Bill Sims Jr. & Mark LaVoie, 2 p.m.

BillSimsJr.com/billmark

Bill Sims Jr. (guitar and vocals) and Mark LaVoie (harmonica) call themselves the American Roots Blues Duo. Bill is from New York City, and Mark lives in Vermont. They have been working together for more than 15 years, mostly in Vermont. In the early '90s while working in Burlington, Vermont, Bill met Mark and they became fast friends after discovering their shared love of acoustic blues.

Greetings, and welcome to the 26th-annual IH Mississippi Valley Blues Festival!

We at the Mississippi Valley Blues Society are proud of our accomplishment of producing this nationally acclaimed festival for more than 25 years. We now embrace the challenge of continuing on this tradition by bringing you quality entertainment for at least another 25 years. To do this we will continue to provide features that our fans have come to expect: world-renowned blues acts at both of our main stages, interactive BlueSKool programs on-site for the young and young at heart, and a free photo exhibit and workshops for one and all at the Freight House.

Chevelle's Sci-Fi Crimes raises one major question: Does the band believe in the paranormal subject matter it tackles with such earnestness on its 2009 record?

"Pete and Dean and I have this ongoing discussion about whether it can happen, whether aliens can even reach us," said drummer Sam Loeffler in a phone interview last week. "It's all in fun."

Which is to say that the members of Chevelle -- brothers Sam and Pete (guitars and vocals) Loeffler and brother-in-law Dean Bernardini (bass) -- aren't believers. Yet.

So when Chevelle headlines Saturday's Rock the District event in Rock Island, feel free to share your beliefs, theories, and evidence with the band. Sam, at least, claims to have an open mind.

Dan Snaith sounds tired of answering questions about math.

He comes from a family of mathematicians; he earned a Ph.D. in the field in 2005. And because he records and performs (under the name Caribou) electronic music, journalists (this one included) ask him a lot of questions about the relationship between his primary academic and musical pursuits. They both involve computers, don't they?

Snaith -- who will be playing with his band at a Daytrotter show at RIBCO on Saturday, June 5 -- said there are some similarities. But not many. "Being able to do what you want ... is kind of an intuitive process," he said in a phone interview last week. "In both mathematics and in music, you kind of have to use some gut-level intuition to piece things together. [But] I think they're very different in many ways."

What's evident listening to the music of Caribou is that Snaith's electronic instruments are largely tools, not ends. There are certainly electronic sounds, but the songs sound organic and feel handmade, and his singing voice is ethereal, warm, and emotive -- a perfect offset to any digital coolness. Put differently, there's nothing mathematical about Caribou's songs.