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Dean Calahan
Attended Johns Hopkins: Ph.D. Biology
Lives in Chesapeake Bay
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Dean Calahan

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I think I'll mostly be re-sharing for a few days (for whatever thin stream of content I do generate), as the only original content or internet stumblings are likely to be quite boring: wordsmithing and references for an article. Bleagh!

I predict (or maybe it's already been done) that someone will take a Tesla chassis and 3D-print their own body and interior.
 
Jim Smith Made the World's First 3D Printed Kayak and It's Vibrantly Fantastic

via Trendhunter
http://www.trendhunter.com/trends/3d-printed-kayak

#3dprinting #kayak #3dprintingnews  
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Dean Calahan

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For some reason, the Botany Department* exhibits don't seem to generate as much excitement!

*Where I'm doing some research related to algae.
 
It's here! The National Trex has arrived at Smithsonian's National Museum of Natural History. We're webcasting the welcome ceremony and un-crating this morning at 9 am ET http://naturalhistory.si.edu/fossil-hall/
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Perhaps a PR fail? Maybe oversubscribed? The Whole Internet replacing their digital certificates after Heartbleed? Sorry, I can't be of any further assistance.
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Courtesy of +Edward Osenbaugh 

Heh heh heh. I fantasize that someone with enough time on their hands could organize a bunch of kickstarters to do this all over the place:

http://www.dailykos.com/story/2014/04/09/1290698/-Innovative-environmental-SWAT-teams-collect-samples-from-Los-Angeles-businesses-to-nab-polluters#
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Three cheers for dust devils!
 
Look how clean Opportunity is now!

While climbing Murray Ridge, Opportunity enjoyed a major cleaning event that has left the rover's solar panels more dust-free than they have been in years. The rover captured a pretty panorama of the newly clean deck with its Pancams, and James Sorenson processed the version shown here.

Read more: http://bit.ly/1iybAtr

(Image: NASA / JPL-Caltech / Cornell / ASU / James Sorenson)
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Buy new, drive till junk. Just like with my 95 Saturn. Not (quite) junk (just) yet. Parts are getting harder to find, says my mechanic.
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Signs of spring are yet few in Baltimore (absence of snow is not evidence of spring!). So when I see red buds against a blue sky, it feels rather like an hallucination.
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Dean Calahan

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#reflexshare  

Ferns are my favorite sporophyte. I have some germinating that I'm hoping to plant out soon. Collected spores from a bunch of different species and mixed them together hoping for cool looking hybrids (note: highly unlikely as I mixed genera, but you never know)
Even in their quietest and stillest moments, forests are places of fierce competition. Sunlight is the one of the most precious commodities here, and plants jostle, circumvent, and kill each other ...
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I'm busy, so I will just lazily re-share. I'm probably not the only other person who thought this would be a cool type of thing to do, but I sure am glad somebody actually did it.
 
Looping stop motion of a 3D printed bear...climbing stairs
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Sisyphursus.
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Testing.
 
Some sporophytes from a recent trip to Charleston, SC, taken at various spots in the Battery. The large, bloomlike feature is a fern fiddlehead taken from the top down. What kind of fern? I don't know. 
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Haven't tried them myself. I've been told that the commercially available ones (in Maryland) are Ostrich Fern, which is rare in nature but easily cultivated (can be invasive).
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Testing.
 
Spherical zillij

This beautiful golden pattern was created by someone who goes by the name of Taffgoch.  He did it by taking a traditional Islamic tiling pattern made of interlocking hexagons and replacing some of them by pentagons.  This lets the original flat pattern 'curl up' and become spherical!

You can see the original flat pattern here:

https://groups.google.com/d/msg/geodesichelp/ayZcCILttBs/bVU6eI5SLUEJ

It's of a type called zillij.   It's fun to read how Taffgoch transformed it into the round version... and see how he improved it step by step.

Puzzle: how many pentagons, and how many hexagons, are in this spherical zillij?

This is similar to a question about fullerenes, which are sheets of graphite - hexagons of carbon - that curl up into spheres because some hexagons are replaced by pentagons.  Fullerenes come in different sizes, with different numbers of hexagons.  But as long as a fullerene is spherical in its topology, with 3 pentagons or hexagons meeting at each corner, the number of pentagons is fixed!  

I'll compute this number now, so if you want to answer the puzzle on your own, maybe you should stop reading.  However, this spherical zillij pattern is not exactly the same as a fullerene... so it's not obvious that it has the same number of pentagons.

Here's how it goes.  Suppose we have a sphere tiled with P pentagons and H hexagons, with 3 of these polygons meeting at each vertex.

How many edges are there in this tiling?  Each pentagon has 5 edges, and each hexagon has 6, but each edge is shared by 2 shapes so the number of edges is

E = (5P + 6H)/2

How many vertices are there?  This is where we need to know 3 polygons meet at each vertex.  Then by the same reasoning as above, the number of vertices is

V = (5P + 6H)/3

How many faces are there?  That's easy:

F = P + H

Now Euler's formula, a fact from topology, says

V  -  E  +  F = 2

So, plugging in the equations for V, E, F, we get

(5P + 6H)/3  -  (5P + 6H)/2  +  (P + H) = 2

or

P + H = 2  +  (5P + 6H)/6

or

P = 12

Note that H cancels out, so we learn nothing about how many hexagons there are.  But pentagons love the number 12... and ultimately, that's why this shape here has

5 × 12 = 60

rotational symmetries!

Puzzle: suppose we have a doughnut with g holes tiled by pentagons and hexagons, 3 meeting at each corner.  How many pentagons are there?

#geometry  
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#reflexshare  
You can see a lot if you just look!
 
Possible Nova Pops in Cygnus

A newly-discovered star of magnitude +10.9 has flared to life in the constellation Cygnus the Swan. Koichi Nishiyama and Fujio Kabashima, both of Japan, made their discovery yesterday March 31 with a 105mm f/4 camera lens and electronic camera. They quickly confirmed the observation with additional photos taken with a 0.40-m (16-inch) reflector. Nothing was seen down to magnitude +13.4  in photos taken the on the 27th, but when they checked through images made on March 30 the star present at +12.4. Good news – it’s getting brighter!

Read more: http://www.universetoday.com/110879/possible-nova-pops-in-cygnus/#ixzz2xdvS5dlS
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People
Have him in circles
7,182 people
Robert Bevins's profile photo
Work
Occupation
Making something happen
Skills
Cell & molecular biology, genetics, bioinformatics, software engineering
Places
Map of the places this user has livedMap of the places this user has livedMap of the places this user has lived
Currently
Chesapeake Bay
Previously
Puget Sound - Willamette Valley
Links
Story
Tagline
Genes, Cells, Informatics, …Algae!
Introduction
Willamette brewed, Puget aged, Chesapeake decanted.
Bragging rights
Walked around Mount Rainier in nine days.
Education
  • Johns Hopkins: Ph.D. Biology
  • Towson University: B.S. Molecular Biology, Biochemistry, & Bioinformatics
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Male
Dean Calahan's +1's are the things they like, agree with, or want to recommend.
Technology Entrepreneurship
venture-lab.org

This course introduces the fundamentals of technology entrepreneurship, pioneered in Silicon Valley and now spreading across the world. You

Deschutes Brewery
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Deschutes Brewery: Courageously Crafted for Fellow Explorers Everywhere

The name is Italian, but the cuisine is Persian. I intend to go back again and again, trying something new each time until I've exhausted everything that strikes my fancy. In general, I would call our meal fantastic. I ordered lamb shank, which comes with a tasty sauce and rice with dill, and falls right off the bone, just like it's supposed to. Spouse ordered chicken kebab. I don't normally order chicken at restaurants that serve beef, lamb, or duck, but the few bites she allowed me will force me to change my mind, at least here. I wouldn't bother with the Persian ice cream, but the baklava was a definite win. They've been open since December. They weren't slammed on a Thursday night, but they were better than half full, and had a steady flow of take-out customers. It's BYO - no corkage fee, and what could be better than the drinks you *want* at a price you *like*?
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Public - a month ago
reviewed a month ago
I drink coffee and work on my laptop here several times a week. Congenial, delicious, and within walking distance. I can almost imagine I'm actually in Seattle!
Public - 2 months ago
reviewed 2 months ago
2 reviews
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