This article explains Reed-Solomon erasure codes and the problems they solve in gory detail, with the aim of providing enough background to understand how the PAR1 and PAR2 file formats work, the details of which will be covered in future articles.

I’m assuming that the reader is familiar with programming, but has not had much exposure to coding theory or linear algebra. Thus, I’ll review the basics and treat the results we need as a “black box”, stating them and moving on. However, I’ll give self-contained proofs of those results in a companion article.

So let’s start with the problem we’re trying to solve! Let’s say you have n files of roughly the same size, and you want to guard against m of them being lost or corrupted. To do so, you generate m parity files ahead of time, and if in the future you lose up to m of the data files, you can use an equal number of parity files to recover the lost data files.

We need to have a lot of difficult conversations in order to resolve the issues we are facing as a society, and the only way these conversations will be productive and enduring is if we all can agree on the facts. Right now, with Americans believing more than 40 percent of the news they see is fake, we aren’t quite there as a society, but that doesn’t mean we can’t be. The internet is an amazing tool, but to use it most effectively we have to embrace its benefits while also understanding the ways in which it makes us vulnerable. If students are still learning dated practices such as cursive writing in school, shouldn’t they be learning how to navigate and consume the internet responsibly as well?

Much misinformation and many falsehoods related to politics circulate online. This paper investigates how youth judge the accuracy of truth claims tied to controversial public issues. In an experiment embedded within a nationally representative survey of youth ages 15-27 (N=2,101), we examined factors that influenced youth judgements regarding the accuracy of the content. Consistent with research on motivated reasoning, youth assessments depended on a) the alignment of the claim with their prior policy position and, to a lesser extent, on b) whether the post included an inaccurate statement. However, and most importantly, among those participants who reported the most media literacy learning experiences, there was a large, statistically significant difference in ratings of accuracy between those exposed to a post that employed misinformation and those who saw an evidence-based post. Implications for educators and policymakers are discussed.

In this blog post, we’ll demonstrate how the HAProxy load balancer protects you from application-layer DDoS attacks that could, otherwise, render your web application dead in the water, unreachable by ordinary users. In particular, we’ll discuss HTTP floods. An HTTP flood operates at the application layer and entails being immersed with web requests, wherein the attacker hopes to overwhelm your application’s capacity to respond.

The open source community produces a large amount of software for different uses. I have already told you about open source tools for interactive fictions. Here are eleven open source tools to help authors be creative.

In contrast to previous assumptions, the learning process leads to a reorganization that extends to deep brain structures in the thalamus and the brainstem. The relatively young phenomenon of human writing, therefore, changes brain regions that are very old in evolutionary terms and already core parts of mice and other mammalian brains.

Lists should keep the From address, the Subject, and the Message totally unchanged. They should add a Sender header to indicate their relay role, and set at least the List-Id and List-Unsubscribe headers for mailbox rules and subscription management.

This configuration will allow mailing lists to function as proper SMTP citizens in the age of DMARC.

Är du nyfiken på programmering och digitalt skapande? Kodboken är sajten för dig som vill komma igång med kod.

Verkar ha en del övningar bland annat i att skapa musik och spel i Scratch. Värt att kolla på.

"I want to go off grid with solar and batteries!"

I hear this, or some variant, increasingly often. It seems to be a more and more popular concept, especially after some of the recent events in which people were left without power for long periods of time. And, quite often, I assume the people asking are genuinely interested in what they see as the benefits of off grid power. They're just not familiar with enough details to really have an understanding of what they're asking, or what it asks of them.

This post is my humble attempt to put a lot of information in one spot, such that I can link people to it when they ask about off grid power. There are quite valid reasons for off grid power, but it's not as easy or as simple as people tend to think. And it's certainly not as cheap as people assume it will be.

Parking spaces are everywhere, but for some reason the perception persists that there’s “not enough parking.” And so cities require parking in new buildings and lavishly subsidize parking garages, without ever measuring how much parking exists or how much it’s used.