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  1. tt_beginner is offline
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    Aaland
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    #41
    there are 2 kinds of DJ40+ ?

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    #42
    BTW, I am upset with myself that I didn't pay to be tested to see if I am naturally immune. If so I wouldn't have to worry about shots. Now Pfizer is saying a third shot may be required. This is BS. Will it ever end?

    Not 100% impossible you may have some natural immunity, if, say, you have been infected with a different coronavirus earlier in life. On the other hand at your age really, why risk it? The new SARS-COv2 variants in particular are likely to make whatever earlier immunity people have less effective and they are more dangerous.

    As for the possibility of needing a third shot, from what I can see it's too soon to say. But biology is not BS. Here is why a booster could be needed:

    The virus mutates during replication at a certain rate. The more it replicates inside people, the more it mutates. The more the pandemic is raging, the more variants will emerge. Every once in a great while a mutation will make it spread better. One way it can do that is by getting into cells better, which also makes it more lethal. (It's not the only way, but it's the way we are seeing in the new variants). The S proteins on its surface are what it uses to get into cells. Those proteins are exposed on the surface and therefore the best targets for vaccine development. Therefore, certain mutations in the S protein can make the virus get into cells better and simultaneously make it so the antibodies we produce may have lower binding affinity for the mutated virus (as we are actually seeing). Now, if we make enough of the antibodies and memory T and memory B cells in response to the current vaccines it probably doesn't matter if the antibodies have a bit lower affinity for the virus. That is why existing evidence indicates that current vaccines are working against the new more dangerous variants. However, one thing we don't know is how long the immune memory induced by the vaccine lasts. So, if (1) the virus mutates so that your antibodies are not recognizing it as well, AND (2) if they have gotten better at binding to ACE2 and getting into human cells, AND (3) if over time we produce a weaker immune response, then yes, a booster shot would be in order (especially if we can administer a vaccine that is tweaked a bit to recognize the currently prevailing variants better). At the present time there is reason to believe that factors 1 and 2 are happening. Factor 3 is not yet known and would probably vary from person to person anyway. The question then is whether the sum of these three effects is big enough to really matter. So far things seem ok but things could change over time. The good thing about mRNA vaccines is that they can be tweaked very quickly. In other words, it is biology, not BS.

    Of course, if you are Pfizer or Moderna, this is also $$$. They are not entirely disinterested parties.

    The best way to prevent this is for the virus to stop replicating, which happens when every person it gets into has a strong immune response to it (they get the vaccines) and if people for just a bit longer take the sensible precautions.


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    #43
    Quote Originally Posted by langel
    What do these percentages mean?
    What is it in numbers?

    are the prescribed parameters of the balls, the percentage indicates the maximum deviation for, weight, roundness and hardness.

    dhs-729.eu

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    #44
    Quote Originally Posted by tt_beginner
    there are 2 kinds of DJ40+ ?

    yes, there are two from the basic DHS D40 + model
    DJ and DJW are exactly the same, only they have stricter quality criteria.

    dhs-729.eu

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    #45
    Quote Originally Posted by harty

    yes, there are two from the basic DHS D40 + model
    DJ and DJW are exactly the same, only they have stricter quality criteria.


    How do you tell them apart? Where on the box are they labelled?


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    #46
    Quote Originally Posted by harty

    are the prescribed parameters of the balls, the percentage indicates the maximum deviation for, weight, roundness and hardness.

    Explain it please, I can.t get it.

    If a ball is expected to have standard weight of 2.7 gr., what would be its min-max weight with 25% deviation?


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    #47
    Quote Originally Posted by harty

    yes, there are two from the basic DHS D40 + model
    DJ and DJW are exactly the same, only they have stricter quality criteria.

    ok, so basically there is only the D40+ and DJ40+?

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    #48
    Quote Originally Posted by tt_beginner
    ok, so basically there is only the D40+ and DJ40+?

    is the basic model D40 +
    DJ and DJW is a selective selection of the D40 + model
    the only difference is in tolerance, where the DJ has stricter criteria than the DJW
    I cut two pictures from the DHS catalog
    Figure 1
    Figure 2

    dhs-729.eu

  9. Baal is offline
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    #49
    In other words DHS is saying that their D40+ balls suck. So you should buy the DJ40+ (which they promise won't suck) or better yet buy Nittaku Premium (Japan). Those are not to be confused with Nittaku ***, which are actually rebranded DHS D40 and therefore suck. But not as much as they did a few years ago.

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    #50
    BROKEN BALLS GONNA TO TELL THE WHOLE TRUTH.
    A fellow engineer of mine, has given a great idea to me. He proved, through mechanical laws of spherical solids, that the balls with a thin outer shell will always be MORE spinny. The newly developed ABS balls all were found to have a distinctly THICKER shell as against the celluloid.
    Hence, of all the ABS brands currently on market, those with a thin shell will be my topmost preference. I picked up some broken balls and made scrupulous measurements for shell thickness. DHS proved out the thinnest, XSF - the most solid shell.
    Make your own choice, please.

    https://sun9-13.userapi.com/R3WYQMa5...UPvoEu41oU.jpg

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    Last edited by igorponger; 3 Weeks Ago at 11:04 PM.

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    #51
    Quote Originally Posted by igorponger
    BROKEN BALLS GONNA TO TELL THE WHOLE TRUTH.
    A fellow engineer of mine, has given a great idea to me. He proved, through mechanical laws of spherical solids, that the balls with a thin outer shell will always be MORE spinny.
    Not always. The ball with the smallest radius and lowest rotational inertia will be more spinny.
    If two balls weigh the same and have the same outside radius then the ball with the thicker shell will be more spinny. This is because more of the mass of the ball is closer to the center of rotation. This means the rotational inertia will be lower.

    Celluloid balls are spinnier because they are a little lighter and the radius is a little smaller. This means the rotational inertia is not as great.

    igorponger needs to find a new engineer or maybe igorponger misunderstood the engineer.
    Why is this so difficult?

    Find the equations for rotational inertia and calculating the angular velocity as a function of tangential speed and radius.

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    #52
    Quote Originally Posted by brokenball
    Not always. The ball with the smallest radius and lowest rotational inertia will be more spinny.
    If two balls weigh the same and have the same outside radius then the ball with the thicker shell will be more spinny. This is because more of the mass of the ball is closer to the center of rotation. This means the rotational inertia will be lower.

    Celluloid balls are spinnier because they are a little lighter and the radius is a little smaller. This means the rotational inertia is not as great.

    igorponger needs to find a new engineer or maybe igorponger misunderstood the engineer.
    Why is this so difficult?

    Find the equations for rotational inertia and calculating the angular velocity as a function of tangential speed and radius.

    Exactly


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    #53
    I'm still wondering what is the actual meaning of "25% weight deviation".


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