فکر بنیانبانک مقالات روان‌شناسی

Ecuador

همهٔ آثار این مفهوم در فکر بنیان

Microcredenciales en la educación superior ecuatoriana: calidad, trazabilidad y gobernanza.

Oscar Antonio Martínez Molina; Richard Antonio Martínez Villegas; Julio Rodolfo Uyaguari Fernández; Octavio Segundo Crespo Castillo Innova Science Journal, 2026, Vol. 4, Issue 4, pp. 381-403 https://doi.org/10.63618/omd/isj/v4/n4/429

چکیده

The growth of short-form certifications requires a clear distinction between attendance certificates and credentials that provide evidence of specific learning outcomes. In Ecuador, a non-binding national technical instrument identifies a fragmented training supply, the absence of shared criteria, limited traceability, and weak links between higher education and the world of work. This study examined the relevance of implementing a national microcredential system and identified the academic, regulatory, and technological conditions required for its adoption. A qualitative documentary study with an analytical-propositional scope and comparative logic was conducted using a corpus of 46 sources published between 2015 and 2026. The analysis combined deductive and inductive thematic coding across seven categories and contrasted the Ecuadorian instrument with international regulations, technical standards, and specialized literature. The results were organized into nine findings concerning systemic relevance, technical-pedagogical design, verifiable assessment, conditional recognition, interoperable digital issuance, multilevel governance, and an informational registry. The evidence indicates that Ecuador has conceptual foundations for a national system, but shared standards are required before provision is expanded. The study concludes that a trustworthy micro credential should integrate six conditions: explicit learning outcomes, verifiable assessment, academic or labor-market relevance, interoperable digital issuance, standardized metadata, and conditional recognition. Without coherent interinstitutional governance, the expansion of short-form certificates may increase fragmentation and weaken their public value.

متن کامل دسترسی آزاد

La ansiedad académica y la producción científica en estudiantes universitarios en Ambato, año 2025.

José Darío Guamán Tacuri; César Paúl Silva-Salazar; Julián Humberto Cepeda-Sagñay; Edwin Gernando Cortez-Cevallos Innova Science Journal, 2026, Vol. 4, Issue 4, pp. 307-318 https://doi.org/10.63618/omd/isj/v4/n4/423

چکیده

Introduction: Ecuadorian higher education has experienced different dynamics in scientific production, presenting a significant challenge regarding the integration and participation of university students. The problem lies in a lack of knowledge analyzing the correlation between academic anxiety and scientific production in a university context in the city of Ambato, Ecuador. Objective: To determine the correlational association between academic anxiety and scientific production among university students in the city of Ambato in 2025. Methodology: The research employed a correlational approach, a quantitative methodology, and a non-experimental design. Data was collected using a structured survey administered to 248 university students, selected through convenience sampling. Results and Discussion: The main results show that 31.45% of students experience physical fatigue when conducting research activities, 57.26% perceive that they are not meeting the demands of a research project, 47.58% avoid engaging in scientific research, and a Pearson correlation coefficient of -0.027 was obtained, demonstrating a negative association between the variables studied. Conclusion: The university students experience physiological, cognitive, and behavioral difficulties when producing a scientific product, where a lack of experience and student support makes scientific research a difficult and uninteresting field for university students to explore.

متن کامل دسترسی آزاد

Estrategia de intervención psicológica motivacional para la mejora del rendimiento físico en las futbolistas femeninas de la sub15

Marla Gabriela Pulley-García; Carlos Hugo Macías Rendón RICEAFS Revista de Investigación en Ciencias de la Educación Actividad Física y Salud, 2026, Issue Edición Especial I, pp. e87 https://doi.org/10.64905/riceafs.eei.e87

چکیده

Introduction: Psychological factors can be important for the physical performance of developing female football players, but research is needed to assess their impact. Objective: To determine the effectiveness of a motivational psychological intervention strategy to improve physical performance in female U-15 football players from a football school in Zone 8 of Guayaquil, Ecuador. Method: Pre-experimental design with a single group and pretest-posttest measurements. Thirty football players participated. For the evaluation of the motivational climate, the PMCSQ-2 was used, while the YYIR1 and the Cooper Test were the instruments employed to assess physical performance. The intervention consisted of 12 sessions of 45 minutes over six weeks. The Shapiro-Wilk test was applied and then the Student's t-test for dependent samples. Results: The overall PMCSQ-2 score did not show statistically significant changes (t(29) = −1.37; p = 0.182; d = −0.250). On the contrary, statistically significant differences with large effect sizes were found for both the YYIR1 (t(29) = −16.08; p < 0.001; d = −2.936) and the Cooper Test (t(29) = −19.54; p < 0.001; d = −3.567). Discussion: Improvements are evident in the evaluated physical indicators, without significant changes in the overall motivational score. This divergence indicates that the physical response and the perception of the motivational climate do not always develop at the same pace. Conclusions: The intervention was associated with significant improvements in physical performance, which supports its application in youth women's football.

سایت ناشر ↗ دسترسی آزاد

Meritocratic admission and the explanatory order in Ecuadorian higher education: a conceptual analysis Rancière

María Giovanna Núñez-Torres; Shirley Duchi; Jorge Buele Frontiers in Education, 2026, Vol. 11, pp. 1975026 https://doi.org/10.3389/feduc.2026.1975026

چکیده

Ecuadorian higher education policy combines the constitutional recognition of education as a right with admission rules that allocate scarce quotas through academic background, evaluations, and affirmative action measures. The objective of this article is to determine under what conditions meritocratic admission fulfills a legitimate allocative function and under which it becomes a judgment about the intellectual value of the applicants. A conceptual analysis is employed: Jacques Rancière's concepts of explanatory order, dumbness, intellectual emancipation, and equality of intelligences are placed in dialogue with meritocracy research, with the current regulatory framework, and with the available evidence on unequal access in Ecuador. The analysis distinguishes three propositions that are often confused: that applicants differ in their demonstrated preparation, that institutions should assign limited quotas, and that the resulting ordering reveals unequal intelligences. Only the first two are necessary to admit; the third is an inference that the framework allows to be questioned. Four conditions are specified: semantic totalization, interpretative monopoly, temporal fixation, and public circulation of the verdict under which an assignative procedure becomes part of an explanatory order, and it is shown that they are separable from assignment and therefore institutionally modifiable. Five rights-oriented design principles are proposed, with their stated foundation. It is concluded that a defensible alternative is not selection without standards, but selection that limits the meaning attributed to its instruments and identifies testable directions for future empirical research.

متن کامل دسترسی آزاد

Public traceability of university co-creation and collaborative governance for sustainability. A documentary audit of Ecuadorian higher education

Nina Aguiar; Roberto Sánchez Montoya; Milena Almeida Frontiers in Political Science, 2026, Vol. 8, pp. 1900676 https://doi.org/10.3389/fpos.2026.1900676

چکیده

Introduction This study examines the public visibility and documentary traceability of university co-creation and collaborative governance for sustainability, based on documentary evidence available on the institutional portals of a set of universities in Ecuador. It explores how publicly available records represent forms of territorial articulation that extend beyond traditional university extension models. Methods The research adopts a documentary case study design supported by a multi-criteria matrix of co-creation indicators, mapping the 59 institutions included in the defined universe. Data were gathered exclusively from verifiable public sources on official university websites, institutional repositories, sustainability reports, strategic plans, and digital documentation spanning the 2024–2025 period, with a standardized corpus closure date of July 24, 2026. Results Evaluated institutions exhibit heterogeneous institutional records regarding their engagement and sustainability initiatives. Five documentary cases were selected for analysis based on information availability, alongside candidate cases retained for sensitivity analysis using “Not Assessable” (NA) coding. The publicly documented cases provide evidence of varying degrees of participation, multi-actor coordination, knowledge-system dialogue, governance arrangements, documented results, project continuity, and articulation beyond traditional third-mission activities. Discussion The findings are restricted to the scope of public documentary visibility and traceability. They should be interpreted as patterns of documentary traceability rather than as direct evidence of the full implementation or effectiveness of co-creation practices in the institutions studied.

متن کامل دسترسی آزاد

Practicum in host educational contexts: school students’ perceptions in Ecuador

Danilo Isaac Reiban Garnica; Diana Saldaña-Gómez Frontiers in Education, 2026, Vol. 11, pp. 1974190 https://doi.org/10.3389/feduc.2026.1974190

چکیده

Introduction Research on the practicum has focused on student teachers, mentors and partnerships between universities and schools, while the pupils in whose classrooms student teachers are placed have rarely been asked about this experience. This study examined how pupils in Ecuadorian host schools perceive the presence, support and influence of student teachers, and to what extent these perceptions can be trusted as evidence. Methods Two age-differentiated questionnaires, with pictographic scales from early childhood education to third grade and verbal scales from fourth grade onward, were administered through a mobile application by the student teachers or by members of the research team hired for data collection (project staff). The dataset comprised 2,453 valid evaluations from 1,140 pupils in 123 classrooms of 38 schools. Analyses included descriptive statistics for the first evaluation of each pupil, agreement between consecutive weekly evaluations, generalized estimating equations that accounted for the nesting of evaluations within pupils, classrooms and schools, a within-pupil comparison of evaluations collected by student teachers and by project staff, and latent class analysis. Results Between 91.5% and 98.5% of pupils gave favorable ratings on seven of eight items, while 69.6% of older pupils always felt comfortable asking student teachers for help. Ratings collected by project staff were lower than those collected by student teachers, especially for comfort in asking for help and perceived influence on learning. Responses of the youngest pupils concentrated in the highest category and did not discriminate reliably between individual pupils, whereas older pupils showed fair to moderate stability on most items and formed highly enthusiastic and moderately favorable profiles. Discussion Pupils perceive student teachers favorably, although part of this favorability reflects social desirability and the developmental limits of young respondents. Pupil voice can inform practicum evaluation when questionnaires are administered by someone other than the student teacher being evaluated and are interpreted according to the age of the pupils.

متن کامل دسترسی آزاد

Comunicación educativa docente en los procesos de enseñanza aprendizaje de estudiantes de educación secundaria: un estudio cualitativo

Carlos A. Zarate; Jessie Patrica Aulla Velastequi; Viviana Nataly Barreno Moreno Revista Multidisciplinaria Investigación Contemporánea, 2026, Vol. 5, Issue 1 https://doi.org/10.58995/redlic.rmic.v5.n1.a277

چکیده

Aim: to analyze teachers’ educational communication in the teaching and learning processes of students in upper secondary education and the baccalaureate. Methodology: a qualitative study was carried out involving 230 students from a private educational institution in Riobamba, Ecuador, during the 2022–2023 academic year. Data were collected through observation and interviews, and subsequently organized into categories relating to interaction, participation, feedback and classroom dynamics. Results: Difficulties in communication between teachers and pupils were identified, as were few opportunities to ask questions and a predominance of activities focused on theoretical content. In contrast, group dynamics, educational games and other participatory activities were accompanied by closer interaction and greater opportunities for exchange. Conclusion: educational communication was closely related to student participation and to the way in which teaching and learning activities were carried out, although the results do not allow causal relationships to be established.

متن کامل دسترسی آزاد

Gamificación para Fortalecer la Comprensión Lectora en Estudiantes de Educación Básica en Ecuador: Revisión Sistemática

Lucy Isabel Zambrano Villarreal; Janeth Rocío Jácome-Gómez Erevna Research Reports, 2026, Vol. 4, Issue 2, pp. e2026066 https://doi.org/10.70171/vmz0b906

چکیده

Justification: Reading comprehension difficulties among basic education students have driven the search for pedagogical strategies such as gamification; however, their effectiveness depends on the specific characteristics of the context in which they are implemented. Objective: Therefore, the aim of this study was to conduct a systematic review of the literature published between 2020 and 2025 on gamification strategies used to strengthen reading comprehension among basic education students in Ecuador and to analyze the reported results regarding their effectiveness. Methodology: The study was conducted following the PRISMA 2020 guidelines. The search was carried out in the Scopus, SciELO, Redalyc, DOAJ, and Latindex databases. A total of 34 records were retrieved, of which 12 studies were selected for analysis. Results: Findings indicate that gamification strategies were mainly developed through digital resources and structured instructional sequences integrating challenges, feedback, rewards, points, levels, badges, narratives, progression systems, and collaborative activities. Regarding effectiveness, the studies reported improvements in literal, inferential, and critical reading comprehension, with greater progress in inferential and critical processes. In addition, increases were found in motivation, participation, engagement, and interest in reading. Conclusion: The findings support the favorable effects of gamification in strengthening reading comprehension among basic education students in Ecuador.

متن کامل دسترسی آزاد

Progressive integration of meaningful summative assessment and formative assessment: a longitudinal analysis of student performance in higher education

ادغام تدریجی ارزشیابی جمع‌بندی معنادار و ارزشیابی تکوینی: تحلیل طولی عملکرد دانشجویان در آموزش عالی

Maria Patricia Ávila-Andino; Karina Yuleisy González-Vázquez; Orlando Agustín Pérez Manzo; Jesennia Del Pilar Cárdenas-Cobo; Jorge Fabricio Guevara-Viejo; Jorge Luis Rodas-Silva Frontiers in Education, 2026, Vol. 11 https://doi.org/10.3389/feduc.2026.1906986

چکیده

Introduction Large-scale longitudinal evidence on how progressive institutional assessment policy reform is associated with student academic performance remains scarce, particularly in Latin American public higher education. This study examined the association between four successive institutional assessment policies and academic performance across four consecutive academic periods at a public university in Ecuador, focusing on the transition from undifferentiated assessment models to competency-differentiated structures integrating formative feedback within the summative framework. Methods A comparative quasi-longitudinal design was adopted using 921,795 student-course enrolment records. Four institutional assessment policies were examined: a balanced distributed model (Policy A: 60% coursework/40% examinations), a single high-stakes final examination (Policy B: 40% coursework/60% examination), a competency-differentiated model separating theoretical and practical components (Policy C: 40% coursework/30% theoretical examination/30% practical examination), and a hybrid model integrating formative feedback through an intermediate practical assessment (Policy D: 40% coursework/30% theoretical examination/15% progress submission/15% final submission). One-way ANOVA, Bonferroni-corrected pairwise post-hoc comparisons, chi-squared tests with Cramér's V , and subgroup analyses by faculty, study modality, and degree programme were conducted. Results Mean final grades increased monotonically from 78.08 under Policy A to 84.38 under Policy D, while pass rates followed a U-shaped pattern, reaching their minimum under Policy B (82.91%). The overall ANOVA was significant, F (3,921,791) = 7,143.53, p < .001, η ² = .023. Post-hoc comparisons revealed a structural inflection between undifferentiated policies (A/B) and competency-differentiated policies (C/D), with cross-block effect sizes ( d = .306-.380) substantially larger than within-block differences (d < .08). Pass rates differed significantly across policies, χ ²(3) = 9,867.90, p < .001, V = .103. Grade dispersion decreased under competency-differentiated policies, with the standard deviation declining from 19.73 under Policy B to 15.69 under Policy D. Faculty-level analyses showed minimal policy-associated variation in Health Sciences (η² = .001), compared with small but consistent effects in the other three faculties (η² = .014–.036). Online students exhibited the greatest performance gains (η² = .043), with the online-face-to-face performance gap shifting from −0.86 points under Policy A to +5.65 points under Policy D. Discussion The transition from undifferentiated assessment models to competency-differentiated structures separating declarative and procedural knowledge was consistently associated with higher mean academic performance, improved pass rates, and reduced grade dispersion. These associations were particularly pronounced among online students, although the observational design does not establish causality. The findings provide large-scale evidence on the relationship between institutional assessment policy design and academic performance, highlighting the relevance of integrating competency differentiation and formative feedback within summative assessment frameworks as an academic quality governance mechanism in public higher education.

مقدمه: شواهد طولی در مقیاس وسیع درباره ارتباط اصلاح تدریجی سیاست‌های ارزشیابی نهادی با عملکرد تحصیلی دانشجویان، به‌ویژه در آموزش عالی دولتی آمریکای لاتین، همچنان اندک است. این مطالعه ارتباط میان چهار سیاست ارزشیابی نهادی متوالی و عملکرد تحصیلی را در چهار دوره متوالی تحصیلی در یک دانشگاه دولتی در اکوادور بررسی کرد و بر گذار از مدل‌های ارزشیابی غیرمتمایز به ساختارهای مبتنی بر تمایز شایستگی با ادغام بازخورد تکوینی در چارچوب جمع‌بندی تمرکز داشت. روش‌ها: یک طرح شبه‌طولی مقایسه‌ای با استفاده از ۹۲۱٬۷۹۵ رکورد ثبت‌نام دانشجو-درس اتخاذ شد. چهار سیاست ارزشیابی نهادی بررسی شد: مدل توزیع‌شده متعادل (سیاست A: ۶۰٪ کار کلاسی/۴۰٪ آزمون)، یک آزمون نهایی با ریسک بالا (سیاست B: ۴۰٪ کار کلاسی/۶۰٪ آزمون)، مدل مبتنی بر تمایز شایستگی با تفکیک مؤلفه‌های نظری و عملی (سیاست C: ۴۰٪ کار کلاسی/۳۰٪ آزمون نظری/۳۰٪ آزمون عملی)، و مدل ترکیبی با ادغام بازخورد تکوینی از طریق ارزشیابی عملی میانی (سیاست D: ۴۰٪ کار کلاسی/۳۰٪ آزمون نظری/۱۵٪ ارائه پیشرفت/۱۵٪ ارائه نهایی). آزمون ANOVA یک‌طرفه، مقایسه‌های پس‌آزمون زوجی با اصلاح بونفرونی، آزمون‌های کای-دو با V کرامر و تحلیل‌های زیرگروهی بر اساس دانشکده، شیوه تحصیل و برنامه تحصیلی انجام شد. نتایج: میانگین نمرات نهایی به طور یکنواخت از ۷۸٫۰۸ در سیاست A به ۸۴٫۳۸ در سیاست D افزایش یافت، در حالی که نرخ قبولی الگوی U شکل داشت و حداقل خود را در سیاست B (۸۲٫۹۱٪) نشان داد. آزمون ANOVA کلی معنادار بود، F (3,921,791) = 7,143.53, p < .001, η² = .023. مقایسه‌های پس‌آزمون، نقطه عطف ساختاری میان سیاست‌های غیرمتمایز (A/B) و سیاست‌های مبتنی بر تمایز شایستگی (C/D) را نشان داد، به‌طوری‌که اندازه اثر بین‌بلوک (d = .306-.380) به‌طور قابل توجهی بزرگ‌تر از تفاوت‌های درون‌بلوک (d < .08) بود. نرخ قبولی در سیاست‌ها تفاوت معناداری داشت، χ²(3) = 9,867.90, p < .001, V = .103. پراکندگی نمرات در سیاست‌های مبتنی بر تمایز شایستگی کاهش یافت، به‌طوری‌که انحراف معیار از ۱۹٫۷۳ در سیاست B به ۱۵٫۶۹ در سیاست D رسید. تحلیل‌های سطح دانشکده نشان داد که تغییرات مرتبط با سیاست در علوم سلامت حداقل بود (η² = .001)، در حالی که در سه دانشکده دیگر اثرات کوچک اما پایدار مشاهده شد (η² = .014–.036). دانشجویان آنلاین بیشترین افزایش عملکرد را نشان دادند (η² = .043)، به‌طوری‌که فاصله عملکرد آنلاین-حضوری از ۰٫۸۶- نمره در سیاست A به ۵٫۶۵+ نمره در سیاست D تغییر یافت. بحث: گذار از مدل‌های ارزشیابی غیرمتمایز به ساختارهای مبتنی بر تمایز شایستگی با تفکیک دانش اظهاری و رویه‌ای، به طور پیوسته با افزایش میانگین عملکرد تحصیلی، بهبود نرخ قبولی و کاهش پراکندگی نمرات همراه بود. این ارتباطات به‌ویژه در میان دانشجویان آنلاین برجسته بود، اگرچه طرح مشاهده‌ای مطالعه علیت را اثبات نمی‌کند. یافته‌ها شواهدی در مقیاس وسیع درباره رابطه طراحی سیاست ارزشیابی نهادی و عملکرد تحصیلی ارائه می‌دهد و اهمیت ادغام تمایز شایستگی و بازخورد تکوینی در چارچوب ارزشیابی جمع‌بندی را به‌عنوان سازوکار حاکمیت کیفیت علمی در آموزش عالی دولتی برجسته می‌کند.

متن کامل دسترسی آزاد

Diagnostic performance in logical mathematical reasoning varies across secondary education institutions in Chone Canton Ecuador

عملکرد تشخیصی در استدلال منطقی-ریاضی در میان مؤسسات آموزش متوسطه شهرستان چونه، اکوادور متفاوت است

Lila Magaly Avellán-Avellán; Rudyard Antonio Arteaga-Solórzano; Ramona Cecilia Párraga Álava; Plinio Abelardo Vargas-Zambrano; Gladys Hermencia Moreira-Borja; Humboltd Octavio Moreira-Menéndez; … Discover Education, 2026, Vol. 5, Issue 1 https://doi.org/10.1007/s44217-026-02186-2

چکیده

Logical-mathematical reasoning is essential for interpreting representations, applying procedures, justifying relationships, and solving problems; however, evidence regarding students’ performance in Ecuadorian school contexts remains limited. The aim of this study was to characterize students’ diagnostic performance in logical-mathematical reasoning and to examine differences in its distribution across the participating educational institutions. A descriptive, exploratory, non-experimental study with a quantitative approach was conducted. A total of 843 third-year upper secondary school students, aged 15 to 17 years, from 21 educational institutions in Chone Canton, Ecuador, participated in the study. Logical-mathematical reasoning was assessed using a five-task diagnostic test, with each task scored from 0 to 4 points and aggregated into an overall score ranging from 0 to 20 points. Of the participants, 76.39% were classified at the low level, 17.08% at the regular level, 5.93% at the good level, and 0.59% at the very good level; no student reached the excellent level. Statistically significant differences were identified among institutions, χ²(60) = 392.62, p_MC = 0.00001, Cramer’s V = 0.394; H(20) = 208.51, p < 0.001, ε² = 0.229. The study provides a multi-institutional baseline of logical-mathematical reasoning in a relatively understudied Ecuadorian context. The findings may support the identification of educational needs and the planning of differentiated support according to students’ initial performance. Because no comparison group or quantitative pretest–posttest measurement was available, it was not possible to evaluate changes in logical-mathematical reasoning or attribute the results to the use of GeoGebra.

استدلال منطقی-ریاضی برای تفسیر بازنمایی‌ها، به‌کارگیری رویه‌ها، توجیه روابط و حل مسئله ضروری است؛ با این حال، شواهد مربوط به عملکرد دانش‌آموزان در زمینه‌های مدرسه‌ای اکوادور محدود باقی مانده است. هدف این پژوهش، توصیف عملکرد تشخیصی دانش‌آموزان در استدلال منطقی-ریاضی و بررسی تفاوت‌های توزیع آن در میان مؤسسات آموزشی شرکت‌کننده بود. این مطالعه به صورت توصیفی، اکتشافی، غیرآزمایشی و با رویکرد کمی انجام شد. در مجموع، ۸۴۳ دانش‌آموز سال سوم متوسطه، در بازه سنی ۱۵ تا ۱۷ سال، از ۲۱ مؤسسه آموزشی شهرستان چونه، اکوادور، در پژوهش شرکت کردند. استدلال منطقی-ریاضی با استفاده از یک آزمون تشخیصی شامل پنج تکلیف ارزیابی شد که هر تکلیف از ۰ تا ۴ امتیاز داشته و مجموع امتیازات بین ۰ تا ۲۰ بود. از میان شرکت‌کنندگان، ۷۶٫۳۹٪ در سطح پایین، ۱۷٫۰۸٪ در سطح متوسط، ۵٫۹۳٪ در سطح خوب و ۰٫۵۹٪ در سطح بسیار خوب طبقه‌بندی شدند؛ هیچ دانش‌آموزی به سطح عالی دست نیافت. تفاوت‌های معنادار آماری میان مؤسسات شناسایی شد، χ²(60) = 392.62, p_MC = 0.00001, V کرامر = 0.394؛ H(20) = 208.51, p < 0.001, ε² = 0.229. این پژوهش خط پایه‌ای چندمؤسسه‌ای از استدلال منطقی-ریاضی در زمینه‌ای نسبتاً کمتر مطالعه‌شده در اکوادور ارائه می‌دهد. یافته‌ها می‌تواند به شناسایی نیازهای آموزشی و برنامه‌ریزی حمایت‌های تفکیک‌شده بر اساس عملکرد اولیه دانش‌آموزان کمک کند. به دلیل نبود گروه مقایسه یا سنجش کمی پیش‌آزمون-پس‌آزمون، امکان ارزیابی تغییرات در استدلال منطقی-ریاضی یا نسبت دادن نتایج به استفاده از GeoGebra وجود نداشت.

سایت ناشر ↗ دسترسی آزاد