[HN Gopher] Frequency comb breathalyzer detects Covid with excel...
       ___________________________________________________________________
        
       Frequency comb breathalyzer detects Covid with excellent accuracy
        
       Author : geox
       Score  : 82 points
       Date   : 2023-04-07 18:54 UTC (4 hours ago)
        
 (HTM) web link (www.nist.gov)
 (TXT) w3m dump (www.nist.gov)
        
       | RicDan wrote:
       | Whilst n = 170 is not bad, this would still need bigger testing
       | group. But seems promising?
        
       | Centigonal wrote:
       | This technology behind this is very cool - I hadn't heard of
       | optical frequency combs before.
       | 
       | My amateur interpretation is that the device shines light at a
       | breath sample, capturing the signatures of the molecules in the
       | sample (kind of like mass spectrometry), and the researchers
       | trained an ML algorithm to classify the signatures as "COVID" and
       | "Not COVID." For the ML part, the training set was n=140 and the
       | testing set was n=30
       | 
       | I think the point of this study was to see if this approach was
       | even possible, i.e. a proof-of-concept. They have a lot of work
       | ahead of them to see if this could become a robust enough system
       | to be used widely.
        
         | was_a_dev wrote:
         | Frequency combs are awesome, and exploit the relationship
         | between temporal and spatial distributions of light.
         | 
         | To have a short (femtosecond) pulse requires it to have a large
         | spectral bandwidth.
         | 
         | Therefore to create a frequency comb to span a large span of
         | wavelengths requires starting with a femtosecond pulsed laser
         | and all the associated optics to amplify, stretch and "comb"
         | the output.
         | 
         | This is very expensive and bulky, there are some interesting
         | approaches to produce chip-scale frequency combs which may make
         | devices such as this more accessible.
        
       | resuresu wrote:
       | [flagged]
        
       | tptacek wrote:
       | _The researchers measured an AUC of 0.849 for their COVID-19
       | predictions. An AUC of 0.8 or greater for medical diagnostic data
       | is considered "excellent" accuracy._
       | 
       | The AUC of a rapid antigen test is over 97%, right?
        
         | gojomo wrote:
         | That sounds _way_ high, even when the antigen tests were new,
         | if the  'true' condition is considered PCR-positivity.
         | 
         | Rapid antigens miss tons of PCR-positives, but that's not as
         | bad as it sounds because plenty of those PCR positives are
         | unlikely to be very infectious, if at all.
         | 
         | Also, I've seen reports that antigen test false-negative rates
         | have been rising, modestly, with newer variants.
        
           | tptacek wrote:
           | Yeah, that was my next comment --- I just had COVID and
           | tested negative 3 days into symptoms. My question would be,
           | if that's the performance you get with 95+% AUC...
        
       | TaylorAlexander wrote:
       | I remember in 2020 when we thought we'd soon have accurate
       | instant tests at the door to venues so we could with high
       | confidence have safe events. I still wish we had that (today's
       | "rapid" tests don't really work for people who recently became
       | contagious).
        
       ___________________________________________________________________
       (page generated 2023-04-07 23:01 UTC)