This book provides a broad introduction to search engines by integrating five different perspectives on Web search and search engines that are usually dealt with separately: the technical perspective, the user perspective, the internet-based research perspective, the economic perspective, and the societal perspective. After a general introduction to the topic, two foundational chapters present how search tools can cover the Web's content and how search engines achieve this by crawling and processing the found documents. The next chapter on user behavior covers how people phrase their search queries and interact with search engines. This knowledge builds the foundation for describing how results are ranked and presented. The following three chapters then deal with the economic side of search engines, i.e., Google and the search engine market, search engine optimization (SEO), and the intermingling of organic and sponsored search results. Next, the chapter on search skills presents techniques for improving searches through advanced search interfaces and commands. Following that, the Deep Web and how its content can be accessed is explained. The two subsequent chapters cover ways to improve the quality of search results, while the next chapter describes how to access the Deep Web. Last but not least, the following chapter deals with the societal role of search engines before the final chapter concludes the book with an outlook on the future of Web search. With this book, students and professionals in disciplines like computer science, online marketing, or library and information science will learn how search engines work, what their main shortcomings are at present, and what prospects there are for their further development. The different views presented will help them to understand not only the basic technologies but also the implications the current implementations have concerning economic exploitation and societal impact.

The Rust programming language is consistent and does its best to avoid surprising the programmer. Like all languages, though, Rust still has its quirks. But these quirks present a teaching opportunity. In this book, you'll work through a series of brain teasers that will challenge your understanding of Rust. By understanding the gaps in your knowledge, you can become better at what you do and avoid mistakes. Many of the teasers in this book come from the author's own experience creating software. Others derive from commonly asked questions in the Rust community. Regardless of their origin, these brain teasers are fun, and let's face it: who doesn't love a good puzzle, right? What better way to exercise your brain and increase your Rust programming knowledge than with a collection of dynamic brain teasers? As you read through each of these puzzles and try to work out the answers, you'll not only learn about Rust's unique quirks and peculiarities, you'll also have loads of fun along the way. Dive right in and get started with example code and sample problems that cover numbers and text, shadowing and memory, and everything in between. Try to figure out why a particular program won't compile, why it produces unexpected output, or why it panics and terminates with an error message. Once you've run the code and read the answer, it's time to get to the heart of the matter with a detailed explanation. Learn why a program produced the result it did, and discover how similar issues might affect the code you write in your own programs, even in production. Sourced from engaging discussions within the Rust community, real-world problems, and even reader feedback, these challenges will certainly surprise, enlighten, and entertain you. Are you ready to experience Rust like never before? Then sharpen your brain and get ready for a challenge! What You Need: This book assumes you have some knowledge of the Rust programming language. To work through the brain teasers in this book, you'll need a working Rust environment on any platform. You can install Rust by visiting https: //rustup.rs/. You'll also need a text editor or Rust-friendly IDE.

Get hands-on experience with SPARQL, the RDF query language. With this concise book, you will learn how to use the latest version of this W3C standard to retrieve and manipulate the increasing amount of public and private data available via SPARQL endpoints. Several open source and commercial tools already support SPARQL, and this introduction gets you started right away. Learn how to write and run simple SPARQL 1.1 queries, then dive into the language's powerful features and capabilities for manipulating the data you retrieve. Learn what you need to know to add to, update, and delete data in RDF datasets, and give web applications access to this data. Updated to reflect SPARQL 1.1. Recommendation version of specifications Understand SPARQL's connection with RDF, the semantic web, and related specifications Query and combine data from local and remote sources Copy, convert, and create new RDF data Learn how datatype metadata, standardized functions, and extension functions contribute to your queries New chapters cover SPARQL Query Results Formats, Query Efficiency and Debugging, RDF Schema, OWL, and Inferencing.Includes a cookbook of SPARQL queries useful in a variety of situations Expanded Application Development chapter

Introduction to Modeling and Simulation with MATLAB and Python is intended for students and professionals in science, social science, and engineering that wish to learn the principles of computer modeling, as well as basic programming skills. The book content focuses on meeting a set of basic modeling and simulation competencies that were developed as part of several National Science Foundation grants. Even though computer science students are much more expert programmers, they are not often given the opportunity to see how those skills are being applied to solve complex science and engineering problems and may also not be aware of the libraries used by scientists to create those models. The book interleaves chapters on modeling concepts and related exercises with programming concepts and exercises. The authors start with an introduction to modeling and its importance to current practices in the sciences and engineering. They introduce each of the programming environments and the syntax used to represent variables and compute mathematical equations and functions. As students gain more programming expertise, the authors return to modeling concepts, providing starting code for a variety of exercises where students add additional code to solve the problem and provide an analysis of the outcomes. In this way, the book builds both modeling and programming expertise with a "just-in-time" approach so that by the end of the book, students can take on relatively simple modeling example on their own. Each chapter is supplemented with references to additional reading, tutorials, and exercises that guide students to additional help and allows them to practice both their programming and analytical modeling skills. In addition, each of the programming related chapters is divided into two parts - one for MATLAB and one for Python. In these chapters, the authors also refer to additional online tutorials that students can use if they are having difficulty with any of the topics. The book culminates with a set of final project exercise suggestions that incorporate both the modeling and programming skills provided in the rest of the volume. Those projects could be undertaken by individuals or small groups of students. The companion website at http://www.intromodeling.com provides updates to instructions when there are substantial changes in software versions, as well as electronic copies of exercises and the related code. The website also offers a space where people can suggest additional projects they are willing to share as well as comments on the existing projects and exercises throughout the book. Solutions and lecture notes will also be available for qualifying instructors.

XML has become the lingua franca for representing business data, for exchanging information between business partners and applications, and for adding structure
and sometimes meaning to text-based documents. XML offers some special challenges and opportunities in the area of search: querying XML can produce very precise, fine-grained results, if you know how to express and execute those queries.
For software developers and systems architects: this book teaches the most useful approaches to querying XML documents and repositories. This book will also help managers and project leaders grasp how querying XML fits into the larger context of querying and XML. Querying XML provides a comprehensive background from fundamental concepts (What is XML?) to data models (the Infoset, PSVI, XQuery Data Model), to APIs (querying XML from SQL or Java) and more.
* Presents the concepts clearly, and demonstrates them with illustrations and examples; offers a thorough mastery of the subject area in a single book.
* Provides comprehensive coverage of XML query languages, and the concepts needed to understand them completely (such as the XQuery Data Model).
* Shows how to query XML documents and data using: XPath (the XML Path Language); XQuery, soon to be the new W3C Recommendation for querying XML; XQuery's companion XQueryX; and SQL, featuring the SQL/XML
* Includes an extensive set of XQuery, XPath, SQL, Java, and other examples, with links to downloadable code and data samples."

Node.js is the platform of choice for creating modern web services. This fast-paced book gets you up to speed on server-side programming with Node.js 8, as you develop real programs that are small, fast, low-profile, and useful. Take JavaScript beyond the browser, explore dynamic language features, and embrace evented programming.Harness the power of the event loop and non-blocking I/O to create highly parallel microservices and applications. This expanded and updated second edition showcases the latest ECMAScript features, current best practices, and modern development techniques. JavaScript is the backbone of the modern web, powering nearly every web app's user interface. Node.js is JavaScript for the server. This greatly expanded second edition introduces new language features while dramatically increasing coverage of core topics. Each hands-on chapter offers progressively more challenging topics and techniques, broadening your skill set and enabling you to think in Node. Write asynchronous, non-blocking code using Node's style and patterns. Cluster and load balance services with Node core features and third-party tools. Harness the power of databases like Elasticsearch and Redis. Work with many protocols, create RESTful web services, TCP socket clients and servers, and more. Test your code's functionality with Mocha, and manage its life cycle with NPM. Discover how Node pairs a server-side event loop with a JavaScript runtime to produce screaming fast, non-blocking concurrency. Through a series of practical programming domains, use the latest available ECMAScript features and harness key Node classes and popular modules. Create rich command-line tools and a web-based UI using modern web development techniques. Join the smart and diverse community that's rapidly advancing the state of the art in JavaScript development. What You Need: Node.js 8.xOperating system with bash-like shellOMQ (pronounced "Zero-M-Q") library, version 3.2 or higherElasticsearch version 5.0 or higherjq version 1.5 or higherRedis version 3.2 or higher

The complete guide to the productivity and performance enhancements in ASP.NET Beginning ASP.NET for Visual Studio 2015 is your ultimate guide to the latest upgrade of this historically popular framework. Fully updated to align with the vNext release, this new edition walks you through the new tools and features that make your workflow smoother and your applications stronger. You'll get up to speed on the productivity and performance improvements, and learn how Microsoft has committed itself to more continuous innovation by increasing its release cadence for all products and services going forward. Coverage includes Async-aware debugging, ADO.NET idle connection resiliency, managed return value inspection, ASP.NET app suspension, on-demand large object heap compaction, multi-core JIT and more. The news of an off-cycle update to ASP.NET came as a surprise, but its announcement garnered cheers at the 2014 Microsoft BUILD conference. This guide shows you what all the fuss is about, and how Microsoft overhauled the latest ASP.NET release. * Get acquainted with the new developer productivity features * Master the new tools that build better applications * Discover what's new in Windows Store app development * Learn how Microsoft fixed the issues that kept you from v5 Over 38 million websites are currently using ASP.NET, and the new upgrade is already leading to increased adoption. Programmers need to master v6 to remain relevant as web development moves forward. Beginning ASP.NET for Visual Studio 2015 walks you through the details, and shows you what you need to know so you can get up and running quickly.

Transition from a back-end developer to a full-stack developer with knowledge of all the dimensions of web application development, namely, front-end, back-end and server-side software. This book provides a comprehensive overview of Streamlit, allowing developers and programmers of all backgrounds to get up to speed in as little time as possible. Streamlit is a pure Python web framework that will bridge the skills gap and shorten development time from weeks to hours. This book walks you through the complete cycle of web application development, from an introductory to advanced level with accompanying source code and resources. You will be exposed to developing basic, intermediate, and sophisticated user interfaces and subsequently you will be acquainted with data visualization, database systems, application security, and cloud deployment in Streamlit. In a market with a surplus demand for full stack developers, this skill set could not possibly come at a better time. In one sentence, Streamlit is a means for the empowerment of developers everywhere and all stand to gain from it. What You'll Learn Mutate big data in real-time Visualize big data interactively Implement web application security and privacy protocols Deploy Streamlit web applications to the cloud using Streamlit, Linux and Windows servers Who is this Book for? Developers with solid programming experience wanting to learn Streamlit; Back-end developers looking to upskill and transition to become a full-stack developers; Those who wish to learn and become more acquainted with data visualization, database systems, security and cloud deployment with Steamlit

How prepared are you to build fast and efficient web applications? This eloquent book provides what every web developer should know about the network, from fundamental limitations that affect performance to major innovations for building even more powerful browser applications--including HTTP 2.0 and XHR improvements, Server-Sent Events (SSE), WebSocket, and WebRTC.

Author Ilya Grigorik, a web performance engineer at Google, demonstrates performance optimization best practices for TCP, UDP, and TLS protocols, and explains unique wireless and mobile network optimization requirements. You'll then dive into performance characteristics of technologies such as HTTP 2.0, client-side network scripting with XHR, real-time streaming with SSE and WebSocket, and P2P communication with WebRTC.Deliver superlative TCP, UDP, and TLS performanceSpeed up network performance over 3G/4G mobile networksDevelop fast and energy-efficient mobile applicationsAddress bottlenecks in HTTP 1.x and other browser protocolsPlan for and deliver the best HTTP 2.0 performanceEnable efficient real-time streaming in the browserCreate efficient peer-to-peer videoconferencing and low-latency applications with real-time WebRTC transports

Master the foundational HTML5 and CSS3 skills that are needed to create outstanding basic websites using this practical, user-friendly book from the popular Illustrated Series. HTML5 AND CSS3 ILLUSTRATED INTRODUCTORY, 2E covers today's basic concepts and must-know skills for developing web pages and websites using the latest HTML5 and CSS3 standards and best practice. Updates throughout this new edition introduce key principles of website design, while integrating coverage of mobile design and testing. This edition provides beginners with the "nuts-and-bolts" and offers more experienced users the opportunity to brush up on the basics and then move to more advanced topics. Each two-page spread focuses on a single skill, making even complex topics, such as coding with HTML5, easy to follow and absorb.

A great many varied and interesting visual effects can be achieved with computer graphics, for which a fundamental understanding of the underlying mathematical concepts – and a knowledge of how they can be implemented in a particular programming language – is essential.

"Computer Graphics for Java Programmers, 2nd edition" covers elementary concepts in creating and manipulating 2D and 3D graphical objects, covering topics from classic graphics algorithms to perspective drawings and hidden-line elimination. 

Completely revised and updated throughout, the second edition of this highly popular textbook contains a host of ready-to-run-programs and worked examples, illuminating general principles and geometric techniques. Ideal for classroom use or self-study, it provides a perfect foundation for programming computer graphics using Java.

Information architecture (IA) is far more challenging-and necessary-than ever. With the glut of information available today, anything your organization wants to share should be easy to find, navigate, and understand. But the experience you provide has to be familiar and coherent across multiple interaction channels, from the Web to smartphones, smartwatches, and beyond. To guide you through this broad ecosystem, this popular guide-now in its fourth edition-provides essential concepts, methods, and techniques for digital design that have withstood the test of time. UX designers, product managers, developers, and anyone involved in digital design will learn how to create semantic structures that will help people engage with your message. This book includes: An overview of IA and the problems it solves for creating effective digital products and services A deep dive into IA components, including organization, labeling, navigation, search, and metadata Processes and methods that take you from research to strategy, design, and IA implementation

Static websites-sites with fixed content-are the simplest type of web pages. In addition to being easier to create and maintain, they're inherently more secure that dynamic pages. And with the Hugo static site engine, you can render them in milliseconds. Hugo in Action is a step-by-step guide to using Hugo to create static websites that really show off the advantages of simplicity. Working with a complete example website and source code samples, you'll learn how to build and host a low-maintenance, high-performance site that will wow your users and stay stable without relying on a third-party server. Key Features * Installing Hugo and building your first web page * Using the Go Template language * Forking themes * Building your own APIs For web developers with intermediate knowledge of HTML/CSS and basic knowledge of JavaScript. About the technology With the Hugo engine, you can build and render static web pages in milliseconds. Written in Go, the Hugo engine takes your directory of content and templates and renders it as a full HTML and CSS website. It uses Markdown files for its data, making it quick to code, capable of running from any directory, and a great choice when working on a shared system where you don't have full privileges. Perfect for blogs, documentation, and portfolio sites, Hugo makes web development fast and fun again. Atishay Jain is a Senior Computer Scientist at Adobe, who has developed web-based software used by millions of Adobe Creative Cloud customers on a daily basis.

Description Why use several languages for a web application when you only need one? Node.js is a server-side platform and runtime that readers can use to build full stack web applications entirely in JavaScript! Get Programming with Node.js teaches readers to write server-side code in JavaScript using Node.js. In 34 fast-paced, fun, and practical lessons, readers discover how to extend their existing JavaScript skills to write back-end code for their web applications. Key features * Fast-paced * Practical lessons * Hands-on guide Audience Written for developers who know HTML, CSS, and JavaScript. No prior experience with Node.js is required. About the technology Node supports scalable, high-performance applications with easy asynchronous communication, an event-driven mindset, and a vast ecosystem of tools and modules. Node can handle the real-time response rates that games, chat sites, and statistical services need, and you get to program everything in JavaScript. Author biography Jonathan Wexler has an extensive background in computer theory and web development. Having curated a Node.js curriculum as the academic director and lead developer for The New York Code and Design Academy, Jonathan has instructed multiple intensive programs in full stack development and currently works as a senior developer for Bloomberg LP.

Learn the business and technical importance of API design and architecture using the available cloud services from Azure and AWS. This book starts off with an introduction to APIs and the concept of API Economy from a business and organizational perspective. You'll decide on a sustainable API strategy and API architecture based on different case scenarios. You'll then look at actual examples on API development guidelines, providing a practical view and approach towards the API development and aligning teams in API development. This book walks you through the API gateway services available in Azure and AWS and reviews different approaches to API Security. This will prepare you for understanding the trade-off between security and the frictionless API experience. What You'll Learn Implement API Gateways to streamline API Development Examine Security Mapping with API gateways from Azure and AWS Apply API implementation using Serverless architecture Review evolving APIs for monitoring and changing business requirements Use code samples in API security implementations Who This Book Is For Developers and architects with .NET and web development experience who want to learn about API design.

"Beginning Python: Using Python 2.6 and Python 3.1" introduces this open source, portable, interpreted, object-oriented programming language that combines remarkable power with clear syntax. This book enables you to quickly create robust, reliable, and reusable Python applications by teaching the basics so you can quickly develop Web and scientific applications, incorporate databases, and master systems tasks on various operating systems, including Linux, MAC OS, and Windows. You'll get a comprehensive tutorial that guides you from writing simple, basic Python scripts all the way through complex concepts, and also features a reference of the standard modules with examples illustrating how to implement features in the various modules. Plus, the book covers using Python in specific program development domains, such as XML, databases, scientific applications, network programming, and Web development.

Note: CD-ROM/DVD and other supplementary materials are not included as part of eBook file.

Here is your perfect companion for learning about and developing React applications. This book introduces concepts innovatively, using real-world examples based on the most recommended practices to help you establish a firm foundation. This comprehensive approach provides a strong focus on building components by using React hooks. You'll begin by learning web fundamentals, next-generation JavaScript, and how React fits into this. In the chapters that follow, you'll build a React application from scratch and learn about JSX, components, props, state management, prop drilling, context, and lifecycle events. Along the way you'll build a multi-component app and see how the components interact. Debugging and styling React applications are also discussed. You'll then take an in depth look at React hooks and see how to create a custom hook. There is also a penultimate chapter that explores important concepts such as routing and authentication. The book concludes with a review of some exciting features in the upcoming release of React 18. After reading Just React you will be equipped with the skills necessary to build complex web and mobile user interfaces using this flexible JavaScript library. What You'll Learn Examine the details of modern React concepts through example projects Set up your own React project Debug and style React components Take a look at routing, authentication, HTTP requests, Redux, and the new features of React 18 Who This Book Is For Web developers, React developers, and JavaScript developers

Description Aurelia is a web framework that makes it much easier to create single page web applications. Aurelia was written with ES6, so modern JavaScript design principles are baked in from the ground level. Aurelia in Action teaches readers how to build fantastic single page applications with the Aurelia framework. By the end of the book, readers will be able to tune, secure, and deploy their finished SPAs, giving them everything they need to create modern web apps for a modern world. Key features * Step-by-step instructions * Hands-on examples * Clear introduction Audience Written for developers comfortable with JavaScript and MVC-style web development. Some experience with ES6 is helpful, but not required. About the technology Adopting a Rails-like convention-over-configuration mindset, Aurelia makes it a snap to start even complex projects, because the most common design principles and best practices are implemented in new projects by default. Author biography Sean Hunter is a software developer in Melbourne, Australia with 9 years of web development experience.

What would you do if you found your own name on a hit list? Seddon addresses this terrifying question in an explosive novel. One of the most exciting, brave and clever books I have ever read. The Hit List is my book of the year. Gillian McAllister, author of How to Disappear This novel kept me guessing to the end. A twisty, intelligent thrill ride. Excellent! Will Dean, author of Black River This meticulously plotted novel will suck you ever deeper into its dark underbelly. Sinister, clever and utterly compelling. Lesley Kara, author of WHO DID YOU TELL? On the anniversary of her husband's accidental death, Marianne seeks comfort in everything Greg left behind. She wears his shirt and cologne, reads their love letters and emails. Soon she's following his footsteps across the web, but her desperation to cling to any trace of him leads her to the dark web. And a hit list with her name on it. To try to save herself from Sam, the assassin hired to kill her, Marianne must first unpick the wicked web in which Greg became tangled. Was Greg trying to protect her or did he want her dead? A gripping and emotional ebook bestseller about a woman who discovers a shocking secret about her late husband that will hook you from the first page 'Smart, twisty and totally compelling.' Jane Fallon 'Dark, twisty, beautifully written and very clever. Loved it!' Claire Douglas A beautifully written book that tackles complex issues on a very personal level. A dark, fast-paced thriller with a hard-hitting emotional impact. Nikki Smith, author of All In Her Head.

Creating Intelligent Content with Lightweight DITA documents the evolution of the Darwin Information Typing Architecture (DITA) - a widely used open standard for structuring technical content. DITA has grown in popularity and features since its origins as an internal grammar for structuring technical documentation at IBM. This book introduces Lightweight DITA (LwDITA, which should be read as "Lightweight DITA") as a proposed version of the DITA standard that reduces its dependence on complex Extensible Markup Language (XML) structures and simplifies its authoring experience. This volume aims to reconcile discrepancies and similarities in methods for authoring content in industry and academia and does so by reporting on DITA's evolution through the lens of computational thinking, which has been connected in scholarship and media to initiatives for learning to code and programming. Evia's core argument is that if technical communicators are trained with principles of rhetorical problem solving and computational thinking, they can create structured content in lightweight workflows with XML, HTML5, and Markdown designed to reduce the learning curve associated with DITA and similar authoring methodologies. At the same time, this book has the goal of making concepts of structured authoring and intelligent content easier to learn and teach in humanities-based writing and communication programs. This book is intended for practitioners and students interested in structured authoring or the DITA standard.

Creating Intelligent Content with Lightweight DITA documents the evolution of the Darwin Information Typing Architecture (DITA) - a widely used open standard for structuring technical content. DITA has grown in popularity and features since its origins as an internal grammar for structuring technical documentation at IBM. This book introduces Lightweight DITA (LwDITA, which should be read as "Lightweight DITA") as a proposed version of the DITA standard that reduces its dependence on complex Extensible Markup Language (XML) structures and simplifies its authoring experience. This volume aims to reconcile discrepancies and similarities in methods for authoring content in industry and academia and does so by reporting on DITA's evolution through the lens of computational thinking, which has been connected in scholarship and media to initiatives for learning to code and programming. Evia's core argument is that if technical communicators are trained with principles of rhetorical problem solving and computational thinking, they can create structured content in lightweight workflows with XML, HTML5, and Markdown designed to reduce the learning curve associated with DITA and similar authoring methodologies. At the same time, this book has the goal of making concepts of structured authoring and intelligent content easier to learn and teach in humanities-based writing and communication programs. This book is intended for practitioners and students interested in structured authoring or the DITA standard.

Java is a programming language designed for use on networks, in particular the Internet, and can also be used to write full-scale applications. It is based upon C++ and is very similar in its style and structure. Java Made Simple 2nd edition concentrates on getting the reader started and assumes no prior programming knowledge. Once the essentials have been mastered, it provides the confidence to go deeper into the language and broaden and develop invaluable programming skills.

Troubleshoot the most widespread and pernicious Java performance problems using a set of open-source and freely-available tools that will make you dramatically more productive in finding the root causes of slow performance. This is a brief book that focuses on a small number of performance anti-patterns, and you'll find that most problems you encounter fit into one of these anti-patterns. The book provides a specific method in a series of steps referred to as the "P.A.t.h. Checklist" that encompasses persistence, alien systems, threads, and heap management. These steps guide you through a troubleshooting process that is repeatable, that you can apply to any performance problem in a Java application. This technique is especially helpful in 'dark' environments with little monitoring. Performance problems are not always localized to Java, but often fall into the realms of database access and server load. This book gives attention to both of these issues through examples showing how to identify repetitive SQL, and identify architecture-wide performance problems ahead of production rollout. Learn how to apply load like an expert, and determine how much load to apply to determine whether your system scales. Included are walk-throughs of a dozen server-side performance puzzles that are ready to run on your own machine. Following these examples helps you learn to: Assess the performance health of four main problems areas in a Java system: The P.A.t.h. Checklist presents each area with its own set of plug-it-in-now tools Pinpoint the code at fault for CPU and other bottlenecks without a Java profiler Find memory leaks in just minutes using heapSpank, the author's open-source leak detector utility that is freely available from heapSpank.org The repeatable method provided in this book is an antidote to lackluster average response times that are multi-second throughout the industry. This book provides a long absent, easy-to-follow, performance training regimen that will benefit anyone programming in Java. What You'll Learn Avoid the 6 most common ways to mess up a load test Determine the exact number of threads to dial into the load generator to test your system's scalability Detect the three most common SQL performance anti-patterns Measure network response times of calls to back-end systems ('alien systems') Identify whether garbage collection performance is healthy or unhealthy and whether delays are caused by problems in the old or new generation, so you know which generation needs to be adjusted Who This Book Is For Intermediate and expert Java developers and architects. Java experts will be able to update their skill set with the latest and most productive, open-source Java performance tools. Intermediate Java developers are exposed to the most common performance defects that repeatedly show up in Java applications, ones that account for the bulk of slow-performing systems. Experts and intermediates alike will benefit from the chapters on load generation.