Month: July 2017

Site performance issues

I am aware that site performance here is less than ideal in at least three ways:

  • Sometimes pages are simply slow to load
  • Pages that do exist sometimes fail to load entirely, producing a 404 error instead
  • Sometimes, pages load without images or CSS, showing only text

It’s much worse on the administrative side, with frequent page load errors and constant problems with image file uploads.

This site is WordPress-based, which means it uses PHP and a MySQL database. Instead of generating each page dynamically every time it is requested, it uses WP SuperCache, and I have tried experimenting with the plugins various settings, so far without fully resolving the problems.

The site is hosted on DreamHost’s standard, approximately $100/year unlimited storage / unlimited bandwidth shared hosting plan. It would be possible to upgrade to a virtual private server, but it’s significantly more expensive and offers rather limited storage (only 30GB for the cheapest plan).

I will work on trying to diagnose exactly what’s causing these speed and reliability problems. If WP-savvy people have any suggestions, I’d be happy to hear them.

Grating coupler arrays as cameras

A recent Economist article describes a novel camera design with the promise to be far thinner than those that exist now, with some novel features:

Not only do Dr Hajimiri’s cameras have no moving parts, they also lack lenses and mirrors—in other words, they have no conventional optics. That does away with the focal depth required by today’s cameras, enabling the new devices to be flat.

…

To mimic the image-making role of the optics in conventional cameras, the OPA manipulates incoming light using electrons. Dr Hajimiri compares the technique to peering through a straw while moving the far end swiftly across what is in front of you and recording how much light is in each strawful. In the OPA this scanning effect is created by manipulating the light collected by the grating couplers electronically, using devices called photodiodes. These place varying densities of electrons into the amplified light’s path through the OPA, either slowing it down or speeding it up as it travels. That shifts the arrival times of the peaks and troughs of the lightwaves. This “phase shifting” results in constructive interference between waves arriving from the desired direction, which amplifies them. Light coming from other directions, by contrast, is cancelled through destructive interference. Change the pattern of electrons and you change the part of the image field the OPA is looking at. Scanning the entire field in this way takes about ten nanoseconds (billionths of a second).

…

To zoom in for a close-up, the device selects a specific part of the image and scans it more thoroughly. To zoom out for a fish-eye, it scans the entire optical field, including light from the edges of that field. To change from zoom to fish-eye takes nanoseconds.

Doubtless, such cameras will have some interesting applications. Unfortunately, that will certainly include further entrenching the surveillance state — increasingly using devices too small to see.

Open thread: pipelines under B.C.’s NDP-Green government

Pipeline politics remain exceptionally contentious in Canada, with one faction seeing them as a path to future prosperity through further bitumen sands development and another seeing them as part of a global suicide pact to permanently wreck the climate and the prospects of all humans for thousands of years.

The replacement of British Columbia’s pro-fossil-fuel Liberal government with an NDP-Green coalition promises to re-open the question of the Kinder Morgan TransMountain pipeline, among other projects.

It also sets up conflict between B.C. and Alberta, and between B.C. and Prime Minister Justin Trudeau, who has so far been pretending quite implausibly that Canada can meet its climate commitments while continuing to allow growth in the fossil fuel sector.

Security of Pakistani nuclear weapons

Nevertheless, the exact nature of launch authorization procedures is ambiguous. Several sources refer to a system of two separate codes—one civilian and the other military—amounting to a “dual key” system. However, several authoritative accounts mention a three-man rule. In particular, the code to arm a weapon can only be inserted in the presence of three persons. It is possible that a two-man rule is adopted for movement of warheads and a three-man rule is adopted for employment authorization. According to Pakistani planners, the number of persons involved varies “for technical reasons”—three at some points in the chain of command, two at other points.

Pakistan is not explicit about its arrangements for weapons security, but it has developed physical safety mechanisms and firewalls both in the weapon systems themselves, as well as in the chain of command. No single individual can operate a weapon system, nor can one individual issue the command for nuclear weapons use. The NCA command and control system ensures that weapons can be operationally ready on short notice, yet unauthorized arming and/or use never takes place.

Pakistan does not keep its nuclear weapons on hair-trigger alert. The nuclear weapons are few in number and probably kept in disassembled form; their components are reportedly stored separately, at dispersed sites. Keeping the weapons in a disassembled form, along with the use of authorization codes, reduces the risk of capture or unauthorized use. Naturally, there is considerable uncertainty about the location of Pakistani nuclear weapons and about procedures for actual use. After September 11, Pakistan ordered a redeployment of the country’s nuclear arsenal to at least six secret new locations, according to one account. Fissile materials are obviously stored in secret locations; probably in initial stages they are near installations such as Kahuta or Khushab, or close to Rawalpindi. Additionally, from a security standpoint sensitive material sites are carefully chosen, in safe areas and within quick reach of designated rapid reaction forces, which are specially trained and operate under command of the security division of SPD. Although Pakistan’s system is not as sophisticated as the U.S. permissive action links (PALs), it is deemed reliable enough to preclude unauthorized arming or launching of its nuclear weapons.

Dummy locations are also reportedly employed to minimize the risks of destruction or capture. SPD Head Lieutenant-General Khalid Kidwai, in a lecture at the U.S. Naval Postgraduate School in October 2006, clarified that “no delegation of authority concerning nuclear weapons is planned.” The conclusion, therefore, is that centralized control is retained by the NCA at the Joint Services Headquarters. Beyond this clarification, operational control plans cannot be made public by any nuclear state and thus remain a national security secret, as was the case with the United States and other nuclear powers during the Cold War.

Khan, Feroz Hassan. Eating Grass: The Making of the Pakistani Bomb. Stanford University Press; Stanford. 2012. p. 331–2