Monday, March 29, 2010

My Eye!!

Many of the Pixar animated movies have a few catch phrases like "I'm okay!!" or "My Eye!!" Having only been to an eye doctor once before, years ago, to find out if there was any reason to be concerned about "floaters," today I went to find out whether there was anything more to the blurry focus in my right eye than just the ordinary effects of getting older. I was relieved to learn that "I'm okay!!"

I learned a few more things about eyes too that I might have figured out, based on what I know about photography, if I'd given it any thought. For the few weeks prior to the eye exam today, I had been checking each eye under different conditions so I'd have more useful ways to describe how my right eye was bothering me. One thing I had noticed is that in lower lighting, one of my eyes seemed to give me a darker image but the same wasn't true in the brightly lit outdoors. The other thing I noticed is that looking at certain things like a television or the moon seemed to cause double vision worse than other things like a shelf full of small objects or dishes on a table.

So, as it turns out, my right eye is just not focusing quite right any more at a distance. However, that didn't readily explain the comparative brightness in low light only. If I had thought a bit about it, I would probably have remembered that to increase the depth of field, i.e. expand the range of things that are projected sharply on a camera's back-plane, the aperture can be made smaller. This lets less light through, so the projected image, although sharper, is also darker. With a camera, a brighter flash can offset the darker image but with an eye, the available light is fixed. Apparently, one of the things the eye will do in order to compensate for the failure of the lens shape to project a sharp image on the retina is to constrict the pupil to increase the depth of field. So, like a camera with the aperture narrowed, less light gets to the retina. It makes sense that blurry results in darker, but it isn't really obvious.

Double vision puzzled me because it seemed to only appear when I viewed things that were far away, somewhat high contrast, and, to the naked eye, essentially 2D / flat, like TV or the moon. I probably learned in grade school that the image projected on the retina is actually inverted up/down left/right from the scene that appears before the eye. The brain does the work of flipping everything back around so it all makes sense and you don't end up reaching low and to the left to catch a ball passing high and to your right. The brain also compensates a little when your eyes don't quite line up with one another. That's easy for 3D objects that are up close because the actual image differs enough that the brain is composing a 3D perception anyway. When the brain is attempting to align the distant image from two perfectly focused eyes it's easy to match up edges too, but when one of the eyes is sharp and the other is blurry, the brain-alignment doesn't work as well. The result is that the brain partially surrenders the task of compensating for what is perceived as physical mis-alignment of the eyes, and delivers a halo or a double image. This also makes perfect sense if you consider the challenge of overlaying a blurry image and a sharp image in a graphics program like Photoshop. It would be almost impossible to determine the exact positioning with crisp edges upon which to align in only one of the images.

So this simplified explanation is for my own benefit later, when I've forgotten what I came to understand today, and it's here in case someone else stumbles over it and finds my particular way of explaining it easier to understand than some other way.

Thursday, March 18, 2010

Two Things Wrong with Health Insurance

1. Most of it is NOT insurance!

Insurance is a concept of voluntary pooling of resources to counteract a potential risk that, statistically, could never affect all of those pooling their resources, but will, statistically, affect a very small percentage of those pooling their resources to a degree that would require the most or all of the resources that have been pooled. Insurance isn't too different than a bet on a race where the loser is awarded the winnings. Just like bets though, it would never be fair to enter the game once you already know the outcome. If that were allowed, those who pooled their resources with the expectation of offsetting their own risk would ALWAYS lose.

Health insurance that pays for pre-existing conditions is NOT insurance. Because employers forcibly set aside part of their employee's compensation as a health care "benefit" and government regulation (COBRA) forces employers to accept known risk with new employees, most health insurance is a coerced sharing system where the healthy are compelled to bear the cost of the unhealthy.

2. If the health insurance business actually provided insurance, the profitability could never get so wildly out of control.

The business of insurance should be a service that is provided to those pooling resources to assess the risk, determine differential cost based on risk, and prevent fraudulent claims on the pooled resources. For this, the administrators of an insurance plan, as a neutral third party that manages the pooled resources, are due a reasonable fee for performing that service, but they are not entitled to keep a share of the pooled resources based on their ability to deny the distribution of those resources.

This may sound anti-capitalist, but it is no different than saying that a bank is NOT entitled to claim, as their own, the money they have on deposit so long as they can keep their customers from coming into the bank to make a withdrawal. There is opportunity for insurance companies to earn what they're paid by providing a legitimate service, just as banks do. That still fits perfectly in a capitalist based economic system.

Friday, March 12, 2010

A "Likely Story" from an EBay Seller

I purchased something on EBay on the 3rd of the month and got a USPS tracking number back right away. I was thinking I should probably see the package on about the 9th. However, on about the 10th, the info reported on the USPS tracking web site from the tracking number I was given still said:

    The U.S. Postal Service was electronically notified by the shipper on {-month-} 4, 20xx to expect your package for mailing. This does not indicate receipt by the USPS or the actual mailing date. Delivery status information will be provided if / when available. Information, if available, is updated periodically throughout the day. Please check again later.

So, I was getting a little worried that I was being scammed (which, despite EBay's efforts to fight it, is still WAY too common on EBay), so I sent a message to the seller on the 10th to ask if the item had actually shipped yet. The reply I got was as follows:

Note: The names, etc. below are redacted (edits in [brackets]) for now, just in case it isn't that of which it reeks.

    I would first like to apologize for your purchase being delayed.
    ...My name is [---------] ...I am part owner...and I have been out of town along with [----] the other owner since [the] 1st.
    ...Our Shipping Manager of 4 months....has been printing orders off Pay pal to make them look as if they are being shipped.... but in fact as we found out late last night, when we returned.. They have not been shipped.
    ...We have basically been robbed blind by someone we had trusted.
    ...No orders have shipped out since [the] 2nd.
    ..He has stole everything we had in stock and new shipments that have come in. In all we have been robbed of over 2700 [item-1] and almost 3000 [item-2].
    ...where as we have had Him arrested this morning...He refuses to tell the Police where the merchandise is.
    ...We have another shipment coming in on the 12Th....along with other dealers who are selling us some items to help to cover shipments that have already been paid for...and we have called in extra help to assist us with getting all orders shipped out [the 12th].
    ..I am very sorry for any loss of business this may have caused many of our dealers...and to any of our regular customers who where just buying these for personal use.
    ...Please feel Free to call me if you have any questions at [000-000-0000]
    ..please leave a message if you get voice mail due to high call volume I will be expecting.
    ..I will call everyone back.
    ...again...There is no way to explain how embarrassing this is to us as a company and I can only Hope that you will understand that we are working hard to process each and every order to make sure we get every ones items shipped out in a timely manner.
    ...please, as stated above...if you have any questions ..please call me.

    - [-----------]

I'm posting this in case this seller's excuse for not shipping something is habitual, and so that if someone else gets a similar story from this seller, they might find this, outside of EBay, as an indication that they're being jerked around by the same seller. Other feedback comments from buyers for this seller are nearly all positive and contain many reports of immediate shipping, but curiously, there is no gap in the dates of those feedback items as you might expect if nothing had shipped for a week. Perhaps the seller was actually robbed by his shipping guy, and perhaps the timing of my purchase was just that precisely bad. However, it seems very fishy to me that the seller happened to have suffered this misfortune exactly one day prior to my purchase, and then happened to return home and discover it on exactly the day I decided to inquire. If there were a way to ask EBay to take a look at past communications sent from this seller, I wouldn't be surprised at all if I learned that a nearly identical set of circumstances happened to have been described by this seller in the past, to other buyers, as an excuse for non-shipped items.

I finally received the items I purchased on the 17th but I remain suspicious that the story I got was just a stall tactic. If anyone finds this and has been told a similar tale, send me a message with names. If they match, I'll confirm.

SELinux becomes SDLinux

I still don't know how it happened, but on my CentOS 5 (a.k.a. Red Hat Enterprise Linux 5) system, something changed the SELinux context of the /etc/services file from what it is supposed to be to object_r:rpm_script_tmp_t. Several days later, I noticed that no messages were being added to system logs. /var/log/messages was empty. /var/log/secure was empty. /var/log/cron was empty. Just about every log file written to /var/log ended up with 0 (zero) bytes.

My guess is that some RPM I installed, or that got installed via yum, changed the SELinux context of /etc/services. So, without log messages, the security of the system is a bit degraded (so I'll dub that SDLinux for "Security Degraded Linux"). My first thought was that somehow someone managed to get past the certificate-only source-ip-restricted SSH login and zap the logs. However, since no additional log messages were being written, that isn't as suspect as I had feared.

To get logging started again wasn't too complicated:
  1. restorecon /etc/services
    (changes the SELinux context back to what it should be, which is
    system_u: object_r:etc_t)
  2. service syslog restart
Testing to be sure things were working was easy too:
  1. logger -p daemon-warn "this is a test"
  2. tail /var/log/messages
Verify the SELinux context for /etc/services is correct with:
  • ls -Z /etc/services

Here's a reference to the bug that makes this quieter and uglier than it should be: