Become an iOS Developer

Dev colleagues, in the  Become an iOS Developer program you will master the Swift programming language, and create a portfolio of iOS apps for iPhone and iPad to showcase your skills. Start by learning the basics of iOS app development using the Swift programming language and Xcode, Apple's development environment. Then, you’ll progress to build more complex and advanced applications, using networking, and Apple’s Grand Central Dispatch and Core Data, and will be ready to publish your capstone project to the App Store.  Training modules - each with hands-on projects - include: 1) Intro to iOS App Development with Swift - build your first app with Swift and Xcode, Apple’s programming environment for app development. You’ll learn how to use AutoLayout, UIButtons, and UILabels to create an interface, and how to react to touch events in an app using ViewController and multiple views. You’ll also learn how to set up audio recording and playback in a voice recording app (Project: Pitch Perfect); 2) UIKit Fundamentals - develop an app with UIKit, Apple’s front-end framework for developing fast and powerful web interfaces. Learn about the delegate pattern to make connections between the app’s model, view, and controller, and add table views and navigation to your app (Project: Meme - Parts 1 & 2); 3) Network Requests and GCD - incorporate networking into your apps, and harness the power of APIs to display images and retrieve data. Use Apple’s Grand Central Dispatch, or GCD, framework to create asynchronous apps, ensuring a smooth user experience, even while your apps run lengthy operations in the background (Project: On the Map); 4) Data Persistence- learn about simple persistence, the iOS File System, and the “sandbox.” Set up the classes we need to get Core Data up and running so that we can create, save, and delete model objects. Enable user interfaces to reactively update whenever the model changes, and safely migrate user data between versions (Project: Virtual Tourist). This is your chance to let your iOS Developer skills shine - design and build your own iOS app, taking the design from the drawing board to the App Store.

Sign-up today (teams & execs welcome):  https://tinyurl.com/2p8bsk3r 

Much career success, Lawrence E. Wilson - Online Learning Central

Introduction to Linux, Open Source Development, and GIT (LFD301) - Linux Foundation

OSS colleagues, the Introduction to Linux, Open Source Development, and GIT (LFD301)  program from the Linux Foundation introduces you to the world of Linux development and gives you the background and training you need to start working with Linux. Linux is exploding, and the demand for Linux developers has never been stronger. If you’ve been thinking about getting into Linux development, this is the best place to start. Learn about the history of Linux and what differentiates it from other UNIX-like operating systems, what the main ingredients of a Linux system are and how to use them, the essentials of system administration, such as user accounts and groups, essential commands, filesystems, security, and more, networking and threading models, aspects of compiling and using libraries, working with Java under Linux. Acquire high-demand skills in Open Source Software, Why Use Open Source Software?, Examples of Successful OSS Projects, How to Work in OSS Projects, Continuous Integration, OSS Licensing and Legal Issues, Leadership vs Control and Why Projects Fail, Respecting and Encouraging Diversity in OSS, GitHub and Other Hosting Providers, Linux and the Operating System, Graphical Environments and Interfaces, System Administration, Text Editors, Shells, bash, and the Command Line, Filesystem Layout, Partitions, Paths and Links, System Initialization, Memory, Networking, Command Details, Users and Groups, Linux Filesystems, Essential Command Line Tools, Bash Scripting, Files and Filesystems, Compiling, Linking and Libraries, Java Installation and Environment, Building RPM and Debian Packages, Introduction to GIT, Git Installation, Git and Revision Control Systems, Using Git: - an Example, Git Concepts and Architecture, Managing Files and the Index, Commits, Branches, Diffs, Merges, Managing Local and Remote Repositories, Using Patches, and Advanced Git Interfaces: Gerrit.

Register today (teams & execs welcome): https://tinyurl.com/4xepvmcp 

Much career success, Lawrence E. Wilson -  Online Learning Central

Python Desktop Application Development

Dev colleagues, the Python Desktop Application Development program enables you to easily create desktop applications using the simplicity of Python and the power of Qt. Learn how easy it is to write desktop applications using Python and its amazing friend, Qt. Python is famous for being simple yet powerful, and the same is true for Qt; in as little as 50 lines of code, you'll be able to write a fully functioning application. Not only that, but your application will also run on all major operating systems, and it will look like it's written for that operating system! Is Python good for desktop applications? Yes! Python is frequently used for creating desktop applications and GUI (graphical user interface) apps. Python is great for backend web development, and is famous for being simple yet powerful. And what is Qt? Qt is a free tool for creating GUI (graphical user interfaces). Qt makes it easier to incorporate buttons, windows, and several other widgets for users to interact with in your application. This Python Desktop Application Development course will teach you how to create desktop apps with Python and Qt, including: Why use Python for desktop application development?, Helpful tools, Basic code structure, QWidgets and how to use them, Events and layouts, Basic UI design and Functionality.

Sign-up today (teams & execs welcome):  https://tinyurl.com/2p9xs96c 

Much career success, Lawrence E. Wilson - Online Learning Central

Open Source Virtualization - Linux Foundation (LFS462)

Colleagues, the Open Source Virtualization (LFS462) from the  Linux Foundation takes a deep dive into KVM (Kernel-based Virtual Machine) and Xen, the most popular hypervisor virtualization technologies in the open source ecosystem, along with deployment and use of containers. This program provides KVM training from the ground up with a focus on QEMU and libvirt, as well as Xen. You will learn how these and other related open source components can be assembled to create a virtual IT infrastructure. There is a focus on practical deployment skills, securing the virtual infrastructure, and administering solutions, as well as detailed material about using containers. Lab exercises focus on virtual images and snapshots, deployment, VM creation and maintenance, integration with networking infrastructure, device pass-through and more. Skill-based training modules address: 1) Virtualization Overview, 2) KVM Quick-Start, 3) KVM Architecture and Relationship with Linux, 4) Running KVM Using QEMU, 5) libvirt, 6) Hardware Support, 7) Tuning for Performance, 8) KVM Security, 9) Xen Hypervisor Architecture, 10) Installing and Configuring Xen, 11) Administration of Xen domains, 12) Xen Performance and Tuning, 13) Xen Security, and 14) Working with Linux Containers.

Enroll today (individuals & teams welcome): https://tinyurl.com/2zs8cewy 

Much career success, Lawrence E. Wilson -  Online Learning Centra

AWS Machine Learning Engineer

Colleagues, the AWS Machine Learning Engineer program enables you to meet the growing demand for machine learning engineers and master the job-ready skills that will take your career to new heights. master the skills necessary to become a successful ML engineer. Learn the data science and machine learning skills required to build and deploy machine learning models in production using Amazon SageMaker. Training modules with hands-on projects cover: 1) Introduction to Machine Learning In this course, you'll start learning about machine learning through high level concepts through AWS SageMaker. Create machine learning workflows, starting with data cleaning and feature engineering, to evaluation and hyperparameter tuning. Finally, you'll build new ML workflows with highly sophisticated models such as XGBoost and AutoGluon (Project: Bike Sharing Demand with AutoGluon), 2) Developing Your First ML Workflow - machine learning workflows on AWS. Learn how to monitor machine learning workflows with services like Model Monitor and Feature Store. With all this, you’ll have all the information you need to create an end-to-end machine learning pipeline (Project: Build and ML Workflow on SageMaker), 3) Deep Learning Topics within Computer Vision and NLP - train, finetune, and deploy deep learning models using Amazon SageMaker. Learn about advanced neural network architectures like Convolutional Neural Networks and BERT, as well as how to finetune them for specific tasks. Finally, you will learn about Amazon SageMaker and you will take everything you learned and do them in SageMaker Studio (Project: Image Classification using AWS SageMaker), 4) .Operationalizing Machine Learning Projects on SageMaker - deploy professional machine learning projects on SageMaker. It also covers security applications. Learn how to deploy projects that can handle high traffic and how to work with especially large datasets (Project: Operationalizing an AWS ML Project), and 5) Capstone Project - .Inventory Monitoring at Distribution Centers. To build this project, students will have to use AWS Sagemaker and good machine learning engineering practices to fetch data from a database, preprocess it and then train a machine learning model. This project will serve as a demonstration of end-to-end machine learning engineering skills that will be an important piece of their job-ready portfolio.

Enroll today (eams & execs welcome): https://tinyurl.com/yckjbdnb 

Much career success, Lawrence E. Wilson - Artificial Intelligence Academy (https://tinyurl.com/2p9aj9n5) 

Become a Java Web Developer

Developers, in the Become a Java Web Developer program you will learn enterprise scale back-end development with Java, and be prepared for the software engineering jobs that are in demand at a majority of Fortune 500 companies like Google, Amazon, Netflix, and more. To optimize your chances of success in the Java Web Developer Nanodegree program, we recommend intermediate knowledge of Java. See detailed requirements.Training modules - each with a hands-on project include: 1) Spring Boot Basics - learn the fundamentals of Java while being introduced to a Spring Boot framework and associated integrations and plugins (Project: Build a Web-Based Personal Storage Application); 2) Web Services and APIs - explore the differences between web services, APIs, and microservices. Develop REST and GraphQL APIs, and learn how to secure, consume, document, and test those APIs and web service (Project: Build the Back-End System for  a Car Website), 3) Data Stores & Persistence - build applications that read and write to relational databases using both the Java Persistence API (JPA) and SQL. Use standard design patterns to make your persistence layer easy to test and integrate with a Spring Boot application (Project: Design the Data Model for a SAAS Application), and 4) Security and DevOps - learn about Git, version control, and best practices for authorization and authentication. Use Jenkins to build a CI/CD pipeline to deploy code to production 

Sign-up today (teams & execs welcome): https://tinyurl.com/yrv8rcwz 

Much career success, Lawrence E. Wilson - Online Learning Central

SAS Advanced Programmer Professional Certificate

Dev colleagues, earn the SAS Advanced Programmer Professional Certificate and grow your career with a SAS® Credential. Learn to process data using Structured Query Language in the SAS environment   , use the SAS macro facility to design, write, and debug dynamic macro programs along with the advanced DATA step techniques and procedures to manipulate data. The three courses in this Professional Certificate include: 1) Structured Query Language (SQL) using SAS - learn how SQL can be used in SAS programs to create reports and query your data, Query and subset data, Summarize and present data, Combine tables using joins and set operators., Create and modify tables and views, Create data-driven macro variables using a query and Access DBMS data with SAS/ACCESS technology ; 2) technology. SAS Macro Language - learn advanced techniques within the DATA step and procedures to manipulate data, Perform text substitution in SAS code, Use macro variables and macro functions, Automate and customize the production of SAS code, Conditionally or iteratively construct SAS code, Write self-modifying, data-driven program; and 3) Advanced SAS Programming Technique - learn advanced techniques within the DATA step and procedures to manipulate data - Use additional functions (LAG, FIND/FINDER, and COUNT/COUNTC/COUNTW), Perform pattern matching using PRX functions, Process repetitive code, rotate data, and perform table lookups using arrays, Perform table lookups and sort data using hash and hash iterator objects, Create numeric templates using the FORMAT procedure, and Create custom functions using the FCMP procedure.

Sign-up today (teams & execs welcome): https://tinyurl.com/2h26z596 

Much career success, Lawrence E. Wilson - Online Learning Central

Self-Driving Car Engineer (Training)

Colleagues, become a Self-Driving Car Engineer and accelerate your career growth. Self-driving cars are transformational technology, on the cutting-edge of robotics, machine learning and engineering. Learn the skills and techniques used by self-driving car teams at the most advanced technology companies in the world. Learn the techniques that power self-driving cars across the full stack of a vehicle’s autonomous capabilities. Using Deep Learning with radar and lidar sensor fusion, you will train the vehicle to detect and identify its surroundings to inform navigation.. Prerequisite knowledge of  Python, C++, Linear Algebra and Calculus is desired.  Training modules with a hands-on project include: 1) Computer Vision - develop critical Machine Learning skills that are commonly leveraged in autonomous vehicle engineering. You will learn about the life cycle of a Machine Learning project, from framing the problem and choosing metrics to training and improving models.You will build convolutional neural networks using TensorFlow and learn how to classify and detect objects in images. (Project: Object Detection in an Urban Environment); 2) Sensor Fusion - besides cameras, self-driving cars rely on other sensors with complementary measurement principles to improve robustness and reliability. Also learn how to fuse camera and lidar detections and track objects over time with an Extended Kalman Filter. Gain a solid foundation to work as a sensor fusion engineer on self-driving cars (Project: 3D Object Detection); 3) Sensor Fusion-Localization - learn all about robotic localization, from one-dimensional motion models up to using three-dimensional point cloud maps obtained from lidar sensors. Iterative Closest Point (ICP) and Normal Distributions Transform (NDP), which work with 2D and 3D data - utilize these scan matching algorithms in the Point Cloud Library (PCL) to localize a simulated car with lidar sensing, using a 3D point cloud map obtained from the CARLA simulator (Project: Scan Matching Localization); 4) Planning - route vehicles from one point to another, and it handles how to react when emergencies arise. The Mercedes-Benz Vehicle Intelligence team will take you through the three stages of path planning. Generate a safe and comfortable trajectory to execute that maneuver (Project: Motion Planning and Decision Making for Autonomous Vehicle); and 5) Control - control a car once you have a desired trajectory. In other words, how to activate the throttle and the steering wheel of the car to move it following a trajectory described by coordinates -  most common controller: the Proportional Integral Derivative or PID controller. You will understand the basic principle of feedback control and how they are used in autonomous driving techniques.(Project: Control and Trajectory Tracking for Autonomous Vehicles)

Sign-up today (teams & execs welcome): https://tinyurl.com/pabx6dkw 

Much career success, Lawrence E. Wilson - Online Learning Central

Become a C++ Developer

Dev colleagues, Become a C++ Developer and expand your career-income potential. Learn C++, a high-performance programming language used in the world's most exciting engineering jobs -- from self-driving cars and robotics, to web browsers, media platforms, servers, and even video games. Learn C++ by Coding Five Project Get hands-on experience by coding five real-world projects. Learn to build a route planner using OpenStreetMap data, write a process monitor for your computer, and implement your own smart pointers. Finally, showcase all your newfound skills by building a multithreaded traffic simulator and coding your own C++ application. To optimize your chances of success in the C++ Nanodegree program, we recommend intermediate knowledge of any programming language. Training modules: 1)  C++ Foundations - develop, compile, and execute C++ programs as well as syntax, functions, containers, and how to link together multiple files (Project: Route Planner); 2) Object-Oriented Programming (OOP) - build classes, interfaces, and generic templates to create an object-oriented C++ program. Learn how modern C++ includes many tools for writing clean, reusable code (Project: Process Monitor); 3) Memory Management - control static and dynamic memory in C++ using the Resource Acquisition Is Initialization pattern, pointers, references, and move semantics (Project: Memory Management Chatbot); 4) Concurrency - launch process and threads in order to execute logic in parallel. Then advance to thread synchronization and communication, to experience the full power of concurrent programming (Project: Concurrent Traffic Simulation); and 5) Capstone Project - put all of your new C++ skills to use! Utilize the core concepts from this Nanodegree program - object-oriented programming, memory management, and concurrency - to build your own application using C++  (Project: Build your own C++ Application).

Sign-up today (teams & execs welcome): https://tinyurl.com/upkbb42s 

Much career success, Lawrence E. Wilson - Online Learning Central

Linux Certification Bundle (10-Pack)

OSS colleagues, this Linux Certification Bundle enables you to earn certifications in ten (10) Linux disciplines. They include: 1 - Advance Linux System Administration, 2 - Start Learning Unix And LinuxRedHat Linux Essentials, 3 - RedHat Linux Essentials, 4 - Learn Linux In 5 Days And Level Up Your Career, 5 - Linux Administration Bootcamp: Go From Beginner To Advanced, 6 - Learn  Linux The Easy Way, 7 - Learn Linux - Beginners Level, 8 - Linux, Unix OS Command Line And Introduction To Shell Scripting, 9 - Linux Shell Scripting: A Project-Based Approach To Learning, and 10 - Linux Tutorial For Beginners And Level Up Your Career. This bundle features Multiple courses, Lifetime access to each course, Certificate on completion of each course, discounts on individual courses as a bundle, and high priority after sales support. Take your open source career and income to the next level.

Register today (teams & execs welcome): https://tinyurl.com/d2jhjvvb 

Much career success, Lawrence E. Wilson -  Online Learning Central

How to Debug JavaScript Errors

Dev & QA colleagues, the How to Debug JavaScript Errors program guides you through the basics of debugging and handling JavaScript errors to build a growth mindset approach to programming and prevent a crash in your applications. Learn how to debug your code and learn to predict and handle errors in your web applications. Intermediate JavaScript is a prerequisite, and you should be comfortable with arrays, objects, and looping through arrays.  Skill-based training modules address: 1) Debugging JavaScript Code - Error Stack Traces, Read Error Stack Traces, Error Types, Debugging Errors, Locating Silent Bugs, Debugging with Console Log, Finding Documentation, Stack Overflow, and 2) Introduction to Seaborn -  Use Seaborn, a Python data visualization library, to creabar charts for statistical analysis.te bar charts for statistical analysis

Sign-up today (teams & execs welcome): https://fxo.co/Ccqu 

Much career success, Lawrence E. Wilson - Online Learning Central

Data Visualization (Training)

Colleagues, in the Data Visualization training program you will build data visualizations and dashboards, considering your audiences to be as effective as possible. Then, youÕll move into drafting presentations using storytelling techniques, visualizations, and animations to provide data-driven recommendations.Combine data, visuals, and narrative to tell impactful stories and make data-driven decisions. Communicating effectively is one of the most important skills needed today, and every business is collecting data to make informed decisions. To be successful in this program, you should have basic statistics and data analysis skills. See detailed requirements. Learn how to select the most appropriate data visualization for an analysis, evaluate the effectiveness of a data visualization, and build interactive and engaging Tableau dashboards The three skill-based training modules - each with a hands-on project include: 1) Dashboard Designs - Design and create a dashboard in an enterprise environment. Discover user needs, identify key metrics, and tailor your dashboard to a particular audience (Project: Design a Data Dashboard); 2) Data Storytelling - Learn the end to end process for telling a story and providing a recommendation based on data. You'll define an effective problem statement, structure a data presentation, scope analyses, identify biases and limitations within your dataset, and pull together an end-to-end analysis (Project: Build a Data Story); and 3) Advanced Data Storytelling - Learn advanced data visualization and storytelling techniques. Learn to use Tableau Storypoint to add interactivity and other visual elements to a story, and add animation and narration with Tableau Pages and Flourish (Project: Animate a Data Story).

Sign-up today (teams & execs welcome): https://tinyurl.com/4jmzwt8a 

Much career success, Lawrence E. Wilson - Online Learning Central

Deploying Apps with Netlify and Heroku

Colleagues, the Deploying Apps with Netlify and Heroku training equips you to create a site or an app on your local computer, and now you want to share it with the world. What do you do? You could spend days on the deployment process—finding a hosting service, server space, a domain, and more—or you could use Heroku or Netlify! Heroku and Netlify are cloud platforms designed to make it easy for you to deploy your creations on the web. Netlify is specialized for static sites, while Heroku lets you create your own backend and deploy that way. Whether you want a step-by-step guide to Heroku, Netlify, or both, Codecademy has you covered. Learn the unique features of Netlify and Heroku and determine when to use each. Come away knowing how to deploy a range of static or dynamic apps and sites quickly, simply, and securely. If you need to get a static site up and running to share with people, Netlify got you covered. Gain knowledge and skills in Review core concepts you need to learn to master this subject, Deploying, Linking a Repo, Continuous Deployment, Site Logs, and Services. Quickly deploy applications using Heroku to get your Minimal Viable Product or Proof of Concept up and running.

Sign-up today (teams & execs welcome): https://fxo.co/Ccqm 

Much career success, Lawrence E. Wilson - Online Learning Central

Full Stack JavaScript Developer (Training)

Dev colleagues, the Full Stack JavaScript Developer program equips you to master the skills necessary to become a successful full stack developer. Learn how to build UI and UX, create APIs and server side business logic and develop the persistence layer to store, process and retrieve data. Training modules with hands-on projects include: 1) Backend Development with Node.js. There are quite a few technologies involved to build the backend of an application that’s enterprise ready - go through working with Node.js and the core modules available, writing TypeScript for developer error reduction, testing with Jasmine to introduce unit testing in a Test Driven Development environment, and working with Express as a framework for building APIs (Project: Image Processing API); 2) Creating an API with PostgreSQL and Express This course covers the primary skills required for API development. Students will build a RESTful JSON API with Node and Postgres. Along the way, you will cover essential topics like databases and querying, API architecture, database migrations, REST, CRUD (Project: Build a Storefront Backend); 3) Angular Fundamentals - In Angular Fundamentals, students will learn the most important and foundational skills for building Single Page Applications (SPAs). You will discover the architecture of an application, explore how to retrieve and flow data throughout an application, and see how applications scale in a maintainable and performant way. Upon completion of the course, you will be able to build new and expand existing Angular applications (Project: My Store); and 4) Deployment Process - Being able to deploy your own application is a skill that is often overlooked by developers, thus making it a rare and valuable skill to have! By building an automated pipeline and scripts students will gain insights into the world of automated deployments that has been revolutionizing how fast companies are able to deliver features to their customers.

Sign-up today (teams & execs welcome):  https://tinyurl.com/2f6fkf6v 

Much career success, Lawrence E. Wilson - Online Learning Central

Developing Applications For Linux - Linux Foundation (LFD401 Training)

OSS Colleagues, the Developing Applications For Linux - Linux Foundation (LFD401 Training) will equip you  to develop applications for Linux. This comprehensive program is for experienced developers. Students should be proficient in C programming and be familiar with basic Linux utilities and text editors. Skill-based training modules cover: 1) OSS Projects, 2) Compilers, 3) Libraries, 4) Source Control, 5) Debugging Tools and Core Dumps, 6) System Calls, 7) Memory Management and Allocation, 8) Filesystems in Linux, 9) File I/O, 10) Advanced File Operations, 11) Processes, 12) Pipes and Fifos,13) Asynchronous I/O, 14) Signals, 15) POSIX Threads, 16) Networking and Sockets (Addresses and Hosts, Ports and Protocols, Clients, Servers, Input/Output Operations, Options, Multiplexing and Concurrent Servers, Netlink Sockets), 17) Inter Process Communication, 18) Shared Memory, and 18) Semaphores and Message Queues.

Register today. Two live virtual instructor-led classes: https://tinyurl.com/2x3fwua9  (December 13-16, 2021 & January 10-13, 2022)

Contact OLC for Group Registration rates (internetdigitalentrepreneur@gmail.com) 

Much career success, Lawrence E. Wilson -  Online Learning Central

Full Stack Web Development with Angular Specialization

Dev colleagues, the Full Stack Web Development with Angular Specialization equips you to build complete web and hybrid mobile solutions. Master front-end web, hybrid mobile app and server-side development in five comprehensive courses. The Applied Learning Project provides you with hands-on exercises, culminating in development of a full-fledged application at the end of each course. Each course also includes a mini-Capstone Project as part of the Honors Learn to  implement client-side web UI frameworks, use of Angular Material and Angular Flex-Layout for UI design, utilize the Ionic mobile application framework, and build mobile apps for multiple platforms with a single codebase. Gain highly marketable skills including Bootstrap (Front-End Framework), Node.Js, Jquery, SASS (Stylesheet Language), Angularjs, Reactive Programming, Typescript, Authentication, Mongodb and. Express.Js. Training modules address: 1) Front-End Web UI Frameworks and Tools: Bootstrap - client-side web UI frameworks, in particular Bootstrap 4. You will learn about grids and responsive design, Bootstrap CSS and JavaScript components. You will learn about CSS preprocessors, Less and Sass. You will also learn the basics of Node.js and NPM and task runners like Grunt and Gulp, b) Create a responsive web page design, and c) Make use of web tools to setup and manage websites, 2) Front-End JavaScript Frameworks: Angular - learn Javascript based front-end frameworks, and in particular the Angular framework (Currently Ver. 6.x). This course will use Typescript for developing Angularjs applications. Typescript features will be introduced in the context of Angular as part of the exercises. You will also get an introduction to the use of Angular Material and Angular Flex-Layout for responsive UI design. You will be introduced to various aspects of Angular including components, directives and services. You will learn about data binding, Angular router and its use for developing single-page applications. You will also learn about designing both template-driven forms and reactive forms, and 3) Server-side Development with NodeJS, Express and MongoDB - Web protocols: HTTP and HTTPS. We examine NodeJS and NodeJS modules: Express for building web servers. On the database side, we review basic CRUD operations, NoSQL databases, in particular MongoDB and Mongoose for accessing MongoDB from NodeJS. We examine the REST concepts and build a RESTful API and review backend as a service (BaaS) approaches, including mobile BaaS, both open-source and commercial BaaS services.

Sign-up today (teams & execs welcome): https://tinyurl.com/47cdhbbc  

Much career success, Lawrence E. Wilson - Online Learning Central