Telescopes
Pipdog
7 years ago
last modified: 7 years ago
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Covid-19 Wrong End of Telescope?
Comments (114)I just heard Jacob Ward* on CNN say a few interesting things. 1. That with the case of the woman patient in Northern California, 36 nurses had to be quarantined! That’s a lot of staff missing from duty. 2. That the travel ban is misdirected. (Could you guess that xemophobe Stephen Miller wrote Trump’s speech? “Foreign” Disease.” The Covid-19 virus is here in the US and elsewhere already already. (not sure if rest is from Jake Ward or another good guest) 3. TESTING TESTING TESTING (and no backlogs, please)! Testing allows epidemiologists to learn where our own hotspots are. We need to be able to plan & allocate resources. A few days ago, some expert said that one thing large scale testing for the Covid-19 virus does, is allow pretty good zeroing in on who’s got the virus, where they are. They (epidemiological detectives) can interview patients and use various paper, mobile phones and electronic tracking to help them figure out common trail and sources. (Cue up Forensic File music.) 4. One of the expert guests suggested, depending on how “hot” your area seems to be or likely will be, to postpone elective surgery to free up hospital beds. I guess my surgery is elective ;-/ but I am in significant discomfort/pain. I think it is a go home that day, but light general anesthesia or just put me in a coma. Small joint surgery. Alisande, Isn’t that laparoscopic gb surgery pretty much go home the next day? See what your docs advise. 5. The US has tested only a few hundred and there is a backlog on getting the tests processed. South Korea has tested a few thousand individuals, and weeks ago. The US has handled this situation so very poorly. The virus has exploded in such a short while. Maybe someone has accolades for the CDC leadership (Reddington (spelling), a nodding bobble head. Top leadership has been abysmal. Don’t hold out for a vaccine, even in 18 months. This is a tremendously difficult thing to achieve with a coronavirus. We can attempt to slow the spread, to flatten the curve, but this disease is going to sweep over us. “Social distancing” is one way to help slow things down. It is too late to stomp it out (on this planet anyway). Gird you’re loins, folks. Seniors congregated close together in nursing homes is a perfect set up for lots of very ill and dying citizens. It’s not going to be nice. ”We’re fighting an enemy and we don’t even know where it is,” says Ron Klain, former Obama Ebola czar, speaking of the incredible lack of testing. He also said that when you look at the Johns Hopkins virus map and see no red dots or blobs in an area (day Maine or Gondwanaland), it cannot be interpreted as meaning no Covid-19 there. Rather, it indicates that there has been no testing there. (Returning my tix to Gondwanaland.) * Jacob Ward is excellent. Smart, calm, trained, experienced....See Morerecessed ceiling hood vs telescoping downdraft?
Comments (14)Hard to find two different ventilation approaches that deviate so much from the efficient performance achieved by (and demanded from) commercial hoods. Downdraft Pop-ups. These cannot flow much air and cannot capture effluent except that which rises next to their tiny intake vents. If the greasiest food to be cooked is slowly simmering bacon on a back burner, then they might be functional. And in the illustration, the downdraft is narrower than the cooktop, violating the required function of capturing rising and expanding cooking plumes. Ceiling registers. Even those that provide filtering over their entire area have a few issues. First, the plume expansion, along with the effects of drafts, requires the ceiling area used for capture to be large, at least a foot wider and deeper than the cooktop. Airflow requirements, and make-up air requirements, will demand a large CFM blower for each. The particular design shown seems to have metal plates with slots at the edges. This should be good for added noise, and higher velocity plumes may easily reflect from the flat areas and thence out of the effective capture area of the slots. The mesh version should be chosen. Cleaning could be difficult. Cooler plumes at the ceiling might affect how much grease condenses where -- I have no data. Commercial ceiling ventilation such as Haydahl supplies http://www.kitchen-ventilation.co.uk/heydal generally cover large areas and have specialized grease containment or destruction schemes. Opinion. If my only two choices were the ones proposed by the OP, I would be forced to go with the ceiling vent, only because that is where the cooking plumes will go no matter what the pop-up attempts to achieve. I would use a pair of the largest mesh units, tied to suitable ducts and blowers, or maybe joined into a 14 inch duct with a roof mounted up-blast blower. If attic room allowed, I would use a compatible Fantech silencer to go with the roof blower. A largish passive or active MUA system would also be needed. Flow velocity measured below the ceiling should be at least 60 ft/min, assuming some cooling of the plumes, 90 otherwise. So multiply 60 times the areas of two 63 x 27 inch units and get 24 square ft x 60 = 1400 CFM actual. Zero static pressure blower rating would have to be in the 1800 CFM range, depending on the blower's fan curve, the mesh filter pressure loss, duct pressure loss, and imperfect MUA pressure loss....See MoreAdvice on Buying a Telescope
Comments (10)Add Celestron brand to your list of considerations. What to get for the first optical device for a 14 yr old is a shot in the dark unless you know his interests, experience with distance viewing devices, and degree of maturity. You need to mention other important factors, one being access to a dark night sky, and another, the neighborhood. You did say you were on a lake. Are you in a rural area with widely spaced neighbors, or do you have nearby neighbors. [Neighbors can get upset if they think someone is trying to look into their windows to spy on them. If your grandson has an expressed interest in astronomy, then a good telescope may be a great gift. If you don't know, don't force, Talk with him enough to explore is interests and wishes and let that be your guide. A good entry point might be binoculars. These are portable and can offer many hours of medium distance viewing. I recommend starting with binoculars suitable for bird watching. A pair of 7 x 35 wide angle are easy to use. When hand-held, the scene will be steady and offer pleasant viewing. aA you go up in magnification and narrowing of the view angle, the scene get jumpy not satisfying. I have a pair of 8 X 50 binoculars. Those are nice, but I can not hand hold a steady view. Some sky viewing can be done with binoculars and is easier for lengthy periods if the instrument can be mounted on a tripod. With binoculars, you can get a good view of the moon, and planets are visible. You may not be able to see the rings of Saturn nor any of its moons. Stars will be just stars, but you might see a few more. Ok, let assume that you heart is set on a telescope. (I don't own one, but do know a little about those.) No matter which type you buy, you will need a mount, the bigger the scope, the more stiff and strong the mount must be. Don't skimp on the tripod. One accessory I recommend for serious viewing is a drive mount that compensates for earth's rotation. Depending on the angle of view of the 'scope, an image of the moon can move across the entire view in 5 to 15 minutes requiring constant fiddling with the aim to keep an object in view. A drive mount will allow time to study an object and you can look away and 10 minutes later, your object is still there. There are 2 types of telescopes, refractory and mirror. The refractory type has uses all glass optics whereas the mirror type uses a mirror for its primary light gathering device. In general, in the same price range, the mirror can be made larger than the lens, thus has more light gathering power per dollar. Also, the mirror type can be made shorter and more compact. A primary parameter of a telescope is light gathering, the more, the better. The amount of light it can gather is a direct function of the area of the lens or mirror. For the mirror type, there are some loss due to secondary mirrors and lens at the center of the 'scope's barrel. Losses in the refractory type is due to the amount of glass the light must pass through. Also, there are optical aberrations that need compensating lens. A simple scope usually has a small lens (about 4 to 5 inches) without compensation. The perfect shape for a lens is parabolic, however, most glass lens are spherical owing to the manufacturing process for grinding to shape. When the lens diameter is small, the error is also small. The error grows with increasing diameter. Glass lens also have chromatic aberration; The spectrum of visible light does not all bend exactly the same while passing through the lens. The red end of the spectrum bends a little bit differently than the blue end causing color fringing in the image. A good camera lens adds extra pieces of differing glasses to compensate for this, but this will be missing in low to medium priced telescopes. Adding extra glass reduces the amount of light passing to the viewer. It adds cost, too. I have seen hobby kits where you grind your own objective glass, These are limited to 3 or 4 in diameter, and when you are finished (after many hours of lens shaping and polishing), you'll have a small telescope that works, but have low light gathering power and very small viewing angle. These are good for a hobby project and to learn about lens grinding, and that's about it. For more serious sky viewing, I lean toward bigger light gathering power which favors the mirror type. If you must cut cost, omit the drive mount, but do select a telescope that has provision for a drive. This can be added later if Grandson's interest grows. It'll make another a really nice gift a year or 2 later....See MoreTelescope Casual Patio Furniture
Comments (0)Does anyone own this brand patio furniture? 15 year warranty but 4K for a 6 top 84” dining set. Been in business since 1905 so must be doing something right. I have come across limited forum posts about Telescope patio furniture....See MorePipdog
7 years agocmm1964
7 years agoPipdog
7 years agolast modified: 7 years agoveggiegardnr
7 years agocmm1964
7 years agoFun2BHere
7 years ago
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