reference request – What are some advanced background topics I’ll need for distributed systems and networks research?

I am a new graduate student in Computer Science who would like to be able to read and understand modern and new distributed systems research papers. My current background / courses and understanding is in the level of undergraduate and beginner graduate level courses in:

  • Networks (TCP/IP stack and applications)
  • Distributed Systems (Graduate level course with Time (logical/vector clocks), 2PC and 3PC, Multicast and membership, election, Consistency , Consensus and Quorums (Paxos), DHTs and Overlays and some modern applications like ZooKeeper etc)
  • Undergraduate Algorithms, Discrete Mathematics and Theory of Computation (basic DFA/NFA and intro to Turing Machines with no rigorous mathematics)

However, I find this background insufficient to read modern research in networks and distributed systems and in particular, I am not aware of modern protocols like QUIC and the formal methods mentioned in the papers which I believe include some sort of model checking and the likes. Also many of the topics I have mentioned above in distributed systems – I lack the background to verify and prove correctness of these protocols and even follow the proofs that they have given.

Any suggestions on a reading list that can prepare me to be in a position to understand modern research in this area would be very helpful.

depth of field – How can I maximize the “blurry background, sharp subject” (bokeh) effect?

Here’s how to make the background as blurry as possible while keeping the subject sharp.

It’s the contrast between a sharp subject and a very blurry background that makes this effect stand out. Simply setting a wide aperture and getting a shallow depth of field is not how you get this effect, because then the subject may not be fully in focus. Background blur depends not just on the aperture setting, but also on the positioning of the camera, subject, and background, and on the the focal length of the lens.

First, decide how large the subject should appears within the frame. That’s the magnification (relative to the frame size, ignoring differences between formats). The magnification is an important aspect of the composition that will probably override all other considerations for sharpness and blurriness, so this procedure assumes the relative magnification will be decided first and held constant.

Next, find the largest aperture (smallest f-number) that keeps the subject entirely in sharp focus. That means the focus field must be just deep enough to include the subject front-to-back, with nothing in front of or behind the subject in sharp focus. Focus must also be set accurately to include the entire subject. Note that the subject appearing sharp on a screen (or in a print) depends on how it is viewed. If you are viewing the image on a screen at reduced resolution or from a far distance, more of the image will appear sharp (that is, the focus field will be deeper). So try to emulate the final viewing conditions as best you can. If you want the image to appear sharp according to the limit of your camera’s resolution, use your camera’s focus magnification feature to zoom in all the way as you are adjusting the aperture and focus. For a given magnification and format, the focus field’s depth depends largely on the f-number, and is largely independent of the distance between the camera and the subject, and the focal length. So with the aperture now set, it shouldn’t require much adjustment from this point on. (Though with the subject very close to the camera and with a very wide lens, the focus field is deeper for a given f-number and format.)

With the magnification and the f-number now set and held constant, background blur is maximized by maximizing the camera-to-subject distance and the subject-to-background distance. Longer focal length lenses let you move the camera further from the subject and increase the background blur while maintaining the desired magnification.

Shooting indoors, where the camera-to-background distance is constrained, background blur is maximized by placing the camera as far as possible from the background, and placing the subject halfway in between. If your longest lens doesn’t give you enough magnification, move the subject closer until you get the magnification you want.

Shooting outdoors where the distance to the background is large, use your longest lens and back the camera far enough away from the subject to achieve the desired magnification. A more distant background will appear blurrier, but the effect increases more slowly as the distance approaches infinity, so don’t worry about trying to make the subject-to-background distance really large.

Note that moving the camera back also changes the perspective, making background objects appear larger relative to the subject.

A note about formats and lenses: If you are shooting with high magnification, the focus field will be shallow even at moderate f-numbers, and so having a fast lens is not important. In fact you might not be able to get the entire subject in focus even at the lens’s smallest aperture setting. Smaller format cameras have lenses with smaller apertures, which can overcome this problem. If you are shooting with low magnification (the subject is far away or the angle of view is wide), the focus field can be deeper than you want even with a fast lens. Larger format cameras can overcome this problem by having lenses with larger apertures.

mac – MacOS Dock disappears and background black when connecting monitor

My dock disappears as soon as I connect my display. The Dock process is killed. When I disconnect, the Dock process becomes available.

➜  ~ killall Dock
No matching processes belonging to you were found

Looks similar problem to this question, although for them it is happening with their main display. My OS is latest – Catalina 10.15.5 (updated May 26, 2020)

I am also unable to change the background. The settings all work fine, just the background doesn’t show. Before you answer about showing/hiding dock settings, or changing background, this question is something else entirely:

  • my monitor is 4k 60Hz, works fine with my wife’s Macbook (exactly same model), with same usb-c cable, same settings. I just plug the USB-C cable to mine and don’t do anything different
  • there are other monitors I have tested that have the same problem with my mac. Although, it’s random (sometimes they work with no problem). My monitor just always has this problem since last month’s update
  • I have tried deleting the finder plist and dock plist and restarting. But probably those have nothing to do with the problem
  • I tried resetting NVRAM and PRAM. This problem seems to be something screwed in OS settings

I am suspecting this may be a problem in the settings of how my mac handles a display, and I was wondering if there’s a way to reset the detection of monitors or display settings/configurations altogether. Also, how can I force-start the dock with the monitor?

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magento2.3 – Add div background image in email template

I have created a custom email template and I want to add background image to one of its div element. I have added html file in my email with below content.

    background-image: url('{{view url="My_Module/img/myimage.png"}}');
    padding: 20px 60px;
    background-size: cover;

But its not working. It removes whole style tag from my div in final email.
If I am using complete image static url, it works correctly like below.

    background-image: url('');
    padding: 20px 60px;
    background-size: cover;

Please note here that I want to add background image and not img field with src. I have checked and found that the image path is correct so no issues with image path here.
Does anyone know how we can add background image in email template content.

lore – What is the scene depicted in the second “Waterdeep Digital Background” art?

In the Free Remote D&D Resources archive that Wizards of the Coast is providing, for April 30, 2020 there is a “Waterdeep Digital Backgrounds” zip file that includes artwork that one might be able to use as a background while videoconferencing. The second file (named “DnD_Video_bg-WDDH2”) looks to be a scene outside of Waterdeep proper, with people along a path, a building (maybe some kind of temple), and the wall of Waterdeep in the background. I’m presuming putting a smaller version here counts as fair use:

Waterdeep scene 2

What is that building, and more generally where is this scene set? Is it part of the Waterdeep: Dragon Heist book or storyline? (I don’t remember seeing it in there, though probably I just missed it, but the filename saying “WDDH” makes me think it’s related.)