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Showing posts from January 29, 2019

Multiple USB streams at the same time

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0 Some computers have multiple USB controllers, for example one on the motherboard and one on a PCIe card. Does anyone know [by actually doing it] whether data can be read from two different devices at the same time? I need to get data from more than one instrument but each one takes more than half the USB 2 bandwidth. They are USB2 devices with no USB3 equivalent. If they were on different controllers that is technically possible. I could do it with an embedded processor with two USB controllers. The question is can Windows 7 or 10 do it? There will be two or more instruments. Each will take close to half the bandwidth of USB2 not so much from the data rate as they are just slow and require several short transfers of query/response for every long transfer. The maximum instrument data rate is 320kB/s. It might be...

Is the total ring of fractions mod the regular functions flasque?

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1 1 $begingroup$ I want to show that $$0to mathcal O_{mathbb{P}_k^1}to mathcal Kto mathcal K/mathcal O_{mathbb{P}_k^1}to 0$$ is a flasque resolution of $mathcal O_{mathbb{P}_k^1}$ with $k$ infinite, but not necessarily algebraically closed. Where $mathcal K$ is the total ring of fractions. I was able to show that $mathcal K$ is flasque, and by extension, the presheaf $Umapsto mathcal K(U)/mathcal O_{mathbb{P}_k^1}(U)$ is 'flasque' as a presheaf. However, being a quotient, we aren't guaranteed that this is a sheaf. I tried to show that it was, but I kept running into troubles. So, instead, I tried to show flasqueness of the sheafification, but again, I couldn't lift any of the maps. Additionally, $mathcal O_{mathbb{P}_k^1}$ isn't flasque; so, I'm stuck. Any advice is greatly appr...