- OT: Covid-19 personal protection ideas, and related - 10 Updates
- PAL/NTSC - chroma phase vs. colour documentation - 4 Updates
| N_Cook <diverse@tcp.co.uk>: Mar 18 06:30PM On 18/03/2020 14:06, Jeff Layman wrote: >> travel, eat well. > No argument there, except I would use "stop" instead of "limit". If it's > unnecessary, why do it at all? One consideration is the gelling agent must reduce the alcohol content proportion. Part of my mask design is the outer micro-fibre cloth , as used for only an hour is damp, from the disinfectant spray, which I assume is better at trapping aerosols than dry. A functional note, the loop of silicone sleeving requires 4 small thin C-clips to reliably hold the cloth around the underlying dust mask. I sliced up some crimp connector plastic sheathing. -- Monthly public talks on science topics, Hampshire , England <http://diverse.4mg.com/scicaf.htm> |
| Jeff Layman <jmlayman@invalid.invalid>: Mar 18 07:02PM On 18/03/20 18:30, N_Cook wrote: >> unnecessary, why do it at all? > One consideration is the gelling agent must reduce the alcohol content > proportion. I think there is some misconception about the need for it to be a gel. Of course, a gel stays on the hand for longer, but really even a non-viscous solution will do the job if you make sure you wipe all your hands' surfaces carefully. I make my own; see final line here: <https://en.wikipedia.org/wiki/Hand_sanitizer#Composition> > A functional note, the loop of silicone sleeving requires 4 small thin > C-clips to reliably hold the cloth around the underlying dust mask. > I sliced up some crimp connector plastic sheathing. That sounds sensible. Anything which adds to the effectiveness of a mask is worthwhile. You might also want to consider close-fitting googles (see Screwfix ones which hold on with an elasticated band around the back of the head - not one which uses ear bars). -- Jeff |
| gregz <zekor@comcast.net>: Mar 19 07:54AM >> So, social isolation, common sense, clean hands, limit unnecessary travel, eat well. > No argument there, except I would use "stop" instead of "limit". If it's > unnecessary, why do it at all? A mask helps prevent you from touching your mouth area with finger. Greg |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Mar 19 04:20AM -0700 OK, Guys and Gals - time to put a few facts on the table, if you will have them: a) Nothing short of total isolation will stop COVID19, and then only if that total isolation extends for considerably more than the two-week incubation period. Times bandied about by 'the experts' are long enough to push up against the vaccine development time-line. b) Social isolation, hand santizers and any other palliative measures are not intended to stop the virus, but only to flatten the infection curve such that the health systems are able to cope with it. c) Nothing short of an effective virus will actually 'stop' the disease, and that is no less than a year away. d) There are anti-virals, but unlike antibiotics, they are not very effective and come with lots of baggage (side-effects). e) The virus is able to live for hours to weeks on ordinary clothing, ordinary surfaces and so forth. It is able to live as an airborne virus for a bit longer depending on ambient conditions. NOTE: "Weeks" is speculative, with the longest absolutely proven survival being ~80 hours to-date. Please do not time it with a stop-watch and think that one is safe 'just because' some period of time went by. f) Which brings us to masks and goggles. Against "sneezed droplets", has been suggested. Said "sneezed droplets" can (and will) still get onto the wearer of these devices, including clothing, ears, hair, and so forth. g) These "sneezed droplets" will still get onto shoes, surfaces remain as micro particles in the air, become bound to dust, and so forth. So, unless one undresses into a laundry bag on one outside stoop, wears sanitizer-saturated booties and gloves on the way to an immediate shower when home, "and so forth", those masks and goggles are about as effective as nailing Jell-O. Some material may remain on the board, but most of it does not. Ladies and Gentlemen, Boys and Girls, and Children of All Ages - this is the first time mankind has been confronted with a dangerous disease with a long (and silent) incubation period, a relatively high infection rate *together* with a great deal more understanding of how infections work. Every response created prior to COVID19 is instantaneously obsolete - as just a glance out a window, or 5 minutes listening to the news will make clear. Try not to give bad advice conveying a false sense of security or effectiveness. Worst of all, if you believe it yourself and are giving it sincerely. Ignorance is curable, stupidity is not. Learn something before opining. Please. Peter Wieck Melrose Park, PA |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Mar 19 05:14AM -0700 Correction to c): That would be Vaccine..... Peter Wieck Melrose Park, PA |
| N_Cook <diverse@tcp.co.uk>: Mar 19 12:16PM > Try not to give bad advice conveying a false sense of security or effectiveness. Worst of all, if you believe it yourself and are giving it sincerely. Ignorance is curable, stupidity is not. Learn something before opining. Please. > Peter Wieck > Melrose Park, PA Where does the doseage effect come into play? Where a medic , despite normal PPE practices, gets infected, it seems to be more acute in its effect, presumably because ne/she has had multiple sources of infection over days and weeks. If that is the case, then on the other end of the scale, any reduction of the doseage to a joe-public person rarely coming into contact with the virus, would be advantageous, ie reducing the doseage, perhaps redusing the degree of any infection. -- Monthly public talks on science topics, Hampshire , England <http://diverse.4mg.com/scicaf.htm> |
| John-Del <ohger1s@gmail.com>: Mar 19 05:23AM -0700 On Thursday, March 19, 2020 at 8:16:51 AM UTC-4, N_Cook wrote: > of the doseage to a joe-public person rarely coming into contact with > the virus, would be advantageous, ie reducing the doseage, perhaps > redusing the degree of any infection. I wondered the exact same thing when I first read of the Chinese doctor who died of Covid19 despite being young and otherwise healthy. Others have reported the effect being like a cold or even less, so it makes me wonder if the level of exposure is like having a single trooper storming a barricade, or thousands. Worse, it's speculated that those that have recovered from Covid19 are not immune from reinfection. Weird times. |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Mar 19 05:46AM -0700 https://www.healthline.com/health/r-nought-reproduction-number Please quit speculating and get some knowledge. There are two (2) strains of COVID19 (at least) in circulation. Similar enough that immunity should cross between. https://www.forbes.com/sites/brucelee/2020/03/15/can-you-get-infected-by-coronavirus-twice-how-does-covid-19-immunity-work/#dd8a5695c0f8 But this virus is too new and the tests, bluntly, too crude to be fully certain. Generally an otherwise healthy individual does not get the same virus twice. But, as with flue, viruses mutate and change about as often as some here change their underwear, and more often than they change their socks. So one may get many cases of the "flu", just not exactly the same one twice. Once again, this venue demonstrates that speculation, false information, poor logic, false equivalencies, and the need to do things without encumbrance by the thought process are the preferred means for any action, or an excuse for otherwise wretched behavior. If you think I am being snarky - bad information, information based on poor or false understandings, and unsupported advice in this case is, bluntly, fucking around with the lives of Human Beings - and if that is not enough to get one to simply stop doing it.... Peter Wieck Melrose Park, PA |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Mar 19 07:08AM -0700 https://www.livescience.com/coronavirus-myths.html |
| N_Cook <diverse@tcp.co.uk>: Mar 19 02:43PM On 19/03/2020 12:23, John-Del wrote: > Others have reported the effect being like a cold or even less, so it makes me wonder if the level of exposure is like having a single trooper storming a barricade, or thousands. > Worse, it's speculated that those that have recovered from Covid19 are not immune from reinfection. > Weird times. It will be interesting to see how much the mortality rate drops, when antibody testing of the more general public comes in and all the minor cases are addid in. I know someone in the UK who probably had "atypical" Covid19, he just put down to food poisoning and ordinary flu, not the pandemic. Mid Feb 2020 an extended period of disabling dry coughing. Because of the early date and no fever/temperature/tiredness or headaches , he dismissed it. Also about 3 days before he'd serious diarrhoea, intense tiredness and nausea for a day but not actually vomiting, eating next to nothing, put down to food poisoning as no other symptoms. He could not think of a source of such poisoning though, as totally normal food consumption. About 2 clear days between the "food poisoning" and the unremitting coughing,so assumed it was separate issues. Now there is more detailed symptomology out there, there is such as this. https://www.sciencealert.com/latest-research-on-covid-19-reveals-the-pattern-of-symptoms-to-watch-for Early symptoms could also include diarrhoea The new study also found that patients who ended up in the ICU had more abdominal pain and appetite loss than patients with milder coronavirus cases. The researchers noted some early, "atypical" symptoms as well: They found that 14 patients developed diarrhoea and nausea one to two days before their fever or difficulty breathing set in. This might suggest another way the virus is spreading. According to the study, one patient with abdominal symptoms was sent to the surgical department, since the symptoms didn't align with typical coronavirus cases. That person went on to infect at least four other hospitalised patients – all of whom showed "atypical abdominal symptoms" as well – and at least 10 healthcare workers. -- Monthly public talks on science topics, Hampshire , England <http://diverse.4mg.com/scicaf.htm> |
| Rob <nomail@example.com>: Mar 18 07:56PM > It was better in terms of colour fidelity and resolution. It was worse > in terms of flickering, due to lower refresh rate and some el cheapo > decoders being employed too often. The refresh rate has nothing to do with the color standard (NTSC vs PAL), it is because of the different mains frequency in the countries that used the standard, and the advantage of approximately synchronizing the vertical refresh with the mains frequency on older receivers. In Brazil, PAL is (was) used with the same refresh rate as was used for NTSC in the USA. |
| Rob <nomail@example.com>: Mar 18 08:00PM > From what I've read PAL is very similar to NTSC. It has a scheme with a comb filter that makes a phase (tint) control unnecessary, 50Hz frame rate rather than 60 and a higher horizontal rate resulting in more lines in the raster. (your spelling says you are across the pond) The different frame rate is not an attribute of PAL vs NTSC, but of the underlying B/W standard that was optimized for the local mains frequency. PAL is used with ~60Hz frame rate in Brazil. NTSC with 50 Hz frame rate is possible, but there just happened to be no country where a 50 Hz mains frequency was in use and where NTSC color was selected. |
| Phil Allison <pallison49@gmail.com>: Mar 18 02:55PM -0700 Rob wrote: -------------- > The refresh rate has nothing to do with the color standard (NTSC vs PAL), > it is because of the different mains frequency in the countries that used > the standard, and the advantage of approximately synchronizing the vertical refresh with the mains frequency on older receivers. ** Early tube based ( B&W ) receivers were locked to the supply frequency as were the local TV transmitters. This simplified PSU design and prevented hum bars rolling down the screen. Later this was changed to non locked. 60Hz was had an inherent problem cos it conflicted with frames rates used by film cameras. 50 Hz was far better since is was close to double the 24 fps rate used for movies - so on TV they ran slightly faster than in a cinemas. 60Hz TV has to use tricks (repeated frames) to play 24fps movies and can look jerky - even today. .... Phil |
| Silver Dream ! <email@domain.com>: Mar 19 10:39AM +0100 On 2020-03-18 19:56:39 +0000, Rob said: > it is because of the different mains frequency in the countries that used > the standard, and the advantage of approximately synchronizing the vertical > refresh with the mains frequency on older receivers. True - refresh rate is defined in other standards, which define also number of lines. see Rec. ITU-R BT.470-6 p. 2 That was an inaccurate mental shortcut from my side. Caused by the fact that I live on the other side of the pond, where "M" norm (525/60) you refer to wasn't used. OTOH NTSC isn't used with anything else than "M". This opens the trap I fell into and inaccurately combined PAL characteristics with non-M refresh rate/resolution, even if I myself corrected other people on occasions before. > In Brazil, PAL is (was) used with the same refresh rate as was used > for NTSC in the USA. Right - PAL/M -- SD! |
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