New backups in Paradise...

New backups in Paradise...  Well, that was totally painless!  The hardest part of bringing up our new backup RAID was ... unpacking it.  The damned hard disks were swathed in plastic that my (sharp!) pocket knife had a heck of a time cutting.  Other than that, all I did was plug in cables and disks, and OS X led me through the rest of the setup.  I'm making a backup right now.  What a piece of cake!

Progress in Paradise...

Progress in Paradise...  It was so beautiful here this morning that I just couldn't stand to work inside, despite the fact that all my higher priority projects are there.  Instead, I decided to fix our lawnmower (a riding “zero-turn” type).  The last time I mowed, I noted a rather awful problem: the left side of the mowed swath was cut about an inch and a half lower than the right side.  This gave our lawn a distinctly odd look :) 

Without even looking, I figured that the mechanism that raises and lowers the deck must have gotten out of whack.  So I used a floor jack to raise each end of the mower and put it up on jack stands to make it easy to see and reach the deck-adjusting mechanism.  I also figured it would a good moment to pull off the blades and sharpen them.

Well, a careful inspection of the deck-adjusting mechanism showed no problems at all!  Everything was intact, all the fasteners were present, nothing was bent.  Even the lubrication was up to snuff.  Puzzling over this unexpected finding, I leaned against the mower – and noticed that the left front tire was soft.  Soft, as in completely flat.  The right front tire was perfectly inflated.  Dang!  Well, at least I knew what the problem was now.  So I pulled the tire off (easy, since the mower was up on jack stands) and ran it up to Hyrum Tire to be repaired.  Then I came back home, pulled off and sharpened the blades,  reinstalled them, and added grease at every zerc fitting.  This was much easier with the mower on jack stands – that's how I'll be handling that chore from now on!

That left me with a couple hours to kill while waiting for the tire to get fixed.  It was still cool and beautiful outside, so I decided to do some pruning.  Several of our blue spruces had taken a hit when I sprayed the lawn with 2,4-D.  From the symptoms, it looks like new growth at a particular stage was killed or damaged.  This made some of the lower branches look very odd, with light brown tips where it should be blue or green.  Also there were two beautiful blue spruces along the canal that had an upstart hawthorn growing up through their branches. 

So I trimmed up 4 blue spruces, getting rid of those brown ends, and in two cases trimming them away from the driveway a foot or so.  Then I really made that hawthorn's day a miserable one.  It had 17 trunks (I counted them!) ranging from 1" to 4" in diameter.  The hawthorn wood is ridiculously easy to saw, so I had them all cut in a matter of a couple minutes.  Getting them out of the blue spruces without damaging the spruces turned out to be the challenging bit – the hawthorn branches were practically tied in knots around the blue spruce branches.  It took a bunch of precision cutting, but I finally did get it all out.  I only lost one small blue spruce branch in the process.  I thought removing that hawthorn would leave a big hole between the two blue spruces, but in fact it did not – there were still blue spruce branches growing inside the hawthorn (which is why it was so hard to disentangle them).  Instead it just looks like a less-dense patch in the blue spruces.  If you weren't looking for it, you probably wouldn't even notice.  Great!

After finishing up the pruning and carrying all the brush to the brush pile, I helped Debbie wash her hair and take a bath (of sorts).  This is quite an operation when you can't put any weight on one leg, can't stand up unassisted, and must spend most of the time sitting on a roll-around chair.  We're getting good at this, with all the practice.  It makes Debbie feel much better, but still, I'm sure she's really looking forward to being able to take a shower again.

Then I ran up to Hyrum Tire, picked up my fixed tire (it had an inch-and-a-half long thorn in it – almost certainly from a hawthorn!), and put my mower back together.  A little test run in an obscure corner of the yard proved that the problem was fixed.  Yay! 

For the hour or so preceding this happy resurrection of my mower, there were thunderstorms rumbling in the distance.  A couple times we got sprinkled on a little bit.  Just as I was putting the mower away, it started to rain a little more seriously – and we were getting almost continuous thunder overhead, sounding very close.  I couldn't see any lightning, so it must have been cloud-to-cloud lightning above the dense layer of clouds that was dumping water on me.

Now I'm about to put together a new backup disk.  The 3TB backup disk we've had for three years died a couple days ago, so I ordered the parts for a replacement.  This time, to choose the disks I used the drive reliability data gathered by BackBlaze to select HGST 4TB drives (HGST Megascale 4000.B).  The enclosure I selected is a RocketStor 5212, with a Thunderbolt interface, good reviews, and compatibility with OS/X software RAID.  This will become the Time Machine backup disk for our OS/X server and Debbie's iMac.  Hopefully this will be as easy as my past experiences with similar devices!

Are medical screening tests valuable?

Are medical screening tests valuable?  The answer isn't always as clear as you might think.  Study the chart for breast cancer screening (mammograms) below to see one example of this (more details here).  Some kinds of screening (example: colonoscopy) themselves pose a risk, and though that risk is generally quite small so are the positive detections.  Mammograms involve exposure to high-energy radiation, which is a known risk for causing cancer.  All kinds of screening have a false-positive problem – and these false positives put the patient through a lot of stress and additional testing, which also has risks. 

This stuff is hard.  Some kinds of medical screening absolutely make sense.  Some of them absolutely do not make sense.  Most of them are a lot less clear...

I can scarcely believe...

I can scarcely believe ... that I can do this in my browser!  A realtime, interactive, 3D display of all tracked objects in orbit around Earth.  Holy JavaScript, Batman!

Evening walk in Paradise...

Evening walk in Paradise...  Just Miki, Race, and I tonight.  I let Mo'i wander about in our back yard at his own pace, stopping when he needs to.  The three of us marched at a quick pace a little over a mile (with 300' elevation gain) to an abandoned quarry, and back.  Normally on these walks, paced by Mo'i, my muscles don't even notice it.  Tonight I can feel a little burn in my quads and calves.  It's a good thing!  Or at least that's what I'm told...

The photos below are from that walk.  The first one is looking to the southeast from right near that quarry.  In the foreground is the corner garden I took photos of earlier.  In the background is the home of the gardener, about 3/4 mile away.  That family owns a couple thousand acres of prime hay fields in this area, and they plunked their home right down in the middle of it.  I haven't met them yet, but I can tell they're probably my kind of people :)  The second photo is a panorama looking due west.  I was trying to capture the 22 visible strings of irrigation lines all running right now.  Most of the alfalfa fields have now had their first cutting, so sunshine and water are the farmer's primary objectives.  They want a nice growth burst for the second cutting – and this year, they're getting it in spades.  The last photo is take slightly north of west, showing part of what's in that panorama – but bigger.  You can't see all 22 strings in that photo, but you can pick out 17 if you try really hard.  There's a lot of water being squirted around right now!  Click to embiggen.

One of my readers had the gall to email, complaining that he couldn't understand the diagram I published earlier.  He wanted a photo.  Ok, here's your photo (at right).  I took this photo before I had the brilliant idea of taping the wires together in the correct orientation; at this point I was orienting them by hand, very tediously.

I finished wiring up the air compressor today, both the 240 volt circuit and the 120 volt circuit.  I also capped off the output so we can test the pressure tank when the technicians go through the startup testing (hopefully later this week).

I have an appointment for this Thursday to have my tooth root-rootered, or possibly yanked if it's damaged beyond repair.  If they do yank it, it will be the first tooth (not counting my deliberately removed wisdom teeth) that I've ever actually lost.  I'm hoping that's not required...

Another set of neighbors (Gary and Elaine S.) came by today to see Debbie.  This community is kind of amazing this way.  We just barely know Gary and Elaine.  They live on the other side of the highway from us and probably because of that we don't have much contact with them.  Our previous contacts with them have mostly been waving and saying “hi”.  Today they came over and stayed with Debbie for an hour, and Elaine promised to come by a few times a week – and to bring us a dinner tomorrow night.  They came by because they'd heard from another neighbor (Tim D.) that Debbie was ailing, and that was all the nudging it took for them to take the initiative to see if we needed any help.  They behaved exactly the way you'd expect a good friend to behave.  What a place we landed it!

Asphodelus aestivus...

Asphodelus aestivus...  Common name: summer asphodel.  The bee ain't bad, either!  Via BPOD, of course...

Morning in Paradise, in the shadow of the mountain edition...

Morning in Paradise, in the shadow of the mountain edition...  Took the two younger dogs (Miki and Race) out for our morning perambulation.  Mo'i isn't feeling too well after pooping all over the kitchen; he's resting up for his next adventure.

I took the first photo below as we were walking to the east, away from home.  The sun is just below that minor peak in shadow.  The sky is lit up brightly because technically it's after dawn.  The official dawn starts when the sun peeks above the theoretical horizon – where the horizon would be if there were no mountains.  This almost never occurs in the real world on land, but on the sea it happens all the time.

The second photo was taken about 10 minutes later, as we were headed downhill and west, toward home.  The sun is at our back, but we're deep in the shadow of that silhouetted peak.  To the right of the dirt road you can (barely) make out the alfalfa field that was mowed 11 days ago.  It's now around 15" high, so that alfalfa is growing at just over 1" per day.  In the distance you can see the Wellsville Mountains all lit up, and below them the nearby foothills – they're about a mile and a half from where I was standing.  They're all lit up as well, and you can see very nicely how all the fields with their different kinds of grass, forage, or grain have changed in appearance from the similar photo I took about a month ago.  Many of the fields have been mowed now, and a few have even been plowed and replanted.

The rainstorm yesterday delivered 0.55" of rain, according to my rain gauge.  That's a bit more that forecast, and very welcome.  We have three more days with roughly a 50% chance of rain in the forecast, so we might get even more.  That sound you hear is all the local farmers cheering.  Except, of course, for those who just mowed their fields.  They've now got soppy windrows that will have to dry for several days before they can bale...

Floating point follies...

Floating point follies...  I ran across this blog post in my morning reading, and as I was reading it I thought “Jeez — this is like a litany of all the floating point problems I’ve seen programmers stumble into!”  Two memorable occasions:

1. While working at a firm that provided hedge fund IT infrastructure as a service, I worked with a team implementing an algorithmic trading server.  This was implementing a relatively simple algorithm called “pairs trading”.  Part of the calculation involved raising a pair of fixed numbers to a series of powers, looking for a particular relationship between the results.  The powers were 1.00 to 1.99, in increments of 0.01.  The programmer's initial approach was to calculate the two fixed numbers raised to the 0.01 power, then accumulate as he iterated through the increments.  The programmer did this in the belief that he'd speed up the calculation by avoiding the power computation (which wasn't actually true on the server the code executed on, though it was true on his laptop).  However, much to his surprise and consternation there was a considerable error in his computation by the time he got to the end.  He sought my help on this, and we changed a few lines of code to eliminate the accumulated additions by doing the power raising for each iteration, and the error disappeared (of course).  I was tempted to tell the programmer that the problem was caused by his choice of Visual Basic as the programming language, but that didn't seem fair :)
2. While working at a different electronic trading firm, we had a problem wherein the cost we computed for a trade didn't match what NASDAQ computed and charged us.  Usually the difference was a few cents and we just ignored it, but one day a trader bought a huge number of shares of a very low cost stock, and the difference was over $100 – enough for my boss to tell me “Go figure that out, damn it!”  When I dug into our calculations, I could find no errors, so I called my peer at NASDAQ, a pleasant fellow named Gary.  He told me he'd run into this a few times before, but had never figured it out.  He sent me the block of code that did the calculations on his end.  Our code was Java; theirs was C++, but in both cases the code used the underlying x86 machine's floating point processor.  After staring at the two pieces of code side-by-side for a while, I realized that we were doing a particular multiplication with the operands in a different order.  We were multiplying shares x price, and they were multiplying price x shares.  When I swapped the order of our multiplication, the difference suddenly disappeared.  I called Gary back and told him what the problem was, and he told me I was crazy – multiplication was associative and that was that!  An hour or so later he called me back and said he'd duplicated my results.  That was one very disillusioned programmer!  After that, he and I had several phone calls (at his request) so I could educate him a bit about floating point numbers.  Despite having a very responsible position on staff in a large exchange, he knew next to nothing about them – most especially about the sorts of things outlined in the blog post linked above.
   

Bullwinkle...

Bullwinkle...  Our neighbors have named the moose who visited us a couple days ago.  Here's a photo Alan L. took with an actual camera, showing Bullwinkle in our alfalfa/grass field:

To the voters of America...

To the voters of America...

Evening in Paradise...

Evening in Paradise...  Took the dogs for their evening walk, but we didn't go very far as Mo'i wasn't feeling like it.  At one point he backed out of his choke collar, turned around, and started trotting for home.  We had to jog to catch up with him!  I guess he really just wanted his nice, soft doggie bed :)

There's an impressive line of storms to our west, heading for us, as I write.  The photo at right was taken to the northwest, where it's very dark right now.  You can't see it, but our house is behind the trees at the left edge of the photo.  I think we're about to get rained on, and the radar (at left, click to embiggen) shows that.  Paradise is where that little circle with a plus sign is, and just to the left (west) of it you can see the yellows, oranges, and reds of an intense rain cell...

This guy set a new record...

This guy set a new record ... for being completely insane.  I don't know how you can top this one!

Progress in Paradise...

Progress in Paradise...  We actually had some progress today, on wiring up my new air compressor.  I ran most of the 240 volt circuit today, about 60' of the total of 85' that I have to run it.  I did the hard parts today, through two walls and into the main circuit breaker panel.  All that's left is the final 25' across a wall, and terminating in a junction box.  Should be a piece of cake to get that done tomorrow.  Then all I have left (for the air compressor) is a short run of 120 volt line for the air dryer that's built into the compressor.

The 240 volt line I was running today is comprised of three 8 gauge copper wires, colored red, black, and green.  I'm running them inside a 1/2" PVC conduit, so in cross-section it looks something like the diagram at right (the scale is approximately correct).  As you can see from the diagram, the three wires fit inside the conduit with plenty of room to spare – and yet, running those wires through the conduit proved to be quite a challenge!

Why would this be challenging?  Well, imagine moving that red wire over to the other side of the green wire.  At one point in that process, all three wires would have to fit side-by-side inside the conduit – and the conduit just isn't big enough for that to happen.  In practice what this meant is that I had to “comb out” the three wires and tape around them every foot or so, to make sure they stayed in the same orientation.  Otherwise I could never have gotten them through the conduit!  Also, I had to do this one piece of conduit at a time, so that at most I had just a single bend to navigate.  This made the process quite tedious.  Of course, if I had been bright enough to buy 3/4" conduit...

These heavy wires are needed only because the start-up current for the air compressor is unusually high.  Under full load that motor (5HP) will draw about 21 amps – but during startup, according to the documentation, it will spike as high as 35 amps.  Yikes!  So I have to have a 40 amp breaker, and that means 8 gauge wire is the smallest safe size.  That's a whole lot of copper when you're talking about an 85' run, which is what I have...

Pictures from Paradise...

Pictures from Paradise...  The first photo below is attempting to show the beautiful droplets hanging from green berries on a tree I haven't identified in my back yard.  The second is a local “corner garden”.  These are pretty common around here, in the corners of fields where the turning radius prevents the mowers, balers, and other equipment from getting into.  Rather than waste the space, people grow little gardens in them.  This on is drip irrigated, and is growing very quickly.  It's far enough from any waterway that it's not likely to have racoons stealing everything from it.  Skunks and magpies will be there, though.  The rest of the photos are from a barley field a half mile east of our house...

It's no longer spritzing...

It's no longer spritzing ... it's raining.  We've already had a tenth inch, in just the past 10 minutes or so.  Go, rain!

Morning in Paradise...

Morning in Paradise...  For some reason I've slept particularly well the past couple of nights.  Generally speaking, a solid night's sleep is a rarity for me – something that happens maybe once a month.  In a good month.  To have two such nights sequentially is most unusual.  If this is a change brought about by ancientness, then I may embrace my ancientness more!

At 5 am, before dawn, the dogs and I took off on a morning walk.  Our heat wave appears to have broken last night – it was cool and humid this morning, and it even spritzed on us a bit.  The forecast is calling for a high of just 78° today, which (assuming that pans out) will feel downright chilly compared with the high 90s we've been experiencing.  The forecast for today also has a good chance of rain, with 4/10ths predicted.  That will be welcome here, especially for all the hay farmers around me.

We only saw one exciting thing on our walk.  Our first sighting was from about 150' away, an animal the size of a small dog scampering through alfalfa that had been mowed 10 days ago.  It was too dark to see it clearly, but it was headed right for us.  It was too big to be a skunk, so I just stopped.  The dogs went on full alert, staring intently at the moving shape.  It was downwind of us, so they had no odor cue, and didn't know what it was.  Finally it emerged from the field onto the road, just 6' or so in front of us – and then we could see that it was a gigantic house cat!  It was an orange tabby (I think – the light was very dim), and had the look of an intact male.  It's attitude was all cat: it glanced at us disdainfully, dismissively, and continued on its way at its own pace.  This despite the fact that all three dogs were slavering, barking, bouncing at the end of their leash trying to get at it.  The cat saw no threat at all, which really tweaked the dogs; they renewed their efforts to seem fearsome.  They failed.  Cat: 1, dogs: 0.  Human?  Laughing :)

As I write this post, it's just starting to get light outside my window.  The sky is deeply overcast, and it's sprinkling just a little.  I just got out my binoculars and looked at my rain gauge; it shows 3/100ths" last night.  That's about right if it spritzed most of the night, which I suspect it did, as everything is damp outside.

My mom and I have started playing a Scrabble-like game (called Lexulous) over the Internet.  So far I am clobbering her in an embarrassing fashion.  She claims its my good letters.  I did something to make her laugh (no idea what!), so it's a good morning :)

Oh, noz!

Oh, noz!  New Horizons is having problems.  I sure hope they get this resolved before the flyby, which is only 9 days away!

Curiosity...

Curiosity ... is looking at odd rocks on Mars...

Zeta Ophiuchi...

Zeta Ophiuchi...  Gorgeous false-color photograph taken by the Spitzer Space Telescope in infrared wavelengths.  Via APOD, of course.  Full resolution version here...

Intuition...

Intuition...  I ran across this blog post in my reading this morning.  It caught my attention mainly because it has a Feynman story in it; one that I was familiar with, but hadn't thought about in a while.  In it, Feynman talks about the importance of developing an “intuition” about physics problems, in addition to understanding the mathematics describing them.  Sometimes that intuition will get you to an answer long before you can prove it with the math.

I think that same observation applies across many kinds of science, and even some math itself.  I've noted the same phenomenon with arithmetic many times.  In particular, developing the skill to do arithmetic mentally or on slide rules (which actually involves quite a bit of mental arithmetic) helps you develop an intuition for the general value of a solution to an arithmetic problem.  Almost any problem in more advanced mathematics (say, a differentiation problem) involves, in the end, simple arithmetic, then having such an intuitive grasp on arithmetic helps you avoid errors in the more complex math.  I've used a variation of this to argue for the value of slide rules over calculators or spreadsheets.  As I read this blog post, it occurred to me that what I was really arguing for was developing an intuition for arithmetic, as Feynman argues for physics.

Several other fields I'm familiar with demonstrate the same value of an intuition.  Analog electronics, for example – having an intuitive understanding of how the basic components (resistors, capacitors, inductors, diodes, transistors) work is an incredibly powerful base to build an understanding of electronics on.  As Feynman might have said, you could analyze any circuit with mathematical tools, but it's far easier if you have a good intuition for how the parts work.  I think the same thing could be said for programming, or mechanical engineering, or concrete mix design...