Free Chemical Structures Searching

Editor,

I saw that you have some chemistry-related information at http://www.scifair.org/research/chemistry.shtml. Are you familiar with http://www.FreePatentsOnline.com?

Free chemical searching of the world's major patent collections has been added to the site (http://www.freepatentsonline.com/surechem/).

This allows chemical structure searches on patent data via SMILES strings, or graphical entry of a structure, resulting in far more comprehensive results than regular keyword searching.

If such a search capability would be of interest to your users, a link would be great.

Sincerely,

James Ryley, PhD

Near Spacecraft Questions for Paul Verhage . . .

Paul,

I have been reading your articles in the SAS TCS with some interest. I have also downloaded and am reading your online book and Nuts & Volts articles. This is the kind of science I could get involved in (except for the chasing all across the country).

Some questions I have which I so far have not found in reading your articles. How much RF power have you found is needed for the beacon and telemetry transmitters? Do the ground stations use omni antennas or are directional antennas sometimes used? I signed on to the KNSP Yahoo group. It seems to be only flight announcements and results. Is there any list that has ongoing technical discussions?

Thanks in advance,

Jim Hannon
WB0TXL

. . . Paul Verhage Responds

Jim,

I use a 300 mW radio on my near spacecraft. As long as the antenna is a 1/4 wave dipole and not the rubber ducky, it transmits with plenty of power. A whip antenna on the ground is fine since amateur radios have such good circuitry. If the near spacecraft is transmitting a video signal (high bandwidth), then a directional antenna is needed on the ground. A yagi is good enough for this purpose.

I recommend the GPSL group on Yahoo Groups. Also, if you have the time, plan to attend the Great Plains Super Launch. It takes place at the end of this month and beginning of August. It's free and in Kansas City. Check out www.superlaunch.org.

Onwards and Upwards,

Paul

How Do Vultures Detect Their Meals?

Editor,

I just read Forrest Mims’ wonderful World of Science article "Vulture Season." I live in Trinidad and Tobago in the Southern Caribbean and we have a considerable number of the smaller black vultures. Here they are known as Corbeaux, which is a patois word (an old Creole French dialect) that I think originally meant raven.

Recently on a drive with my wife during a heavy down pour, we saw a number of the birds perched on the highway light poles, typically about four to a pole, riding out the rain. They truly looked miserable in the rain, kind of like a human in a black suit who just got drenched. I told my wife that in the rain they can’t glide because their wings are soaked, hence their sad state of affairs.

I would like to know how these birds detect their meal. Is it by sight or by smell? Either way their senses must be remarkable considering the height of the kettle they usually form in the sky.

Fasil Muddeen
Lecturer, Department of Electrical and Computer Engineering
University of the West Indies
Cavendish Experiment Question

Readers, as I've shared with Fasil, there's plenty of information on this topic online. Can you add anything from personal experience? If so, please send replies to Backscatter so they may be published here. Please use a non-spam subject line to make sure your e-mail arrives. Editor.

A Cavendish Experiment Question

Editor,

I have been studying General Relativity on my own for the past couple of years, and I have a question related to the Cavendish experiment and oscillating bodies that perhaps someone at The Citizen Scientist has experience with.

Do you know of any Cavendish-type experiments where the gravitational source ("the big lead spheres") has been replaced with objects that oscillate rapidly?

The reason I ask is because I am curious to know if the isotropic nature of the nuclear and electromagnetic interactions within the gravitational source is a direct reflection of the isotropic nature of the gravitational potential.

It seems to me that this could be tested if one could make the gravitational source oscillate in such a manner that its internal interactions would be forced to occur along significantly less than three spatial dimensions. I suppose an extreme case of this would involve a body that moves back and forth between two points at a speed as close to c as possible, similar in principle to the photon that bounces back and forth within Einstein's light clock in the rest frame.

Although my question is presented earnestly, it does stand on the edge of fantastic speculation, so I am not certain that it would be something that The Citizen Scientist would be interested in considering for official publication.

Thank you for any information that you may have. I realize that your line of work leaves you very busy, so I will understand if you do not have the time or interest to reply.

Shawn Halayka
Regina, SK Canada

Readers, please send replies to Shawn's question to Backscatter so they may be published here. Please use a non-spam subject line to make sure your e-mail arrives. Editor.

Can Hawks Count?

Editor,

Reading Lewis Smith's letter to backscatter reminded me of an attempt a friend and myself made years ago to photograph a red tail hawk. My friend was quite interested in hawks and had one he was training for falconry. He had been given permission from the wildlife people to keep the hawk. We had set up a blind and arranged a lure to attract wild hawks. My friend said the hawks were very observant and would notice that someone had gone into the blind. But he said that they could not count, so the two of us went to the blind and after a while one left. This was supposed to make the hawk believe that the blind was now unoccupied.

Jim Hannon

Letters to "Backscatter" are welcome. Important: It's very important to use a meaningful subject line! E-mails with subject lines that read, "Hi," "Hello," "Question," "A comment," and so forth are routinely deleted as spam or junk mail. Please include both your first and last name and the author and full title of any article(s) from THE CITIZEN SCIENTIST cited in your letter. We'll add the hyperlink. Letters are subject to light editing to correct punctuation, spelling and grammar. By placing "Backscatter" in the subject line, you give us permission to consider publishing your letter. Send your letter to Backscatter.