Archive for January, 2011

Can you imagine walking this street blindfolded? Thanks to the help of guide dogs, those who do have vision loss are not alone.

While out and about on the busy streets of New York City, you can see some pretty fascinating things. One thing that has always fascinated me is seeing people with vision loss make their way around the bustling streets of Manhattan alone. Well, not entirely alone. They have an amazingly talented canine companion with them, their guide dog. This is not just any dog, it has been extensively trained to proudly and precisely lead the way for its owner or handler.

But guide dogs do more than just lead the way! They have to know how to work as a team with their handler to keep them both safe at all times. This means stopping at all curbs and remaining there until being told to proceed, stopping at the bottom and top of stairs, and watching out for narrow passageways or low hanging beams overhead that the handler would not be able to fit through or might bump their head on! That to me is really profound, they are actually aware of the physical space around not only themselves but also around the much taller and larger person next to them. Guide dogs also know how to carefully navigate through the environment around them. They easily move around obstacles and ignore distractions such as food, other people, and other dogs. These dogs are so smart they actually bring their handlers up to elevator buttons and also can bring them to familiar destinations that the handlers ask for, like their favorite coffee shop or their doctor’s office. Boarding buses and subways is also not a problem for the dog and their handler (source 1). These dogs give their handlers a sense of freedom and independence that they may not be capable of otherwise without the help of a friend or family member.

Perhaps the most incredible thing these clever canines practice is something called Selective Disobedience. This means ignoring the handler’s verbal commands when the dog knows it might put them both in danger! It takes a very intelligent dog to override all his training and trust his better judgement against the word of his owner.

Black Labradors are one of the types of dogs picked to be guide dogs, although this little guy is a Lab/Boxer combo.

You might think that these dogs do so much work that they have little time for play but that is not the case. They, like some people, actually enjoy their work, it gives them a sense of pride and energizes them. When the work day is done and they are at home and out of their harness, they can play and receive praise just like other dogs do (source 2).

However, if you see a guide dog ‘on the job,’ meaning, in its harness with its handler, it is important not to talk to the dog, pet the dog or offer it treats. Doing so may distract the dog from its crucial role of helping its handler and staying focused.

To find out more information about guide dogs, or to learn how you can help raise guide dog puppies for a year before they go into ‘active duty’ at the training academies, you can visit the following websites.

Guide Dog Foundation for the Blind on Long Island in Smithtown, NY

Freedom Guide Dogs Central New York near Utica, NY

Also, please consider making a donation to this inspirational and important cause. I hope you enjoyed reading this article as much as I did writing it! I learned a ton and my appreciation and amazement for guide dogs and their handlers grew tenfold. What a great team!

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Copying this Blog

If you find the information from this blog useful and you would like to copy it for your own personal or professional use, it is required that you contact the writer of this blog first, Dr. Cheryl G. Murphy. You can easily do this through the ‘Contact Me’ page of this blog.

I would then be happy to grant permission for my articles to be used by others on a case by case basis as long as I am cited as the original author wherever it is copied (be it websites, blogs, social media sites such as twitter and Facebook, pamphlets or any other form of distribution, hard copy or web-based.) The citation should be in 8 pt font or larger; a proper example would be: “Original article written by Dr. Cheryl G. Murphy.”

A link back to the original article is also recommended and very thoughtful though not required as long as the original author is clearly displayed as previously explained.

Thank you for reading this blog and liking its content! I am honored that others think of it so highly that they would like to quote from it as long as it is done in the right way, plagiarism is not ok.

Now let's get ready to learn something new!

Sincere Thanks,

Cheryl G. Murphy



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This is a question that most kids ask their parents at some point, but does the average adult really even know the answer? In order to truly understand why the sky is blue we must first review a couple of basic concepts about light and the atmosphere.

Roy G Biv, if you please

The light from the sun is white light. White light contains all of the colors of the rainbow. You may remember “ROY G BIV” from science class. The mnemonic device, Roy G Biv, helps us remember the colors of the rainbow or visible light spectrum which are Red, Orange, Yellow, Green, Blue, Indigo, and Violet. These colors travel through the air like waves and they have different wavelengths. Red has longest and lowest frequency wavelength (let’s think of it as being long and strong). Blue is one of the smallest and highest frequency wavelengths (he is the little guy, the pushover).

Rayleigh Scattering, Big Red gets through, Lil' Blue not so muchAs the white light from the sun shines down, it travels through the atmosphere but not without encountering obstacles along the way. The white light bumps into particles of solid and gas in the atmosphere. When the different wavelengths of light hit these different particles, some of the colored light is absorbed and then re-dispersed and scattered all about. This happens most often to short wavelengths of light like blue, remember, he is the pushover and gets pushed around by those particles a lot. Longer (and ‘stronger’) wavelengths of light with lower frequencies like Red, why he is so strong he moves right through the atmosphere and all of the particle matter practically unscathed. This phenomenon was first observed by John Tyndall in 1859 and became known as the Tyndall effect. It was then studied further by Lord Rayleigh and is most commonly known as Rayleigh Scattering to physicists today. However, Rayleigh Scattering wasn’t fully accepted until Einstein confirmed it by applying a detailed formulation to calculate the scattering of light by molecules in 1911. So, since we have all of this blue light being absorbed and bounced around all over the atmosphere and in every direction, it becomes the main color dispersed in the atmosphere. And that is the short answer (was it really?) to why the sky is blue!

Go get a latte, come back, and I will talk to you about sunsets next.

You there? Ok, great. Let’s get started. First, before we bid the topic of the bright blue sky adieu, some of you that have already had your coffee before you started reading this article may have caught a little flaw in the explanation of the sky being blue. I said that the smaller, high frequency wavelengths of light are the colors which get thrown around the most by particulate matter in the atmosphere, that they are the pushovers. However, have you stopped to think about the whole spectrum of color.

Violet is the shortest wavelength of visible light, shouldn't he scatter most?

Blue is not the wavelength with the highest frequency in the visible spectrum (think back to ‘Roy G Biv’). Indigo and Violet are on the spectrum after Blue, they have even smaller, more frequent wavelengths than blue. So why is it that the sky is not Indigo? Or Violet, the shortest of all wavelengths, shouldn’t Violet be the wavelength to scatter the most?

One reason why the sky isn’t Violet is that Violet gets scattered by the higher atmosphere and is already absorbed and scattered so high above us that we don’t really see its hue in the sky. Another reason is our eyes are actually LESS sensitive to the color Violet and MORE sensitive to the color BLUE! Yes, that is right, our eyes actually pick up on the color blue easier and more readily than Violet. Let’s ‘take a look’ at the eye and see why this is so.

Our retina (which is like the film for our eyes’ camera) has rods and cones in it. The cones are the color detectors’ and there are three types, red, green and blue. When these color detectors are stimulated in different proportions, a color is formed in our mind’s eye. Since the sky has the least amount of red light scatter (remember, red is the long and strong wavelength, undeterred by particles in the atmosphere), the red cones are stimulated only a small amount when we look at the sky. The green color detectors are stimulated a little more than the red and the blue color detectors are stimulated the most when looking at the sky (because blue scatters best). The colors of Indigo and Violet actually have a slight reddish tinge to them so the eye has its red color detecting cones stimulated again, but a little more than before this time. The net result is that the red and the green color detectors in our eyes are stimulated by about the same amount when we look at the sky, while the blue color detectors are stimulated much, much more. So BLUE WINS and again, we see the sky as being the color blue, not Violet. (Sorry, Violet.)

Ok, our last quick factoid about the sky has to do with sunsets. Again, we will go back to concepts we talked about earlier in this article, one of which is how Roy G Biv demonstrates for us how ‘long and strong’ red wavelengths of light are and how small and easy-to-push-around blue wavelengths are.

The light from the setting sun has to travel a far distance along the horizon to meet your eye. That means its white light is traveling through the lower atmosphere, the air closest to earth. The lower atmosphere can be filled with large solid or vapor particles in the air such as pollutants, vapors, dust, ash, pollen and even salt from the sea. On a clear day, the sky and the setting sun will appear yellow. However, when there are solid or vapor particles in the air, these particles are big and they can sort of ‘block’ the smaller wavelengths of light before the light travels the distance to your eyes. Sometimes only the “longer and stronger” wavelengths of visible light can make it through the obstacle course of the lower atmosphere to reach your eyes. That is why our eyes see the sunset in wonderful shades of red, orange, yellow and maybe even pink.

Simply, beautiful. Simply Science.

Hope you enjoyed today’s topic! I would be happy to take suggestions for more, if not, I will find some inspiration again soon, don’t you worry!

(drawings and sunset photograph all by C. Murphy; do not duplicate)


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Just wanted to announce a new category of articles I will be hosting on my blog, this new category is going to be called, ‘Your Vision, Your World.’ I have written about many subjects pertaining to eyecare and why it should be an essential part of your health check-ups and your life. Since I now feel I have written about a lot of topics that are sort of, FAQ by patients to their eye doctors, I thought I would have a little fun and venture out to explore outside of the box to teach you a little bit about your vision and how exactly it takes in all of the information in the world around you. If you are into science, or have always wondered about things like ‘why is the sky blue?’ then you will love this category of posts. Writing about it is nostalgic for me because it gives me the chance to imagine myself back in Science class, sitting at my desk with my large spiral notebook, jotting down in amazement all of the beautiful answers and factoids about the world that science had to offer. These articles will be less formal and I will probably make a few corny jokes here and there or explain things in a silly way but hey, we might both get a laugh out of it or learn something new together.

Sincere Thanks to my loyal Readers and

Hello to the new ones,

Cheryl G. Murphy, O.D.

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