bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development and validation of the 12-item video consultation self-efficacy scale
Authors: Baluszek Joanna Barbara , Wiig Siri , Myrnes-Hansen Kai Victor , Brønnick Kolbjørn Kallesten 
Published: June 2024

Background: Video consultations in healthcare are remote solutions for delivering assessments and treatments to patients. The acceptance and use of video consultations may depend on self-efficacy among healthcare practitioners. Measuring self-efficacy in providing video consultations may identify individuals with insufficient self-efficacy and enable targeted interventions and support. No valid and reliable scale was available for measuring self-efficacy in the Norwegian context. Therefore, our aim was to develop (Study 1) and validate (Study 2) a new research-based video consultation self-efficacy scale for Norwegian practitioners in specialized healthcare. Method: In Study 1, we developed preliminary scale items, based on results from a systematic review. These items were subjected to experts’ opinions in a modified Delphi method-based study. The experts also suggested additional items. These results were then used in developing an initial video consultation self-efficacy scale. In Study 2, this scale was validated in a questionnaire study. Reliability was examined by using item analysis and Cronbach’s alpha (internal consistency). Construct validity was examined by using exploratory factor analysis and Spearman’s correlation (convergent and divergent validity). Results: In Study 1, a total of 56 scale items were considered, and resulted in a preliminary 15-item scale. In Study 2, item analysis and exploratory factor analysis resulted in a unidimensional 12-item video consultation self-efficacy scale. Cronbach’s alpha (internal consistency) was (α) = .974. The Spearman’s correlations showed a moderate positive correlation between the 12-item scale and the Digital Competence Questionnaire, a weak positive correlation between the 12-item scale and the General Self-Efficacy Scale, and a weak positive correlation between the 12-item scale and the WHO-5 Well-Being Index. These results suggest that the scale is a reliable and valid measure for assessing practitioners’ self-efficacy in providing video consultations to patients in specialized healthcare. Implications: We recommend further, more comprehensive, validation of the scale in different contexts in Norwegian specialized healthcare, such as in different clinical specialties and with larger samples.
Keywords: development and validation, self-efficacy scale, specialized healthcare, practitioners, video consultation
The Concepts of Lex and Iustitia, and the “Art” of Making Laws in Liber Iudiciorum
Authors: Valentinova Dorothea 
Published: June 2024

Abstract
Liber Iudiciorum, the first Visigothic law code with territorial jurisdiction applied to the Visigoths and Hispano-Romans, replaced the Codex Euricianus and the Breviarium Alaricianum, both following the tradition of legal reception from the ius Romanum. The continuing influence of the Roman law on Liber Iudiciorum is particularly evident in the concepts of lex (law) and iustitia (justice), as well as in the legally and morally defined figure of the lawmaker, referred to as the artifex legum, the creator of art who imparts true wisdom and knowledge to the law and upholds truth and justice. Through translation, reading, and analysis of selected texts, this article tries, albeit in a modest format, to serve as an introduction to the thought-world of the authors of the Liber Iudiciorum and to their perceptions of law and justice, whose essence lies in the fundamental questions formulated at the very beginning of the code: “Quid est iustitia, lex et ius?” and “Quid sit, agit, erit lex, quare fit lex?”. Within its realm, the law itself represents the epitome of supreme virtues and moral principles.
Finding The Torch of United Methodist Hispanic Ministry in Texas and New Mexico
Authors: Campoverde Jonathan 
Published: June 2024

ABSTRACT
At their 1971 annual meeting, the Rio Grande Conference (RGC) celebrated the centennial anniversary of the ordination of the first native Spanish speaking Methodist minister—Alejo Hernandez. To commemorate the event, Rev. Alfredo Náñez, D.D., gave a series of lectures tracing the Methodist church’s work amongst Hispanics in Texas and New Mexico. He charged the annual conference to carry forward the torch that spiritual ancestors such as Hernandez have passed to them. This article takes up the torch Náñez claimed in 1971, following the history of the RGC through to its churches’ mergers with other annual conferences. Tracing this history via membership statistics from 1971 to the present, this article shows that torch has dimmed over the last 50 years, despite the hard work of Rio Grande Conference clergy and to the detriment of the United Methodist Church’s ministry in Texas and New Mexico.
Lauluihin varautunut menneisyys: Nostalgiset laulut muistin paikkoina KOM-teatterin esityksessä Baikalin lapset
Authors: Vainikainen Topi 
Published: June 2024

Käsittelen artikkelissani nostalgisten laulujen merkitystä menneisyyttä käsittelevässä teatteriesityksessä. Analysoin helsinkiläisessä KOM-teatterissa vuonna 2002 ensi-iltansa saanutta esitystä Baikalin lapset, joka kahdessa toisiinsa kiertyvässä aikatasossa käsitteli taistolaista liikettä ja sen muistamista. Esityksessä käytettiin paljon 1970-luvusta muistuttavia lauluja, jotka olivat esityksessä sekä mennyttä kuvittavia että tarinaa eteenpäin vieviä elementtejä. Hahmotan laulut muistin paikoiksi, jotka säilövät mennyttä aikaa. Kun lauluja kuunnellaan myöhemmin uudelleen, myös niihin sisällytetyt tunnekokemukset aktivoituvat uudelleen. Lähestyn lauluja tarkastelemalla niiden käyttöä pohdiskelevana nostalgiana, jossa korostuu menneeseen aikaan sisältyvän kaipauksen ohella menneisyyden peruuttamattomuuden tunnustaminen. Todennan artikkelissani, että laulut ilmentävät esityksessä toisaalta kollektiivista ja toisaalta eksistentiaalista kaipausta. Samaan aikaan lauluja käytettiin välineenä ottaa kantaa kulttuurissa käytyyn keskusteluun taistolaisuuden perinnöstä, mitä voimisti myös esityspaikka, taistolaiseen kulttuuriliikkeeseen liitetty KOM-teatteri.
Asiasanat: teatteri, esitys, KOM-teatteri, muistin paikka, pohdiskeleva nostalgia, taistolaisuus
Kaipuu ja muuttuvat identiteetit
Authors: Nikkola Jari 
Published: June 2024

Artikkeli analysoi amerikansuomalaisen omaelämäkerrallisen kirjoittamisen (life writing) nostalgiakuvausten piiristä nousevia suomalaisuuden merkityksiä, sukupolvista muutosta sekä tarvetta itseymmärryksen uudelleenmäärittelyyn alkuperäisen maahanmuuttokulttuurin jälkeisessä tilanteessa. Artikkelin aineistona toimivat Jingo Viitala Vachonin, Jane Piirron ja Inkeri Väänänen Jensenin omaelämäkerralliset tekstit. Kirjoittajat edustavat toista ja kolmatta amerikansuomalaista sukupolvea. Nostalgia käsitetään artikkelissa kaksoisfunktion omaavaksi ilmiöksi, jota kuvaavat sekä positiiviset että negatiiviset tunteet.
Asiasanat: amerikansuomalaiset, nostalgia, itseymmärrys, etninen identiteetti, life writing, sukupolvinen muutos.
Nostalgia: Tunteita, muistoja ja identiteetin rakentamista
Authors: Grönholm Pertti , Paalumäki Heli 
Published: June 2024

Tässä Historiallisen aikakauskirjan numerossa syvennytään nostalgiaan historiallisena tunteena ja kulttuuri-ilmiönä. Nostalgiaan on modernina aikana liitetty kaksijakoisia mielleyhtymiä, niin kultareunaista muistelua ja tunnelmointia kuin pakonomaista kaipuuta kadotettuun menneisyyteen.
Xác định ADN mã vạch giống Keo lai TB01 và BV71 (Acacia mangium x Acacia auriculiformis) phục vụ giám định giống cây
Authors: Thị Mai Hương Bùi , Hà Văn Huân 
Published: June 2024

Giống Keo lai TB01 (Acacia mangium x Acacia auriculiformis) và BV71 (Acacia mangium x Acacia auriculiformis) là giống cây có giá trị kinh tế cao đã được công nhận giống theo quyết định 1998/QĐ/BNN-KHCN ngày 11/07/2006. Tuy nhiên, đối với những người nông dân việc xác định giống chỉ bằng hình thái là hết sức khó khăn. Do đó, mục đích của nghiên cứu này là sử dụng phương pháp ADN mã vạch để xác định các giống Keo lai TB01, BV71. ADN tổng số được tách chiết từ các mẫu lá của TB01, BV71 và được sử dụng để nhân bản các đoạn gen matK, rbcL, trnH-psbA và ITS2 bằng kỹ thuật PCR. Các kết quả chỉ ra rằng các băng của sản phẩm PCR đúng với kích thước dự kiến như 485 bp, 815 bp, 423 bp và 377 bp cho rbcL, matK, trnH-psbA và ITS2, tương ứng. Các trình tự này sau đó được so sánh với các trình tự trên Ngân hàng gen Quốc tế (NCBI). Kết quả đã chỉ ra rằng giống Keo lai TB01, BV71 có tỷ lệ tương đồng 100% của trình tự đoạn gen rbcL, tương đồng 99,75% của đoạn gen matK, tương đồng 99,76% của đoạn gen trnH-psbA, tương đồng 99,73% của đoạn gen ITS2. Kết quả cho thấy có thể sử dụng các chỉ thị matK, trnH-psbA và ITS2 làm ADN mã vạch để giám định giống Keo lai TB01, BV71 ở Việt Nam. Kết quả nghiên cứu là cơ sở quan trọng cho việc xác định giống Keo lai TB01, BV71 đang trồng ở nước ta phục vụ các định hướng phát triển trong tương lai.
Transtorno de déficit de atenção e hiperatividade e uso de telas: qual a relação?
Authors: Melo Soraya Sarmento de , Cordeiro Lisandra Karoll Torres Pinheiro , Sousa Francisca Larissa Silva de , Queiroga Gabriela Vieira , Dias Matheus Mendes , Alves Matheus da Silva , Vieira Carlos Vitor Miranda , Souza Marina de Oliveira Gadelha , Braga Anne Letícia Gadelha , Araújo Larissa Vitória Barros , Silva Maria Thalya Camila , Nunes Filho Sérgio Ednaldo Couto , Queiroga Nicole Sarmento , Caminha Rafaela Trindade do Ó , Gadelha Neto Afonso Queiroga 
Published: June 2024

Introdução: As telas muitas vezes são usadas para acalmar, como ferramenta educacional ou para entretenimento enquanto os cuidadores realizam suas atividades profissionais e domésticas. No entanto, há preocupações expressas por pais e mães sobre os efeitos dessa exposição precoce, levando-os a se sentirem culpados pelo excesso de tecnologia na vida de seus filhos. Objetivo: Mostrar a relação entre o uso de telas e o transtorno de déficit de atenção e hiperatividade. Método: Foi realizada uma revisão integrativa da literatura, entre os meses dezembro de 2023 a maio de 2024, utilizando os descritores “Attention Deficit Disorder with Hyperactivity” e “Technology Addiction”, através das bases de dados Scielo, BVS e PubMed. Foram incluídos 10 artigos na presente revisão. Resultados e discussões: Diversos estudos apontam que tanto o vício na internet (IA) quanto o transtorno de déficit de atenção e hiperatividade (TDAH) afetam níveis de regulação emocional e o reconhecimento de habilidades emocionais. A regulação emocional, que envolve a consciência, a compreensão e a capacidade de agir objetivamente sem ser dominada pelas emoções, é prejudicada em adolescentes com dificuldades nessa área, levando-os a utilizar a internet de forma compulsiva para evitar ou suprimir emoções negativas. Conclusão: O uso excessivo de telas, especialmente em atividades como videogames e redes sociais, está associado a uma piora nos problemas emocionais e comportamentais. Estratégias de manejo devem incluir a limitação do tempo de tela e a promoção de atividades físicas, além de suporte emocional e educacional para minimizar os impactos negativos e melhorar a qualidade de vida dos jovens com TDAH.
Successful Management of Trypanosomiais in a Cow
Authors: LM Arun Kumar , Haridas Vijayakumar , S Kavitha 
Published: June 2024

A 6-year-old Jersey cow was presented with signs of respiratory distress and sternal recumbency at the Madras Veterinary College Outpatient Unit. Physical examination revealed congested mucous membrane, enlarged prescapular lymph node and severe dehydration. Musculo skeletal examination was done and the orthopaedic involvement was ruled out. Thrombocytopenia, decreased packed cell volume, and haemoglobin levels were noticed. Peripheral blood smear confirmed the presence of Trypanosoma evansi. The animal was treated with isometamidium chloride. The animal had uneventful recovery and was able to walk.
Keywords: Jersey cow, Trypanosomiasis, Isometamidium chloride
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Socially Responsible Higher Education: International Perspectives on Knowledge Democracy By Hall, B. L., & Tandon, R. (Eds.)
Authors: Tsirigotis E. George 
Published: June 2024

Book Review of
SOCIALLY RESPONSIBLE HIGHER EDUCATION: INTERNATIONAL PERSPECTIVES ON KNOWLEDGE DEMOCRACY

Hall, B. L., & Tandon, R. (Eds.), 2021 Leiden: Brill/Sense, 305 pages.
БАШТАЛГЫЧ МЕКТЕПТЕ ИНТЕГРАЦИЯЛАНГАН САБАКТАР ОКУУЧУЛАРДЫ АР ТАРАПТУУ ӨНҮКТҮРҮҮНҮН ЖАНА ТААНЫП БИЛҮҮ ИШМЕРДҮҮЛҮГҮН АКТИВДЕШТИРҮҮНҮН ЖОЛУ КАТАРЫ
Authors: Мендибаева Нуркан 
Published: June 2024

Бул макалада интегралдык билим берүүнү уюштурууда ар түрдүү билимдерди: адабиятты, музыканы, сүрөт тартуу менен дүйнөнү ар тараптуу көрсөтүүгө боло тургандыгы белгиленген. Интегралдык сабактар окуучулардын эмоционалдык өнүгүүсүнө жана анын чыгармачылык ой жүгүртүүсүнүн калыптанышына шарт түзөт. Мындай окутуу айрым окуу предметтер боюнча билимдерди бир бүтүнгө бириктирүүчү, толуктаган, тартипке келтирген, бириктирген сабактардын тутумун билдирет, мунун негизинде балдардын дүйнөнү бирдиктүү кабыл алуусу калыптанат. Мындай окутууда окуу предметтери өз ара аракеттенишет, бирок ошол эле учурда өз алдынча жана мазмуну, түзүмү жана аларды окуп-үйрөнүүгө бөлүнгөн убакыт көлөмү боюнча бирдей бойдон калышат. Мындай окутуунун аркасында окуучулар тилдерди, математиканы, мекен таанууну, көркөм өнөрдү жана башка сабактарды окуп жатканда, бир сабакта калыптанган билимди жана көндүмдөрдү турмуштук практикада гана эмес, башка сабактарда да колдонсо болоорун түшүнүшөт. Предметтерди бүтүн биримдикке интеграциялоо башталгыч мектепте көбүрөөк эффективдүү болоору берилди.
RENDIMIENTO Y CALIDAD FÍSICA DEL GRANO DE CAFÉ (Coffea arabica L.) VARIEDAD COSTA RICA 95
Authors: De Dios-León Gloria Esperanza , Angel-Lara María Alva , Osorio-Hernández Paola , Coria-Gil Norma Ana Beli 
Published: June 2024

<p><strong>Background: </strong>Coffee is the second most consumed drink in the world, only after water. Quality characteristics are the most recurrent demands of consumers, which are of multifactorial origin and among which is agronomic management where soil nutrition or foliar nutrition of the plant is considered. <strong>Objective:</strong> To evaluate the yield and physical quality of the bean and cup of coffee (Coffea arabica L.) variety Costa Rica 95 by applying foliar fertilizer. <strong>Methodology: </strong>The evaluation was carried out in the La Laja community, municipality of Tlaltetela, Veracruz between 2018 and 2019. The age of the plantation used was four years and established with chalahuite shade (<em>Inga spuria</em> Humb. &amp; Bonpl. ex Willd). The design used was a complete randomized block with two treatments (commercial control and treatment with foliar fertilization), with three repetitions each; the experimental unit consisted of a 300 m<sup>2</sup> plot and five coffee harvests were carried out, which were according to the number of flowerings during the 2018-2019 cycle. The physical evaluation was carried out according to the Official Mexican Standard NMX-F-162-SCFI-2008 and the NOM SCAA (2013). <strong>Results: </strong>The highest cherry yield and brix degrees were observed in the fertilized treatment with 12,897.8 kg ha<sup>-1</sup> and 20.06, respectively; in floats (waste) and snail (malformation), the highest weights were observed in the control treatment with 1,696.11 kg ha<sup>-1</sup> and 21.4 grams, respectively. The total sum of the sensory analysis was 81.3 and 85.2 for the treatments: control and fertilized, respectively. Higher numbers of grains were observed in sieves 19, 18 and 17 that are classified for the international scale. <strong>Implications: </strong>There is a positive effect of foliar fertilizer on the yield of cherry coffee and cup quality of Costa Rica coffee 95 and opens a range of possibilities to carry out a greater number of fertilization tests in the field, being able to compare an additional factor such as, for example, the climate (rain, drought, cold, heat, etc.). These studies should be carried out in the same area in which this experiment was carried out to compare whether the response shown is due solely to foliar fertilizer or there is an influence of climate, as well as management. It must be considered that the quality of coffee is multifactorial; in addition to environmental and genetic factors, there is management (nutrition, phytosanitary protection, pruning), harvest, among others. <strong>Conclusion: </strong>Foliar fertilization considerably improved the variables of interest evaluated in Costa Rica 95 coffee through the application of foliar fertilization, in addition to the fact that no primary or secondary defects were significantly present.</p>
PERCEPCIÓN DE PEQUEÑOS PRODUCTORES RESPECTO A LOS EFECTOS DEL CAMBIO CLIMÁTICO EN LA FLORACIÓN Y PLAGAS DE AGROECOSISTEMAS CAFETALEROS: UN ESTUDIO DE CASO
Authors: Beristain-Moreno Martha Escarlet , Ramírez-Martínez Alejandra , Sósol-Reyes David , Osorio-Acosta Francisco 
Published: June 2024

<p><strong>Background. </strong>The coffee production in Veracruz state is important in the economic, social, cultural, and environmental sectors, mainly for the small producers who are dedicated to this activity. However, this sector has different problems that have generated its stagnation or abandonment, some of these are caused by the effects of climate change, coupled with the inadequate management of coffee agroecosystems that favor deforestation, low biodiversity and the elimination of natural enemies of pest organisms. <strong>Objective</strong>. To assess the perception of small coffee producers about the relationship among flowering, pests and climate change in Sabanas, Veracruz. <strong>Methodology</strong>. Eleven producers were interviewed through a questionnaire with open questions that allowed them to state how they perceive coffee flowering, pest problems, climate change and how they relate to each other. Results. The main problems they mentioned are pests, drought, and delayed flowering. The main pests they mention are rust, nematodes, and the berry borer, and they also indicate the presence of the coffee stem borer, which they had not previously observed. Finally, they perceive that herbicides, deforestation and pollution negatively affect their agroecosystems. <strong>Implications.</strong> The work suggests carrying out monitoring in the study area and/or surrounding areas to know the dynamics and distribution of the pests present in the crop. <strong>Conclusion.</strong> Small producers relate the increase in severity and the occurrence of new pests with climate change. In addition, they observe that changes in temperature and precipitation influence the delay in flowering and generate certain stress in the plantations, which they consider it is aggravated by practices such as the application of herbicides and the removal of shade trees.</p>
ANÁLISE DA TRAJETÓRIA HISTÓRICA E LEGAL DA EDUCAÇÃO DE ALUNOS COM ALTAS HABILIDADES/SUPERDOTAÇÃO- AH/SD
Authors: Campelo Almervanda de Souza , Soares Helciyane do Firmamento Silva , Lima Márcia Raika e Silva 
Published: June 2024

Pessoas com superdotação apresentam potencial elevado nas diferentes áreas do conhecimento em comparação à população. As políticas públicas, no Brasil, voltadas às altas habilidades/superdotação (AHSD) ocorrem há cerca de um século, considerando as primeiras publicações. Porém, somente na LDB 5692/71, oficialmente, em âmbito nacional, menção a esses alunos. Buscando resposta ao questionamento: em quais leis, decretos e iniciativas, que tratam da Educação Especial no Brasil, a partir da atual LDB (9394/96), são garantidas políticas públicas aos AH/SD? E com o objetivo geral de analisar a legislação educacional brasileira, a partir da atual LDB (9394/96) no que tange às políticas públicas de atendimento aos alunos com AH/SD, o texto faz uma cronologia partindo da Lei de Diretrizes e Bases (LDB 9394/96) perpassando por normativas e iniciativas públicas e privadas que trouxeram e trazem contribuições ao atendimento a esse público até o ano de 2023, com a promulgação do Parecer CNE/CP Nº: 51/2023 que especifica os passos do atendimento a alunos com AH/SD. A pesquisa documental, com abordagem qualitativa concluiu que há, no Brasil, leis e documentos norteadores, que fazem referências à garantia de atendimento a alunos AH/SD, porém os números de matrículas, no Censo Escolar, mostram a não efetivação dessas normativas.
Gesamtplanung in der Eingliederungshilfe – quo vadis?
Authors: Rohrmann Albrecht 
Published: June 2024

Die Regelungen zur Gesamtplanung in der Eingliederungshilfe (§§ 117 ff. SGB IX) dürften zu den weitreichendsten Änderungen zählen, die durch das Bundesteilhabegesetz vorgenommen wurden. Der Implementationsprozess gestaltet sich schwierig. Albrecht Rohrmann erörtert ausgehend von der Entwicklung der Gesamtplanung in der Eingliederungshilfe einige grundlegende Fragen der Umsetzung.
Anti-Xa Activity Test Is Needed but Is Not Enough for Monitoring Fondaparinux Therapy Among Critically Ill Patients
Authors: Ling Liqin , Liu Chaonan , Huang Xunbei , Liu Siqi , Liao Juan , Jia Jin , Fu Yang , Zhou Jing 
Published: June 2024

Context.—
Fondaparinux monitoring is not required among noncritically ill patients due to a predictable dose-response effect. However, this is debatable among critically ill patients, because fondaparinux bioavailability can be influenced by complicated medical conditions.

Objective.—
To investigate fondaparinux monitoring among the critically ill.

Design.—
Retrospective analysis of patients admitted in intensive care unit from February 2021 to December 2021 who received prophylactic fondaparinux and had anti-Xa activity tests.

Results.—
Of 156 anti-Xa values, 86 (55.1%) were within 0.10–0.50 μg/mL (the recommended prophylactic range), 38 (24.4%) were less than 0.10 μg/mL, and 32 (20.5%) were greater than 0.50 μg/mL, demonstrating an unpredictable dose-response effect. Among 70 patients, thrombotic tendency was controlled in 32 (45.7%), thrombosis progressed in 22 (31.4%), and bleeding events occurred in 16 (22.9%). Patients with progressed thrombosis had 17 of 54 (31.5%) anti-Xa values less than 0.10 μg/mL; even though this proportion was greater than that of patients with controlled thrombotic tendency (11 of 72, 15.3%), it was similar to that of patients with bleeding (10 of 30, 33.3%), indicating a weak practicability of anti-Xa for monitoring fondaparinux efficacy. Thrombin-antithrombin complex showed a gradual decline among patients with controlled thrombotic tendency but a bounce-back effect among patients with progressed thrombosis. Thrombelastography R value above the upper reference value occurred more frequently among patients with bleeding (4 of 6, 66.7%) compared to patients without bleeding (4 of 22, 18.2%) (P = .01).

Conclusions.—
The fondaparinux dose-response effect was unpredictable among the critically ill; anti-Xa activity combined with thrombin-antithrombin complex and thrombelastography can be helpful to guide a precise fondaparinux therapy in this population.
Tinjauan Hukum Islam Terhadap Jual Beli Pupuk Kandang: Analisis Terhadap Persepsi dan Praktik Masyarakat Blok 15 Aceh Singkil
Authors: Wahidah Z Wahidah Z 
Published: June 2024

Penelitian ini bertujuan untuk mendiskripsikan jual beli pupuk kandung yang dipraktikkan masyarakat blok 15 Kecamatan Gunung Meriah Kabupaten Aceh Singkil Provinsi Aceh. penelitian ini menggunakan penelitia kualitatif dengan pendekatan deskriptif. Hasil penelitian menunjukkan bahwa praktik jual beli pupuk kandang ini ada di kampong Blok 15 dan telah memenuhi rukun dan syarat jual beli dengan hukum islam, karena telah ada ijab qabul, penjual dan pembeli , telah mummayiz , dan terdapat barang atau objeknya. Persepektif hukum Islam terhadap Jual Beli Pupuk Kandang di Kampong Blok 15 Kecamatan Gunung Meriah Kabupaten Aceh Singkil telah memenuhi rukun dan syarat jual beli