Vaccinations, TypeScript, Hebrew Numbers

1. Vaccinations in the UK

It's important for the population for a large percentage (usually somewhere around 90% depending on the disease) to be vaccinated to provide herd immunity (if enough are vaccinated, the disease can't jump from person to person and so is unable to spread much.) Herd immunity helps to protect children too young to have the vaccine, and those who have compromised immune system such as those receiving cancer treatments or with AIDS.

Different countries have different policies to attempt to achieve this. In the article Should childhood vaccination be compulsory in the UK?, I learnt some of the issues determining policies. One of the problems of forcing children to be vaccinated is that it erodes trust between the parents and health provider, and between the parents and government. Parents who do not vaccinate their children tend to do so because of a fear of doing harm, a fear as to the safety of vaccines, or the belief that their child will not catch the infection, or if they do, it will not be severe.

Vaccination in the UK is not compulsory, yet there is a high uptake.

2. TypeScript

TypeScript is a superset of JavaScript which means that any JavaScript file is already a TypeScript file. TypeScript compiles into JavaScript (ES3, ES5 or ES6). It has type annotation, where you declare a type such as in

var x: number = 3;

and type inference, where it knows the type from what you set the variable equal to. In the next example, it infers that x is of type number.

var x = 3;

Since TypeScript is compiled into JavaScript, it has no impact on runtime.

3. Hebrew Numbers

Hebrew numbers are written using the letters in the alphabet, so א is used to represent 1. In order to show that it's the number 1 instead of the letter, it is prepended by ׳ giving ׳א. Numbers not represented by the letters of the alphabet, are formed by summing, so 12 is written using the symbols for 10 (י) and 2 (ב) giving י״ב. The ״ is used to show that it is a number rather than a word. It is placed before the last number (reading right to left) so 780 would be written as תש״פ where פ is 80, ת is 300, and פ is 400. Note that Hebrew is written from right to left, with the usual convention that the smallest number is on the left. There are some exceptions. To avoid writing the names of god, 15 is written as 9+6 ט״ו‎, and 16 as 9+7 ט״ז‎‎. Sometimes the order is rearranged to avoid words with negative connotations.