Mostrando 9,901 - 9,920 Resultados de 13,276 Para Buscar '"Risk"', tiempo de consulta: 0.13s Limitar resultados
  1. 9901
    por Institute of Medicine (U.S.).
    Publicado 1992
    Tabla de Contenidos: “…Nutrition Issues in Developing Countries -- Copyright -- Contents -- PART I DIARRHEAL DISEASES -- Introduction -- REFERENCES -- 1 Summary -- 2 Feeding Practices and Their Determinants -- FEEDING PRACTICES, FOOD, AND DIARRHEA RISK -- SOCIOCULTURAL DETERMINANTS OF BREASTFEEDING -- Women's Work -- Health Services and Personnel -- Marketing Practices of Infant Formula Manufacturers -- Urbanization -- INITIATING BREASTFEEDING: COLOSTRUM AND PRELACTEAL FEEDS -- INTRODUCTION OF FOODS IN ADDITION TO BREAST MILK -- FEEDING METHODS -- SEVERANCE: THE CESSATION OF BREASTFEEDING -- SPECIFIC DETERMINANTS FOR INTERVENTION PLANNING -- Food Availability to the Community -- Food Availability at the Household Level -- Food Availability to the Child -- Cultural Beliefs -- Allocation of Caretaker Time for Food Preparation -- Availability of Fuel Water, and Other Food Preparation Resources -- Family Food Consumption Patterns -- Child Feeding Methods and Practices -- SUMMARY -- REFERENCES -- 3 Relationships Between Nutrition and Diarrhea -- EVIDENCE THAT MALNUTRITION PREDISPOSES THE HOST TO DIARRHEAL DISEASE -- IMMUNOLOGICAL CONSEQUENCES OF MALNUTRITION -- THE CONTRIBUTION OF DIARRHEA TO MALNUTRITION -- HUMAN MILK AND DIARRHEAL DISEASES -- Protective Factors in Human Milk -- Lactation Performance -- Effects of Maternal Nutritional Status on Lactation Performance -- Effects of Food Supplementation, on Lactation Performance -- Manipulation of Immunologic Protein Factors in Human Milk -- WEANING FOODS -- Nutrient Composition of Common Foods -- Bioavailability of Nutrients -- NUTRIENT REQUIREMENTS OF INFANTS AND YOUNG CHILDREN -- SUMMARY -- REFERENCES -- 4 Feeding Practices, Food, and Diarrhea Risk -- FOOD CONTAMINATION -- FECAL CONTAMINATION OF WEANING FOOD IN DEVELOPING COUNTRIES -- Source of Contamination -- Relationship of Weaning Food Contamination to Diarrhea…”
    Libro electrónico
  2. 9902
    Publicado 2024
    Tabla de Contenidos: “…Speak Genuinely -- Reflect and Act: Enlist Others -- Reflect -- Act -- Practice #3: Challenge the Process -- Reflections from the Student Leadership Practices Inventory -- Chapter 5 Commitment #5: Search for Opportunities -- Seize the Initiative -- Make Something Happen -- Encourage Initiative in Others -- Challenge with Purpose -- Exercise Outsight -- Look Outside Your Experience -- Listen to and Promote Diverse Perspectives -- Treat Every Experience as an Adventure -- Reflect and Act: Search for Opportunities -- Reflect -- Act -- Chapter 6 Commitment #6: Experiment and Take Risks -- Generate Small Wins -- Build Psychological Hardiness -- Break It Down and Accentuate Progress -- Learn from Experience -- Be an Active Learner -- Create a Climate for Learning -- Strengthen Resilience and Grit -- Reflect and Act: Experiment and Take Risks -- Reflect -- Act -- Practice #4: Enable Others to Act -- Reflections from the Student Leadership Practices Inventory -- Chapter 7 Commitment #7: Foster Collaboration -- Create a Climate of Trust -- Be the First to Trust -- Show Concern for Others -- Share Knowledge and Information -- Facilitate Relationships -- Develop Cooperative Goals and Roles -- Support Norms of Reciprocity -- Structure Projects to Promote Joint Efforts -- Support Face-to-Face and Durable Interactions -- Reflect and Act: Foster Collaboration -- Reflect -- Act -- Chapter 8 Commitment #8: Strengthen Others -- Enhance Self-Determination -- Provide Choices -- Structure Tasks to Offer Latitude -- Foster Accountability -- Develop Competence and Confidence -- Educate and Share Information -- Organize Work to Build Competence and Ownership -- Foster Self-Confidence -- Coach -- Reflect and Act: Strengthen Others -- Reflect -- Act -- Practice #5: Encourage the Heart -- Reflections from the Student Leadership Practices Inventory…”
    Libro electrónico
  3. 9903
    Publicado 2020
    Tabla de Contenidos: “…Litz -- Student Service Members/Veterans' Mental Health on Campuses: Risk and Resources / Dan Nyaronga -- Resilience and Clinical Issues in Survival Behaviour under Isolation and Captivity / Vasile Marineanu…”
    Libro electrónico
  4. 9904
    Publicado 2023
    Tabla de Contenidos: “…-- Figuring out your 'why' -- Challenging your 'why' -- Adding a time frame -- Chapter 3 Setting Strong Foundations -- Foundation 1: Respect your earnings -- Foundation 2: Pay attention to your spending -- Foundation 3: The cost of money is interest -- Foundation 4: Be realistic -- Foundation 5: Reward yourself -- Part II Strategy Stacking -- Chapter 4 Understanding the Strategy Stacking Philosophy -- Understand your 'why' -- Remember the five foundations -- Start with the Basic Stack: Budgeting, where earnings meet spending -- Use a Risk Assessment Strategy -- Stack your strategies appropriately -- Assess, execute, review, refine and repeat -- Chapter 5 Strategy Stacking around Significant Life Events -- Redundancy -- Marriage and divorce -- An unexpected windfall -- Trauma and disability -- Stacking for the next generation -- Chapter 6 Getting Started: Assessing Your Starting Position -- Know your money truths before you begin -- The Strategy Stacker's Starting Position -- Working out your starting position -- Chapter 7 Making a Plan: The Strategy Stacking Calendar -- Chapter 8 Strategy Stacking Scenarios -- Strategy stack: 'I want to save more and buy a house one day'…”
    Libro electrónico
  5. 9905
    Publicado 2024
    Tabla de Contenidos: “…Keeping up with the open source OSINT landscape -- Blogs and websites -- Conferences and workshops -- Evaluating new tools -- Engaging with the OSINT community -- Summary -- Chapter 6: The Eyes and Ears of Threat Intelligence - How OSINT Helps Mitigate Cyber Risks -- Introduction to threat intelligence and OSINT -- Cyber threats and OSINT -- Phishing -- Social engineering -- Malware and ransomware -- APTs -- Combining OSINT with internal security -- Cyber threat intelligence platforms and OSINT integration -- Some big names in the game -- Incorporating OSINT data into threat intelligence workflows -- Sharing OSINT-derived intelligence with other platforms and teams -- Building an OSINT-driven cyber threat intelligence program -- What are intelligence requirements? …”
    Libro electrónico
  6. 9906
    Publicado 2023
    Tabla de Contenidos: “…CHAPTER 9: Get Out of the Building: How to Gather Customer Discovery Data with Interviews -- OUTSIDE‐IN LOGIC -- TALKING TO CUSTOMERS -- CUSTOMER INTERVIEWS FOR IDEATING, INCUBATING, AND SCALING -- DOS AND DON'TS OF CUSTOMER INTERVIEWS -- NOTES -- CHAPTER 10: Value Propositions: Using Value Flows and Design Criteria Maps to Create Customer Delight -- INSIGHT TO DELIGHT -- CREATING VALUE FLOW AND DESIGN CRITERIA MAP -- NOTE -- CHAPTER 11: Business Experiments: De‐risking Execution Spend Through Experiments -- INSTINCT OR DATA -- DE‐RISKING INNOVATION -- STRUCTURED LEARNING CYCLES -- NOTES -- CHAPTER 12: Ecosystems: Building an Ecosystem Playbook for Scaling a New Venture -- CO‐INNOVATION -- BUILDING THE ECOSYSTEM PLAYBOOK -- KEY SUCCESS FACTORS -- NOTES -- CHAPTER 13: Validation: Managing the Journey from Concept to Scale -- HUNTER STRATEGY -- VENTURE MATURITY -- GROWTH VALIDATION PROCESS FOR CORPORATE VENTURES -- NOTES -- SECTION III: EXPLORE ORGANIZATION AND LEADERSHIP -- CHAPTER 14: Ambidextrous Organization: What It Is, When to Use It -- SEPARATING EXPLORE FROM CORE -- AMBIDEXTROUS ORGANIZATION DECISION -- FOUR SUCCESS FACTORS -- NOTES -- CHAPTER 15: Explore Unit: How to Build a Team for Exploration -- RHYTHM OF EXPLORE -- PURPOSE -- RESOURCE ALLOCATION -- DECISION MAKING -- TEAM -- OPERATING MODEL -- NOTES -- CHAPTER 16: Strategic Diversity: Selecting and Developing Corporate Exploration Teams -- EXPLORE TEAMS -- STRATEGIC DIVERSITY -- GROWTH CURVES -- HUMAN BEHAVIOR -- IMPLICATIONS FOR CORPORATE EXPLORERS -- NOTE -- CHAPTER 17: Leading High‐Stakes Conversations: Getting the Senior Team Onboard -- SENIOR TEAM COMMITMENT -- VALUE OF TENSION -- CREATE: GETTING THE CONVERSATION INTO THE ZONE OF PRODUCTIVE TENSION -- CONTROL: KEEPING THE CONVERSATION IN THE ZONE OF PRODUCTIVE TENSION -- CLOSING TENSION -- PRODUCTIVE TENSION TECHNIQUES -- NOTES…”
    Libro electrónico
  7. 9907
    Publicado 2023
    Tabla de Contenidos: “…5.7 Application to the Pareto Distribution -- 5.8 Application to Continuous Degradation Processes -- 5.8.1 Problem Statement -- 5.8.2 RUL for Wiener Process With Drift -- 5.8.3 RUL for Gamma Process -- 5.9 Exercises -- Bibliography -- 6 Properties of the Dg Metric -- 6.1 Introduction -- 6.2 Derivative of G(t) -- 6.3 Differential Equation for MRL -- 6.3.1 Example: The Rayleigh Distribution -- 6.3.2 Other Example: The Gamma Distribution -- 6.4 Second Derivative of G(t) -- 6.4.1 Weibull Distribution -- 6.4.2 Gamma Distribution -- 6.5 Upper Bound for the Average RUL Loss Rate -- 6.6 Exercises -- Bibliography -- 7 Multiple Failure Or Degradation Modes -- 7.1 Introduction -- 7.2 General Formulation -- 7.3 Illustration in Special Case -- 7.4 Exercises -- Bibliography -- 8 Statistical Estimation Aspects -- 8.1 Introduction -- 8.2 Nonparametric Estimation -- 8.3 Parametric Estimation-Illustration On Two Case Studies -- 8.3.1 Parametric Estimation: The Maximum Likelihood Estimation Method -- 8.3.1.1 Maximum Likelihood Estimator -- 8.3.1.2 Desirable Properties of the Maximum Likelihood Estimator -- 8.3.1.3 Derivation of a Confidence Interval -- 8.3.2 First Case Study: Light-Emitting Diodes (LEDs) -- 8.3.3 Second Case Study: Redundant System -- 8.4 Surrogate Model for the G(t) Transformation -- 8.5 Bayesian Estimation -- 8.6 Exercises -- Bibliography -- 9 Implications for Maintenance Optimization -- 9.1 Introduction -- 9.2 Maintenance Decisions: Balancing Costs and Risks -- 9.3 Quantifying Costs and Risks -- 9.3.1 Rejuvenation and Maintenance Efficiency -- 9.3.2 Minimal Maintenance (ABAO) -- 9.3.3 Perfect Maintenance (AGAN) -- 9.4 Predictive Maintenance -- 9.5 Exercises -- Bibliography -- 10 Advanced Topics and Further Research -- 10.1 The Gini Index -- 10.2 Entropy and the K Parameter -- 10.2.1 Entropy -- 10.2.2 Differential Entropy…”
    Libro electrónico
  8. 9908
    por Lewinson, Eryk
    Publicado 2022
    Tabla de Contenidos: “…Validation methods for time series -- Feature engineering for time series -- Time series forecasting as reduced regression -- Forecasting with Meta's Prophet -- AutoML for time series forecasting with PyCaret -- Summary -- Chapter 8: Multi-Factor Models -- Estimating the CAPM -- Estimating the Fama-French three-factor model -- Estimating the rolling three-factor model on a portfolio of assets -- Estimating the four- and five-factor models -- Estimating cross-sectional factor models using the Fama-MacBeth regression -- Summary -- Chapter 9: Modeling Volatility with GARCH Class Models -- Modeling stock returns' volatility with ARCH models -- Modeling stock returns' volatility with GARCH models -- Forecasting volatility using GARCH models -- Multivariate volatility forecasting with the CCC-GARCH model -- Forecasting the conditional covariance matrix using DCC-GARCH -- Summary -- Chapter 10: Monte Carlo Simulations in Finance -- Simulating stock price dynamics using a geometric Brownian motion -- Pricing European options using simulations -- Pricing American options with Least Squares Monte Carlo -- Pricing American options using QuantLib -- Pricing barrier options -- Estimating Value-at-Risk using Monte Carlo -- Summary -- Chapter 11: Asset Allocation -- Evaluating an equally-weighted portfolio's performance -- Finding the efficient frontier using Monte Carlo simulations -- Finding the efficient frontier using optimization with SciPy -- Finding the efficient frontier using convex optimization with CVXPY -- Finding the optimal portfolio with Hierarchical Risk Parity -- Summary -- Chapter 12: Backtesting Trading Strategies -- Vectorized backtesting with pandas -- Event-driven backtesting with backtrader -- Backtesting a long/short strategy based on the RSI -- Backtesting a buy/sell strategy based on Bollinger bands…”
    Libro electrónico
  9. 9909
    Tabla de Contenidos: “…THE SOCIAL IMPACT OF AIDS IN THE UNITED STATES -- Copyright -- Acknowledgments -- Contents -- 1 Introduction and Summary -- EPIDEMICS, IMPACTS, AND RESPONSES -- GENERAL FINDINGS AND CONCLUSIONS -- SPECIFIC FINDINGS AND CONCLUSIONS -- Public Health -- Health Care -- Clinical Research and Drug Regulation -- Voluntary and Community-Based Organizations -- Religion and Religious Groups -- Correctional Systems -- Public Policies on Children and Families -- New York City -- TECHNICAL NOTE -- REFERENCES -- 2 The Practice of Public Health -- HISTORICAL APPROACHES TO DISEASE CONTROL AND "EXCEPTIONALISM -- HIV TESTING -- REPORTING AND CONTACT TRACING -- Reporting Cases of AIDS and HIV Infection -- Partner Notification and Contact Tracing -- Confidentiality Versus the Physician's "Duty to Warn -- QUARANTINE, ISOLATION, AND CRIMINAL PROSECUTION -- Use of Quarantine Statutes -- Use of Criminal Statutes -- STATE AND LOCAL PUBLIC HEALTH PRACTICE -- Infectious Disease Epidemiology -- Clinical Services -- Planning and Financing Care -- CONCLUSIONS -- NOTES -- REFERENCES -- 3 Health Care Delivery and Financing -- THE HEALTH CARE SYSTEM AS A SERVICE PROVIDER -- Challenges for Traditional Health Care Delivery -- Organization of HIV/AIDS Care -- Hospital Care -- Out-of-Hospital Care -- Connections with Community-Based Services -- THE HEALTH CARE SYSTEM AS EMPLOYER -- Recruiting and Training Providers -- Physicians -- Nurses -- Confronting Occupational Risks -- HIV-Infected Practitioners and Risks to Patients -- The Burden of Caring for AIDS Patients -- The Influence of Prejudice -- Defining the Scope of Professional Obligation -- THE HEALTH CARE SYSTEM AS A MARKET -- HEALTH CARE FINANCING -- CONCLUSIONS -- NOTES -- REFERENCES -- 4 Clinical Research and Drug Regulation -- HISTORICAL PERSPECTIVE1 -- Randomized Clinical Trials…”
    Libro electrónico
  10. 9910
    Publicado 1990
    Tabla de Contenidos:
    Libro electrónico
  11. 9911
    Publicado 2006
    Tabla de Contenidos: “…V: COPING WITH DIVORCE AND RELATIONSHIP DISSOLUTION20 Divorce as Prelude to Stepfamily Living and the Consequences of Redivorce; 21 Communication Processes That Promote Risk and Resiliency in Postdivorce Families; 22 No Breakup Occurs on an Island: Social Networks and Relationship Dissolution; VI: VARIATIONS IN DIVORCE AND RELATIONSHIP DISSOLUTION PATTERNS AND PROCESSES; 23 Divorce in the Context of Being African American; 24 Same-Sex Relationships and Their Dissolution; 25 Divorce and Relationship Dissolution Among Latino Populations in the United States…”
    Libro electrónico
  12. 9912
    Publicado 2012
    Tabla de Contenidos: “…6 Fear, maths, brief dramatherapy and neuroscience7 Violence and laughter: how school-based dramatherapy can go beyond behaviour management for boys at risk of exclusion from school; 8 All the better to see you with: healing metaphors in a case of sexual abuse; 9 Romeo and Juliet and dramatic distancing: chaos and anger contained for inner-city adolescents in multicultural schools; 10 Looking for meaning with bereaved children and families: `Bring back my Daddy' and other stories; 11 Education, the Playground Project and elements of psychodrama…”
    Libro electrónico
  13. 9913
    Publicado 2012
    Tabla de Contenidos: “…-- Methods -- The questionnaire -- Writing the future: imagined life stories -- Outline of the book -- Essaying difference: Comparing essays across the sub-samples -- Introduction: 'Choice' or 'risk' biography? -- Young women and their mothers: From caring for family to caring professions -- Young men's and women's life stories compared -- Young men: Cars and sports -- Sex and love -- Gendered career aspirations -- The homosexual imaginary -- Disadvantaged stories: No bridges from now to the future -- Aboriginal youth: Family and politics -- Young migrants' dreams -- Learning from their parents: Inter-generational change and continuity -- Narratives of becoming: Women change their lives (and minds) -- Women's lives transformed by access to paid work -- Psychic transformation -- Men's disadvantage or opportunity? …”
    Libro electrónico
  14. 9914
    por Bourquin, Tim
    Publicado 2013
    Tabla de Contenidos: “…Wealthy traders determine position size based on risk, not round numbers; 19. Wealthy traders buy strong markets and sell weak markets; 20. …”
    Libro electrónico
  15. 9915
    por Rand Corporation.
    Publicado 2013
    Tabla de Contenidos: “…Cover; Title Page; Copyright; Preface; Contents; Figures; Tables; Summary; Acknowledgments; Abbreviations; CHAPTER ONE Introduction; Our Approach; Description of Survey Sample and Survey Recruitment; Survey Instrument; Survey Response; Survey Analysis; Overall Sample Characteristics; Organization of This Report; CHAPTER TWO The Health Status of Contractors Who Are Deployed to Conflict Environments Is Not Well Understood: A Review of the Literature; Physical and Mental Health Risks Faced by Contractors in Conflict Environments…”
    Libro electrónico
  16. 9916
    Publicado 2013
    Tabla de Contenidos: “…5 The Pharmacodynamics of Antimicrobial AgentsIntroduction; Interpreting the MIC from a Clinical Perspective; Understanding the Drug Response; Understanding the Exposure-Response Relationship; PK/PD and Dose Predictions: Putting It All Together; Conclusion; Bibliography; 6 Principles of Antimicrobial Drug Selection and Use; Risks Associated with Antimicrobial Treatment; Factors Determining Choice of Antibiotic; Principles of Antimicrobial Treatment; Bibliography; 7 Antimicrobial Stewardship in Animals; Introduction; What Is "Prudent Use" of Antimicrobials?…”
    Libro electrónico
  17. 9917
    Publicado 2021
    Tabla de Contenidos: “…3 Early Life Transitions Increase the Risk for HIV Infection: Using Latent Class Growth Models to Assess the Effect of Key Life Events on HIV Incidence Among Adolescent Girls in Rural South Africa -- Introduction -- Methods -- Study design -- Statistical analysis -- Missing data -- Measures -- Results -- Specific life events and HIV incidence -- Cumulative life events and HIV incidence -- Conclusions -- References -- 4 Achieving the Sustainable Development Goals: Evidence from the Longitudinal Parenting Across Cultures Project -- Introduction -- Participants -- Procedure and measures…”
    Libro electrónico
  18. 9918
    Publicado 2021
    Tabla de Contenidos: “…Frontmatter 1 Contents 5 Preface to the English Edition 9 Foreword to the Italian Edition 13 Introduction 17 Ways to Read this Book 21 Art System (Kunstsystem) 27 Asymmetrization (Asymmetrisierung) 31 Attribution (Zurechnung) 35 Autopoiesis 37 Code 41 Communication (Kommunikation) 45 Complexity (Komplexität) 49 Conflict (Konflikt) 53 Constructivism (Konstruktivismus) 57 Differentiation (Differenzierung/Ausdifferenzierung) 61 Differentiation of Society (Differenzierung der Gesellschaft) 65 Dissemination Media (Verbreitungsmedien) 71 Double Contingency (Doppelte Kontingenz) 75 Economic System (Wirtschaftssystem) 79 Education System (Erziehungssystem) 83 Event (Ereignis) 87 Evolution 91 Expectations (Erwartungen) 95 Functional Analysis (Funktionale Analyse) 99 Identity/Difference (Identität/Differenz) 101 Inclusion/Exclusion (Inklusion/Exklusion) 105 Information 109 Interaction (Interaktion) 111 Interpenetration and Structural Coupling (Interpenetration und strukturelle Kopplung) 115 Language (Sprache) 121 Legal System (Rechtssystem) 125 Love (Liebe) 129 Mass media (Massenmedien) 133 Meaning (Sinn) 137 Meaning Dimensions (Sinndimensionen) 141 Medical System (Krankensystem) 145 Medium/Form 149 Morality (Moral) 151 Negation 155 Operation/Observation (Operation/Beobachtung) 157 Organization (Organisation) 163 Paradox (Paradoxie) 167 Political System (Politisches System) 171 Power (Macht) 175 Process (Prozess) 179 Program (Programm) 181 Property/Money (Eigentum/Geld) 185 Protest 187 Psychic Systems (Psychische Systeme) 189 Rationality (Rationalität) 191 Redundancy/Variety (Redundanz/Varietät) 193 Re-entry 195 Religious System (Religionssystem) 197 Risk/Danger (Risiko/Gefahr) 201 Scientific System (Wissenschaftssystem) 205 Self-description (Selbstbeschreibung) 209 Self-Reference (Selbstreferenz) 213 Semantics (Semantik) 217 Social System (Soziales System) 221 Society (Gesellschaft) 223 Sociological Enlightenment (Soziologische Aufklärung) 225 Structure (Struktur) 227 Symbolically Generalized Media (Symbolisch generalisierte Kommunikationsmedien) 229 System/Environment (System/Umwelt) 235 System of Families (System der Familien) 239 Time (Zeit) 243 Truth (Wahrheit) 247 Values (Werte) 251 World (Welt) 253 World Society (Weltgesellschaft) 255 List of Luhmann's works 259…”
    Libro electrónico
  19. 9919
    por Kelly, Ashley Scott
    Publicado 2021
    Tabla de Contenidos: “…5 Infrastructural Connectivity and Difference -- 1 Introduction -- 2 Curating Rural Connectivity: Strategic Maintenance of Temporary Access Roads of the China-Laos Railway -- 3 Before the Bulldozer: Strategic Agricultural Cooperation for an Uncertain Rail Alignment -- References -- 6 Western Alternative Development and Chinese Development -- 1 Introduction -- 2 Low-Labor Landscapes: An Agricultural Response to Short-Term Construction Employment on the China-Laos Railway -- 3 Water Risk and Responsibility: A Political-Chemical Land Genealogy for the Muang Sing Valley, Laos -- References…”
    Libro electrónico
  20. 9920
    Publicado 2023
    Tabla de Contenidos: “…-- She Will Shake the World -- Hot Stocks in the Heart of Capital -- All Rules Are Off -- Trade War or Tech War -- Sino‐Sustainability: How China Went Woke -- The Next Center of the Universe -- Notes -- Chapter 2: Gem on the Pacific Rim -- The Fall of Saigon -- Dairy Queen: Innovation in the South Pacific -- Turbulence -- The Silver‐Tongued Minister -- Environmental and Social Risks at the Red River Delta -- His Eyes Are Always Watching -- Notes -- Chapter 3: Global Flows -- The Commodities Rut -- Woman in a Strange Land -- Opening the Doors -- Crown's Jewel -- Gleam of Success -- Notes -- Chapter 4: Submerging Markets? …”
    Libro electrónico