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From: dagmargoodboat on 6 Apr 2006 04:47 David DiGiacomo wrote: > In article <1144098413.584807.257510(a)v46g2000cwv.googlegroups.com>, > <dagmargoodboat(a)yahoo.com> wrote: > >Fearful patients going into surgery have much higher > >infection rates (don't have the figures handy). > > That's just a correlation. > > As I said before, maybe the fearful patients can sense that they are > sicker than the more confident ones. Yes, of course. One supposes that competent clinicians are competent enough to anticipate this objection and compare outcomes between patients in similar condition, eliminating your concern. > >Attitude makes a huge difference. > > I don't see any basis for this conclusion in the above correlation. > What's your basis for claiming causation? The section you quoted below was the basis, as well as the data from my mom. I don't expect *you* to believe her reports -- you don't know her. I do. She's sharp, and she's treated god knows how many cancer patients these past 30 years. That's what she does. > >Scads of hard science shows fear > >and distress measureably and dramatically suppress immune function ... > > What's your basis for favoring this over the alternative explanation that > suppressed immune function causes fear and distress? (Or that some as-yet > unidentified factor causes both.) That's certainly an appealing explanation. With any illness, of course distress and anxiety are natural; people who overcome these are the exception. They have better outcomes. > Is there really a way to do a double blind study where random patients are > distressed or reassured to see how they survive surgery? Standardized questionaires could easily be used to assess anxiety. One study compared patients' wound-healing with and without relaxation training prior to surgery. Here's some info on effect of stress on wound-healing: http://www.google.com/search?q=wound%20healing%20days Exercise helps too: http://researchnews.osu.edu/archive/exereld.htm Stress affects lizards too: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16188256&query_hl=7&itool=pubmed_docsum which hypothesizes: when psychologically stressed, energy is diverted from the immune system (fact), presumably to make it available for a hasty escape (hypothesis). Being presumptuous, we presume that lizards do not predict, rejoice, or lament their impending fates. Also, note that wound-healing, like recovering from cancer, is an immune response. I recall a year or so ago it was reported that exercising breast cancer survivors had stunningly lower recurrance rates. I'm personally curious to know whether that'll turn out to be due either to the exercise iitself, or vitamin D obtained thereby. (A credible guy on National Public Radio mused not long ago that vitamin D deficiency is more common than thought, and believes this contributes to a large number of cancers.) Sorry for the late reply ... I missed your post. Best, James Arthur
From: Fred Bloggs on 6 Apr 2006 09:37 John Larkin wrote: > On Sun, 02 Apr 2006 08:10:30 -0700, Jim Thompson > <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: > > >>On Tue, 28 Mar 2006 16:08:01 -0700, Jim Thompson >><To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >> >> >>>In some prior posts there have been inquiries regarding low distortion >>>oscillators. >>> >>>Out of curiosity I simulated a 200Hz oscillator made simply from an >>>A1A-style gyrator BP filter, then wrapped a positive feedback loop >>>around it, with back-to-back diodes used to limit the drive to the >>>input to the BP filter. >>> >>>Result: 3rd harmonic was at -58dB >>> >>> ...Jim Thompson >> >>Nobody has commented on the _oscillator_ ;-) >> >> ...Jim Thompson > > > OK. I don't like railing U5, because it may do funny things to the > delay around the loop, and waste power... some opamps get weird when > you do this. And the diode hard clipping creates more distortion than > you'd get if you soft-clipped the tops of the feedback but left it > sorta sinusoidal. > > I'd expect that you might get more distortion, especially 2nd > harmonic, in real life, as compared to the sim. > > You did ask. > > I should post my 1-transistor, low-distortion, super-amplitude-stable > oscillator, which I did as a kid, for the Boresight Alignment System > on the C-5A. > > John > Single transistor? That would almost certainly be some kind of frequency selective positive feedback into the BE junction of a CE for natural limiting of amplitude- say through a bridged-T feedback. That would limit out to loop gain of one- and play with the DC bias point for low distortion.
From: John Larkin on 6 Apr 2006 11:21 On Thu, 06 Apr 2006 13:37:20 GMT, Fred Bloggs <nospam(a)nospam.com> wrote: > > >John Larkin wrote: >> On Sun, 02 Apr 2006 08:10:30 -0700, Jim Thompson >> <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >> >> >>>On Tue, 28 Mar 2006 16:08:01 -0700, Jim Thompson >>><To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >>> >>> >>>>In some prior posts there have been inquiries regarding low distortion >>>>oscillators. >>>> >>>>Out of curiosity I simulated a 200Hz oscillator made simply from an >>>>A1A-style gyrator BP filter, then wrapped a positive feedback loop >>>>around it, with back-to-back diodes used to limit the drive to the >>>>input to the BP filter. >>>> >>>>Result: 3rd harmonic was at -58dB >>>> >>>> ...Jim Thompson >>> >>>Nobody has commented on the _oscillator_ ;-) >>> >>> ...Jim Thompson >> >> >> OK. I don't like railing U5, because it may do funny things to the >> delay around the loop, and waste power... some opamps get weird when >> you do this. And the diode hard clipping creates more distortion than >> you'd get if you soft-clipped the tops of the feedback but left it >> sorta sinusoidal. >> >> I'd expect that you might get more distortion, especially 2nd >> harmonic, in real life, as compared to the sim. >> >> You did ask. >> >> I should post my 1-transistor, low-distortion, super-amplitude-stable >> oscillator, which I did as a kid, for the Boresight Alignment System >> on the C-5A. >> >> John >> > >Single transistor? That would almost certainly be some kind of frequency >selective positive feedback into the BE junction of a CE for natural >limiting of amplitude- say through a bridged-T feedback. That would >limit out to loop gain of one- and play with the DC bias point for low >distortion. I'll post it to abse later... my camera's not handy. It's actually... common-base. includes frequency trim, but no other adjustments frequency tc below 50 ppm/K amplitude exactly predictable and repeatable, essentially zero tc, pretty much zero component sensitivity; that was a requirement to drive the Talyvel inclinometers. [1] total of 5 cheap parts. In the meantime, speculation is welcome. John [1] dang, they haven't changed much but the color! http://www.taylor-hobson.com/elevels.htm
From: Fred Bloggs on 7 Apr 2006 08:10 John Larkin wrote: > On Thu, 06 Apr 2006 13:37:20 GMT, Fred Bloggs <nospam(a)nospam.com> > wrote: > > >> >>John Larkin wrote: >> >>>On Sun, 02 Apr 2006 08:10:30 -0700, Jim Thompson >>><To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >>> >>> >>> >>>>On Tue, 28 Mar 2006 16:08:01 -0700, Jim Thompson >>>><To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >>>> >>>> >>>> >>>>>In some prior posts there have been inquiries regarding low distortion >>>>>oscillators. >>>>> >>>>>Out of curiosity I simulated a 200Hz oscillator made simply from an >>>>>A1A-style gyrator BP filter, then wrapped a positive feedback loop >>>>>around it, with back-to-back diodes used to limit the drive to the >>>>>input to the BP filter. >>>>> >>>>>Result: 3rd harmonic was at -58dB >>>>> >>>>> ...Jim Thompson >>>> >>>>Nobody has commented on the _oscillator_ ;-) >>>> >>>> ...Jim Thompson >>> >>> >>>OK. I don't like railing U5, because it may do funny things to the >>>delay around the loop, and waste power... some opamps get weird when >>>you do this. And the diode hard clipping creates more distortion than >>>you'd get if you soft-clipped the tops of the feedback but left it >>>sorta sinusoidal. >>> >>>I'd expect that you might get more distortion, especially 2nd >>>harmonic, in real life, as compared to the sim. >>> >>>You did ask. >>> >>>I should post my 1-transistor, low-distortion, super-amplitude-stable >>>oscillator, which I did as a kid, for the Boresight Alignment System >>>on the C-5A. >>> >>>John >>> >> >>Single transistor? That would almost certainly be some kind of frequency >>selective positive feedback into the BE junction of a CE for natural >>limiting of amplitude- say through a bridged-T feedback. That would >>limit out to loop gain of one- and play with the DC bias point for low >>distortion. > > > > I'll post it to abse later... my camera's not handy. It's actually... > > common-base. > > includes frequency trim, but no other adjustments > > frequency tc below 50 ppm/K > > amplitude exactly predictable and repeatable, essentially zero tc, > pretty much zero component sensitivity; that was a requirement to > drive the Talyvel inclinometers. [1] > > total of 5 cheap parts. > > > In the meantime, speculation is welcome. > > John > > > [1] dang, they haven't changed much but the color! > > http://www.taylor-hobson.com/elevels.htm > > This Talyvel inclinometer was some kind of RVDT? From what I see about these things, the amplitude and distortion requirements are whole percentage points and not a lot of effort was expended on producing super pure and stable sine wave generation.
From: John Larkin on 7 Apr 2006 10:55
On Fri, 07 Apr 2006 12:10:45 GMT, Fred Bloggs <nospam(a)nospam.com> wrote: > > >John Larkin wrote: >> On Thu, 06 Apr 2006 13:37:20 GMT, Fred Bloggs <nospam(a)nospam.com> >> wrote: >> >> >>> >>>John Larkin wrote: >>> >>>>On Sun, 02 Apr 2006 08:10:30 -0700, Jim Thompson >>>><To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >>>> >>>> >>>> >>>>>On Tue, 28 Mar 2006 16:08:01 -0700, Jim Thompson >>>>><To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >>>>> >>>>> >>>>> >>>>>>In some prior posts there have been inquiries regarding low distortion >>>>>>oscillators. >>>>>> >>>>>>Out of curiosity I simulated a 200Hz oscillator made simply from an >>>>>>A1A-style gyrator BP filter, then wrapped a positive feedback loop >>>>>>around it, with back-to-back diodes used to limit the drive to the >>>>>>input to the BP filter. >>>>>> >>>>>>Result: 3rd harmonic was at -58dB >>>>>> >>>>>> ...Jim Thompson >>>>> >>>>>Nobody has commented on the _oscillator_ ;-) >>>>> >>>>> ...Jim Thompson >>>> >>>> >>>>OK. I don't like railing U5, because it may do funny things to the >>>>delay around the loop, and waste power... some opamps get weird when >>>>you do this. And the diode hard clipping creates more distortion than >>>>you'd get if you soft-clipped the tops of the feedback but left it >>>>sorta sinusoidal. >>>> >>>>I'd expect that you might get more distortion, especially 2nd >>>>harmonic, in real life, as compared to the sim. >>>> >>>>You did ask. >>>> >>>>I should post my 1-transistor, low-distortion, super-amplitude-stable >>>>oscillator, which I did as a kid, for the Boresight Alignment System >>>>on the C-5A. >>>> >>>>John >>>> >>> >>>Single transistor? That would almost certainly be some kind of frequency >>>selective positive feedback into the BE junction of a CE for natural >>>limiting of amplitude- say through a bridged-T feedback. That would >>>limit out to loop gain of one- and play with the DC bias point for low >>>distortion. >> >> >> >> I'll post it to abse later... my camera's not handy. It's actually... >> >> common-base. >> >> includes frequency trim, but no other adjustments >> >> frequency tc below 50 ppm/K >> >> amplitude exactly predictable and repeatable, essentially zero tc, >> pretty much zero component sensitivity; that was a requirement to >> drive the Talyvel inclinometers. [1] >> >> total of 5 cheap parts. >> >> >> In the meantime, speculation is welcome. >> >> John >> >> >> [1] dang, they haven't changed much but the color! >> >> http://www.taylor-hobson.com/elevels.htm >> >> > >This Talyvel inclinometer was some kind of RVDT? From what I see about >these things, the amplitude and distortion requirements are whole >percentage points and not a lot of effort was expended on producing >super pure and stable sine wave generation. The one we used has a lamination suspended on wires, that moves with inclination and varies the reluctance of a couple of coils, a lot like an LVDT. I think it's filled with oil for damping. I used this oscillator to excite it, and a synchronous detector+lowpass filter to condition the output. Amplitude stability was important, distortion much less so. It also turns out that the output is fairly nonlinear and asymmetric at larger inclinations, so I had to compensate for that. This was about 1972, and I was just a brat, so I can't claim it was the most brilliant design possible. I just thought the oscillator was cute. I had the guys in the machine shop donate a 55-gallon drum. We placed it on the ground-floor concrete slab, filled it with sand, and clamped a 2" thick machined-flat steel plate on top. The guys fabbed a neat platform, pivoted on ball bearings, driven by a micrometer, so I could crank in angles with arc-second precision (finding horizontal is easy: just reverse the Talyvel.) It worked great as long as nobody walked around nearby and bent the slab. This was part of the Boresight Alignment Kit for the C-5A. It worked with a bunch of fixtures, lasers, and retroreflectors to align a bunch of stuff, inertial guidance, compasses, radar, things like that. I got to do the laser power supply, too. John |