When I was a wee hacker I wrote a manual for using the Internet, which had recently become available to researchers at the University of Puerto Rico. The Office of Information Systems later updated and republished the manual, and there are several copies in the UPR library system. Yesterday I …

I got eclipse glasses from the EcoExploratorio and we saw part of the eclipse on Saturday, October 14, 2023.

Around 2:00 PM AST (18:00 UTC) it got cloudy, and we lost our chance to see the maximum extent, which happened around 2:24 PM. Fortunately, we have access …

Oscar Moreno de Ayala, PhD was my thesis advisor and mentor. He passed away in 2015, and his colleagues described him as "the spirit of mathematics in Puerto Rico". And while that is true, I think it misses out on the impact Oscar had on computer science in Puerto Rico …

Hace unos meses compartí acerca de las mujeres en la ciencia (de cómputos). Cuando escribí eso, sentí que se quedaron fuera varias mujeres que han sido importantes en mi carrera. Pero no en el aspecto de la ciencia de computos, sino por otras razones.

Y aqui hay un efecto curioso …

Introduccion

La Dra. Liz Diaz me invitó a participar del Segundo Simposio El Poder de la Mujer en las Ciencias, el 15 y 16 de abril de 2021. Se supone que para presentar los programas de ciencia de computos. Pero su invitación y el tema de la conferencia me hicieron …

While learning about Mastodon and the fediverse (more on that later, in a separate post), I ran across a group of people learning and working with Plan 9. Plan 9 is an operating system developed at Bell Labs in the 1990's, a sort of successor to some of the ideas …

Introduction

I sometimes direct the UPR High Performance Computing facility, or as my colleagues like to call it, the medium performance computing facility. We've run largish linux clusters and big sgi machines since the early naughts.

So it's a little surprising I'm also interested in low-power computing. Until you hear …

It's been a few months since I wrote anything in the blog. Like everyone, I've been busy with the Covid-19 pandemic. We moved all classes online in March, and Fall 2020 is online only too. Teaching online is hard, maybe as hard as learning online. I'm grateful to the Carpentries …

Introduction

Puerto Rico had a swarm (or sequence) of earthquakes at the end of 2019 and the start of 2020. So far, the largest was a magnitude 6.4 on January 7, 2020.

Since around December 28, there have been hundreds of quakes in the region. Several researchers have made …

I just ran a Software Carpentry Introduction to R Programming workshop with Sofia Melendez for the IQ-Bio-REU. We had three great helpers, Briknie Baez, Israel Dilán, and Marc De Jesus Ellsworth. With Juan S Ramirez lending moral support as needed. We ran the workshop over 5 half-days instead of the …

Introduction

During the 2015 drought I wrote niveles-carraizo, an openshift app to monitor the water levels at the reservoir close to my home. Openshift changed the way apps work, so the app stopped working a while back.

The app used a cronjob to scrape data from our water works, but …

Introduction

We were discussing in our department the pre-requisites for different courses in computer science, and I started wondering about the "normal progression" of students in our Computer Science bachellor's degree. We have a suggested 4 year curriculum, but hardly any students graduate in 4 years. I wanted to see …

I watched a nice video today of a lecture by Rob Pike on the history of UNIX from his personal perspective. It's fun to watch stuff like this, it's different than reading about UNIX in a book or online.

I once had the opportunity to watch Linus Pauling give a …

Introduction

The University of Puerto Rico has a G Suite Education Edition agreement. Several researchers are interested in using Google Drive to backup and securely share data and results. We set up a Team Drive for testing in one of our projects, and it was working nicely, but one of …

Last year I wrote a toy bitcoin-like python implementation for the Systems and Network Security course. This year I found a much nicer toy implementation called dumbcoin, written by Julien Rebetez. His implementation is much cleaner than mine, and includes several classes for transactions, wallets, and blocks. He illustrates mining …

After Hurricane Maria hit Puerto Rico on September 20, 2017 I bought a solar panel kit. The kit had a 100 Watt solar panel (12 V), a charge controller, and cabling. I had already purchased a 1200 Watt inverter after Hurricane Irma, and pulled the battery from one of the …

Saturday afternoon I had a nice ride on my longboard out on the Paseo Puerta de Tierra. I started out in Condado, by the lagoon, and followed the bike path up to Escambrón. The weather was great, and there wasn't a lot of traffic on the path. Once past Escambrón …

Scuttlebutt

I've been playing with scuttlebutt, a secure decentralized social network for a few days, and wanted to share some information on it.

Scuttlebutt isn´t so much a program as an ecosystem, a collection of programs, protocols, servers and people that allow users to share information peer-to-peer.

Patchwork

The …

C. TItus Brown showed us this really cool service called binder in the mRNAseq data analysis workshop on Saturday.

If you go to

http://mybinder.org/

and paste in a github repository like

https://github.com/humberto-ortiz/ama

that contains some data and some jupyter notebooks, binder will redirect you …

Theorem 1. In a uniform juggle with dwell time \(D\), vacant time \(V\), flight time \(F\) then

$$\frac{F+D}{V+D}=\frac{B}{H},$$

where \(B\) is the number of balls and \(H\) the number of hands.

Scientific Aspects of Juggling.

In Claude Elwood Shannon: Collected Papers. Edited by …

The University is mostly closed for winter break, so I went skating around the Condado Lagoon. It was really windy (15-25 knots), so the eastbound leg was pretty hard. It was nice to get out and ride.

Introduction

Many projects produce valuable digital data that should be preserved. In the PR-NETS project we have deployed a fault-tolerant distributed filesystem called Tahoe-LAFS to store project files.

The Tahoe-LAFS system consists of an introducer, a kind of directory for storage servers, and multiple storage servers. The introducer and storage …

We're in the middle of an extended draught, and water has been rationed for almost a month in most of the metropolitan area.

I made an openshift app using Flask and pygal to scrape the data from the water authority's page and plot it.

The source code for everything is …

I've been a bit under the weather for a couple of months. I had a bout of chikunguya fever, and a lingering pain in my right shoulder. It turns out the shoulder was frozen. I've had a week of physical therapy at Tort Therapeutic Elements, and am starting to feel …

Introduction

After a long hiatus running Mac OS X, I decided to return to linux on my main PC. My MacBook is showing signs of dying, and a hard drive crash during a backup made me finally decide to get a new machine.

I got a HP Pavilion 13-A010dx X360 …

I had a good skate session today. I took a lap around the Condado Lagoon. I'ts about 4.4 miles, and took me some 38 minutes. It was partly cloudy and windy, but only sprinkled on the course. The pavement wasn't too bad, and it was mostly dry. The bike …

First post, testing pelican

I went to the 2014 Tech Summit Hackathon, but knew I had to leave early, so I did a solo hack.

One of the newly released data sets included some historical GPS data from the Autoridad Metropolitana de Autobuses. I decided to try to look at the bus service on …

Introduction

I was looking for a project to learn how to use the GPIO on the raspberry pi, and started with an adafruit tutorial on checking mail and turning on LEDs. Since I get too much email, I decided to change the application to check for sucessful and failed ssh …

Using matplotlib to view aggregated network flows in python.

Slideshow on the use of scala at twitter to build distrubuted systems. They use the applicative and functional aspects to compose applications as layers of interfaces.

Twitter is heavy into scala, they have courses and best practices too.

I went for a quick row on the Parque paseo lineal del Rio Bayamón. I hit a pretty good pace, it was overcast and cool. It sprinkled a little when I started and when I finished, but the weather cooperated. My shoulders are sore, I hadn't gone that fast in …

Abstract

The Seattle distributed system is a framework for running python programs across many computers on the Internet.

Introduction

I've been interested in distributed scripting since I was a graduate student in The University of Texas at San Antonio. I was pleasantly surprised to see that there is a new …

Christian A. Rodriguez showed me his MathJax enabled pages, and I just found out org-mode supports mathjax too. You just put latex equations in html, and load the javascript. It renders the equation in any browser.

Here's an example from the MathJax home page:

The raw latex:

   $$ J_\alpha(x …

Cassandra went to MIT CONVERGE for the weekend and left me her Duncan Juggling Rings. I got a little practice in with them yesterday and today. They're not fancy, but they work. I hope I can practice enough I can take a stab at dinner plates! I also juggled a …