Tuesday, August 31, 2010
Playing with Pixelisation ;-)eading the gutter press recently and saw yet another story about a pedophile Irish catholic priest (he was grateful fur small Murphys ;-) ) coming up for trial. The paper had 'anonymised' his photo as he had not (yet) been convicted. It got me wondering about the efficacy of pixelisation as an anonymisation tool for photos. So here are some of my experimental results, myself as the subject.
Original 3 photos, JPG save-quality 80%
Same 3 photos, just pixelised
The pixelisation does not achieve its aim, the person would still be identifiable. It helps if you deliberately unfocus your eyes when looking at the bottom row.
When I then shrank the pixelised photos by a factor of 4, the figures became even more recognisable. The human brain is a wonderful pattern recognition device :-)
Pixelised then shrunk by factor 4
Finally: Re-expanded by factor 4
Now the effect of the pixelisation has gone, the 3 photos merely look blurry, the person is identifiable, I'm sure.
Obviously, I needed to change the sequence of actions.
First shrunk by factor 4
First shrunk then pixelised
Finally, after pixelisation: Re-expanded by factor 4Not identifiable, and looking like a piece of cubist art. Picasso turns in his grave ;-)
PS: The SW used for this experiment was IrfanView 4.27, recommendable Freeware :-)
PPS : Here in Germany, using some amateur button-pushers' photos, you have to be careful. The resulting 'Cubist art' should not display a swastika, illegal here nowadays.
Sunday, August 29, 2010
Fast roads through the agesbout 3 weeks ago, a fellow biker was complaining that most modern roads seem to be boringly straight. After all, we bikers prefer the old-style, curving, hilly, twisty country lanes. I told him to be grateful for those straights, after all, they bring us in the fastest possible way between the interesting bits of road ;-)
Anyway, this led to a discussion about average speeds over longer distances [An aside: the shortest possible biker joke : Several bikers met and none of them bragged ;-) ]. As it happened, I had some stats from previous club outings. The choppers group averages 56 km/h over a day, the regulars average 65 km/h and the fast group manages 82 km/h, all on average country roads, no motorways etc.
None of this would be possible without the invention of asphalt (Ta, MacAdam, scottish inventor, 1816 ;-). Actually the first known city to have its streets paved with tar was Baghdad in the 8th century AD, but I'm talking about tarmac. Hooley's 1901 patent for Tarmac involved mechanically mixing tar and aggregate prior to lay-down, and then compacting the mixture with a steam roller. Previously there had been only compacted dirt and stone roads which were adequate for use by horses and carriages or coaches, but they were very dusty and subject to erosion with heavy rain. They did not hold up to higher speed motor vehicle use, the Dukes brothers notwithstanding ;-)
Looking at some of the average speeds recorded over the previous centuries, we find the following numbers in various historical texts :- The news of Charles V being chosen as emperor in France on 28/6/1519 was spread by fast horseback messengers who managed more than 150 kms per day. In 1072 Henry IV travelled by coach from Goslar to Regensburg (416 kms) taking 29 days to do so, still a good speed 400 years later. Shorter trips were faster - Barbarossa is recorded as doing 85kms/day for 2 days in 1158 AD. Around 1450 AD 32kms/day was a good speed.
So be grateful for our modern tarmac roads, despite the traffic jams taking you back to medieval speeds sometimes ;-) And now, Bikers, pick up any of the challenges :-)
Friday, August 27, 2010
Understanding Medical Screening statisticsack in mid-march of this year a lady co-blogger and I told you to get your Cancer screening done regularly. Two of you blogreaders subsequently pointed out that the results can be misleading. True, but no excuse for not getting the screenings done. So today I want to show you how to interpret Medical Screening.
What is Medical Screening? It is a strategy used to detect a disease in individuals without signs or symptoms of that disease. It is cheap (which is why they do it) and cheerful (i.e. mostly painless), with few side-effects. Examples of successful screening for e.g. cancer include: Ladies' Pap smear to detect potentially precancerous lesions with the aim of preventing cervical cancer, ladies' mammography (radiation side-effect) to detect breast cancer, men's blood tests to detect prostrate cancer indicators, colonoscopy to detect colorectal cancer, dermatologist visit to detect melanoma.
But you need to understand the numbers properly. So here is a worked example :- Assume the cheap and simple screening indicator (eg a PSA blood sample test for a prostrate cancer indicator) claims a 98% accuracy; that means that 2% of the results will be wrong. Also assume a low incidence of the disease, say an assumed ½%.
Now let's look at what this means when 10,000 people are screened. ½% disease incidence implies that 50 of the 10,000 will have the disease. But 2% inaccuracy implies that 200 results of the 10,000 are wrong. 2% of those 50 means one person is told he has no indication of the disease, whereas he does in fact have it. And 199 of the 200 are told they have indication of the disease and need further testing although they do NOT have it. So of the 250 sent for further testing only 49 have the disease; you have an over 80% (200/250) chance of NOT really having it :-)
The further testing (more expensive) may be painful and messy ( see our March 2010 article), but you need to get it done to see whether the initial cheap and cheerful screening indicator was right or wrong. Don't bet on that 80% misindication!
Catching the disease early means the difference between a 5-year survival rate of over 90% (detected at stage 1) versus below 15% if caught late at stage 4 ! Put another way, you can increase your life expectancy from 2 years (late stage 4 detection) to 10-15 years by getting diagnosis and treatment as early as possible. Go get checked!
Wednesday, August 25, 2010
700th Geocache found :-)
unday morning, Dieter and I rode for a Bikers' Breakfast over to Gut Albrock. Since it looked as if it might rain, we were the only people there around 10 am. Scarcely were we seated in the beer garden, when a police car pulled into the parking lot. Oh dear, 'speedy' review of recent potential sins ;-)
However, it turned out that the cops too had heard that the Bikers' Breakfast there is great value for money and it was a change from getting donut crumbs in their car ;-)
Afterwards, Dieter and I went geocaching, finding some eight caches, one of which - it turns out - was my 700th geocache since january 2009 :-)
Unfortunately, it was one of those boring micros (35mm plastic film roll cans), not nearly as interesting as the one up this medieval keep (=tower) I found on a high ridge in the woods recently. Oh yes folks, I prefer the more difficult ones ;-)
Apropos difficult ones, I have a D5 T1 cache (i.e. highest difficulty rating but terrain suitable for wheelchaired cachers) out there since over two months which noone has managed to find yet despite me adding progressively easier cryptic hints on a weekly basis. Come on cachers, pull your fingers out & find GC2AB11 real soon! Not SO hard!
Monday, August 23, 2010
My Classic Bike Photos, Schotten, 2010 :-)
To give you an idea how low these Kneeler outfits are: knee-high to a blogger ;-)
Sunday, August 22, 2010
Stupid Spammers ;-)ere is hilarious piece of buggy spam which I just received this very morning ;-)
Note that, not only is it not personalised (merely addressed to an email address, rather than a person's name), it is not even addressed to ME!!! ;-)
Furthermore, mousing over any and all of the links shows that they do not go to Amazon.com but to some strange other address (bfbwhpax.info), so I was careful not to click on any of them.
Note next that the 'Subtotal of Items' (an unbelievable $884.10 for two paperbacks), plus 'Shipping & Handling' ($0.05) do not add up the 'Total for this Order' ($167.61), which in turn is not identical to the 'Order Grand Total' ($091.67). And why does the latter have a leading zero? Furthermore, the individual line items do not add up to their 'Subtotal of Items' ;-) Seems to me that arbitrary random numbers have been plugged into this 'bill' ;-)
Also, I am urged to 'Get the Amazon.com Rewards Visa Card...'. Yeah, like I would give them my credit details and bank account connections ;-)
What's more, their 'Delivery estimate`is not only in the past, it also runs backwards in time (July 23, 2010 - June 25, 2010) ;-)
The first book title is not only an appeal to religion, it is also designed to appeal to Jews (which I'm not). But at least they are real books, which means I can look them up on Amazon. The spammer wants to charge $640.51 for a book that costs less than 12 Euros. And $024.06 for the second book, available from Amazon used for a mere 86 cents ;-)
The spam arrived five times, alledgedly sent by 5 different people, just the numbers in each line of each bill changed. Stupid Spammers, this alone makes the bills suspicious :-(
Of course, my homebuilt Bayesian spam filter sorts this sort of crap out of my mailbox at a 99.9%+ confidence level, but it's good to have a laugh occassionally, and to share it with my blogreaders :-)
Thanks for your order, firstname.lastname@example.org! Want to manage your order online? If you need to check the status of your order or make changes, please visit our home page at Amazon.com and click on Your Account at the top of any page. Purchasing Information: E-mail Address: email@example.com Order Grand Total: $091.67 Get the Amazon.com Rewards Visa Card and earn 3% rewards on your Amazon.com orders. Order Summary: Shipping Details : (order will arrive in 1 shipment) Order #: 070-4998531-3251963 Shipping Method: Standard Shipping Shipping Preference: Group my items into as few shipments as possible Subtotal of Items: $884.10 Shipping & Handling: $0.05 ------ Total for this Order: $167.61 Delivery estimate: July 23, 2010 - June 25, 2010 1 "In My Brother's Image: Twin Brothers Separated by Faith after the Holocaust" Eugene L. Pogany; Paperback; $640.51 Sold by: Amazon.com, LLC 1 "After Long Silence" Helen Fremont; Paperback; $024.06 Sold by: Amazon.com, LLC
BTW, I bet the page to which they link is malware too, secretly downloading a trojan / keylogger :-(
Comments (1) : Anon asks "Aren't you afraid of getting hammered by those spammers for mocking them?" No. But there were several attempts to mail me a trojan in the 24 hours after posting this article, all caught by my uptodate virus-killer. Like those pedophile Irish catholic priests, I'm grateful for small Murphys ;-)
Friday, August 20, 2010
Past fast men :-)ne of the neat things about classic and veteran motorcycle races, such as those in Schotten last weekend, is that you get to meet past motorcycle racing champions. Having only ever been competitive at the club level myself (on a 250cc Ducati like this one), I certainly looked up to the fast boys who were far more talented than I ever was. In previous years at Schotten I'd met Sir Phil Read and also Jim Redman etc. This year I met another three ex-champions there :-
Waldi aka Ralf Waldmann, posing with the famous vintage blown DKW bike for Audi,
On monday I'll be showing you lots of photos of the classic bikes I saw at Schotten :-)
Thursday, August 19, 2010
In Memoriam : Bill Millin, the D-Day PiperIt is a Scottish military tradition that a piper accompany the infantry into battle. Unarmed - except for the dreaded Great Highland Pipes - he will motivate the soldiers (and demoralise the sassenachs) by playing patriotic tunes while the soldiers melee. This was effective for 500 years or more when the fighting was done point blank with swords and pikes etc. Less so you would imagine when the lads were being mown down by machine guns from bunkers 400 yards away across an empty beach. Nevertheless Bill Millin, 22 at the time, stormed ashore on D-day skirling 'Highland Laddie' for all he was worth. The Germans respected his bravery and spared him the bullet (however his pipes were punctured by shrapnel on day four of the invasion).
Now Bill Millin has died, aged 88. A brave wee laddie, not forgotten! Rest in Peace, Bill.
Comments (1) : Morag (UK) : "Movingly written, Stuart. Thankyou for the news."
Wednesday, August 18, 2010
Blogfriend surprise encounter :-)hat pleasant surprises life has in store for us when least expected :-)
Last thursday I'd mentioned here that I was riding my trusty white steed (alias the Triumph Street Triple) down to Schotten for the weekend to watch the classic motorcycle races. Blogreader Doctor C42 - whom I'd never seen before but I knew also has a couple of Triumph motorcycles - read that particular blog entry and decided spontaneously to come there too on the off chance of seeing me there.
So I'd just trotted over the pit lane bridge onto the Old Railway Island when this chap came up to me and just said "You're Stu Savory, I always read your blog!" , didn't even introduce himself ;-) So - since he was wearing a Triumph T-Shirt, I took a flying guess and asked "Doctor C42, I presume?", and yes it was he! But then folks, the intersection set of bilingual vintage bike fans and bloggers is probably pretty small ;-)
So here we are, courtesy of a pretty young blonde lady who snapped the two of us enjoying a coffee and trying to hold a shouted conversation just a bare yard from the trackside during the absolutely deafening saturday morning practice sessions :-
This year's Schotten vintage and classic races focussed on the NSU and DKW bikes (still photos to follow), and so it was doubly apt that Doctor C42 had read my call for information on the NSU R54 back in May and had brought a CD of data for me. Ray Battersby and Kevin Cameron (of Top Dead Center fame) will be delighted :-)
Having bored you with this account of our encounter, let me compensate with a couple of very short videos of the action at Schotten. First the classic sidecars touring around Post Office corner slowly on their reconnaissance(sp?) lap. Next up, coming out of Old Station Corner onto the back straight, we see the Junior solos. Finally, I have a birds' eye view of a solo class taken from the pit lane bridge. All videos taken with my pocket camera whose microphone always complained that it was overloaded. The sound it recorded doesn't do these classic bikes justice. Nor do you get the smell of burnt Castrol R to complete the visual/aural and nasal experience :-( An acquired taste ;-)
BTW, when I was in the Team Yamaha tent, I heard it confirmed that Valentino Rossi will be riding for Ducati next year. So expect some good races against Jorge Lorenzo:-)
Monday, August 16, 2010
Born again quanta : Two out of three ain't bad ;-)
uantum mechanics has some astounding phenomena. Here's an easy experiment which will blow your mind...
Take a low intensity laser and shine it through a single slit and you will get the diffraction pattern on the other side of the slit as shown on the left above. But with that same laser shining through a double slit you will get the diffraction pattern as shown on the right above. The quanta act as waves and interfere with each other causing the intensity-peaks and -troughs as seen. The light goes through both slits and where the waves are in phase we get a bright spot, but at angles where the waves are 180° out of phase they cancel each other out and we get a dark spot in the pattern. So much for quanta as waves.
But now turn down the intensity of the laser so far that the light is emitted one quantum at a time, one after the other. Now what do you get? Well, if you accumulate the result of the quanta passing through the slit(s) you get exactly the same pattern ! This implies that a single quantum of light is going through both slits and the pattern shows the probability of where each individual quantum ends up!!
That's a classical result, known as Young's experiment, re-interpreted with quanta as particles. Now comes the mindblowing bit...What happens if you use three slits?
Well, to cut a long story short - and omit all of Max Born's maths - you might expect to see a diffraction pattern as if the light passed equally through all 3 slits and the waves interfered with themselves accordingly. But you don't !!! Let's call the three slits L,C and R for left, centre and right. What you get instead is a superimpostion of three patterns, as if 1/3 of the light went through slits L and C, 1/3 through C and R and 1/3 through L and R BUT none through all 3 slits L,C, and R at the same time! That is, the individual quanta 'choose' to go through only two of the three slits at a time.
Now does that blow your mind or what?
Comments (2) :
Thursday, August 12, 2010
Gone racing :-)
ff to the vintage races being held in Schotten this weekend, with my team of good friends Matthias, Dieter, Alex, Bob, Paul etc. Normal blog service will be resumed next week, hopefully with more photos of the classic racers there :-)
Monday, August 9, 2010
The Voice of Satan :-)ot, as you might think, the sound over Nagasaki 65 years ago today.
In fact just a few months back I was watching a rerun of Martin Scorcese's The Last Temptation of Christ, a much acclaimed 1988 movie, which upset many traditional mores-bound Christians, when I heard The Voice of Satan. Now the more religious of my readers, Liz and Vic etc. will probably gleefully exclaim "Well of course you would, you're an Atheist!" (shock, horror, rage! ;-)
But the point is, I recognised the voice! (shock, horror, complete lack of surprise! ;-) However, I couldn't place it and missed the credit roll at the end due to a call of nature. Not until weeks later did my subconcious suddenly pop up with a name, none other than Leo Marks, little known British WW2 cryptographer :-)
This coincidence led me to obtain his long-classified and fascinating world war two autobiography Between Silk and Cyanide, wherein he talks about Giskes' Englandspiel, which the UK lost. In an ideal world I would have bought it from Marks & Co bookshop at 84 Charing Cross Road, but it is long defunct, so I had to make do with Amazon. At least I got to visit Marks & Co (and Foyles) during my student days in London :-)
All this is by way of recommending the 614 page book, published by Harper Collins under ISBN 0-00-710039-6. It explains in layman's terms how to break transposition codes by multiple anagramming, and tells how Marks independently (from Bletchley Park) discovered letter one-time pads and worked-out-codes (for transpositions). As I hinted, there is also Marks' account of the UK's views of Das Englandspiel. His book is a fascinating read, which I could barely put down over the whole weekend :-)
Much more difficult to obtain is the German's account of "Das Englandspiel". However, there is a book in English by the German spymaster Abwehr Major Hermann Giskes called LONDON CALLING NORTH POLE (208 pages) by H. J. Giskes, published by the British Book Centre ($3.50), ISBN 0553227033. Amazon still has some used copies, afaik.
"To acquire the habit of reading is to construct for yourself a refuge from almost all of the miseries of life." ~ W. Somerset Maugham
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Friday, August 6, 2010
oday we remember the first time a nuclear weapon was used in anger; in Hiroshima. And on the 9th in Nagasaki. I've visited Ground Zero in Hiroshima (some 25 years ago). And I've also visited the Trinity Site where a test explosion was carried out beforehand (July 16th 1945) at White Sands (USA).
The Trinity Site is only open for public visits twice a year, the first Saturdays in April and October. Nearby stores would sell Alamogordo Glass to collectors in the early post-war days, but that is now illegal, although the green glass is only very mildly radioactive (about 10 times background activity).
Today there are ~ 26.000 nuclear warheads with a total yield of almost ½ million times the Hiroshima bomb (15 kilotons), mostly owned by Russia, Israel, China and the USA. Significantly, these are the four of the seven countries which just last week refused to sign the Cluster Munitions Convention:-(
Presumably, these countries - principally the USA - have failed to understand that they cannot achieve their aims by bombing the hell out of other (3rd world) countries :-(
Just FYI, today's blogtitle is a pacifist's request, not a tactical military status report!
Comments (7) :
Thursday, August 5, 2010
Happy Birthdaytoday, Happy Birthday, Neil Armstrong, first man to walk on the Moon.
My favourite line, upon being asked for the Umpteenth time by a young reporter what it was like to walk on the Moon "Been there, done that" ;-)
Meanwhile Peter Harris sent me this link to a video of a russian space-launch ;-)
Comments (3) :
Wednesday, August 4, 2010
Oh Crap! :-(
h, Buggrit, Buggrit!!!
I bashed the car on monday and the repair estimate shows it will be MUCH more expensive than I'd hoped :-(
I'd driven up a country lane in a nearby National Park and it turned out to be a dead-end.
However, there was a field entrance near the top of the hill and the double metal gate was open so
I pulled in there aiming to back out uphill, making a three point turn. But as I backed out,
Called a tow truck (thanks to whoever invented the mobile phone) which had to back up the last mile of country lane uphill! What with that and the cost of a rental car while mine gets repaired, it's gonna cost me a pretty penny (2k€?), all for a second of my inattention. So crap & buggrit!!! But the good news is that nobody was hurt :-)
And now, as if that wasn't enough, the cooling fan on this laptop is getting loud and turning slowly, so the CPU slows down to avoid overheating, and thus I'm pre-loading this blog entry and may be offline(?) for the duration while I get this fan fixed :-(
Comments (1) :
Tuesday, August 3, 2010
Teaching GeocachingLast week I taught an introductory course on 'Geocaching for Beginners' to 3 adults and 5 children (aged ten and up). Photo by Uwe Jordan (Lichtenau Marketing Club).
We skipped doing the Internet searches as I had made several copies of the print-outs of the caches' database pages. First we did a really easy one, after a quartermile stroll along the riverside, the children found the cache box 'By the Rivers of Atteln'.
The second one was more realistic, it involved a 1000 yard uphill hike along a singe-file woodland path replete with man-high nettles, blackberry thorns and a possibilty of tics. When we reached the '12 apostles', a formation of trees on a thickly wooded slope, individually named, GPS reception was bad due to the leaf canopy, so the error radius was 20 meters instead of just 3 :-( However, there was a hint ('A hint? I have my doubts') and one girl was sufficiently acquainted with the New Testament to know which apostle (and thus which labelled tree) held the cache. Much joy as they found it and each child got a small toy I had hidden in the box previously :-)
Of course I checked everyone for tics after we left the woods, luckily noone had any!
Two adults then left, but the others wanted to try something harder, preferably on their own [I just tagged along for safety's sake]. The third cache they did (almost) on their own with very little help from me :-) It was a so-called Multi-stage Cache. The first little box merely held a plastic slip bearing the coordinates of the second box. And 500 yards later - with only one hint from me - they found the second box. The second little box merely held a plastic slip bearing the coordinates of the third and final box. After struggling through the thorns one of the larger lads found the final box and everyone signed the log (and I took a GeoCoin out). Struggling back out of the woods, everyone nevertheless agreed they'd had a fun time. Two of the children aim on borrowing the town's loan-GPS receivers as soon as Uwe Jordan has made that loan possible. Let's see how many take up the hobby and stick with it :-)
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Blogfriend encounter :-)
Born again quanta
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