Kucharski, Adam (Mathematician), author

Mr. Johnson is due to announce the next steps in Britain’s battle to tackle the novel coronavirus following a review by ministers of the current measures

New Delhi [India], May 7 (ANI) As per the modeling data and the way India's COVID-19 cases are increasing, it is likely that peak can come in June and July, said AIIMS-Delhi Director Dr Randeep Guleria on Thursday.

The bacille Calmette-Gurin (BCG) vaccine has a documented protective effect against meningitis and disseminated TB in children, according to the World Health Organisation. It is part of the mandatory childhood immunization programme in many countries including India.

Listen to stories on the first mirror image molecule spotted in outer space, looking at the role of touch in the development of autism, and grafting on lab-built bones, with online news editor David Grimm.   Karen Ersche talks about why cocaine addiction is so hard to treat and what we can learn by bringing addicted subjects into the lab with host Sarah Crespi.   [Image: Science/Music: Jeffrey Cook]

Geneticists and anthropologists studying historical records and modern-day genomes are finding traces of previously unknown migrants to Latin America in the 16th and 17th centuries, when Asians, Africans, and Europeans first met indigenous Latin Americans. Sarah Crespi talks with contributing correspondent Lizzie Wade about what she learned on the topic at the American Association of Physical Anthropologists’s annual meeting in Austin. Sarah also interviews Kang-Keun Ni about her research using optical tweezers to bring two atoms—one cesium and one sodium—together into a single molecule. Such precise control of molecule formation is allowing new observations of these basic processes and is opening the door to creating new molecules for quantum computing. This week’s episode was edited by Podigy. Listen to previous podcasts. [Image: Juan Fernando Ibarra; Music: Jeffrey Cook] 

Pirate’s gold may not be that far off, as there are valuable metals embedded in potato-size nodules thousands of meters down in the depths of the ocean. Host Meagan Cantwell talks with Staff Writer Paul Voosen about the first deep-sea test of a bus-size machine designed to scoop up these nodules, and its potential impact on the surrounding ecosystem. In an expedition well above sea level, the Hayabusa2 spacecraft touched down on the asteroid Ryugu last month. And although the craft won’t return to Earth until 2020, researchers have learned a lot about Ryugu in the meantime. Meagan speaks with Seiji Sugita, a professor at the University of Tokyo and principal investigator of the Optical Navigation Camera of Hayabusa 2, about Ryugu’s parent body, and how this study can better inform future asteroid missions. This week’s episode was edited by Podigy. Download transcript (PDF) Listen to previous podcasts. About the Science Podcast [Image: Japan Aerospace Exploration Agency; Music: Jeffrey Cook]

Though a law requiring clinical trial results reporting has been on the books for decades, many researchers have been slow to comply. Now, 2 years after the law was sharpened with higher penalties for noncompliance, investigative correspondent Charles Piller took a look at the results. He talks with host Sarah Crespi about the investigation and a surprising lack of compliance and enforcement. Also this week, Sarah talks with Brett Finlay, a microbiologist at the University Of British Columbia, Vancouver, about an Insight in this week’s issue that aims to connect the dots between noncommunicable diseases like heart disease, diabetes, and cancer and the microbes that live in our guts. Could these diseases actually spread through our microbiomes? This week’s episode was edited by Podigy. Listen to previous podcasts. About the Science Podcast Download a transcript (PDF). [Image: stu_spivack/Flickr; Music: Jeffrey Cook]

Briggs, Lynelle, author

Online Resource

Dewey Library - RG613.V4713 2019

Consistent death bowling from a Bumrah and spinners picking up wickets in the middle overs is why the average run-rate in the last few years hasn't exploded the way one would have expected, says Dhruv Munjal.

Rajneesh Gupta highlights important numbers for the Bangladesh team from World Cups.

The India captain broke quite a few records during the second ODI match against the West Indies in Port of Spain.Rajneesh Gupta does a quick recount.

Rohit ShelatkarVice-President at Vitabiotics, Meyer Organics1. Being something of an early bird, I enjoy starting my day by 6:30 am. Armed with my eve

Former mayor of Baltimore Catherine Pugh was sentenced to federal prison for her role in a fraudulent scheme to defraud taxpayers, a scheme which involved children’s books. Pugh authored a series of books designed to highlight healthy physical activity. However, the popularity of her books was ...

The defender was forced to issue an apology last month after media reports that he had hosted a party at his home.

The members of the All India Football Federation Technical Committee, chaired by Shyam Thapa, discussed the idea through video-conferencing on Friday.

The organisers said Brazilian Ronaldo Souza, who was to fight Uriah Hall on the undercard, will not take part in the event.

The dog even peeks while counting!

The Union home minister had alleged that the state government was being unjust to migrant workers by not allowing ‘Sharmik’ special trains.

Online Resource

Rotch Library - GF75.O87 2019

Online Resource

Online Resource

Dewey Library - JK2071.R85 2019

Online Resource

Pradhan said interrogations revealed that Imtiaz, along with few others, had gone to Patna on Saturday.

New York : Springer, [2006]

Pretty, Jules N., author

the panelists discuss the ES6 module loader polyfill, SystemJS, and jspm with Guy Bedford.

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John-David Dalton is probably best known for the Lodash library. He's currently working at Microsoft on the Edge team. He makes sure that libraries and frameworks work well in Edge.

The JavaScript Jabber panel discusses the ECMAScript module system port to Node.js. John wanted to ship the ES module system to Node.js for Lodash to increase speed and decrease the disk space that it takes up. This approach allows you to gzip the library and get it down to 90 kb.

This episode dives in detail into:

• ES Modules, what they are and how they work
• The Node.js and NPM package delivery ecosystem
• Module loaders in Node.js
• Babel (and other compilers) versus ES Module Loader
• and much, much more...

Links:

• Lodash
• ES Module Loader for Node
• Node
• CommonJS
• Babel
• TypeScript
• FlowType
• Microsoft
• ESM Blog Post
• Meteor
• Reify
• ESM Spec
• PhantomJS
• zlib module in Node
• AWS Lambda
• NPM
• Webpack
• Rollup
• John-David Dalton on Twitter

Picks:

Cory:

• Trending Developer Skills
• The Devops Handbook

Aimee:

• Nodevember
• ES Modules in Node Today (blog post)
• Dating is Dead

Aaron:

• Ready Player One trailer breakdown
• Jim Jefferies  Show
• I Can't Make This Up by Kevin Hart
• Work with Aaron at SaltStack

Chuck:

• Angular Dev Summit
• ZohoCRM
• Working on Cars - Therapeutic working with your hands doing physical work

John:

• TC39 Proposal for Optional Chaining
• ToyBox 3D Printer

Twitter Lite uses Redux for state management and relies on code-splitting. However, Redux’s default API is not designed for applications that are incrementally-loaded during a user session.

This post describes how I added support for incrementally loading the Redux modules in Twitter Lite. It’s relatively straight-forward and proven in production over several years.

Redux modules

Redux modules comprise of a reducer, actions, action creators, and selectors. Organizing redux code into self-contained modules makes it possible to create APIs that don’t involve directly referencing the internal state of a reducer – this makes refactoring and testing a lot easier. (More about the concept of redux modules.)

Here’s an example of a small “redux module”.

// data/notifications/index.js

const initialState = [];
let notificationId = 0;

const createActionName = name => `app/notifications/${name}`;

// reducer
export default function reducer(state = initialState, action = {}) {
  switch (action.type) {
    case ADD_NOTIFICATION:
      return [...state, { ...action.payload, id: notificationId += 1 }];
    case REMOVE_NOTIFICATION:
      return state.slice(1);
    default:
      return state;
  }
}

// selectors
export const selectAllNotifications = state => state.notifications;
export const selectNextNotification = state => state.notifications[0];

// actions
export const ADD_NOTIFICATION = createActionName(ADD_NOTIFICATION);
export const REMOVE_NOTIFICATION = createActionName(REMOVE_NOTIFICATION);

// action creators
export const addNotification = payload => ({ payload, type: ADD_NOTIFICATION });
export const removeNotification = () => ({ type: REMOVE_NOTIFICATION });

This module can be used to add and select notifications. Here’s an example of how it can be used to provide props to a React component.

// components/NotificationView/connect.js

import { connect } from 'react-redux';
import { createStructuredSelector } from 'reselect';
import { removeNotification, selectNextNotification } from '../../data/notifications';

const mapStateToProps = createStructuredSelector({
  nextNotification: selectNextNotification
});
const mapDispatchToProps = { removeNotification };

export default connect(mapStateToProps, mapDispatchToProps);

// components/NotificationView/index.js

import connect from './connect';
export class NotificationView extends React.Component { /*...*/ }
export default connect(NotificationView);

This allows you to import specific modules that are responsible for modifying and querying specific parts of the overall state. This can be very useful when relying on code-splitting.

However, problems with this approach are evident once it comes to adding the reducer to a Redux store.

// data/createStore.js

import { combineReducers, createStore } from 'redux';
Import notifications from './notifications';

const initialState = /* from local storage or server */

const reducer = combineReducers({ notifications });
const store = createStore(reducer, initialState);

export default store;

You’ll notice that the notifications namespace is defined at the time the store is created, and not by the Redux module that defines the reducer. If the “notifications” reducer name is changed in createStore, all the selectors in the “notifications” Redux module no longer work. Worse, every Redux module needs to be imported in the createStore file before it can be added to the store’s reducer. This doesn’t scale and isn’t good for large apps that rely on code-splitting to incrementally load modules. A large app could have dozens of Redux modules, many of which are only used by a few components and unnecessary for initial render.

Both of these issues can be avoided by introducing a Redux reducer registry.

Redux reducer registry

The reducer registry enables Redux reducers to be added to the store’s reducer after the store has been created. This allows Redux modules to be loaded on-demand, without requiring all Redux modules to be bundled in the main chunk for the store to correctly initialize.

// data/reducerRegistry.js

export class ReducerRegistry {
  constructor() {
    this._emitChange = null;
    this._reducers = {};
  }

  getReducers() {
    return { ...this._reducers };
  }

  register(name, reducer) {
    this._reducers = { ...this._reducers, [name]: reducer };
    if (this._emitChange) {
      this._emitChange(this.getReducers());
    }
  }

  setChangeListener(listener) {
    this._emitChange = listener;
  }
}

const reducerRegistry = new ReducerRegistry();
export default reducerRegistry;

Each Redux module can now register itself and define its own reducer name.

// data/notifications/index.js

import reducerRegistry from '../reducerRegistry';

const initialState = [];
let notificationId = 0;

const reducerName = 'notifications';

const createActionName = name => `app/${reducerName}/${name}`;

// reducer
export default function reducer(state = initialState, action = {}) {
  switch (action.type) {
    case ADD_NOTIFICATION:
      return [...state, { ...action.payload, id: notificationId += 1 }];
    case REMOVE_NOTIFICATION:
      return state.slice(1);
    default:
      return state;
  }
}

reducerRegistry.register(reducerName, reducer);

// selectors
export const selectAllNotifications = state => state[reducerName];
export const selectNextNotification = state => state[reducerName][0];

// actions
export const ADD_NOTIFICATION = createActionName(ADD_NOTIFICATION);
export const REMOVE_NOTIFICATION = createActionName(REMOVE_NOTIFICATION);

// action creators
export const addNotification = payload => ({ payload, type: ADD_NOTIFICATION });
export const removeNotification = () => ({ type: REMOVE_NOTIFICATION });

Next, we need to replace the store’s combined reducer whenever a new reducer is registered (e.g., after loading an on-demand chunk). This is complicated slightly by the need to preserve initial state that may have been created by reducers that aren’t yet loaded on the client. By default, once an action is dispatched, Redux will throw away state that is not tied to a known reducer. To avoid that, reducer stubs are created to preserve the state.

// data/createStore.js

import { combineReducers, createStore } from 'redux';
import reducerRegistry from './reducerRegistry';

const initialState = /* from local storage or server */

// Preserve initial state for not-yet-loaded reducers
const combine = (reducers) => {
  const reducerNames = Object.keys(reducers);
  Object.keys(initialState).forEach(item => {
    if (reducerNames.indexOf(item) === -1) {
      reducers[item] = (state = null) => state;
    }
  });
  return combineReducers(reducers);
};

const reducer = combine(reducerRegistry.getReducers());
const store = createStore(reducer, initialState);

// Replace the store's reducer whenever a new reducer is registered.
reducerRegistry.setChangeListener(reducers => {
  store.replaceReducer(combine(reducers));
});

export default store;

Managing the Redux store’s reducer with a registry should help you better code-split your application and modularize your state management.