ICT PSY1 stem psychrometer: how to apply sensor calibration after recording a dataset

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for the past 2+ years i’ve been working with the PSY1 Stem Psychrometer by ICT International. as with any precision instrument, calibration is a crucial step to ensure good data. however, we’ve found that with some older firmware versions, the PSY1 sometimes just dropped its calibration files and reverted to the generic factory-calibration, which reads at +/- 0.5 MPa absolute precision.
after some discussion with ICT, i’ve put together a little R script that allows the application of calibration parameters to an existing file which was recorded with any (or no) calibration. this way, you can recalculate proper water potential readings from already recorded PSY1 csv-files.

ICT PSY1 stem psychrometer: how to apply sensor calibration after recording a dataset

the complete script, documentation and more are available here: psy-posthoc-calib — bitbucket

[category: science] [tags: , ]

raspberry pi: raspbian jessie start menu screenshots

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when you’re booting up a raspberry pi and have no display/cable/adapter at hand, it can be useful to navigate the start menu blindly using only the keyboard, e.g. to open a terminal and run a short command.

raspberry pi: raspbian jessie start menu screenshots

here are screenshots of the raspberry pi’s operating system and start menu, raspbian jessie (v. 16.02.2017, kernel 4.9) that you can use as a guide: [more...]

[category: computers & technology] [tags: ]

an australian giant cuttlefish changes colour and shape [video]

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cuttlefish are amazing creatures! here’s some footage of one of the resident australian giant cuttlefish (sepia apama) at bass point, shellharbour. it changes not just colour, but also forms seaweed-like appendages on its back to blend in with its new environment.

these three screengrabs from the video above show how much it changed in less than 30 seconds: [more...]

uluru and kata tjuta at sunset [photo]

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here are three photos of uluru (“ayers rock”) and kata tjuta (“the olgas”) at sunset. i have seen many perfect pictures and postcards of uluru before finally visiting the place, but it took nothing away from the sense of marvel and appreciation when we were actually standing in front of these massive rock formations!

uluru in golden sunset light

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[categories: photo, travel] [tags: , , ]

inside the cape otway lighthouse lantern room [360]

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on our great Great Ocean Road road trip, we happened to visit the cape otway lighthouse. i was actually not very interested in lighthouses when we visited the area (and much more excited about the almost guaranteed koala sightings along the road to the lighthouse), but the entrance fee was included in our accommodation and we decided to checked it out. good decision!
it’s a fascinating piece of engineering, and worth talking to a visitor guide who will explain its history and functioning!

inside the cape otway lighthouse lantern room

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[categories: photo, travel, video] [tags: , , ]

pink and purple sunset at wentworth falls [360]

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here’s a 360-degree sunset photo taken at wentworth falls in sydney’s blue mountains, a few days ago:

[category: photo] [tags: , , ]

Archon D32VR: an inexpensive dive light for underwater photo and video

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Archon D32VR photo/video light (a.k.a. Archon W38VR) underwater photography is expensive! underwater housings for digital cameras – point and shoot as well as SLR or mirrorless cameras – often cost much more than the actual cameras, and other components such as underwater strobes or video lights are similarly expensive (starting at 500 USD for the cheapest brand name lights, and >1000 USD for the ones other divers recommend). however, artificial light makes all the difference under water, where light is increasingly limited the deeper you dive.

i’ve been taking pictures with a Sony RX100 and Meikon RX100 housing, and have also shot some underwater video using GoPro cameras (Hero 3 Black and Hero 5 Black), but until now this was mostly with available light rather than an external light source. because i can’t really justify buying these expensive parts with my relatively infrequent diving trips, i’ve been looking for a relatively inexpensive way to get lights that can be used both for video and still photography.

after several nights of online research, i have decided on an Archon dive light which is both very affordable and popular in online forums (and therefore tested by the masses).
here’s my new setup:

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