bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Simulation of an Oscillating Water Column (OWC) Wave Energy Converter (WEC) on a Breakwater Using OpenFOAM®
Authors: Conde J.M.P. , Condeço M.B.S.P.
Published: August 2019

This paper presents the application of the OpenFOAM® software package, using the IHFoam/OlaFlow solver, in the simulation of the water waves and air flow in an OWC-WEC located on a breakwater, the Mutriku power station in the north of Spain. The numerical code solves the transient Reynolds averaged Navier-Stokes (RANS) equations, using the Volume of Fluid (VoF) technique to identify the free surface. The standard k-ε turbulence model was used evaluate the Reynold stresses. Two geometries were considered: one with the pneumatic chamber completely open to the atmosphere; and other with the chamber connected to the turbine duct. The solutions obtained by OpenFOAM® are compared with those obtained by the commercial code Fluent.
Reproducibility of a Real Case of an Oil Spill during Vessel Supply Operation in an Estuarine Zone
Authors: Monteiro Caroline Barbosa , Oleinik Phelype Haron , Lopes Bruno Vasconcellos , Leal Thalita Fagundes , da Silva Douglas Vieira , Möller Junior Osmar Olinto , Marques Wiliam Correa
Published: August 2019

The global transportation of fossil fuels occurs mainly by sea and grows annually, along with the risks to the marine ecosystems, especially in the vicinity of navigation routes. Numerical simulations able to reproduce realistic oil spill scenarios can be utilised for planning risk mitigation actions. This study is based on simulating the behaviour and weathering rates recorded during the first 24 h after an oil spill that occurred in an estuarine region. The numerical system used is the ECOS (Easy Coupling Oil System) oil spill model coupled to the three-dimensional hydrodynamic model Telemac-3D. The hydrodynamic results were analysed considering wind velocity fields and currents, which are the dominant forces in the displacement and behaviour of the oil. The reproducibility of the oil leak was confirmed by comparing the results of the simulations with the official environmental emergency report of the accident. The strong correlation between the simulation and the report showcases the capacity of the simulation methodology to reproduce real case scenarios of oil spills.
Evaluation of a Differential Evolution/Constructal Design Algorithm for Geometrical Optimization of Double T-Shaped Cavity Intruded into a Heat Generating Wall
Authors: Gonzales Gill Velleda , Isoldi Liércio André , Rocha Luiz Alberto Oliveira , da Silva Neto Antônio José , dos Santos Elizaldo Domingues
Published: August 2019

In the present work it is investigated the performance of an algorithm that associates Differential Evolution and Constructal Design for geometrical optimization of a heat transfer problem. It is considered the intrusion of a cooled Double T-shaped cavity into a rectangular conducting solid wall with internal heat generation. The main purpose here is to evaluate the algorithm capability to reproduce the effect of geometric ratios over the dimensionless maximum excess of temperature (performance indicator of the heat transfer problem), as well as, the influence of Differential Evolution (DE) parameters over the optimization analysis. The definition of search space for each degree of freedom and problem constraints is performed with Constructal Design, while the Differential Evolution algorithm is used in the optimization process. Here parameters as mutation operator (M), crossover constant (CR), differential amplification factor (F), Population Size (PS) and Generations number (G) are evaluated. A theoretical recommendation about the suitable parameters set for the optimization algorithm for this kind of heat transfer problem is proposed. Results indicated that the crossover constant (CR) and amplification factor (F) are important parameters for suitable prediction of the effect of degrees of freedom over thermal performance. Moreover, when CR = 0.7 and F = 1.5 results obtained with the algorithm are more robust for the achievement of the best shapes and requires lower number of iterations (IT = PS × G) for reproduction of effect of geometric variables over performance.
Geometry Evaluation of Heat Transfer by Mixed Convention in Driven Cavities with Two Inserted Fins
Authors: Rodrigues Priscila M. , de Escobar Cicero C. , Rocha Luiz Alberto Oliveira , Isoldi Liércio André , dos Santos Elizaldo Domingues
Published: August 2019

In this work, a numerical study of a flow with heat transfer by mixed convection are carried out. The objective is the geometric evaluation through the application of the Construtal Design and the exhaustive search method. The behavior of a lid-driven cavity with stable stratification subjected to an incompressible, laminar and two-dimensional flow is investigated. The cavity has two rectangular fins inserted in the lower surface. The problem is subject to three constrains: three geometric constraints: the area of the cavity, two fin areas. The investigated geometry has three degrees of freedom: the ratio between height and cavity length (H/L) and the ratio between height and length of each fin (H1/L1 and H2/L2). The effect of the fin geometry over spatial-averaged Nusselt (NuH) is investigated for Reynolds number (ReH) = 400 and Richardson (Ri) = 0.1. The conservation equations of mass, momentum and energy are tackled with Finite Volume Method (FVM) through the use of commercial software FLUENT. The results showed that the lower H2/L2 ratios resulted in higher NuH values. An increase in NuH value of approximately 49% between the worst and the best geometrical configuration was found, thus highlighting the importance of geometric evaluation on this kind of problem. It is concluded that for the problem addressed the best behavior is obtained when the fins have a small insertion into the cavity, thus avoiding the restriction of the main vortex flow. The results found highlight the importance of the geometric evaluation for the purpose of theoretical recommendation on the geometric configurations that lead to the best thermal performance.
3-D Scale Model Study of Wave Run-Up, Overtopping and Damage in a Rubble-Mound Breakwater Subject to Oblique Extreme Wave Conditions
Authors: Santos João Alfredo , Pedro Francisco , Coimbra Mário , Figuero Andrés , Fortes Conceição Juana , Sande José , Körner Moritz , Lemos Rute , Bornschein Antje , Weimper Julius , van den Bos Jeroen , Dost Bastian , Hofland Bas , Carvalho Rita F. , Alvarellos Alberto , Peña Enrique , Pohl Reinhard , Kerpen Nils B. , Reis Maria Teresa
Published: August 2019

A set of scale-model tests carried out to enlarge the range of wave steepness values analysed in run-up, overtopping and armour layer stability studies, focusing on oblique extreme wave conditions and on their effects on a gentler slope breakwater’s trunk armour and roundhead, is presented in this paper. A stretch of a rubble mound breakwater (head and part of the adjoining trunk, with a slope of 1(V):2(H)) was built in a wave basin at the Leibniz University Hannover to assess, under extreme wave conditions (wave steepness of 0.055) with different incident wave angles (from 40º to 90º), the structure behaviour in what concerns wave run-up, wave overtopping and damage progression of the armour layer. Two types of armour elements (rock and Antifer cubes) were tested. Non-intrusive methodologies including a new application of laser scanning technique for the assessment of both armour layer damage and wave run-up and overtopping were used. It is expected that such work will contribute also with data to improve empirical formulas as well as to validate complex numerical model for wave-structure interaction.
Analysis of Forces on a Submarine Outfall by a RANS-VoF Numerical Wave Tank
Authors: Didier Eric , Neves Maria Graça , Teixeira Paulo R.F.
Published: August 2019

Knowledge of forces due to the action of waves on submarine outfalls composed by a pipe and stabilizing concrete weights, considering the wave propagation direction to the outfalls, is essential to their design. 3D numerical models based on RANS-VoF (Reynolds-Average-Navier-Stokes Volume-of-Fluid) are able to estimate forces on the pipe and weights. The present study aims to simulate a submarine outfall with stabilizing concrete weights at 1:15 scale which was previously tested in the 3D Shallow Water Basin at the Danish Hydraulics Institute (DHI) to analyse the influence of the direction of the incident wave and the distance from the pipe to the bottom on the outfall forces. In this study, numerical results are compared with experimental ones for waves with four different amplitudes and with wave incidence perpendicular to the outfall. The use of k-ω SST turbulence model led to good agreement between numerical drag and lift forces and experimental ones, with a mean difference of 8.9 and 7.6%, respectively.
Physical Modelling of Motions and Forces on a Moored Ship at the Leixões Port
Authors: Santos João Alfredo , Pinheiro Liliana Vieira , Abdelwahab Hossam S. , Fortes Conceição Juana , Pedro Francisco G.L. , Capitão Rui P. , Hinostroza Miguel A. , Guedes Soares Carlos
Published: August 2019

This paper describes the physical model, experimental setup and tests performed at the Portuguese Civil Engineering Laboratory (LNEC), to study the motions and forces of a moored ship at the Leixões port, for different sea states in irregular waves. The tests were carried out at one of the wave tanks of LNEC, where the Leixões port layout was implemented at scale 1:80 with the detailed model similar to the prototype bathymetry and surrounding structures. The moored ship is a 3.43 m long scale model of the well-known “Esso Osaka” tanker and is moored to the pier A of the oil terminal at 0.135 m draft. Several types of measurements were recorded in this study. The free-surface elevation and wave direction were measured with a set of resistive wave gauges. The wave velocities at the entrance of the harbour were measured with an acoustic Doppler velocimeter. Motions of the moored ship were measured with the OptiTrackTM motion capture system whereas forces on fenders and mooring lines were measured with load cells attached to a complex spring system developed at LNEC. Several tests were carried out for a number of incident sea states characterized by a JONSWAP spectrum, with different significant wave heights and peak periods. The measurement, analysis and results obtained for the incident wave conditions characterized by a significant wave height of 6 m and a peak wave period of 14 s are presented and discussed in this paper.
The Role of Gold Nanoparticles in Sonosensitization of Human Cervical Carcinoma Cell Line under Ultrasound Irradiation: An In Vitro Study
Authors: Shanei Ahmad , Akbari-Zadeh Hadi , Fakhimikabir Hamid , Attaran Neda
Published: August 2019

Abstract:Purpose: The objective of this investigation was to evaluate the combined effects of ultrasound irradiation as a non-invasive and non-ionizing radiation with gold nanoparticles as ultrasound sensitizers on the HeLa cells.Materials and Methods: First, Gold nanoparticles (GNPs) were prepared, and the characterizations of nanoparticles were analyzed using TEM and UV-vis. Different concentrations of nanoparticles (0.2, 1, 5, 25 and 50 μg/ml) were used. Then, cytotoxicity of the GNPs was studied on HeLa cells, and finally concentrations of 0.2, 1 and 5 µg/mL were chosen for supplementary studies. The effects of nanoparticles and ultrasound irradiation with different intensities (0.5, 1 and 1.5 W/cm2) as well as the combination of ultrasound radiation with various concentrations of nanoparticles on 24, 48 and 72 h post-experiment cells’ viability were estimated by MTT and trypan blue assay.Results: Results showed that the sonosensitizing effect of nanoparticles mainly depended on the intensity of ultrasound waves and the concentration of GNPs. By increasing the concentration of GNPs and ultrasound intensity, the nanoparticle's effect of sensitizer was also increased. Moreover, as expected, the highest effect was observed at the highest intensities (1.5 W/cm2) of ultrasound wave and high concentrations (5 μg/ml) of GNPs 72 h after exposure to ultrasound irradiation.Conclusions: It is revealed that GNPs can be used as sonosensitizers of HeLa cells to ultrasound irradiation in order to produce an efficient treatment.
Development and Characterization of Bilayer Wound Healing Patch Nanofiber Fabricated by Electrospinning
Authors: Huanbutta Kampanart , Sittikijyothin Wancheng , Sangnim Tanikan
Published: August 2019

The present study aims to develop bilayer polymeric nanofiber patch (PNP) fabricated by electrospinning technique using for wound dressing. The nanofiber was prepared by various concentrations of polyvinyl alcohol (PVA) and modified tamarind seed gum loaded with clindamycin HCl (CM) in first layer and Eudragit® S100 for a second layer. ​According to the SEM result, the physical appearance, the sprayed products prepared from PVA, mixture of PVA and gum, Eudragit® S100 were in round fiber with different diameter size ranged from 153-1830 nm. The polymer concentration, solution conductivity and surface tension affected on the appearance of the nanofiber. The patch was successfully prepared in form of two layer welded with the nanofiber under the optimized electrospinning condition which are 20 kV of applied voltage, 20 cm of injection distance, 0.25 mL of solution feed rate and 48 rpm of collector rolling rate. The DSC and PXRD indicated that the drug in PNPs was in amorphous form. Biological test revealed that bilayer PNPs contained PVA 10%, modified tamarind seed gum 5% and clindamycin 1% had an efficiency to inhibit Staphylococcus aureus. These results show the possibility of improving nanofiber patch strength by using Eudragit® S100 and modified tamarind gum seed as a natural material in nanofiber patch formulation.
On the Matano Plane Position in Multicomponent Diffusion Couples
Authors: Leszczyński Henryk , Lademan Karolina , Tkacz-Śmiech Katarzyna , Bożek Bogusław , Zajusz Marek , Danielewski Marek
Published: August 2019

Even though several methods of diffusion analysis avoid a necessity for the Matano plane determination, the Matano plane locations are of interest in the multicomponent couples and when tracer experiments are performed. The positions of the Matano plane calculated from the concentration profiles should be exactly the same. However, due to experimental errors, the results can differ significantly. In the paper we consider Matano plane for multi-component couples of conserved and non-conserved overall volumes. We use Darken method and Sauer-Freise scheme, respectively and show that looking for the Matano plane as an inverse problem leads to a system of linear algebraic equations which are over-determined. The relations for the Matano plane position are derived by virtue of the least-squares methodology. The exemplary computations shows that the method is particularly useful in analysis of experimental data and allows decreasing computing errors.
Entropy Generation on Maxwell Fluid Flow Past an Inclined Stretching Plate with Slip and Convective Surface Conditon: Darcy-Forchheimer Model
Authors: Yusuf Tunde Abdulkadir , Gbadeyan Jacob Abiodun
Published: August 2019

In this study the effect of entropy generation on two dimensional magnetohydrodynamic (MHD) flow of a Maxwell fluid over an inclined stretching sheet embedded in a non-Darcian porous medium with velocity slip and convective boundary condition is investigated. Darcy-Forchheimer based model was employed to describe the flow in the porous medium. The non-linear thermal radiation is also taken into account. Similarity transformation is used to convert the non-linear partial differential equations to a system of non-linear ordinary differential equations. The resulting transformed equations are then solved using the Homotopy analysis method (HAM). Influence of various physical parameters on the dimensionless velocity profile, temperature profile and entropy generation are shown graphically and discussed in detail while the effects of these physical parameters on velocity gradient and temperature gradient are aided with the help of Table. Furthermore, comparison of some limiting cases of this model was made with existing results. The results obtained are found to be in good agreement with previously published results. Moreover, increase in local inertial coefficient parameter is found to decrease the entropy generation rate.
The Significance of Fin Profile and Convective-Radiative Fin Tip on Temperature Distribution in a Longitudinal Fin
Authors: Ndlovu Partner Luyanda
Published: August 2019

In this article, the one dimensional nonlinear transient heat transfer through fins of rectangular, convex parabolic and concave parabolic is studied using the two dimensional Differential Transform Method (2D DTM). The thermal conductivity and heat transfer coefficient are modeled as linear and power law functions of temperature respectively. The fin tip dissipate heat to the ambient temperature by convection and radiation. A comparison is made between the proposed convectiveradiative fin tip boundary condition and the adiabatic (insulated) fin tip boundary condition which is widely used in literature. It is found that the fin with a convective-radiative tip dissipates heat to the ambient fluid at a faster rate when compared to a fin with an insulated tip. The results further show that the longitudinal fins of parabolic profiles dissipate more heat when compared to the conventional rectangular fin profile. The accuracy of the analytical method is demonstrated by comparing its results with those generated by an inbuilt numerical solver in MATLAB. Furthermore, a wide range of thermo-physical parameters are studied and their impact on the temperature distribution are illustrated and explained.
Proliferation of Resident Macrophages Is Dispensable for Protection during Giardia duodenalis Infections
Authors: Fink Marc Y , Maloney Jenny , Keselman Aleksander , Li Erqiu , Menegas Samantha , Staniorski Christopher , Singer Steven M
Published: August 2019

Infection with the intestinal parasite Giardia duodenalis is one of the most common causes of diarrheal disease in the world. Previous work has demonstrated that the cells and mechanisms of the adaptive immune system are critical for clearance of this parasite. However, the innate system has not been as well studied in the context of Giardia infection. We have previously demonstrated that Giardia infection leads to the accumulation of a population of CD11b+, F4/80+, ARG1+, and NOS2+ macrophages in the small intestinal lamina propria. In this report, we sought to identify the accumulation mechanism of duodenal macrophages during Giardia infection and to determine if these cells were essential to the induction of protective Giardia immunity. We show that F4/80+, CD11b+, CD11cint, CX3CR1+, MHC class II+, Ly6C−, ARG1+, and NOS2+ macrophages accumulate in the small intestine during infections in mice. Consistent with this resident macrophage phenotype, macrophage accumulation does not require CCR2, and the macrophages incorporate EdU, indicating in situ proliferation rather than the recruitment of monocytes. Depletion of macrophages using anti-CSF1R did not impact parasite clearance nor development of regulatory T cell or Th17 cellular responses, suggesting that these macrophages are dispensable for protective Giardia immunity.
Diode Laser Assisted Excision of a Gingival Pyogenic Granuloma: A Case Report
Authors: Andreadis Dimitrios , Lazaridi Ioanna , Anagnostou Eleftherios , Poulopoulos Athanasios , Panta Prashanth , Patil Shankargouda
Published: August 2019

Pyogenic granuloma is a non-neoplastic, exuberant, reactive lesion seen in response to local irritation or trauma caused by dental calculus, bacterial plaque, caries and restorations, with a strong predilection for the gingiva. It is among the frequently encountered oral lesions, occurring at a challenging oral site, the gingiva. Herein, we report a 71-year-old medically compromised Caucasian female who presented with a relatively large lobulated pyogenic granuloma on the buccal gingiva of the maxillary molar-premolar region. Total surgical excision was performed with an 840nm diode laser followed by the placement of hyaluronate gel and relevant periodontal dressing. Two weeks after surgical excision, complete healing was observed, but patient denied replacement of dental restoration. After 4 months of follow-up, an overall reduction of associated teeth mobility was also observed, with a minor recurrence in gingival inflammation. The objective of this report is to briefly review clinical, radiographic and histological findings of pyogenic granuloma along with a detailed discussion on its management through a diode laser.
Exertional Heat-Stroke Preparedness in High School Football by Region and State Mandate Presence
Authors: Kerr Zachary Y. , Scarneo-Miller Samantha E. , Yeargin Susan W. , Grundstein Andrew J. , Casa Douglas J. , Pryor Riana R. , Register-Mihalik Johna K.
Published: August 2019

Context

Exertional heat stroke (EHS) is a leading cause of sudden death in high school football players. Preparedness strategies can mitigate EHS incidence and severity.

Objective

To examine EHS preparedness among high school football programs and its association with regional and state preseason heat-acclimatization mandates.

Design

Cross-sectional study.

Setting

Preseason high school football programs, 2017.

Patients or Other Participants

A total of 910 athletic trainers (ATs) working with high school football (12.7% completion rate).

Main Outcome Measure(s)

We acquired data on high school football programs' EHS preparedness strategies in the 2017 preseason via an online questionnaire, looking at (1) whether schools' state high school athletic associations mandated preseason heat-acclimatization guidelines and (2) heat safety region based on warm-season wet-bulb globe temperature, ranging from the milder region 1 to the hotter region 3. Six EHS-preparedness strategies were assessed: EHS recognition and treatment education; policy for initiating emergency medical services response; emergency response plan enactment; immersion tub filled with ice water before practice; wet-bulb globe temperature monitoring; and hydration access. Multivariable binomial regression models estimated the prevalence of reporting all 6 strategies.

Results

Overall, 27.5% of ATs described their schools as using all 6 EHS-preparedness strategies. The highest prevalence was in region 3 schools with state mandates (52.9%). The multivariable model demonstrated an interaction in which the combination of higher heat safety region and presence of a state mandate was associated with a higher prevalence of reporting all 6 strategies (P = .05). Controlling for AT and high school characteristics, the use of all 6 strategies was higher in region 3 schools with state mandates compared with region 1 schools without state mandates (52.9% versus 17.8%; prevalence ratio = 2.68; 95% confidence interval = 1.81, 3.95).

Conclusions

Our findings suggest a greater use of EHS-preparedness strategies in environmentally warmer regions with state-level mandates for preseason heat acclimatization. Future researchers should identify factors influencing EHS preparedness, particularly in regions 1 and 2 and in states without mandates.
Debunking the one-size-fits-all approach to human resource management: A review of human resource practices in small and medium-sized enterprise firms
Authors: Nyamubarwa Willard , Chipunza Crispen
Published: August 2019

Orientation: This article argues that the best practice approach (BPA) to HRM fails to capture the peculiarities of HR practices in small and medium-sized enterprises (SMEs). The article instead articulates the view that the different and unique traits inherent in SMEs firms allows the firms to adopt distinct HR practices, which may not cohere with the prescriptive one-size-fits-all view which BPA advocates.Research purpose: The article aims to further the thesis that the long-held BPA approach to HRM does not always apply to SME firms given their unique characteristics which renders HR prescriptions applied in large firms invalid in SME firms.Research approach/design and method: As a theoretical article, a systematic literature review was conducted to draw findings and conclusions.Main findings: The article concludes that the eclectic nature of SME HR practices complicates the extent of generalisability of such practices across organisational settings, thus showing that HR practices that work in SME firms cannot be applied in large firms with equal success.Practical/managerial implications: The findings provide a platform to enhance the understanding surrounding managing human resources in SME firms by revealing the differences between people management in SME firms as compared to their larger counterparts.Contribution/value-add: The article is groundbreaking as it has opened new avenues in the quest to understand the nature and contribution of HRM in SME firms.
Saberes docentes de professoras de Educação Física sobre o conteúdo dança
Authors: Souza Ana Aparecida Almeida de , Brasileiro Lívia Tenorio
Published: August 2019

Este estudo tem como objetivo geral: analisar os saberes docentes que os/as professores/as de Educação Física têm para ensinar o conteúdo de dança. Desenvolvemos uma pesquisa com base em uma metodologia colaborativa, uma das modalidades da pesquisa-ação, que envolve investigadores e professores/as, na medida em que estes reconhecem sua situação educativa, seu contexto de ação e sejam capazes de indagarem e teorizarem a própria prática. A pesquisa foi realizada com duas professoras, ambas licenciadas em Educação Física, na cidade de Campina Grande-PB, através de uma entrevista semiestruturada, sendo analisadas através das reflexões ontológicas e epistemológicas. Os saberes identificados nas falas dos sujeitos nos permitem apontar que há uma valorização do saber experiencial, saberes esses que constituem essas professoras como pessoas que dançam ao longo de suas vidas, dentro e fora da escola.
A participação de ginastas do Rio Grande do Sul nos jogos olímpicos: trajetórias, narrativas e memórias
Authors: Bender Natália , Goellner Silvana Vilodre
Published: August 2019

Fundamentado no aporte teórico-metodológico da História Oral, este texto tematiza a participação de ginastas do Rio Grande do Sul nos Jogos Olímpicos, tendo como foco suas narrativas. Como fontes foram utilizadas entrevistas realizadas com os/as sete ginastas gaúchos/as participantes desse megaevento e outras narrativas cujo conteúdo se relaciona com o tema. As entrevistas foram cotejadas com outras fontes como reportagens, livros, artigos acadêmicos e atlas esportivos. A análise de conteúdo foi utilizada como ferramenta analítica, considerando as etapas de pré-análise, exploração do material empírico e tratamento dos dados. Do entrecruzamento entre as fontes, identificamos que os/as ginastas iniciaram sua trajetória esportiva na escola e posteriormente se transferiram para clubes, onde tiveram formação básica na ginástica, e para aprimorar suas performances migraram para outros estados. A participação nos Jogos Olímpicos foi representada como um momento ímpar em suas trajetórias, inscrevendo a ginástica em suas memórias, histórias e corpos.
A Educação Física nos periódicos da Academia Imperial de Medicina entre 1870 e 1889
Authors: Dos Santos Felipe Lameu
Published: August 2019

A educação física era uma das preocupações do pensamento médico na cidade do Rio de Janeiro durante boa parte do século XIX. Nesse artigo trataremos das representações sobre a educação física em dois periódicos da Academia Imperial de Medicina entre 1870 e 1889. Nos interessa inquirir em suas páginas os debates, representações e discussões erigidos acerca do tema educação física, ao longo período de circulação dos mesmos nos anos de 1870 a 1889. Pela analise das fontes percebe-se que a educação física estava relacionada a uma preocupação com a formação da Nação brasileira nas décadas de 1870 e 1880. A higiene deveria criar a gramática de como criar o povo brasileiro pela educação física.
Supercondutividade: aplicação em veículos de levitação magnética
Authors: Morais Cicero Igor Freire de , Moreira Antônio Philipi Alves
Published: August 2019

Este trabalho visa descrever os fenômenos físicos associados à supercondutividade em materiais condutores utilizados em veículos de levitação magnética, especificando os efeitos da resistência e de magnetismo. Os dados que corroboram a pesquisa foram coletados a partir de pesquisas em trabalhos já publicados e partem desde a descoberta do estado de supercondutividade da matéria, observada pela primeira vez em 1911 pelo físico holandês Heike Kamerlingh Onnes. Alem disso, haverá uma breve abordagem sobre os custos envolvidos, bem como a aplicação dos efeitos da supercondutividade no meio de transporte supracitado.
Bank Lobbying
Authors: Igan Deniz , Lambert Thomas
Published: August 2019

In this paper, we discuss whether and how bank lobbying can lead to regulatory capture and have real consequences through an overview of the motivations behind bank lobbying and of recent empirical evidence on the subject. Overall, the findings are consistent with regulatory capture, which lessens the support for tighter rules and enforcement. This in turn allows riskier practices and worse economic outcomes. The evidence provides insights into how the rising political power of banks in the early 2000s propelled the financial system and the economy into crisis. While these findings should not be interpreted as a call for an outright ban of lobbying, they point in the direction of a need for rethinking the framework governing interactions between regulators and banks. Enhanced transparency of regulatory decisions as well as strenghtened checks and balances within the decision-making process would go in this direction.
The Expansionary Lower Bound
Authors: Cavallino Paolo , Sandri Damiano
Published: August 2019

We provide a theory of the limits to monetary policy independence in open economies
arising from the interaction between capital flows and domestic collateral constraints. The
key feature of our theory is the existence of an “Expansionary Lower Bound” (ELB),
defined as an interest rate threshold below which monetary easing becomes
contractionary. The ELB can be positive, thus acting as a more stringent constraint than
the Zero Lower Bound. Furthermore, the ELB is affected by global monetary and
financial conditions, leading to novel international spillovers and crucial departures from
Mundell’s trilemma. We present two models under which the ELB may arise, the first
featuring carry-trade capital flows and the second highlighting the role of currency
mismatches.
From Basel I to Basel III
Authors: Ferreira Caio , Jenkinson Nigel , Wilson Christopher
Published: August 2019

Developing economies can strengthen their financial systems by implementing the main elements of global regulatory reform. But to build an effective prudential framework, they may need to adapt international standards taking into account the sophistication and size of their financial institutions, the relevance of different financial operations in their market, the granularity of information available and the capacity of their supervisors. Under a proportionate application of the Basel standards, smaller institutions with less complex business models would be subject to a simpler regulatory framework that enhances the resilience of the financial sector without generating disproportionate compliance costs. This paper provides guidance on how non-Basel Committee member countries could incorporate banks’ capital and liquidity standards into their framework. It builds on the experience gained by the authors in the course of their work in providing technical assistance on—and assessing compliance with—international standards in banking supervision.
Liquidity Ratios as Monetary Policy Tools
Authors: Monnet Eric , Vari Miklos
Published: August 2019

This paper explores what history can tell us about the interactions between macroprudential and monetary policy. Based on numerous historical documents, we show that liquidity ratios similar to the Liquidity Coverage Ratio (LCR) were commonly used as monetary policy tools by central banks between the 1930s and 1980s. We build a model that rationalizes the mechanisms described by contemporary central bankers, in which an increase in the liquidity ratio has contractionary effects, because it reduces the quantity of assets banks can pledge as collateral. This effect, akin to quantity rationing, is more pronounced when excess reserves are scarce.
The Impact of Remittances on Economic Activity
Authors: Perez-Saiz Hector , Dridi Jemma , Gursoy Tunc , Bari Mounir
Published: August 2019

We propose a simple macroeconomic model with input-output sectoral linkages based on Acemoglu et al. (2016) to quantify how changes in aggregate demand due to additional income from household’s remittances propagates through the network of input-output linkages in Sub-Saharan African countries. We first propose two network centrality measures to assess the role of some sectors as key input providers in the economy. Then, we use these measures to quantify the effect of sectoral linkages on sectoral and total output following an increase in remittances inflows. Our empirical results suggest that the effects of remittances on recipient economies increase with the degree of linkages across sectors, which is especially prominent in the case of the financial intermediation sector. Our paper contributes to the emerging macroeconomic literature on the propagation of shocks across sectors and the implications for the whole economy.
The Economic Impact of Healthcare Quality
Authors: Helsø Anne-Line Koch , Pierri Nicola , Wang Adelina Yanyue
Published: August 2019

We study the costs of hospitalizations on patients’ earnings and labor supply, using the universe of hospital admissions in Denmark and full-population tax data. We evaluate the quality of treatment based on its ability to mitigate the labor market consequences of a given diagnosis and propose a new measure of hospital quality, the "Adjusted Earning Losses" (AEL). We find a 4 percentage points difference in lost earnings between the best and worst large Danish hospitals, all else equal. We show that AEL contains significant additional information relative to traditional measures and does not suffer from worse selection issues. We also document a large decline in the labor cost of hospitalizations over time, with large variations across diseases. We find that the average post-hospitalization reduction in labor earnings declined by 25 percent (50 percent) on the intensive (extensive) margin between 1998 and 2012.
Labor Market Slack and the Output Gap
Authors: Hansen Niels-Jakob , Mongardini Joannes , Zhang Fan
Published: August 2019

Output gap estimates are widely used to inform macroeconomic policy decisions, including in Korea. The main determinant of these estimates is the measure of labor market slack. The traditional measure of unemployment in Korea yields an incomplete estimate of labor market slack, given that many workers prefer involuntary part-time jobs or leaving the labor force rather than registering as unemployed. This paper discusses a way in which the measure of unemployment can be broadened to yield a more accurate measure of labor market slack. This broader measure is then used to estimate the output gap using a multivariate filter, yielding a more meaningful measure of the output gap.
Public Sector Balance Sheet Strength and the Macro Economy
Authors: Yousefi Seyed Reza
Published: August 2019

This paper introduces concepts of public sector balance sheet (PSBS) strength, taking into account different aspects of what governments own in addition to what they owe. It develops measures of PSBS strength and investigates their macroeconomic implications. Empirical estimations show that in their pricing of sovereign bonds, financial markets account for government assets and net worth in addition to their liabilities. Furthermore, economies with stronger public sector balance sheets experience shallower recessions and recover faster in the aftermath of economic downturns. This faster return to growth can be explained by the greater space for countercyclical fiscal policy in countries with stronger balance sheets.
State Institutions and Tax Capacity
Authors: Akanbi Olusegun Ayodele
Published: August 2019

Would better state institutions increase tax collection, or would higher tax collection help improve state institutions? In the absence of conclusive guidance from theory, this paper searches for an empirical answer to this question, using a panel dataset covering 110 non-resource-rich countries from 1996 to 2017. Employing a panel vector error correction model, the paper finds that tax capacity and state institutions cause and reinforce each other for a wide range of country groups. The bi-directional causality results suggest that developing tax capacity and building state institutions need to go hand in hand for best results, particularly in developing countries. Based on the impulse response analyses, the paper also finds that the causal effects in advanced economies are generally low in both directions, while in developing countries, both tax capacity and institutions shocks have larger positive impacts on institutions and tax capacity, respectively.
Lao People’s Democratic Republic
Authors:   International Monetary Fund. Asia and Pacific Dept
Published: August 2019

After more than a decade of high growth with low inflation, Lao P.D.R. is solidifying its progress towards graduating from the Least Developed Country (LDC) status. However, more than one fifth of the population remains poor, regional disparities are persistent, and recurring natural disasters pose risks for poverty reduction. A large current account deficit, low level of reserves, a high level of debt, managed exchange rate, and a dollarized banking system amplify macro-vulnerabilities. The authorities recognize the current economic challenges and their comprehensive reform programs aim at rebalancing the economy from a resource-based to a more diversified growth model by investing in human development and improving competitiveness.
Gender Equality and Electoral Violence in Africa
Authors: Ouedraogo Rasmané , Ouedraogo Idrissa
Published: August 2019

We examine the impact of gender equality on electoral violence in Africa using micro-level data from the sixth round of Afrobarometer surveys. The sample covers 30 countries. We find that gender equality is associated with lower electoral violence. Quantitatively, our estimates show that an increase in female-to-male labor force participation ratio by 1 percentage point is correlated with a reduction of the probability of electoral violence across the continent by around 4.2 percentage points. Our results are robust to alternative ways to measure electoral violence and gender equality, as well as to alternative specifications. The findings of this paper support the long-standing view that women empowerment contributes to the reduction of violence and underscore the urgency of addressing gender inequality in Africa.
Union of Comoros
Authors:   International Monetary Fund. African Dept.
Published: August 2019

Tropical Cyclone Kenneth struck Comoros on April 23-24. The cyclone caused several casualties; displaced thousands; and damaged substantial parts of the building stock, infrastructure, and plants used in subsistence and commercial farming, thereby lowering productive capacity. Request for Fund support. Reflecting the large budgetary and external financing gaps arising from emergency assistance and reconstruction needs, the authorities are seeking financial assistance under the Rapid Credit Facility (RCF) and Rapid Financing Instrument (RFI) exogenous shock windows. Comoros’ qualification is based on urgent balance of payments needs following a severe natural disaster. In the attached letter, the authorities request a disbursement under the RCF and purchase under the RFI of a combined SDR 8.9 million, equivalent to 50 percent of quota, with the full amount to become available upon Board approval. Staff supports this request. IMF involvement in the international effort to assist Comoros will play also a catalytic role in securing grants from Comoros’ development partners.
People’s Republic of China
Authors:   International Monetary Fund. Asia and Pacific Dept
Published: August 2019

Selected Issues
Pb and Zn contamination as rate-regulation agents on decomposition of two emergent macrophytes: a systemic approach
Authors: Moitas Marcel Loyo , Bianchini Júnior Irineu , Cunha-Santino Marcela Bianchessi
Published: August 2019

Modeling the carbon cycling in aquatic environments is relevant for predicting the detritus processing capacity in metal-affected environments. Considering the potential toxic effect of Zn and Pb on microbial metabolism, we hypothesize that the presence of these metals decreases decomposition rates of macrophytes detritus. We examined the anaerobic decomposition of Hedychium coronarium and Urochloa subquadripara in presence of Zn and Pb at 15 and 25Â°C. The mass decay was parameterized by first-order kinetic model. The higher concentration of Zn promoted reduction on mineralization of particulate organic carbon (POC) in the U. subquadripara and H. coronarium detritus. The Q10 (H. coronarium: 0.95 to 1.75 and U. subquadripara: 1.26 to 1.59) showed a positive effect of temperature increasing during macrophytes anaerobic degradation. Considering the metal type and concentration, the high Zn concentration acted as a driving force over POC decay and consequently affecting the yields in the plant detritus mineralization processes since the decrease in POC degradation was effective due to adsorption of metals in this detritus fraction. The use of mathematical models was suitable tool that allows predicting carbon turnover in an ecosystem submitted to an episode of metal contamination.
Toxicity responses for marine invertebrate species of brazilian occurrence
Authors: Artal Mariana Coletty , Santos Amanda , Dornelas Leticia Lawall , Vannuci-Silva Monizze , Vacchi Francine Inforçato , De Albuquerque Anjaina Fernandes , Lotufo Guilherme Ribeiro , Umbuzeiro Gisela De Aragão
Published: August 2019

To assess the risk of chemical contaminants it is desirable to derive toxicity data from representative species of the ecosystem intended to be protected. However, species of occurrence in Brazil are rarely used in toxicity tests, especially for marine and estuarine environments. To address this need, we evaluated the toxicity of different toxicants such as metals and organic compounds to marine invertebrates of Brazilian occurrence, representative from tropical regions and cultivated in laboratory. We used two epibenthic test species of Brazilian occurrence, Parhyale hawaiensis, a deposit feeding amphipod and Nitocra sp, a harpacticoid copepod. Nitocra sp. was more sensitive than other copepods to zinc, and more sensitive than P. hawaiensis to disperse dyes. Sensitivity species distribution revealed that Nitocra sp. and P. hawaiensis were similarly responsive as other marine species to zinc, and Nitocra sp. was among of the most sensitive species. Moreover, our study highlighted that organic compounds are poorly explored in toxicity evaluation with marine organisms; therefore, more studies need to be carried out to assess the toxicity of different substances using marine and estuarine organisms representative of tropical ecosystems.
Simulated coordinated impacts of the previous autumn North Atlantic Oscillation (NAO) and winter El Niño on winter aerosol concentrations over eastern China
Authors: Feng Juan , Li Jianping , Liao Hong , Zhu Jianlei
Published: August 2019

Abstract. The high aerosol concentration (AC) over eastern China has attracted
attention from both science and society. Based on the simulations of a
chemical transport model using a fixed emissions level, the possible impact of
the previous autumn North Atlantic Oscillation (NAO) combined with the
simultaneous El Niño–Southern Oscillation (ENSO) on the boreal winter AC
over eastern China is investigated. We find that the NAO only manifests its
negative impacts on the AC during its negative phase over central China, and
a significant positive influence on the distribution of AC is observed over
south China only during the warm events of ENSO. The impact of the previous
NAO on the AC occurs via an anomalous sea surface temperature tripole
pattern by which a teleconnection wave train is induced that results in
anomalous convergence over central China. In contrast, the occurrence of
ENSO events may induce an anomalous shift in the western Pacific subtropical
high and result in anomalous southwesterlies over south China. The anomalous
circulations associated with a negative NAO and El Niño are not
favorable for the transport of AC and correspond to worsening air conditions
over central and south China. The results highlight the fact that the combined
effects of tropical and extratropical systems play a considerable role in
affecting the boreal winter AC over eastern China.
Accurate 3D radiative transfer simulation of spectral solar irradiance during the total solar eclipse of August 21, 2017
Authors: Ockenfuß Paul , Emde Claudia , Mayer Bernhard , Bernhard Germar
Published: August 2019

Abstract. We calculate the variation of spectral solar irradiance in the umbral shadow of the total solar eclipse of August 21, 2017 and compare it to observations. Starting from the sun's and moon's positions, we derive a realistic profile of the lunar shadow at the top of the atmosphere, including the effect of solar limb darkening. Subsequently, the Monte-Carlo model MYSTIC is used to simulate the transfer of solar radiation through the earth's atmosphere. Among the effects taken into account are the atmospheric state (pressure, temperature), concentrations of major gas constituents and the curvature of the earth, as well as the reflectance and elevation of the surrounding area. We apply the model to the total solar eclipse on August 21, 2017 at a position located in Oregon, where irradiance observations were performed for wavelengths between 306 nm and 1020 nm. The influence of the surface reflectance, the ozone profile and mountains surrounding the observer is investigated. An increased sensitivity during totality is found for the reflectance and topography, compared to non-eclipse conditions. During the eclipse, the irradiance at the surface does not only depend on the total ozone column (TOC) but also the vertical ozone distribution, which in general complicates derivations of the TOC from spectral surface irradiance. The findings are related to an analysis of the prevailing photon path and its difference compared to non-eclipse conditions. Using the most realistic estimate for each parameter, the model is compared to the irradiance observations. During totality, the relative difference between model and observations is less than 10 % in the spectral range from 400 nm to 1020 nm. Slightly larger deviations occur in the ultraviolet range below 400 nm and at 665 nm.