Plurrrr

Aphonopelma seemanni: it's a girl

In the afternoon I carefully removed the exuviae of the Aphonopelma seemanni I keep from its burrow. It had started molting yesterday in the evening.

I carefully moistened the molt with some water and manipulated it to open it up enough to see the spermathecae (female) or not (male). As this is a large molt I was able to see the spermathecae with the naked eye; it's a girl!

As the spermathecae look dark I guess they are weakly sclerotized.

I bought this tarantula 7^th of March 2020 and this was the first time it molted in my care.

• spider

Eight tips to relieve those Postgres headaches

Welcome to this practical, non-exhaustive guide to some of the common issues you’ll encounter while using Postgres. We’ll go beyond the basic advice of adding indices to your queries using sequential scans. There are also a few extra tips for those using the AWS RDS service. Enjoy!

Source: Eight tips to relieve those Postgres headaches, an article by Vojtech Vondra.

• postgres

Correlation VS Causation

The concepts of correlation and causation are sometimes confusing to amateur researchers. In practice, I often saw researchers considering a correlation as causation and making mistakes in conclusions. Mathematically, correlation is the necessary but insufficient condition for causation. In other words, if two things have causation relationship, these two things must have correlation relationship as well. However, if two things have correlation relationship, these two things do not necessarily have causation relationship.

In this blog post, I would use an example to talk about the concepts of correlation and causation, how to verify causation using experiments, and the caveats in using experiments to verify causation.

Source: Correlation VS Causation, an article by Lei Mao.

• math