Partial Eclipse 2023

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 …

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Oscar Moreno de Ayala

Moreno tiene corillo: black and white image of a fuzzy haired man in a stripped jacket.

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 …

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Glass Ceiling

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 …

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Mujeres en la ciencia de cómputos

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 …

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First steps in Plan 9

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 …

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Low-power computing

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 …

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Covid-19 and the Random Student Generator

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 …

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2020 Earthquakes

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 …

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Water levels in Carraizo reservoir

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 …

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A map of student progress in CCOM

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 …

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Using Google Drive from the command line

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 …

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Solar Panel

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 …

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Scuttlebutt: a secure decentralized social network

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 …

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Bitpenny: illustrating bitcoin concepts with code

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Shannon's Juggling Theorem

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 …

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Replicated file service on the PR-NETS ScienceDMZ

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 …

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Principal Factors in Asthma in Puerto Rico

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A bigger RSA encryption example

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A very small RSA encryption example

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Skating around the Condado Lagoon

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 …

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Quick row on paseo lineal

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 …

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