If this can be done in a well-structured manner, it will be of great use to salespeople who wish to demo products without allowing the client to have the product, or to run it unsupervised. The document I am attempting to decipher is HOW TO: Shadow a Remote Desktop Session in Windows XP Professional.
Ingredients
What do you need? You need 1 Windows 2003 Server, 1 XP Professional computer, and then two computers, one for the client and one for the sales person. The tricky thing here is that actually making it work involves giving the salesperson and the client access to the Windows Server. That may not be so good. I wonder if you can just host it on the Win2003 Server instead.
Here's what happens:
Computer 1. Grab a terminal session from the Windows 2003 Server. From this session, open a desktop session to the XP professional computer. The real desktop of the XP pro computer will now be locked.
Computer 2. Grab a terminal session from the Windows 2003 Server. Locate the original session ID using the Terminal Serviecs Manager utility under Administrative tools. Open a command prompt and use the shadow command - e.g., if the ID is 2, then you type shadow 2 in the command prompt.
Crazy huh? To disconnect the shadow (computer 2) press CTRL-* on the numeric keypad. Computer 1 just logs out in the normal way.
I was talking to student of Bruce Wooley's yesterday, and it occurred to me that I need to nail down the requirements for a good dry eeg sensor. What's really needed?
Introduction
Three things are required to do dry electrodes. First, the input current must be small, or somewhat equivanlently, the input impedance must be large. Second, the voltage noise must be small in the frequencies of interest, which, in our case, ranges from 0.1 Hz to not more than 100 Hz. In these regions, flicker noise, or 1/f noise, usually dominates. Finally, there must be compensation for the input capacitance so that every electrode experiences exactly the same phase shift.
Input Current
Really the key, three approaches, original is a dielectric contact, stops the current from flowing, need to compensate for chargeup. This is the Richardson electrode. Second is metal contact, dielectric intermediate, then contact - this is Babak's patent. Finally, we have a capacitor made by air, with some support mechanism. This is the Sussex group. Alternative is to use something with low input current already (like the LMC662) as the basis of the sensor, then any complaints go to the chip designer, not us.
Noise
Solution is chopping. Also, we can use the same concept of chopping to take the signal further out - use two amplifiers.
Phase Shift
Need to compensate, review stuff from Bob Pease.
$TYPO3_CONF_VARS["GFX"]["gdlib"] = 1; $TYPO3_CONF_VARS["GFX"]["gdlib_png"] = 1; $TYPO3_CONF_VARS["GFX"]["gdlib_2"] = 1;
What happens when you connect a battery to a light bulb? How do the electrons know to move? How fast does the signal travel? How does it all get instantiated. I don't know... but I probably should.
Date: Tue, 10 Jun 03 13:56:02 -0400 From: NokiaUSA.CustomerCare@nokia.com To: torque@stanford.edu Subject: Re:Concern about Accessories for my phone RequestID: 1-KKSN0 Dear Elwyn, Thank you for contacting Nokia Customer Care regarding problems encountered with the CARK-143 and your Nokia 7250i phone. We understand your frustration and apologize for any inconvenience. A specific release date for the new Nokia 7250i phone you are inquiring about has not been determined. We do not have information available for Nokia products that have not been released in the United States. Nokia is pleased to honor the one year warranty on our phone models manufactured and sold by authorized Nokia dealers in the United States. Nokia does not promote the export of phones outside of the country of origin. Phone models, purchased in another country, that are in need of repair must be taken back to the point of purchase or the cellular service provider. As Nokia continues to develop and introduce new phone models and accessories in the United States, we will update our U.S. website at www.Nokia.com/us. If you would like to learn more about the features of your phone and receive special offers on ring tones and accessories, please sign up for our Free monthly newsletter at https://www.nokiaconnections.com/. If you have additional questions, please contact us. Thank you for choosing Nokia for your cellular needs. Sincerely, Yezid Customer Care Nokia Inc. Nokia.com/us P.S. In an effort to continuously improve Nokia's service to you, please complete our E-mail Customer Care Survey at http://www.klcsurveys.com/surveys/custcare_0603c.htm. Please copy the link and paste it into the address field of your browser.
Date: Tue, 10 Jun 03 18:34:18 -0400
From: reply.customercare@nokia.com
To: torque@stanford.edu
Subject: Re:Concern about Accessories for my phone RequestID: 1-KKSN0
RequestID: 1-KLA8T
Dear Elwyn,
Thank you for your response to Nokia Customer Care regarding the error
message displayed on your Nokia 7250i phone when attached to your car
kit.
We have not made any announcements regarding the Nokia 7250i phone,
nor have we heard any issues regarding the error message you are
receiving. As the Nokia 7250i phone has not been released in the
United States, we do not have specific information or technical
support for your phone at this time.
Please contact Nokia Customer Care in the country you have originally
purchased the phone from. Nokia warranties are valid only in the
country where the product was purchased and is limited to Nokia
Original products. Thus, Nokia does not promote the export of Nokia
products outside the country of origin.
Malfunction issues pertaining to Nokia Car Kits could be isolated as
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Recognizing what is normal operation for your car kit may be the
issue. A brief review of one or two features may be helpful. For
example, when the phone is connected to the Kit, the menu functions
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phone.
Independent levels for each of these functions will be stored for
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If you prefer, you may send the car kit directly to Nokia for warranty
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Nokia Repair Center
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We recommend that you include a short note with your Nokia accessory
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Sincerely,
Michelle
Customer Care
Nokia Inc.
Nokia.com/us
P.S. In an effort to continuously improve Nokia's service to you,
please complete our E-mail Customer Care Survey at
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I finally located James Roman's Dry Electrodes for Physiological Monitoring. It turns out to be in the library after all! For future reference, in case you do not have access to Stanford Libraries, the place to look is the Center for AeroSpace Information Technical Report Server, DO NOT use NASA Technical Reports Server (see I didn't even provide a link). I finally located the technical note with help from Eric at Government Documents. The classification scheme for this sort of material is poor because it is bound together so that a search on NASA TN D-3414, for instance, will fail because the reference is actually NASA TN D-3403-3423. Even searching on that doesn't work, I don't know how Eric did it, but he is the man.
Introduction
In pursuit of a solution for the rapid application of electrocardiogram (ECG) electrodes for long term recording, Patten et al. [1-2] developed "dry" electrodes based on quick-drying conductive glue. The skin is first prepared by subjecting it to 3-seconds of an oscillating toothbrush soaked in electrode paste. Then, a thin layer of the glue is sprayed directly onto the skin using a spray gun or aerosol package. A thin non-shielded wire is captured in the spray. Finally, the electrode is sealed by spraying a second insulating coat. Because of the high impedance of these electrodes, amplifiers with input impedances in excess of 2 MΩ are required. At the time this was very large, though today people talk about trying to do 100s of GΩs or even TΩs.
Technical details
Conductive glue. The conductive glue consists of silver powder suspended in household cement. The exact recipe is given in [1] and is as follows: combine
Application. A DeVilbiss No. 156 atomizer with two valves and a glass supply bottle was modified to launch a lead wire into the spray using a spring-loaded release rod. Both valves were connected to a single air house, with one valve responsible for spraying the conductive glue and the other for blowing air for drying. The air pressure used was 20 pounds per square inch. The insulation-glue spray is applied using an aerosol container and dried using heated air.
Removal. Electrodes are removed by dissolving them in acetone. This is accomplished by patting them with saturated gauze sponges.
References
[1] C. W. Patten, F. B. Ramme, J. Roman, Dry Electrodes for Physiological Monitoring, Nasa Technical Note NASA TN D-3414, National Aeronautics and Space Administration, Washington, D.C., May 1966.
[2] J. Roman, Flight Research Program III - High-Impedance Electrode Techniques, Nasa Technical Note D-3414 Supplement, National Aeronautics and Space Administration, Washington, D.C., June 1966. Preprint of article published in Aerospace Medicine, August 1966.
What is UDP, and how do I use it? UDP stands for User Datagram Protocol, and it is also known as RFC678. What does RFC stand for? UDP is an alternative protocol to TCP, Transmission Control Protocol, which is used for serving webpages. It is used for a variety of things including networked games. I'm interested in understanding how to read the Endpoint Mapper found at port 135 in Window's machine.
In case you are ever doing regexp with Perl, a good thing to remember is the quotemeta command. This allows you to escape (addslashes) to everything that isn't a regular character or number. Otherwise your regexp can get hosed.
This is an update on Philip Richardson, who, with Alfredo Lopez, invented capacitive electrodes. His email bounced, but I was able to locate his phone and address in San Francisco (he mentioned that he opened a practice in SF on his website). One of these days when I'm brave enough I'm going to call him. Hope that he is in good health.
I found Richardson's classmates from Rensselaer (1960, EE).
I'd like to get this:
DRY ELECTRODES FOR PHYSIOLOGICAL MONITORING , Technical Note
Authors:
C. W. Patten, F. B. Ramme and J. A. Roman
Report Number: NASA-TN-D-3414
Performing Organization:
NASA Dryden Flight Research Center, Edwards, CA
Availability:
Currently this document is not available on-line.
From the NTRS FAQ: Where do I go for a hardcopy of the report?
Report Date: May 1966
No. Pages: 40
for free, how!
Another article, written by the third author, James Roman, is available in Aerospace Medicine 37. Unfortunately, while I was at Lane last week this volume was not there, and the attendants said that it had not been checked out. Perhaps I'll check again today. This isn't as substantial as the first report (40 pages) but should shed some light. I can get the first article at ntrs (nasa technical reports server), but it costs $30. I suppose I can get it... I looked around the Stanford Catalog but could not obtain it. There's yet another one called Method of making dry electrodes which does not have a price or number of pages.
Today I found a document about some work SRICO had been doing with the US Army on dry biopotential acquistion. Essentially their device uses lithium niobate to alter the polarization of a beam of light traveling through a fiber. The major technical challenge is noise from the fiber-optic since microphonic noise can affect the beam. How the contact is made is not completely clear though. The sensor is large, about 5 cm square.
One of the projects on scriptlance today was on plugin detection -- I found the answer here. The way to do it is using Javascript. Just in case the site goes down I've thrown it in this blog. Using this, I wrote a small script which allows you to download PDF's but makes sure you have Acrobat Reader before doing so.
Looking for worship songs for tomorrow I stumbled upon Daniel Azuma's music. Wow, I almost started crying - it brought to mind all the wonderful things that God did at Tech, and how much hope I had. It is a blessing to me - thank you Daniel.
I often find myself avoiding writing for the stupidest reasons. Today I made the excuse that (1) I did not have Endnote or Microsoft Word on my room 28 computer, and that (2) without Endnote I couldn't properly cite stuff. That's baloney, so that I don't lose it, UIUC has 16 examples of how to cite, IEEE style. My thought now is to blog my thesis out. One entry at a time, and then someday I'll put it back together.
Although the patent (US3500823) belong's to both Philip Richardson and Alfredo Lopez, Jr., the earliest substantial paper includes Franklyn Coombs and Robert Adams. With some effort, I was able to obtain the original patent from the USPTO. As far as I know, this is really the first capacitive biopotential sensor, though there are some references that talk about dry biopotential sensing prior to this. Amazingly, Richardson has a web presence and even an email address!
Introduction
The development of capacitive biopotential measurement began in the late 60's with Lopez and Richardson's capacitive electrocardiographic sensor [1-3]. Based on a black stained anodized aluminum electrode and an ultra-high input impedance circuit (30,000 MΩ), the sensor was attached to unprepared skin using an elastic strap.
Theory
Preparation of the skin by abrasion and application of a conductive paste or gel are, for the most part, necessary in biopotential recordings such as electrocardiography (ECG), electromyography (EMG), and electroencephalography (EEG). The reason is to minimize the variation of the impedance between electrode and skin with respect to the input impedance of the amplifier. This, in turn, minimizes the amplitude of motion-artifacts. In ECG and EMG, studies inevitably involve movement, e.g., the aerobic stress test. The impact of this movement is somewhat alleviated by the fact that ECG and EMG signals are measured in the millivolts (mV). In EEG, though much less movement is involved, micro-motion artifacts can still be bothersome, as EEG is measured in microvolts (μV).
In addition to electrode-skin impedance variation, artifacts linked to motion can also be coupled into the signal by polarization effects at the electrode due to non-zero DC current. When the electrode is stationary, non-zero DC current from the sensor causes the system to polarize. Because the system is biochemical, there will be a finite response time. Any sudden shifts in electrode position will require the stystem to restabilize. The voltage shifts resulting from this restabilization will contribute to motion artifacts. This will be very complicated - I would guess that the speed at which the system recovers is related to the amount of input current. The more current there is, the faster the polarization will stabilize. So, it makes sense either to have a lot of input current, or none at all.
The claim of Richardson and Lopez is in convential electrodes, change in ohmic contact (via the paste) is responsible for motion artifacts. Since in a capacitive electrode there is no ohmic contact, then there will be no motion artifacts. That this is true is not completely clear. If there is motion the capacitance may change, which would induce a voltage change.
Electrode
Richardson and Lopez used an anodized aluminum disk as the electrode, though in their patent [3], they claim any conductive material such as "copper, aluminum, or stainless steel having an insulation on its outer or skin contacting surface." In this case, the insulating coating was produced using an anodizing process. Here they claim that the aluminum oxide is used so that the film will be "free from pores or grain structure". To produce the film, they immerse the electrode in a standard sulphuric acid anodizing bath for 1.1 hours. The voltage is brought up to 100V using 100A/sq. ft. The process is finalized by dying the oxide, and immersing in hot water for oxide sealing.
To obtain the dimensions of the insulating layer, they measured the capacitance and back-calculated the thickness. For the said electrode, the resistance was greater than 4 GΩ and the capacitance was 5000 pF at 30 Hz. It is unclear why the capacitance is given in terms of frequency. Assuming a dielectric constant of 9, they calculated the thickness to be 0.7 mil.
Conclusions
Richardson, et al. [1] end with a very important (and honest) point, that "the production of motion artifacts caused by change incapacity coupling... limits the use of this type of electrode." In fact, this will the be the problem with a capacitive electrode-skin junction. With any sort of movement, the capacitance will change because the contact area will change. One way of addressing this is to make the contact area conductive, but to have a fixed capacitor between the amplifier and the contacting electrode.
Further Thoughts
One thing that was not mentioned above is the issue of skin potential artifacts in EEG. Present at low frequencies (<0.1 Hz), these artifacts result from biochemical changes in skin and are related to the galvanic skin response. When necessary, the most common way of eliminating such artifacts is to abrade the scalp aggressively, to the point of drawing blood [4].
References
[1] P. C. Richardson, F. K. Coombs, and R. M. Adams, "Some new electrode techniques for long-term physiologic monitoring," Aerosp Med, vol. 39, no. 7, pp. 745-50., 1968.
[2] A. Lopez, Jr. and P. C. Richardson, "Capacitive electrocardiographic and bioelectric electrodes," IEEE Trans Biomed Eng, vol. BME-16, no. 1, p. 99, 1969.
[3] P. Richardson and A. Lopez, Jr., "Electrocardiographic and Bioelectric Capacitive Electrode," U. S. Patent 14,860,040, March 17, 1970.
[4] T. W. Picton, S. Bentin, P. Berg, E. Donchin, S. A. Hillyard, R. Johnson, Jr., G. A. Miller, W. Ritter, D. S. Ruchkin, M. D. Rugg, and M. J. Taylor, "Guidelines for using human event-related potentials to study cognition: recording standards and publication criteria," Psychophysiology, vol. 37, no. 2, pp. 127-152, 2000.
Yesterday ScriptLance had 43 new projects. Assuming that 50% get filled (which is low), that's 20*5 = $100. Not a huge amount, but not bad. Also, not everyone is referred so it could be a bit higher. $100*30=$3000.
Very interesting, Overture has a place where you can enter in a search term and it will tell you how many times in the previous month that word has been searched for along with suggestions. The only thing I wonder is whether this is equivalent to Google's list - wouldn't you suppose that the audience is different? Anyone who is anyone uses Google.