Abstract Global second order effects in reinforced concrete buildings can be estimated using numerical or simplified methods, such as the γz coefficient, presented in the Brazilian standard. This paper proposes a new simplified parameter, which is deduced by the Galerkin’s Method by Weighted Residuals. In order to evaluate the accuracy of the proposed methodology, 42 planar frames (21 framed system structures and 21 dual system structures) were analysed in terms of internal forces and displacements. Such results were compared to those obtained by the γz coefficient and to the reference results obtained throughout a geometric nonlinear elastic finite element program. The precision of the results was defined by statistical analyses, which showed that the results using the proposed parameter were closer to the reference ones, even in the recommended range for using the γz coefficient.

Resumo Efeitos globais de segunda ordem em edifícios de concreto armado podem ser estimados por métodos numéricos ou procedimentos simplificados, como o coeficiente γz, apresentado na norma brasileira. Neste artigo propõe-se um novo parâmetro simplificado, que é deduzido pelo Método de Galerkin por Resíduos Ponderados. De modo a avaliar a acurácia do modelo proposto, 42 pórticos planos (21 com contraventamento por pórticos e 21 com contraventamento por elementos rígidos) foram analisados em termos de esforços internos e deslocamentos. Tais resultados foram comparados aos obtidos pelo coeficiente γz e a resultados de referência obtidos por um programa de elementos finitos com análises de não linearidade geométrica. A precisão dos resultados foi definida por parâmetros estatísticos, que mostram que os resultados obtidos utilizando o parâmetro proposto estavam mais próximos dos resultados de referência, mesmo na faixa recomendada para a utilização do parâmetro γz.

ABSTRACT BACKGROUND: Stroke is a major cause of mortality worldwide. Renal dysfunction is an important risk factor for stroke. Brazilian studies on stroke knowledge are generally population based. Studies stratifying stroke knowledge according to comorbidities are rare. Scientific data are essential to guide the awareness of stroke. OBJECTIVE: To assess stroke knowledge in patients with chronic kidney disease (CKD) on hemodialysis. DESIGN AND SETTING: Cross-sectional analytical study of patients with CKD on hemodialysis in north-eastern Brazil. METHODS: A self-administered questionnaire survey on stroke awareness was administered to patients with CKD on hemodialysis between April and November 2022. The chi-square test and other descriptive statistics were used. Univariate and multivariate analyses were performed using logistic regression. RESULTS: A total of 197 patients were included in the analysis. The Brazilian acronym for stroke was used by 53.5% of the participants. Less than 10.0% of the sample showed optimal decision-making ability regarding stroke. Of the participants, 29.9% knew at least one risk factor and one symptom; however, this was considered as having below the minimum capacity because they did not know the emergency service call number. In the analysis adjusted for income and education, females (odds ratio [OR], 0.40%; 95% confidence interval [CI], 0.20-0.82), older patients (OR, 0.24%; 95% CI, 0.09-0.63) and having at most one comorbidity (OR, 0.48%; 95% CI, 0.23-0.98) were factors for lower levels of knowledge or ideal decision-making capacity against stroke. CONCLUSIONS: Patients on hemodialysis, especially women and older people, have little knowledge about stroke.

ABSTRACT In-depth knowledge of total soil organic phosphorus (TPO) as a potential P source for plants allows for a comprehensive understanding of the adoption of an efficient management system of phosphorus fertilization in forest plantations. Thus, we aimed to compare three TPO extraction methods (Hedley; Bowman; Bowman and Moir) in different Eucalyptus plantations on strongly weathered soils. The TPO concentrations obtained by the “Hedley” (mean of 130 mg kg–1), and “Bowman and Moir” methods (mean of 131 mg kg–1) were similar. The “Bowman” method extracted less than 50 % of the TPO content extracted by the other methods. Both “Hedley” and “Bowman and Moir” methods showed similar TPO extraction efficiency compared to TP determined by acid digestion. However, the “Hedley” method is the most expensive and time-consuming analytical technique. In view of this, the NaOH+Na2EDTA extractor (Bowman and Moir) would be the most suitable since, in addition to showing high extraction efficiency, it offers fast analysis execution, low analytical error, and lower cost.

Abstract Over the last three decades, stroke care has undergone significant transformations mainly driven by the introduction of reperfusion therapy and the organization of systems of care. Patients receiving treatment through a well-structured stroke service have a much higher chance of favorable outcomes, thereby decreasing both disability and mortality. In this article, we reviewed the scientific evidence for stroke reperfusion therapy, including thrombolysis and thrombectomy, and its implementation in the public health system in Brazil.

Resumo Nas últimas três décadas, o tratamento do AVC sofreu transformações significativas, impulsionadas principalmente pela introdução das terapias de reperfusão e pela organização dos serviços de AVC. Os pacientes que recebem tratamento em um serviço de AVC bem estruturado têm uma probabilidade muito maior de resultados favoráveis, diminuindo assim a incapacidade funcional e a mortalidade. Neste artigo, revisamos as evidências científicas para as terapias de reperfusão do AVC, incluindo trombólise e trombectomia e sua implementação no sistema público de saúde no Brasil.

ABSTRACT Through the theory of legitimacy and the theoretical perspective of New Institutional Economics, the purpose of this paper is to analyze the effect of economic freedom over the relationship between Environmental, Social, Governance (ESG) practices and profitability. The sample was finance companies located in the Americas, between 2017 and 2020, using the Refinitiv Eikon® database. The analysis used data modeling in a hierarchical panel. Results demonstrate that ESG practices have a positive and significant impact on profitability. Individually, only the social variable showed a positive and significant relationship over profitability. As for the moderating effect of economic freedom, it was shown that economic freedom enhances the relationship between an ESG index and profitability, and only enhances the relationship between corporate governance and profitability when analyzed individually. Furthermore, findings imply that a country’s institutional quality has an important influence on ESG practices and profitability.

RESUMO Por meio da teoria da legitimidade e da vertente Nova Economia Institucional, o objetivo deste estudo é investigar o efeito da liberdade econômica na relação entre as práticas Environmental, Social, Governance (ESG) e a rentabilidade. A amostra da pesquisa corresponde às empresas do setor de finanças localizadas na América, entre 2017 e 2020, utilizando informações da base de dados Refinitiv Eikon®. A análise utilizou modelagem de dados em um painel hierárquico. Os resultados demonstram que as práticas ESG têm um impacto positivo e significativo sobre a rentabilidade. Individualmente, apenas a variável referente ao pilar social apresentou relação positiva e significativa sobre a rentabilidade. Quanto ao efeito moderador da liberdade econômica, mostrou-se que ela potencializa a relação entre índice ESG e rentabilidade, e somente potencializa a relação entre governança corporativa e rentabilidade quando analisadas individualmente. Além disso, os resultados implicam que a qualidade institucional de um país tem uma influência importante nas práticas ESG e na rentabilidade.

Abstract Objectives: To determine the cut-off point of the cochlear radiation dose as a risk factor for hearing loss in patients with vestibular schwannoma treated with radiosurgery. Methods: A systematic review of the literature was performed without language or publication year restrictions in the MEDLINE/PubMed, EMBASE, Web of Science, LILACS/VHL and Cochrane Library databases. Studies that met the following criteria were included: 1) population: adults of both sexes who underwent radiosurgery for vestibular schwannoma treatment; 2) exposure: cochlear radiation; 3) outcome: hearing loss; 4) type of study: cohort. Two independent reviewers conducted the entire review process. The registration number in PROSPERO was CRD42020206128. Results: From the 333 articles identified in the searches, seven were included after applying the eligibility criteria. There was no standardization as to how to measure exposure or outcome in the included studies, and most studies did not present sufficient data to enable meta-analysis. Conclusion: It was not possible to determine a cut-off point for high cochlear dose that could be considered a risk factor for hearing loss.

ABSTRACT Inside the Brazilian semi-arid region (Caatinga biome) there are vegetation refuges from other biomes that are present mainly at greater elevations in ancient geological formations such as Chapada do Araripe. This study aimed to understand the structure, diversity and floristic similarity of a fragment of humid forest in order to support conservation strategies for this community in Chapada do Araripe, southern Ceará (708m Alt.), an area of relevant ecological, cultural and scenic value. In 13 parcels of 25x25m (0.8 ha) all individuals with DBH ≥ 5cm were inventoried, observing total height. Floristic similarity was observed using the Jaccard method, comparing it with seven other areas in different regions of the Brazil. Sixty-six species were found distributed in 34 families, in a total of 1,544 individuals with DA=1,997.30 ind.ha-1 and AB =32,618 m²ha-1. Fabaceae (25.75%) and Myrtaceae (6%) had the highest number of species and Brosimum gaudichaudii had the highest IVI. The Shannon index (H') was 3.13 and the Pielou equability (J') was 0.75. The beta diversity, compared with other areas of humid forest (core and disjunct), was considered high and the statistics showed greater similarity with the area of the mesoregion of Pernambuco forest. The results allow the characterization of the area as a vegetational refuge of humid forest, corroborating the Refuge Theory and showing strong penetration of savanna species (“Cerradão”, Cerrado, Caatinga/“Carrasco”), emphasizing the action of climatic impulses that occurred in the Quaternary and pointing to the need to conservation strategies due to accelerated anthropism.

RESUMO No interior da região semiárida brasileira (bioma Caatinga), há ocorrência de refúgios de vegetação de outros biomas que se apresentam principalmente em topos de formações geológicas do período Pré-Cambriano, como a Chapada do Araripe. Este trabalho objetivou o conhecimento da estrutura, diversidade e similaridade florística de um fragmento de mata úmida na Chapada do Araripe, sul do Ceará (708m Alt.), visando subsidiar estratégias de conservação dessa comunidade, área de relevante valor ecológico, cultural e paisagístico. Em 13 parcelas de 25x25m (0,8 ha), foram inventariados todos os indivíduos com DAP ≥ 5cm, observando-se altura total. A similaridade florística foi observada pelo método de Jaccard a partir da comparação com outras sete áreas em diferentes regiões do Brasil. Foram encontradas 66 espécies distribuídas em 34 famílias, num total de 1.544 indivíduos com DA=1.997,30 ind.ha-1 e AB=32,618 m²ha-1. Fabaceae (25,75%) e Myrtaceae (6%) apresentaram maior número de espécies e Brosimum gaudichaudii apresentou maior IVI. O índice de Shannon (H’) foi 3,13 e a equabilidade de Pielou (J’) foi 0,75. A diversidade beta, comparada com outras áreas de mata úmida (core e disjuntas), foi considerada alta e a estatística apontou maior similaridade com área da mesorregião da mata pernambucana. Os resultados permitem caracterizar a área como refúgio vegetacional de mata úmida, corroborando com a teoria dos refúgios e evidenciam forte penetração de espécies savânicas (cerradão, cerrado, caatinga/carrasco) enfatizando a atuação de impulsos climáticos ocorridos no Quaternário e apontando para a necessidade de estratégias de conservação devido ao antropismo acelerado.

Abstract Background Evaluation and treatment of primary and secondary headaches is a global public health challenge. Recognizing the epidemiological impact of headaches, a group of researchers linked to the Brazilian Headache Society proposed the Brazilian Headache Registry and drew up its initial protocol. Objective Here we describe the methods and preliminary data obtained from the pilot study. Methods This was a multicenter longitudinal observational study conducted between September 2020 and August 2021. Prospective data were collected in three specialist centers for headache care in states in southern and southeastern Brazil. Patients aged 18 years or older who sought care for headache in tertiary centers and who agreed to participate in the study, were considered eligible. Results Sixty-six patients were included in the pilot study: 43 (65%) from Rio Grande do Sul state and 23 (35%) from Minas Gerais state. Overall, 90% were female, and the subjects' mean age was 38.2 ± 11.2 years. Primary headaches accounted for 85.3% of the diagnoses made. Among secondary headaches, medication overuse headache was the most frequent type (7.1%). Conclusions The pilot study showed the feasibility of the research protocol developed for tertiary centers. The Brazilian Headache Registry will form a source of longitudinal data with the aim of contributing to better characterization of the various phenotypes of patients with primary and secondary headaches, and to detailing the use of health resources and identifying predictors of better clinical outcomes.

Resumo Antecedentes A avaliação e o tratamento das cefaleias primárias e secundárias são um desafio global de saúde pública. Reconhecendo o impacto epidemiológico das cefaleias, um grupo de pesquisadores vinculados à Sociedade Brasileira de Cefaleia propôs a criação de um Registro Brasileiro de Cefaleia e elaborou seu protocolo inicial. Objetivo Nesta publicação descrevemos os métodos e dados preliminares obtidos a partir do estudo piloto. Métodos Trata-se de um estudo prospectivo observacional longitudinal multicêntrico, realizado entre setembro de 2020 e agosto de 2021. Foram coletados dados em três centros especializados no atendimento de cefaleia, em estados da região sul e sudeste do Brasil. Pacientes com idade igual ou superior a 18 anos que procuraram os centros terciários por queixa de cefaleia e concordaram em participar do estudo foram considerados elegíveis. Resultados Sessenta e seis pacientes foram incluídos no estudo piloto, 43 (65%) do Rio Grande do Sul e 23 (35%) de Minas Gerais. Da amostra total, 90% eram do sexo feminino e a idade média dos sujeitos foi de 38,2 ± 11,2 anos. As cefaleias primárias representaram 85,3% dos diagnósticos realizados. Entre as cefaleias secundárias, a cefaleia por uso excessivo de medicamentos foi a mais frequente (7,1%). Conclusões O estudo piloto evidenciou a viabilidade do protocolo de pesquisa desenvolvido para centros terciários. O Registro Brasileiro de Cefaleia constituirá uma fonte de dados longitudinais com o objetivo de contribuir para melhor caracterização dos diversos fenótipos de pacientes com cefaleias primárias e secundárias, detalhar o uso de recursos de saúde e identificar preditores de melhores desfechos clínicos.

Abstract Objective This study aimed to perform an imaging evaluation to prove the existence or not of symmetry between the clavicles of healthy subjects from Curitiba, Paraná, Brazil, and identify potential factors influencing the clavicular length. Method The study analyzed chest computed tomography (CT) scans of 211 patients with no clavicular fracture or malformations (100 women and 111 men). We measured the greatest clavicular diagonal on both sides, and the software automatically generated the maximum distance in millimeters. Relative and absolute frequencies described qualitative variables and mean values; quantitative variables used a 95% confidence interval. Value comparisons employed the student's t-test, and correlations determinations used Pearson's correlation coefficient. The significance level adopted was 5%. Results There was a significant difference between the clavicular length (right clavicle, 143.58 mm; left clavicle, 145.72 mm; p = 0.037), indicating asymmetry. On average, the left clavicle was 3.71 mm larger. Asymmetry was significant for both men and women (p < 0.001). The average difference was 4.13 mm for men and 3.23 mm for women. Seventy-three percent of the sample had < 5 mm of asymmetry, 23.7% had 5 to 10 mm, and 3.3% had > 10 mm of asymmetry. Conclusion The studied population did not present clavicular symmetry. On average, the left clavicle was longer than the right clavicle, with differences of 3.71 mm in the general sample, 3.23 mm in women, and 4.13 mm in men. The only significant factor was gender since men presented longer clavicles and higher differences than women.

Resumo Objetivo Realizar avaliação imagiológica com intuito de comprovar a existência ou não de simetria entre as clavículas de indivíduos saudáveis da cidade de Curitiba/PR, aliada à identificação de possíveis fatores de influência no comprimento clavicular. Método Foram analisadas tomografias computadorizadas de tórax de 211 pacientes sem fratura ou malformações na clavícula (100 mulheres e 111 homens). A maior diagonal clavicular foi medida em ambos os lados e o software gerou automaticamente a máxima distância em milímetros. Foram utilizadas frequências relativas e absolutas para descrever variáveis qualitativas e a média e intervalo de 95% de confiança para as quantitativas. As comparações foram feitas com o teste t de Student e correlações calculadas pelo coeficiente de correlação de Pearson. O nível de significância adotado foi de 5%. Resultados Verificou-se diferença significativa entre o comprimento das clavículas (direita 143.58mm e esquerda 145.72mm, p = 0.037), indicando assimetria. Em média, o lado esquerdo é 3.71mm maior. A assimetria foi significativa tanto para homens quanto para mulheres (p < 0.001). A diferença média foi de 4.13mm para homens e 3.23mm para mulheres. 73% da amostra apresentou <5mm de diferença, enquanto 23.7% apresentou 5-10mm e 3.3% apresentou >10mm de assimetria. Conclusão Não foi possível encontrar simetria nas clavículas da população de Curitiba/PR. Em média, a clavícula esquerda é maior que a direita, com diferenças de 3.71mm na amostra geral, 3.23mm para mulheres e 4.13mm para homens. O único fator significativo foi o sexo, com homens tendo maiores comprimentos claviculares e maiores diferenças em comparação às mulheres.

Resumen En la región semiárida de Paraíba, el caupí es el principal producto de la agricultura familiar. El cultivo tiene baja productividad debido a lluvias irregulares y condiciones climá ticas desfavorables. Además, la productividad también se ve afectada por el uso deficiente de las tecnologías de producción. Con el objetivo de superar estas limitaciones y aumentar la eficiencia de la selección de cultivares superiores, se llevó a cabo un extenso estudio utili zando modelos biométricos en caupí. Este primer trabajo tuvo los siguientes objetivos: i. Cuantificar los efectos directos e indirectos de los componentes primarios y secundarios en la producción de granos; ii. Identificar variables con mayor potencial para la selección de cultivares de caupí en la región semiárida de Paraíba y iii. Determinar las estrategias de selección más adecuadas para el conjunto de variables evaluadas. El experimento se llevó a cabo en un campo experimental en el Centro de Ciencia y Tecnología Agroalimentaria de la Universidad Federal de Campina Grande. Se evaluó la influencia de 6 componentes primarios y 6 componentes secundarios de la producción sobre la variable rendimiento de grano. Los datos se sometieron a ANAVA y se estimaron parámetros genéticos. También se realizaron correlaciones y análisis de ruta. Se identificaron variables con mayor potencial para la selección de cultivares superiores de caupí en la región semiárida de Paraíba. Se encontró que la variable rendimiento de vaina es la más prometedora para la selección de cultivares con mayor rendimiento de grano debido a la magnitud de los efectos fenotípico y genotípico. La selección directa y la selección simultánea son las estrategias más adecuadas para el conjunto de variables evaluadas. Sin embargo, para maximizar las ganancias gené ticas, se continuó el estudio a través de índices de selección.

Abstract In the semi-arid region of Paraíba, cowpea has low productivity due to irregular rainfall and poor use of production technologies. An extensive study aimed at selecting more productive cultivars was conducted using biometric models. This first work had the following objectives: i. Quantify direct and indirect effects of primary and secondary compo nents on grain production; ii. Identify variables with greater potential for cultivar selection in the semiarid region of Paraíba and iii. Determine the most appropriate selection strat egies for the evaluated variables. The experiment was conducted in an experimental field. The influence of 6 primary and 6 secondary production components was evaluated on grain yield. Data were subjected to ANOVA. Genetic parameters, correlations and path analysis were estimated. Given the strong direct phenotypic and genotypic effects, pod yield results the most promising variable for higher grain yield selection. Direct and simultaneous selec tions are the most suitable strategies for the set of evaluated variables. However, further studies on selection indices are necessary to maximize genetic gains.

Resumen En la región semiárida de Paraíba, el caupí (Vigna unguiculata (L.) Walp) es el prin cipal producto de la agricultura familiar. El cultivo tiene baja productividad debido a lluvias irregulares y al uso de cultivares de baja productividad. Con el objetivo de superar estas limitaciones y aumentar la eficiencia de la selección de cultivares superiores, se llevó a cabo un extenso estudio utilizando modelos biométricos en caupí, con los siguientes obje tivos: i. Estimar las ganancias genéticas de los componentes de la producción; ii. Identi ficar el modelo de índice de selección que proporciona las mayores ganancias mediante la selección simultánea de un conjunto de variables y iii. Seleccionar cultivares con mayor productividad. El experimento se llevó a cabo en el campo experimental del Centro de Ciencia y Tecnología Agroalimentaria de la Universidad Federal de Campina Grande. Se evaluaron 13 variables relacionadas con la productividad. Los datos se sometieron a ANOVA y las medias se agruparon según la prueba de Scott y Knott p≤ 0,05. También se estimó el coeficiente de heredabilidad de cada variable. Las ganancias genéticas se estimaron utili zando las siguientes metodologías: respuesta correlacionada, índice de selección clásico, suma de rango e índice basado en las ganancias deseadas. Se encontró que la selección directa del componente de rendimiento de la vaina secundaria proporciona ganancias genéticas significativas en rendimiento de grano. Entre las metodologías utilizadas, el índice de selección clásico proporcionó una mayor distribución de las ganancias genéticas para rendimiento de grano y para los componentes primarios de producción. Estos resultados permiten concluir que los cultivares Costela de vaca, BRS Marataoã y Paulistinha pueden seleccionarse para cultivo y explotación en la región semiárida de Paraíba.

Abstract Low cowpea productivity (Vigna unguiculata (L.) Walp) in the semi-arid region of Paraíba is due, among other factors, to poor-quality cultivars. This research tested biometric models intending to increase productivity of superior cultivars with the following objectives: i. Estimate genetic gains in production components; ii. Identify the selection index model providing the greatest gains through simultaneously selecting a set of variables, and iii. Select cultivars with higher productivity. The experiment was carried out in the experimental field of the Agrifood Science and Technology Center of the Federal University of Campina Grande. Eight cultivars and 13 variables were evaluated. Data were subjected to ANOVA and means were grouped using the Scott and Knott test. Genetic gains were estimated by correlated response, classic selection index, rank sum and index based on desired gains. Direct selection of the secondary pod yield component provides significant genetic gains in main grain yield. Among the methodologies used, the classic selection index provided greater distribution of genetic gains for main grain yield and primary production components. These results allow concluding that Costela de vaca, BRS Marataoã and Paulistinha cultivars should be selected for cultivation and commercial exploitation in the semiarid region of Paraíba.

ABSTRACT Understorey herbs form a diverse and understudied plant assemblage in tropical forests. Although several studies and research teams have long been dedicated to the study of this conspicuous vegetation component in Amazonia, no effort to unify the data has been undertaken to date. In contrast to trees and other life forms for which major data compilations already exist, a unified database dedicated to herbs is still lacking. Part of the problem is in defining what is a herb and how to effectively sample herb assemblages. In this article, we describe the database HERBase, an exhaustive compilation of published and unpublished data on herb inventories in Amazonia. We also describe the structure, functioning, and guidelines for data curation and integration in HERBase. We were able to compile information from 1381 plots from all six Amazonian geographic regions. Based on this dataset, we describe and discuss sampling and knowledge gaps, priority areas for new collections, and recommend sampling protocols to facilitate data integration in the future. This novel database provides a unique biodiversity data repository on understorey herbs that will enable new studies on community ecology and biogeography.

RESUMO As ervas do sub-bosque formam um componente diversificado e pouco estudado em florestas tropicais. Embora vários estudos e grupos de pesquisa tenham se dedicado ao estudo desse componente conspícuo na Amazônia, nenhum esforço foi feito até o momento para unificar essas informações. Em contraste com árvores e outros grupos de plantas para os quais já existem grandes compilações de dados, uma base de dados unificada dedicada às ervas ainda não existe. Parte do problema está em definir o que é uma erva e como amostrar comunidados de ervas de forma eficiente. Neste artigo descrevemos a base de dados HERBase, uma compilação exaustiva de dados publicados e não publicados sobre inventários de ervas na Amazônia. Também descrevemos a estrutura, funcionamento e diretrizes para curadoria e integração de dados na HERBase. Conseguimos compilar informações de 1381 parcelas de todas as seis regiões geográficas amazônicas. Com base nesses dados, descrevemos e discutimos lacunas de amostragem e conhecimento, apontamos áreas prioritárias para novas coletas e recomendamos protocolos de amostragem para facilitar a integração de dados no futuro. Essa nova base de dados fornece dados únicos de biodiversidade sobre ervas do sub-bosque que permitirão novos estudos sobre ecologia e biogeografia de comunidades.

Abstract Purpose We propose and analyze a new operating model for an energy futures exchange that could be implemented in Brazil, where there is low liquidity for these contracts. The clearing house temporarily assumes the position of customers who fail to answer the margin call, instead of closing the position, as would normally be done under normal conditions. Theoretical framework The main theoretical bases were diffusion processes, with jumps and without jumps, and the pricing model developed by Merton (1976). Design/methodology/approach We developed a Monte Carlo simulation model, using diffusion processes, with and without jumps. Findings The results show that the proposed model and the insurance option generate relatively low-cost increments for the operation that could be easily absorbed by the clearing house. Practical & social implications of research This study will be especially useful for market agents who want to evaluate the implementation of a Brazilian energy exchange, which to date is not available. Originality/value The article proposes a new operating model for the Brazilian energy futures market and its results may encourage investment in the sector, which lacks an energy futures exchange.