Search results for "Monetization"

Hits ?▲	Authors	Title	Venue	Year	Link	Author keywords
50	Gerard Hermet, Jacques Combet	Mobile Internet Monetization: A Methodology to Monitor in Real Time the Cellular Subscriber Transactional Itinerary, from Mobile Advertising Exposure to Actual Purchase.	ICMB	2011	DBLP DOI BibTeX RDF	Web Audience Measurement, Monetization, NIS, Passive Consumer Panel, Internet Protocol, Mobile Internet, Mobile advertising
43	John W. Byers, Michael Mitzenmacher, Georgios Zervas	Adaptive weighing designs for keyword value computation.	WSDM	2010	DBLP DOI BibTeX RDF	weighing designs, regression, least squares, design of experiments
27	Anthony P. Badali, Parham Aarabi, Ron D. Appel	Intelligent ad resizing.	WWW	2010	DBLP DOI BibTeX RDF	internet monetization, image processing, image resizing
27	Alex Penev, Raymond K. Wong 0001	Framework for timely and accurate ads on mobile devices.	CIKM	2009	DBLP DOI BibTeX RDF	monetization, mobile device, search, advertising
27	Xin-Jing Wang, Mo Yu, Lei Zhang 0001, Rui Cai, Wei-Ying Ma	Argo: intelligent advertising by mining a user's interest from his photo collections.	KDD Workshop on Data Mining and Audience Intelligence for Advertising	2009	DBLP DOI BibTeX RDF	photo monetization, image understanding, user interest modeling
27	Xin-Jing Wang, Mo Yu, Lei Zhang 0001, Wei-Ying Ma	Argo: intelligent advertising made possible from users' photos.	ACM Multimedia	2009	DBLP DOI BibTeX RDF	photo monetization, image understanding, user interest modeling
27	Xuerui Wang, Andrei Z. Broder, Marcus Fontoura, Vanja Josifovski	A note on search based forecasting of ad volume in contextual advertising.	CIKM	2008	DBLP DOI BibTeX RDF	impression forecasting, internet monetization, online advertising, wand, content match, contextual advertising
22	Qusai Ramadan, Zeyd Boukhers, Muath AlShaikh, Christoph Lange 0002, Jan Jürjens	Data Trading and Monetization: Challenges and Open Research Directions.	CoRR	2024	DBLP DOI BibTeX RDF
22	Zongxian Wang, Jie Song	Data Monetization Pathways and Complex Dynamic Game Equilibrium Analysis in the Energy Industry.	CoRR	2024	DBLP DOI BibTeX RDF
22	Rodrigo G. Rodrigues, Fernando A. F. Ferreira, Alexandra Milici, Elias G. Carayannis, João J. M. Ferreira	Change Management and Advanced Wireless Network Implementation: Detection of Monetization Opportunities and Challenges.	IEEE Trans. Engineering Management	2024	DBLP DOI BibTeX RDF
22	Jonathan (Hua) Ye, Cecil Eng Huang Chua	Monetization for Content Generation and User Engagement on Social Media Platforms: Evidence from Paid Q&A.	IEEE Trans. Engineering Management	2024	DBLP DOI BibTeX RDF
22	Fatemeh Mirbagheri, Hadi Ghanbari, Matti Rossi	Exploring Data Monetization in Established Organizations: A Dynamic Capability Approach.	HICSS	2024	DBLP BibTeX RDF
22	Xin Zhang, Wei Thoo Yue, Yugang Yu, Xiong Zhang 0001	How to monetize data: An economic analysis of data monetization strategies under competition.	Decis. Support Syst.	2023	DBLP DOI BibTeX RDF
22	Qiwei Han, Carolina Lucas, Emila Aguiar, Patrícia Macedo, Zhenze Wu	Towards privacy-preserving digital marketing: an integrated framework for user modeling using deep learning on a data monetization platform.	Electron. Commer. Res.	2023	DBLP DOI BibTeX RDF
22	Mahmoud Abbasi, Javier Prieto 0001, Amin Shahraki, Juan M. Corchado	Industrial data monetization: A blockchain-based industrial IoT data trading system.	Internet Things	2023	DBLP DOI BibTeX RDF
22	Severin Bonnet, Frank Teuteberg	Impact of blockchain and distributed ledger technology for the management, protection, enforcement and monetization of intellectual property: a systematic literature review.	Inf. Syst. E Bus. Manag.	2023	DBLP DOI BibTeX RDF
22	Muhammad Muneem Shabir, Syed Muhammad Danish, Kaiwen Zhang 0001	BlockQoS: Fair Monetization of On-demand Quality-of-Service using Blockchains.	Distributed Ledger Technol. Res. Pract.	2023	DBLP DOI BibTeX RDF
22	Damian Bank	Problematic monetization in mobile games in the context of the human right to economic self-determination.	Comput. Hum. Behav.	2023	DBLP DOI BibTeX RDF
22	Seyed Nima Khezr, Abdulsalam Yassine, Rachid Benlamri	Towards a secure and dependable IoT data monetization using blockchain and fog computing.	Clust. Comput.	2023	DBLP DOI BibTeX RDF
22	Kai Zhu, Qiaoni Shi, Shrabastee Banerjee	Platform Monetization and Unintended Consequences for Digital Cultural Markets: Evidence from a Two-sided Market for Book Promotions.	HICSS	2023	DBLP BibTeX RDF
22	Dan Fitton, Janet C. Read	"Money from the Queen": Exploring Children's Ideas for Monetization in Free-to-Play Mobile Games.	INTERACT (2)	2023	DBLP DOI BibTeX RDF
22	Timo Himmelsbach, Yongli Mou, Stefan Decker, Armin Heinzl	Towards Federated Machine Learning and Distributed Ledger Technology-based Data Monetization.	VLDB Workshops	2023	DBLP BibTeX RDF
22	Cassidy Gibson, Vanessa Frost, Katie Platt, Washington Garcia, Luis Vargas, Sara Rampazzi, Vincent Bindschaedler, Patrick Traynor, Kevin R. B. Butler	Analyzing the Monetization Ecosystem of Stalkerware.	Proc. Priv. Enhancing Technol.	2022	DBLP DOI BibTeX RDF
22	Mohammad Moussa Madine, Khaled Salah 0001, Raja Jayaraman, Ammar Ayman Battah, Haya R. Hasan, Ibrar Yaqoob	Blockchain and NFTs for Time-Bound Access and Monetization of Private Data.	IEEE Access	2022	DBLP DOI BibTeX RDF
22	Vamsi K. Kanuri, Adithya Pattabhiramaiah	Scarcity-driven monetization of digital content.	Frontiers Res. Metrics Anal.	2022	DBLP DOI BibTeX RDF
22	Ken Figueredo, Dale Seed, Chonggang Wang	A Scalable, Standards-Based Approach for IoT Data Sharing and Ecosystem Monetization.	IEEE Internet Things J.	2022	DBLP DOI BibTeX RDF
22	Farshad Firouzi, Bahareh J. Farahani, Mojtaba Barzegari, Mahmoud Daneshmand	AI-Driven Data Monetization: The Other Face of Data in IoT-Based Smart and Connected Health.	IEEE Internet Things J.	2022	DBLP DOI BibTeX RDF
22	Farshad Firouzi, Bahareh J. Farahani, Mahmoud Daneshmand, Cesare Pautasso	Guest Editorial Special Issue on AI-Driven IoT Data Monetization: A Transition From Value Islands to Value Ecosystems.	IEEE Internet Things J.	2022	DBLP DOI BibTeX RDF
22	Yiqing Hua, Manoel Horta Ribeiro, Thomas Ristenpart, Robert West 0001, Mor Naaman	Characterizing Alternative Monetization Strategies on YouTube.	Proc. ACM Hum. Comput. Interact.	2022	DBLP DOI BibTeX RDF
22	Angela Aerry Choi, KiEun Rhee, Chamna Yoon, Wonseok Oh 0001	The Cost of Free: The Effects of "Wait-for-Free" Pricing Schemes on the Monetization of Serialized Digital Content.	MIS Q.	2022	DBLP DOI BibTeX RDF
22	Christian Colot, Philippe Baecke, Isabelle Linden	Toward Decision Support for Telecom External Data Monetization: A Study of the Value of Network- and Personality-Based Metrics for Third-Party Businesses.	Big Data	2022	DBLP DOI BibTeX RDF
22	Riikka Numminen, Markus Juhani Viljanen, Tapio Pahikkala	Bayesian Inference for Predicting the Monetization Percentage in Free-to-Play Games.	IEEE Trans. Games	2022	DBLP DOI BibTeX RDF
22	Ruibin Geng, Xi Chen 0025	Privilege or equality? A natural experiment with content monetization in social media.	Inf. Manag.	2022	DBLP DOI BibTeX RDF
22	Cameron Ballard, Ian Goldstein, Pulak Mehta, Genesis Smothers, Kejsi Take, Victoria Zhong, Rachel Greenstadt, Tobias Lauinger, Damon McCoy	Conspiracy Brokers: Understanding the Monetization of YouTube Conspiracy Theories.	CoRR	2022	DBLP DOI BibTeX RDF
22	Yiqing Hua, Manoel Horta Ribeiro, Robert West 0001, Thomas Ristenpart, Mor Naaman	Characterizing Alternative Monetization Strategies on YouTube.	CoRR	2022	DBLP DOI BibTeX RDF
22	Ye Han, Peter Haried	Show me the Money: Exploring the Monetization of Live Streaming.	AMCIS	2022	DBLP BibTeX RDF
22	Wilson S. Melo, Paulo R. M. Nascimento, Kauã Gomes, Malkai Oliveira, Raphael Machado	Crowdsourcing and monetization as a strategy to reduce vehicular greenhouse gases emissions.	VTC Fall	2022	DBLP DOI BibTeX RDF
22	Zahra Batool, Kaiwen Zhang 0001, Matthew Toews	FL-MAB: client selection and monetization for blockchain-based federated learning.	SAC	2022	DBLP DOI BibTeX RDF
22	Ronja Schwinghammer, Rahild Neuburger, Thomas Hess	Towards an Understanding of the Tensions between Data Privacy and Data Monetization: Uncovering the Sweet Spot between the Tensions.	PACIS	2022	DBLP BibTeX RDF
22	Cameron Ballard, Ian Goldstein, Pulak Mehta, Genesis Smothers, Kejsi Take, Victoria Zhong, Rachel Greenstadt, Tobias Lauinger, Damon McCoy	Conspiracy Brokers: Understanding the Monetization of YouTube Conspiracy Theories.	WWW	2022	DBLP DOI BibTeX RDF
22	Andrew Chu, Arjun Arunasalam, Muslum Ozgur Ozmen, Z. Berkay Celik	Behind the Tube: Exploitative Monetization of Content on YouTube.	USENIX Security Symposium	2022	DBLP BibTeX RDF
22	Peter Waher, Kristjan Araoz, Pablo Pulgar R., Daniel Moström	Tokenization of sustainable real estate in Smart Cities : Monetization as basis for construction, authorization and carbon neutralization in CPS.	IECON	2022	DBLP DOI BibTeX RDF
22	Waluyohadi, Agnieszka Lopatka	90 Days to Achieve Monetization: Implementing Design Thinking in a YouTube Channel.	KES	2022	DBLP DOI BibTeX RDF
22	Felix Sterk, Christian Peukert, Fabian Hunke, Christof Weinhardt	Understanding Car Data Monetization: A Taxonomy of Data-Driven Business Models in the Connected Car Domain.	Wirtschaftsinformatik	2022	DBLP BibTeX RDF
22	Merlijn Sebrechts, Tom Goethals, Thomas Dupont, Wannes Kerckhove, Ruben Taelman, Filip De Turck, Bruno Volckaert	Solid Web Monetization.	ICWE	2022	DBLP DOI BibTeX RDF
22	Farah Mohamad Farouk Saboune	Virtual Reality in Social media marketing will be the new model of advertising and monetization.	SNAMS	2022	DBLP DOI BibTeX RDF
22	Payam Hanafizadeh, Mahdi Barkhordari Firouzabadi, Khuong Minh Vu	Insight monetization intermediary platform using recommender systems.	Electron. Mark.	2021	DBLP DOI BibTeX RDF
22	Youqi Li, Fan Li 0001, Song Yang 0002, Pan Zhou, Liehuang Zhu, Yu Wang 0003	Three-Stage Stackelberg Long-Term Incentive Mechanism and Monetization for Mobile Crowdsensing: An Online Learning Approach.	IEEE Trans. Netw. Sci. Eng.	2021	DBLP DOI BibTeX RDF
22	Haozhao Zhang, Zhe Zhang, Srinivasan Raghunathan	Is More Better? Divide Between Retailer's and Manufacturers' Preferences for Reviews and Review Monetization.	MIS Q.	2021	DBLP DOI BibTeX RDF
22	Sameer Mehta, Milind Dawande, Ganesh Janakiraman, Vijay S. Mookerjee	How to Sell a Data Set? Pricing Policies for Data Monetization.	Inf. Syst. Res.	2021	DBLP DOI BibTeX RDF
22	Bin Fang, Xin Fu, Shaoxia Liu, Shun Cai	Post-purchase warranty and knowledge monetization: Evidence from a paid-knowledge platform.	Inf. Manag.	2021	DBLP DOI BibTeX RDF
22	Muhammad Salek Ali, Massimo Vecchio, Fabio Antonelli	A Blockchain-Based Framework for IoT Data Monetization Services.	Comput. J.	2021	DBLP DOI BibTeX RDF
22	Hua (Jonathan) Ye, Xueping Yang, Xinwei Wang 0002, Theophanis C. Stratopoulos	Monetization Of Digital Content: Drivers Of Revenue On Q&A Platforms.	J. Manag. Inf. Syst.	2021	DBLP DOI BibTeX RDF
22	Christian Dahdah, Coline Van Leeuwen, Ziad Kheil, Jérôme Lacan, Jonathan Detchart, Thibault Gateau	Enabling Monetization of Depreciating Data on Blockchains.	ICISSP	2021	DBLP DOI BibTeX RDF
22	Yi Li	Traffic Monetization on Community E-commerce Platforms: Trust in Virtual Communities and Its Effect on Actual Purchase.	WHICEB	2021	DBLP BibTeX RDF
22	Sa'ar Karp Gershon, José A. Ruipérez Valiente, Giora Alexandron	MOOC Monetization Changes and Completion Rates: Are Learners from Countries of Different Development Status Equally Affected?	EMOOCs	2021	DBLP DOI BibTeX RDF
22	Martin Fadler, Hippolyte Lefebvre, Christine Legner	Data governance: from master data quality to data monetization.	ECIS	2021	DBLP BibTeX RDF
22	Shagun Tripathi, Harris Kyriakou	App Privacy on App Platforms: Developer Side Trade-offs, Monetization Strategies and Third-Party Services.	ICIS	2021	DBLP BibTeX RDF
22	Pol Camps-Aragó, Simon Delaere, Ruben D'Hauwers	Value Networks and Monetization Strategies for C-ITS Safety Use Cases.	VEHITS	2021	DBLP DOI BibTeX RDF
22	Anthony Zappin, Haroon Malik, Elhadi M. Shakshuki, David A. Dampier	YouTube Monetization and Censorship by Proxy: A Machine Learning Prospective.	EUSPN/ICTH	2021	DBLP DOI BibTeX RDF
22	Fatma Outay, Haroon Malik, Anthony Zappin, Kanimozhi Kalaichelvan	Towards Understanding the Monetization and Censorship Aspect of Streaming Media.	DASC/PiCom/CBDCom/CyberSciTech	2021	DBLP DOI BibTeX RDF
22	Kjartan Hauge, Jukka Rantala, Timo Holopainen	Startups Born Out of Academia: Structural Pattern of Monetization Failures, Rectified.	AHFE (9)	2021	DBLP DOI BibTeX RDF
22	Mazin Debe, Khaled Salah 0001, Muhammad Habib Ur Rehman, Davor Svetinovic	Monetization of Services Provided by Public Fog Nodes Using Blockchain and Smart Contracts.	IEEE Access	2020	DBLP DOI BibTeX RDF
22	Matthew E. Perks	How Does Games Critique Impact Game Design Decisions? A Case Study of Monetization and Loot Boxes.	Games Cult.	2020	DBLP DOI BibTeX RDF
22	Petri Parvinen, Essi Pöyry, Robin Gustafsson, Miikka Laitila, Matti Rossi	Advancing Data Monetization and the Creation of Data-based Business Models.	Commun. Assoc. Inf. Syst.	2020	DBLP DOI BibTeX RDF
22	Markus Viljanen, Antti Airola, Anne-Maarit Majanoja, Jukka Heikkonen, Tapio Pahikkala	Measuring Player Retention and Monetization Using the Mean Cumulative Function.	IEEE Trans. Games	2020	DBLP DOI BibTeX RDF
22	Rajesh Challa, Vyacheslav V. Zalyubovskiy, Syed M. Raza, Hyunseung Choo, Aloknath De 0001	Network Slice Admission Model: Tradeoff Between Monetization and Rejections.	IEEE Syst. J.	2020	DBLP DOI BibTeX RDF
22	Abou Zakaria Faroukhi, Imane El Alaoui, Youssef Gahi, Aouatif Amine	An Adaptable Big Data Value Chain Framework for End-to-End Big Data Monetization.	Big Data Cogn. Comput.	2020	DBLP DOI BibTeX RDF
22	Abou Zakaria Faroukhi, Imane El Alaoui, Youssef Gahi, Aouatif Amine	Big data monetization throughout Big Data Value Chain: a comprehensive review.	J. Big Data	2020	DBLP DOI BibTeX RDF
22	Saeid Heshmatisafa, Marko Seppänen	API Utilization and Monetization in Finnish Industries.	XP Workshops	2020	DBLP DOI BibTeX RDF
22	Wiem Badreddine, Kaiwen Zhang 0001, Chamseddine Talhi	Monetization using Blockchains for IoT Data Marketplace.	IEEE ICBC	2020	DBLP DOI BibTeX RDF
22	Julius Baecker, Martin Engert, Matthias Pfaff, Helmut Krcmar	Business Strategies for Data Monetization: Deriving Insights from Practice.	Wirtschaftsinformatik (Zentrale Tracks)	2020	DBLP DOI BibTeX RDF
22	Xi Lin, Christy M. Rhodes	Monetization of Knowledge in China: A new way for online learning?	eLearn Mag.	2019	DBLP DOI BibTeX RDF
22	Ahmed Suliman, Zainab Husain, Menatalla Abououf, Mansoor Alblooshi, Khaled Salah 0001	Monetization of IoT data using smart contracts.	IET Networks	2019	DBLP DOI BibTeX RDF
22	Ahmad Beltagui, Thomas Schmidt 0006, Marina Candi, Deborah Lynn Roberts	Overcoming the monetization challenge in freemium online games.	Ind. Manag. Data Syst.	2019	DBLP DOI BibTeX RDF
22	Van Linh Nguyen, Po-Ching Lin, Ren-Hung Hwang	Preventing the attempts of abusing cheap-hosting Web-servers for monetization attacks.	CoRR	2019	DBLP BibTeX RDF
22	Elena Alfaro, Marco Bressan, Fabien Girardin, Juan Murillo, Ida Asadi Someh, Barbara H. Wixom	BBVA's Data Monetization Journey.	MIS Q. Executive	2019	DBLP BibTeX RDF
22	Bin Fang, Zhiqiang (Eric) Zheng, Qiang Ye 0004, Paulo B. Góes	Social Influence and Monetization of Freemium Social Games.	J. Manag. Inf. Syst.	2019	DBLP DOI BibTeX RDF
22	Martin Ivanov, Helmut Wittenzellner, Marcin Wardaszko	Video Game Monetization Mechanisms in Triple A (AAA) Video Games.	ISAGA	2019	DBLP DOI BibTeX RDF
22	Sameer Mehta, Milind Dawande, Ganesh Janakiraman, Vijay S. Mookerjee	How to Sell a Dataset?: Pricing Policies for Data Monetization.	EC	2019	DBLP DOI BibTeX RDF
22	Atia Javaid, Maheen Zahid, Ishtiaq Ali, Raja Jalees ul Hussen Khan, Zainib Noshad, Nadeem Javaid	Reputation System for IoT Data Monetization Using Blockchain.	BWCCA	2019	DBLP DOI BibTeX RDF
22	Riikka Numminen, Markus Viljanen, Tapio Pahikkala	Predicting the monetization percentage with survival analysis in free-to-play games.	CoG	2019	DBLP DOI BibTeX RDF
22	Stefania Fusco, Francesco Lissoni, Catalina Martínez, Valério S. Almeida	Monetization Strategies of University Patents through PAEs: an Analysis of US Patent Transfers.	ISSI	2019	DBLP BibTeX RDF
22	Baojun Liu, Zhou Li 0001, Peiyuan Zong, Chaoyi Lu, Hai-Xin Duan, Ying Liu 0024, Sumayah A. Alrwais, XiaoFeng Wang 0001, Shuang Hao, Yaoqi Jia, Yiming Zhang 0009, Kai Chen 0012, Zaifeng Zhang	TraffickStop: Detecting and Measuring Illicit Traffic Monetization Through Large-Scale DNS Analysis.	EuroS&P	2019	DBLP DOI BibTeX RDF
22	Sinh Huynh, Kenny Tsu Wei Choo, Rajesh Krishna Balan, Youngki Lee	CryptoCurrency Mining on Mobile as an Alternative Monetization Approach.	HotMobile	2019	DBLP DOI BibTeX RDF
22	Evangelos Markopoulos, Panagiotis Markopoulos, Mika Liumila, Younus Almufti, Vasu Aggarwal	Mapping the Monetization Challenge of Gaming in Various Domains.	AHFE (22)	2019	DBLP DOI BibTeX RDF
22	Francisco de la Vega, Javier Soriano 0001, Miguel Jimenez, David Lizcano	A Peer-to-Peer Architecture for Distributed Data Monetization in Fog Computing Scenarios.	Wirel. Commun. Mob. Comput.	2018	DBLP DOI BibTeX RDF
22	Panagiotis Papadopoulos, Panagiotis Ilia, Evangelos P. Markatos	Truth in Web Mining: Measuring the Profitability and Cost of Cryptominers as a Web Monetization Model.	CoRR	2018	DBLP BibTeX RDF
22	Ruibin Geng, Xi Chen 0025	Economics of 'Tipping' Button in Social Media: An Empirical Analysis of Content Monetization.	PACIS	2018	DBLP BibTeX RDF
22	Tobias Grubenmann	Monetization Strategies for the Web of Data.	WWW (Companion Volume)	2018	DBLP DOI BibTeX RDF
22	Alex Norta, Daniel Hawthorne, Serafin L. Engel	A Privacy-Protecting Data-Exchange Wallet with Ownership- and Monetization Capabilities.	IJCNN	2018	DBLP DOI BibTeX RDF
22	Yalitza Therly Ramos-Gil, Carmelo Márquez-Domínguez, Aldo Romero-Ortega	The Press in the Context of the Andean Community of Nations (CAN): Without Sustainable Monetization in the Digital Economy.	ICITS	2018	DBLP DOI BibTeX RDF
22	Haoran Yu, Man Hon Cheung, Lin Gao 0001, Jianwei Huang 0001	Public Wi-Fi Monetization via Advertising.	IEEE/ACM Trans. Netw.	2017	DBLP DOI BibTeX RDF
22	Bert De Reyck, Ioannis Fragkos, Yael Grushka-Cockayne, Casey Lichtendahl, Hammond Guerin, Andrew Kritzer	Vungle Inc. Improves Monetization Using Big Data Analytics.	Interfaces	2017	DBLP DOI BibTeX RDF
22	Giovane C. M. Moura, Moritz Müller, Marco Davids, Maarten Wullink, Cristian Hesselman	Domain names abuse and TLDs: From monetization towards mitigation.	IM	2017	DBLP DOI BibTeX RDF
22	Roberto Gonzalez, Alberto García-Durán, Filipe Manco, Mathias Niepert, Pelayo Vallina	Network Data Monetization Using Net2Vec.	SIGCOMM Posters and Demos	2017	DBLP DOI BibTeX RDF
22	Martin Skoviera, Piyush Harsh, Oleksii Serhiienko, Manuel Perez Belmonte, Thomas Michael Bohnert	Monetization of infrastructures and services.	EuCNC	2017	DBLP DOI BibTeX RDF
22	Markus Viljanen, Antti Airola, Jukka Heikkonen, Tapio Pahikkala	A/B-Test of Retention and Monetization Using the Cox Model.	AIIDE	2017	DBLP BibTeX RDF
22	Angela Aerry Choi, KiEun Rhee, Wonseok Oh 0001	"Marshmallow Pricing": Effects of "Wait-and-Not-Pay" Schemes on the Monetization of Hedonic Digital Content.	ICIS	2017	DBLP BibTeX RDF
22	Enric Pujol-Gil	Web content delivery, monetization, and search: back-office and advertisement traffic on the Internet.		2017	RDF