidu , Jia-hao Zhou
Published: April 2020

Glioblastoma (GB) is an extremely pugnacious brain cancer originating from neural stem (NS) cell-like cells. Forkhead box G1 (FOXG1; previously recognized as BF-1, qin, Chicken Brain Factor 1, or XBF-1 and renamed FOXG1 for mouse and human, and FoxG1 for other chordates) is an evolutionary preserved transcription factor driven from the forkhead box group of proteins FOXG1 modulates the speed of neurogenesis by maintaining progenitor cells in a proliferative mode as well as obstructing their differentiation into neurons during the initial periods of cortical formation. FOXG1 has been implicated in the formation of central nervous system (CNS) tumors and precisely GBs. Pathophysiologically, joint actions of FOXG1 and phosphatidylinositol- 3-kinases (PI3K) intermediate in intrinsic resistance of human GB cells to transforming growth factor-beta (TGF-β) stimulation of cyclin-dependent kinase inhibitor 1(p21Cip1) as well as growth inhibition. FOXG1 and NOTCH signaling pathways may functionally interrelate at different stages to facilitate gliomagenesis. Furthermore, FoxG1 actively contributed to the formation of transcription suppression complexes with corepressors of the Groucho/transducin-like Enhancer of split (Gro/TLEs). Also, FOXG1 was stimulated by Gro/TLE1 and abridged by Grg6. FOXG1 silencing in brain tumor-initiating cells (BTICs) also resulted in diminished secretion of markers characteristic undifferentiated natural neural stem/progenitor cells (NSPC) states, such as Oligodendrocyte transcription factor (OLIG2), (sex determining region Y)-box 2. (SOX2) and B lymphoma Mo-MLV insertion region 1 homolog (BMI1). This review therefore focuses on the pathogenic and biomarker potentials of FOXG1 in GB.
Microbiology for veterinary technicians
Authors: Van Vuuren M. J.
Published: April 2020

No abstract available.
Equine Medicine and Surgery - Volume 1 & 2
Authors: Van Heerden J.
Published: April 2020

No abstract available
Towards the control of emerging bluetongue disease
Authors: Verwoerd D. W.
Published: April 2020

No abstract available.
AN ASSESSMENT OF THE EFFECTIVENESS OF LEGISLATURE IN BANGLADESH (2001-2006): A QUEST FOR GOOD GOVERNANCE
Authors: DR. MD. SULTAN MAHMUD
Published: April 2020

The research focus on how the legislature functions as a representative organ with its oversight mechanisms exercised upon the executive during 2001-2006 in Bangladesh. The study finds that 185 bills were passed among which 78% of the total bills were enacted without proper scrutiny in the eighth parliament. This study has illustrated that 166 of the total bills were passed escaping the committee stage. It is also found that the eighth parliament made no fruitful effort of establishing parliamentary norms, culture and legislative compromise. The conflict of opinion between the treasury and opposition bench made it impossible to turn the ground into an effective institution to bridge their gap and to settle policy differences on crucial national issues by debate, discussion and negotiations.  The research shows that the constant walkout and boycott of the parliamentary opposition helped the ruling bench to exert discretion. It is located that the opposition boycotted 223 out of the 373 working days. That means 60% working days of the 8th parliament were totally boycotted by the parliament.  Finally, the research explores some dysfunctionalities and ineffectiveness of the 8th parliament which are the barriers of good governance in Bangladesh.
OBTENCIÓN DE ALCOHOL A PARTIR DE LA FERMENTACIÓN ANAEROBIA DEL MOSTO DE UVA
Authors: Alcívar-Bravo Andrés , Barreiro-Cobeña Jandry , Navia-Mendoza Jennifer , Velásquez-Bazurto Selena , Vinces-Muñoz Walker
Published: April 2020

Este trabajo tiene como objetivo principal obtener etanol mediante fermentación alcohólica aplicando procesos biotecnológicos; debido a su alto contenido en azucares se emplea el mosto de uva como sustrato y la levadura Saccharomyces cerevisiae como agente biológico para completar la fermentación, debido a que, este microorganismo ha sido probado en investigaciones anteriores mostrando una elevada tolerancia al etanol. Se tuvo en cuenta variables como el pH, tiempo de fermentación, los grados Brix, formación de biomasa, entre otros. Los rendimientos de etanol y biomasa fueron de 0,483 gg-1 y 0,069 gg-1, respectivamente, además se establecieron las dimensiones del reactor en la escala industrial asumiendo una producción de 30L de etanol.

Palabras clave: etanol, fermentación, mosto de uva.
EVALUACIÓN DEL RENDIMIENTO DE VINAGRE OBTENIDO DE LA PULPA DE BANANO (MUSA PARADISIACA) MEDIANTE FERMENTACIÓN BIFÁSICA ALCOHÓLICA Y ACÉTICA
Authors: Intriago-Ponce María , López-Zambrano Lisbeth , Loor-García Claudio , Mayorga-Zambrano Jefferson , Zambrano-Zambrano Gabriel
Published: April 2020

La importación de vinagre y sucedáneos del vinagre en Ecuador es constante. El vinagre es un líquido miscible, con sabor agrio, proveniente de la fermentación acética del vino a partir, inicialmente, de azúcares fermentables. El objetivo del presente proyecto consistió en evaluar el rendimiento de vinagre obtenido de la pulpa de banano (musa paradisiaca) mediante la fermentación bifásica alcohólica y acética; así como también estimar la producción a una escala industrial junto con el diseño de los reactores para el proceso. Los resultados obtenidos mostraron que inicialmente la producción de etanol se mantiene estable durante la mayor parte del proceso, lo cual brinda un rendimiento del 75 %. Posteriormente en la fermentación acética se obtiene un rendimiento del 16,1 %. Finalmente se concluye que para el caso de la fermentación acética es preciso el control de cultivo y crecimiento con el respectivo ajuste de variables para obtener así mayores rendimientos, también es necesaria la implementación de biorreactores en serie como criterio que garantice el mejor desempeño del proceso productivo.

Palabras clave: banano, fermentación bifásica, vinagre, biorreactores.
INDICADORES DE RIESGO PSICOSOCIAL EN FUNCIÓN DE LOS PUESTOS DE TRABAJO
Authors: Cuesta-Mero Giovani , Andrade-Bastidas Paulo , Sánchez-Arteaga Alex
Published: April 2020

El presente trabajo es un manuscrito de revisión bibliográfica de los indicadores de riesgo psicosocial que se encuentran presentes en los trabajadores. La importancia de evaluar los riesgos psicosociales, radica en que su naturaleza está intrínsicamente relacionada con afectaciones prolongadas en los trabajadores si estos no son controlados adecuadamente. Los trabajadores que se sienten expuestos a riesgos psicosociales, tales como sobrecarga de trabajo, tareas repetitivas o tareas de muy corta duración, exceso de carga mental, entre otros, son aquellos que tienen porcentajes de respuestas de sintomatología psicosomática más elevados. Una vez revisadas las estadísticas de los factores de riesgo psicosocial, podemos notar que los mismos, afectan a un porcentaje significativo de la población trabajadora que fue muestreada en un estudio realizado por el Instituto Nacional de Seguridad e Higiene en el Trabajo (España), por lo cual, es necesario evaluar en cada centro de trabajo si estos factores están presentes en la organización, para de esta forma, garantizar al trabajador un adecuado bienestar en el trabajo, derecho adquirido según normativas legales tanto nacionales, como internacionales. Finalmente, debe considerarse que no todos los factores de riesgo psicosocial, están presentes en todos los puestos de trabajo, sino que existen puestos de trabajo en donde un factor puede estar más arraigado que otro.

Palabras clave: trabajador, seguridad, salud, riesgo laboral, riesgo psicosocial.
RESPONSABILIDAD SOCIAL CORPORATIVA: ESTRATEGIA EMPRESARIAL PARA EL DESARROLLO SOSTENIBLE
Authors: Vásquez-Giler Maritza , Zambrano-Vera Teddy , Muñoz-Menéndez María Belén
Published: April 2020

La Responsabilidad Social Corporativa es actualmente una temática de constante discusión y análisis, puesto que desde distintas perspectivas se busca posicionar este concepto no solo como un mecanismo empresarial de ser agradables ante la sociedad o la comunidad; sino más bien como una estrategia de crecimiento empresarial a mediano y largo plazo. El presente trabajo tiene como objetivo analizar los conceptos, origen y estado actual de las empresas socialmente responsables, para de esta forma establecer pautas que conviertan a las organizaciones en comunidad. Se analizan los criterios que dan soporte a una estructura empresarial responsable con la colectividad. Además, se analiza el grado de responsabilidad con el que se manejan las empresas latinoamericanas en el contexto mundial. Se concluye que si bien las empresas son conscientes de la importancia de la RSC y su consecuente impacto positivo aún quedan tareas pendientes para posicionar políticas de este tipo entre los empresarios y ejecutivos. Las instituciones deben ser concebidas como comunidad, partiendo de valores morales y éticos que fomentan el desarrollo de una identidad replanteada a partir de la apertura hacia las necesidades de los demás.

Palabras clave: comunidad, ambiente, organización, criterios, responsabilidad.
The Effect of Medium of Instruction on Undergraduate Student Learning Style in Video-based Learning
Authors: Mikelic Preradovic Nives , Lauc Tomislava , Panev Ida
Published: April 2020

The study aims to assess the impact of interactive and linear video on learning effectiveness of undergraduate informatics students with different predominant learning styles (visual, aural, read/write and kinesthetic style). The students in different treatment groups (learning with interactive vs. linear video) have achieved very good learning outcomes and those who used interactive videos achieved better learning outcomes. The impact of the kinesthetic predominant learning style on learning with interactive videos was not evident, i.e. the predominant learning style of the undergraduate informatics students did not affect their success, regardless of the type of video
Bioresorbable Scaffolds: Current Technology and Future Perspectives
Authors:   Section of Interventional Cardiology, MedStar Washington Hospital Center, Washington, DC, USA, Forrestal Brian , Case Brian C. , Yerasi Charan , Musallam Anees , Chezer-Azerrad Chava , Waksman Ron
Published: April 2020

Metallic drug-eluting stents have led to significant improvements in clinical outcomes but are inherently limited by their caging of the vessel wall. Fully bioresorbable scaffolds (BRS) have emerged in an effort to overcome these limitations, allowing a “leave nothing behind” approach. Although theoretically appealing, the initial experience with BRS technology was limited by increased rates of scaffold thrombosis compared with contemporary stents. This review gives a broad outline of the current BRS technologies and outlines the refinements in BRS design, procedural approach, lesion selection, and post-procedural care that resulted from early BRS trials.
Republic of North Macedonia
Authors:   International Monetary Fund. European Dept.
Published: April 2020

North Macedonia’s economic outlook has deteriorated substantially due the COVID-19 pandemic. Real GDP is expected to decline by 4 percent due to a fall in both domestic and external demand. This, together with negative shocks to confidence and spillovers from global financial channels, has created an urgent balance of payments need. The elections planned for April 2020 have been postponed, implying that the caretaker government will remain in place for the next months. The Executive Board concluded the 2019 Article IV consultation on a lapse-of-time basis on January 22.
IMF COVID-19 Response—A New Short-Term Liquidity Line to Enhance The Adequacy Of The Global Financial Safety Net
Authors:   International Monetary Fund
Published: April 2020

The COVID-19 pandemic has created severe disruption in the global financial system, with many emerging market and developing countries (EMDCs) facing liquidity shortages.
In the context of intensified demand for liquidity and heightened global uncertainty, staff has revisited the 2017 proposal for a new facility to provide liquidity support to the Fund’s membership.
This paper proposes the establishment of a new Short-term Liquidity Line (SLL) as a special facility in the General Resources Account (GRA), based on the key features of the 2017 blueprint.
Formation of highly oxygenated organic molecules from chlorine-atom-initiated oxidation of alpha-pinene
Authors: Wang Yonghong , Riva Matthieu , Xie Hongbin , Heikkinen Liine , Schallhart Simon , Zha Qiaozhi , Yan Chao , He Xu-Cheng , Peräkylä Otso , Ehn Mikael
Published: April 2020

Abstract. Highly oxygenated organic molecules (HOMs) from atmospheric oxidation of
alpha-pinene can irreversibly condense to particles and contribute to
secondary organic aerosol (SOA) formation. Recently, the formation of nitryl
chloride (ClNO2) from heterogeneous reactions, followed by its
subsequent photolysis, is suggested to be an important source of chlorine
atoms in many parts of the atmosphere. However, the oxidation of
monoterpenes such as alpha-pinene by chlorine atoms has received very little
attention, and the ability of this reaction to form HOMs is completely
unstudied. Here, chamber experiments were conducted with alpha-pinene and
chlorine under low- and high-nitrogen-oxide (NOx, NOx=NO+NO2) conditions. A nitrate-based CI-APi-ToF (chemical
ionization–atmospheric pressure interface–time of flight) mass spectrometer was used to
measure HOM products. Clear distributions of monomers with 9–10 carbon atoms and dimers with 18–20 carbon atoms were observed under low-NOx conditions. With increased concentration of NOx within the chamber, the
formation of dimers was suppressed due to the reactions of peroxy radicals
with NO. We estimated the HOM yields from chlorine-initiated oxidation of
alpha-pinene under low-NOx conditions to be around 1.8 %, though
with a substantial uncertainty range (0.8 %–4 %) due to lack of suitable calibration methods. Corresponding yields at high NOx could not be determined because of concurrent ozonolysis reactions. Our study demonstrates that also the oxidation of alpha-pinene by chlorine atoms
and yield low-volatility organic compounds.
Design and evaluation of CO2 observation network to optimize surface CO2 fluxes in Asia using observation system simulation experiments
Authors: Park Jun , Kim Hyun Mee
Published: April 2020

Abstract. Continuous efforts have been made to monitor atmospheric
CO2 mole fractions as it is one of the most influential greenhouse
gases in Earth's atmosphere. The atmospheric CO2 mole fractions are
mostly determined by CO2 exchanges at the Earth's surface (i.e.,
surface CO2 flux). Inverse modeling, which is a method to estimate the
CO2 exchanges at the Earth's surface, derives surface CO2 fluxes
using modeled and observed atmospheric CO2 mole fraction data. Although
observation data are crucial for successful modeling, comparatively fewer
in situ observation sites are located in Asia compared to Europe or North
America. Based on the importance of the terrestrial ecosystem of Asia for
global carbon exchanges, more observation stations and an effective
observation network design are required. In this paper, several observation
network experiments were conducted to optimize the surface CO2 flux of
Asia using CarbonTracker and observation system simulation experiments
(OSSEs). The impacts of the redistribution of and additions to the existing
observation network of Asia were evaluated using hypothetical in situ
observation sites. In the case of the addition experiments, 10 observation
stations, which is a practical number for real implementation, were added
through three strategies: random addition, the influence matrix (i.e.,
self-sensitivity), and ecoregion information within the model. The simulated
surface CO2 flux in Asia in summer can be improved by redistributing
the existing observation network. The addition experiments revealed that
considering both the distribution of normalized self-sensitivity and
ecoregion information can yield better simulated surface CO2 fluxes
compared to random addition, regardless of the season. This study provides a
diagnosis of the existing observation network and useful information for
future observation network design in Asia to estimate the surface CO2
flux and also suggests the use of an influence matrix for designing
CO2 observation networks. Unlike other previous observation network
studies with many numerical experiments for optimization, comparatively
fewer experiments were required in this study. Thus, the methodology used in
this study may be used for designing observation networks for monitoring
greenhouse gases at both continental and global scales.
Patterns and trends of the dominant environmental controls of net biome productivity
Authors: Marcolla Barbara , Migliavacca Mirco , Rödenbeck Christian , Cescatti Alessandro
Published: April 2020

Abstract. In the last decades terrestrial ecosystems have
reabsorbed on average more than one-quarter of anthropogenic emissions
(Le
Quéré et al., 2018). However, this large carbon sink is modulated by
climate and is therefore highly variable in time and space. The magnitude
and temporal changes in the sensitivity of terrestrial CO2 fluxes to
climate drivers are key factors to determine future atmospheric CO2
concentration and climate trajectories. In the literature, there is so far a
strong focus on the climatic controls of daily and long-term variability,
while less is known about the key drivers at a seasonal timescale and about
their variation over time (Wohlfahrt
et al., 2008). This latter temporal scale is relevant to assess which
climatic drivers dominate the seasonality of the fluxes and to understand
which factors limit the CO2 exchange during the course of the year.
Here, we investigate the global sensitivity of net terrestrial CO2
fluxes, derived from atmospheric inversion, to three key climate drivers
(i.e. global radiation and temperature from WFDEI and soil water content from
ERA-Interim) from weekly to seasonal temporal scales, in order to explore
the short-term interdependence between climate and the terrestrial carbon
budget. We observed that the CO2 exchange is controlled by temperature
during the carbon uptake period over most of the land surface (from 55 % to
52 % of the total surface), while radiation is the most widespread
dominant climate driver during the carbon release period (from 64 % to 70 %
of the total surface). As expected, soil water content plays a key role in
arid regions of the Southern Hemisphere during both the carbon uptake and
the carbon release period. Looking at the decadal trend of these
sensitivities (1985–2016) we observed that the importance of radiation as a
driver is increasing over time, while we observed a decrease in sensitivity
to temperature in Eurasia. Overall, we show that flux temporal variation due
to a specific driver has been dominated by the temporal changes in ecosystem
sensitivity (i.e. the response of ecosystem to climate) rather than to the
temporal variability of the climate driver itself over the last decades.
Ultimately, this analysis shows that the ecosystem response to climate is
significantly changing both in space and in time, with potential
repercussion on the future terrestrial CO2 sink and therefore on the
role that land may play in climate trajectories.
Relationships between low-temperature fires, climate and vegetation during three late glacials and interglacials of the last 430 kyr in northeastern Siberia reconstructed from monosaccharide anhydrides in Lake El'gygytgyn sediments
Authors: Dietze Elisabeth , Mangelsdorf Kai , Andreev Andrei , Karger Cornelia , Schreuder Laura T. , Hopmans Ellen C. , Rach Oliver , Sachse Dirk , Wennrich Volker , Herzschuh Ulrike
Published: April 2020

Abstract. Landscapes in high northern latitudes are assumed to be highly
sensitive to future global change, but the rates and long-term trajectories
of changes are rather uncertain. In the boreal zone, fires are an important
factor in climate–vegetation interactions and biogeochemical cycles. Fire
regimes are characterized by small, frequent, low-intensity fires within
summergreen boreal forests dominated by larch, whereas evergreen boreal
forests dominated by spruce and pine burn large areas less frequently but
at higher intensities. Here, we explore the potential of the monosaccharide
anhydrides (MA) levoglucosan, mannosan and galactosan to serve as proxies
of low-intensity biomass burning in glacial-to-interglacial lake sediments
from the high northern latitudes. We use sediments from Lake El'gygytgyn
(cores PG 1351 and ICDP 5011-1), located in the far north-east of Russia,
and study glacial and interglacial samples of the last 430 kyr (marine
isotope stages 5e, 6, 7e, 8, 11c and 12) that had different climate and biome
configurations. Combined with pollen and non-pollen palynomorph records from
the same samples, we assess how far the modern relationships between fire,
climate and vegetation persisted during the past, on orbital to centennial
timescales. We find that MAs attached to particulates were well-preserved
in up to 430 kyr old sediments with higher influxes from low-intensity
biomass burning in interglacials compared to glacials. MA influxes
significantly increase when summergreen boreal forest spreads closer to the
lake, whereas they decrease when tundra-steppe environments and, especially,
Sphagnum peatlands spread. This suggests that low-temperature fires are a typical
characteristic of Siberian larch forests also on long timescales. The
results also suggest that low-intensity fires would be reduced by vegetation
shifts towards very dry environments due to reduced biomass availability, as
well as by shifts towards peatlands, which limits fuel dryness. In addition,
we observed very low MA ratios, which we interpret as high contributions of
galactosan and mannosan from biomass sources other than those currently monitored,
such as the moss–lichen mats in the understorey of the summergreen boreal
forest. Overall, sedimentary MAs can provide a powerful proxy for fire
regime reconstructions and extend our knowledge of long-term natural
fire–climate–vegetation feedbacks in the high northern latitudes.
WRF-Chem v3.9 simulations of the East Asian dust storm in May 2017: modeling sensitivities to dust emission and dry deposition schemes
Authors: Zeng Yi , Wang Minghuai , Zhao Chun , Chen Siyu , Liu Zhoukun , Huang Xin , Gao Yang
Published: April 2020

Abstract. Dust aerosol plays an important role in the radiative budget and
hydrological cycle, but large uncertainties remain for simulating dust
emission and dry deposition processes in models. In this study, we
investigated dust simulation sensitivity to two dust emission schemes and
three dry deposition schemes for a severe dust storm during May 2017 over
East Asia using the Weather Research and Forecasting model coupled with
chemistry (WRF-Chem). Results showed that simulated dust loading is very
sensitive to different dry deposition schemes, with the relative difference
in dust loading using different dry deposition schemes ranging from
20 %–116 %. Two dust emission schemes are found to produce significantly
different spatial distributions of dust loading. The difference in dry
deposition velocity in different dry deposition schemes comes from the
parameterization of collection efficiency from impaction and rebound effect.
An optimal combination of dry deposition scheme and dust emission scheme has
been identified to best simulate the dust storm in comparison with
observation. The optimal dry deposition scheme accounts for the rebound
effect and its collection efficiency from impaction changes with the land
use categories and therefore has a better physical treatment of dry
deposition velocity. Our results highlight the importance of dry deposition
schemes for dust simulation.
The E3SM version 1 Single Column Model
Authors: Bogenschutz Peter A. , Tang Shuaiqi , Caldwell Peter M. , Xie Shaocheng , Lin Wuyin , Chen Yao-sheng
Published: April 2020

Abstract. The single column model (SCM) functionality of the Energy Exascale Earth System Model version 1 (E3SMv1) is described in this paper. The E3SM SCM was adopted from the SCM used in the Community Atmosphere Model (CAM), but has evolved significantly since then. We describe changes made to the aerosol specification in the SCM, idealizations, and developments made so that the SCM uses the same dynamical core as the full general circulation model (GCM) component. Based on these changes, we describe and demonstrate the seamless capability to ``replay" a GCM column using the SCM. We give an overview of the E3SM case library and briefly describe which cases may serve as useful proxies for replicating and investigate some long standing biases in the full GCM runs, while demonstrating that the E3SM SCM is an efficient tool for both model development and evaluation.