1

Just Chat! / Re: What do you think of copout 28

« on: Yesterday at 14:07:16 »

It is a conference of people who will not do anything because their careers depend on maintaining the status quo.  Politicians have a maximum 5-year horizon and with an average of 2.5y their only interest is in getting re-elected. Kings have a longer horizon but they are either powerless (in a democracy) or corrupt.   Businessmen have a legal duty to maximise shareholder returns. Climate "scientists" and protestors have a vested interest in continued problems, not solutions. The people who will suffer from the changing climate aren't born yet. So nobody inside or outside the meeting will do anything to mitigate the effect  of the inevitable.

2

New Theories / Re: Universal Utopia? What's The Universal Terminal Goal?

« on: 28/11/2023 15:11:01 »

Universal: (a - literal) found everywhere or (b - figurative) present in or adopted or practised by all  humans. You have shown no proof either.

3

Chemistry / Re: A machine that smells as well as a dog

« on: 24/11/2023 19:17:06 »

The breathalyser is very crude compared with even the human nose. The difference is in requirement and specification: for breath alcohol you need a very accurate measure of quite a high concentration of just one material, delivered in a very precise manner. For drugs,  explosives, or hidden people, you need to be able to detect a ridiculously small number (some say as few as 2) molecules of any one of a range of targets which the perpetrator has done his best to hide.

I've worked on breath analysis of a few analytes such as hydrogen, hydrogen peroxide, and COVID. Again, the collector was very precise and the concentration of the target was well within the scope of A level analytical chemistry - several orders of magnitude above a canine threshold.

Not ever policeman or soldier needs a dog, but there are enough folk who want to handle dogs in uniform, and enough dogs that enjoy the work, that the K9 van is usually available when needed, and the occupant is often multiskilled.  You can tell a dog to search an area that is inaccessible to Constable Plod's big boots, or to roam around a dockside where he is "just a dog" and ignored until he finds something of interest.

At one demonstration I learned  that the British army had been asked to supply search and rescue dogs to the Polish police after an earthquake. Apparently it was quicker to teach the dogs Polish commands than to teach the police officers English, and they were on the scene within 2 days.

It is also interesting to note that a lot of sniffer dogs are recruited from rehoming centers. Some dogs are unsuitable as pets because they have obsessive traits, but these are just  what is required: they are easily retrained to hunt for cocaine, gun oil, or whatever, instead of shoes, and aren't distracted by noise or other animals when they are at work.

4

Plant Sciences, Zoology & Evolution / Re: Can Animals Appreciate Beauty ?

« on: 23/11/2023 17:24:33 »

There is no reason to suspect otherwise.

Human senses are very dull compared with most other species, and our brains are so busy with standing and moving on two legs  (a triumph of software over bad mechanical design), warfare, the Meaning of Life,  tax avoidance, and imagined insults, that we probably have far less capacity for aesthetic appreciation than a sheep.

What is this life if, full of care,
We have no time to stand and stare.
No time to stand beneath the boughs
And stare as long as sheep or cows........

WH Davies,1911.

5

Physiology & Medicine / Re: How are humans effected by the seasons?

« on: 22/11/2023 19:24:35 »

Different phenomenon, same cause. If you google "blue light hazard" you will come across all sorts of assertions and denials of permanent retinal damage caused by exposure to intense blue light including the "unshaded daylight" above the  cloud layer. Suffice it to say that the International Commission on NonIonising Radiation Protection recognises a number of effects including disturbance of circadian rhythm and possible macular damage, and has published guidance on safe acute and continuous exposure levels across the visible spectrum. 

The finding that intrigued me was a temporary and possibly cumulative loss of color discrimination at "unshaded daylight" levels of exposure. This work dates from the 1990s  and compared the color vision of military (short sorties, low level, with a helmet and visor)  and airline (long sectors above cloud, no protective eyewear) pilots. Despite being in almost every other  matter recruited from identical groups, airline pilots definitely showed decreased color discrimination compared with military pilots at similar ages, and the temporary acute effect (immediately after exposure) was enough to raise a concern about the conspicuity of "glass cockpit" displays. Guidance from unions and aviation authorities was to always wear sunglasses when flying in the "blue bowl".

6

Physiology & Medicine / Re: How are humans effected by the seasons?

« on: 22/11/2023 10:19:48 »

There is some physiology involved. It seems than an absence of blue light produces "seasonal affective disorder"  in many people, leading to lethargy and even clinical depression. It is thought that the problem is due to the production of excessive melatonin and reduced serotonin but I can't claim to understand the connection between the retina and the hypothalamus.

I worked with a company to optimise the spectrum and dosimetry of "SAD lights", trying to maximise the beneficial effect without inducing blue light disruption to color vision, which has been found inter alia to affect the performance of airline pilots reading modern full-color instruments after flying in the "blue bowl".

7

Plant Sciences, Zoology & Evolution / Re: Can Animals Appreciate Beauty ?

« on: 15/11/2023 19:54:41 »

We really need to address the more fundamental question of what characteristics make a scene visually appealing to us, then ask how these might map onto the experiences, sensory spectrum and aspirations of another species.

I think a lot depends on experience and aspiration (which is to a large extent determined by experience). I recall a woman who had grown up in landscapes dominated by sand and camels, being appalled by the English midlands: "It's all too green!" but on the other hand  when I described Essex to a colleague from Sierra Leone as "flat, dry, sunny, and too cold for mosquitoes"  he said "It sounds like heaven."

8

Physiology & Medicine / Re: How Does The Placebo Effect Work ?

« on: 15/11/2023 16:06:30 »

The placebo may have a curative effect, but the placebo group will also contain a number of subjects who would have recovered with no intervention. This is quite difficult to determine as merely recruiting someone into a trial, even if you gave them no further attention beyond writing down their name,  could be considered an intervention!   
 

9

New Theories / Re: Universal Utopia? What's The Universal Terminal Goal?

« on: 07/11/2023 22:17:12 »

Elon Musk will say anything that makes money, even if it is meaningless. Indeed the best advertising has no meaning, so you can't be prosecuted for failing to deliver.

10

New Theories / Re: Where does quantization of energy of electromagnetic radiation come from?

« on: 02/11/2023 17:39:34 »

Quantisation in analogue to digital converters and quantisation of photon energy are entirely separate phenomena.

What makes them different?

The word has two different meanings (a) representing a continuous function with a discontinuous function and (b) modelling the behavior of electromagnetic radiation as a stream of particles each having a discrete quantity of energy.

11

Physiology & Medicine / Re: What challenges are there in building a better artificial heart?

« on: 28/10/2023 22:57:18 »

The materials problem can be circumvented in principle by using a brushless motor axial turbo pump. Total heart function has been replaced for short periods in animal experiments but it seems that pusatile flow is actually essential to prevent thrombus formation, and whilst a reversible axial turbo can achieve this in principle, it is difficult to prevent damage to the blood cells in contact with a hard edge. Such pumps are used for a short period as left ventricle assist devices  to allow heart muscle recovery.

Powering a implanted pump is a nontrivial matter. FDA will not sanction percutaneous (plug and socket) connection  for a permanent implant and transcutaneous (like a contactless phone charger) charging is still problematic. Although mechanical pumps are more efficient than the real thing, when I was involved in this work we were looking at a continuous 5 watt requirement. 50Wh is obtainable from reliable laptop batteries, and such a device could indeed be implanted, but we faced the same problem as battery-powered vehicles, only worse. You need to restrict your charging rate to prevent overheating - you don't want to raise the local temperature around the battery by more than a degree, or you will upset the body's thermoregulation and produce discomfort if not actual harm. But you don't want to tie your patient to the recharging point for more than, say, an hour per day, perhaps in two 30 minute sessions, so, allowing for battery inefficiency, and a margin of error (you don't want your patient to die because the bus was late)   you need to transfer about 150W (no problem) without cooking the patient (problem!) The solution is to use a large receiver antenna so the power (i.e. heat) lost in the transmission process is distributed over a large area. And now we run into a mechanics and materials problem - human flesh is flexible and elastic: how do we implant a wire cage that doesn't impede movement or breathing, and won't tear into muscles or organs?  Fortunately we have a large, rigid structure with a good blood flow - the head. So we might make a recharging helmet that supplies a coil buried under the scalp. Except that whilst the heart and contents of the chest cavity generally are fairly robust, doing extensive surgery around the head and neck (you need to connect the receiver coil to the battery)  adds a lot of complications because of all the other rather critical "wiring" in the area. Maybe the pelvis, and a "hot seat"?

It's an intriguing prospect for the next generation of clinical engineers. Good luck!

12

Just Chat! / Re: Man suffocates to death from blocked nose during sleep.

« on: 17/10/2023 15:03:21 »

From sleepfoundation.org

Although uncommon, it is possible to die during sleep from untreated obstructive sleep apnea. Observational research has found that OSA increases a person?s risk of sudden death. This risk is believed to be higher in people of older age, in people with a critical illness, and in people with severe OSA.

Most of the time pauses in breathing from obstructive sleep apnea are just temporary. When changes in respiration cause oxygen levels to drop, a person partially awakens in order to restore breathing. However, there are rare reports of people dying because of an inability to properly reinitiate breathing.

When OSA is not treated, it can also interfere with the normal functions of the cardiovascular and nervous systems. This may provoke abnormalities in a person?s heart rhythms and other problems that can cause sudden cardiac death.

13

Physics, Astronomy & Cosmology / Re: Which bit of the Shell theorem is not working?

« on: 16/10/2023 09:02:09 »

I don't recall Newton ever saying that gravity was the gradient of a potential.   It is just the force that a unit mass would experience when it is put somewhere.

No. It is (and always has been) an attractive force between masses. The vector has magnitude GMm/r² and direction toward the barycenter of the masses. In the absence of a barycenter it has no direction.

If you insert an arbitrary point mass in an infinite homogeneous medium, the barycenter is the point mass itself! 

14

Just Chat! / Re: Man suffocates to death from blocked nose during sleep.

« on: 15/10/2023 11:22:44 »

Blocking the mouths of TV presenters is a public service. It should be applied rigorously to priests and politicians.

15

Physics, Astronomy & Cosmology / Re: Which bit of the Shell theorem is not working?

« on: 15/10/2023 11:19:35 »

there is no reason why a well defined gravitational field g can't exist throughout space

There is no reason why fairies should not exist, but in the absence of the Mother of All Fairies, they can't. And in the absence of a density gradient, you can't have a gravitational field because there is nowhere for the vectors to go.

∇anything is meaningless, ergo no field, in an infinite homogeneous medium.

16

Just Chat! / Re: Man suffocates to death from blocked nose during sleep.

« on: 14/10/2023 07:57:35 »

Yes and no! Chronic sleep apnea  (signalled by persistent loud snoring) is associated with cardiovascular insufficiency and symptomatic heart disease, and mouth breathing can be obstructed when unconscious (hence the need to clear the tongue when starting artificial respiration) so it is quite possible that the guy may indeed have suffocated, particularly if he had taken any sedative medication (including alcohol) that suppressed his gag reflex. 

So it's quite likely to be an indirect effect of acute nasal restriction exacerbating a chronic condition. There are plenty of cases where chronic apnea is associated with sudden death when asleep, but the opinion varies as to precise causality.

 

17

Physics, Astronomy & Cosmology / Re: Which bit of the Shell theorem is not working?

« on: 14/10/2023 07:44:46 »

This seems to come down to the question of whether an infinite homogeneous medium can be considered spherically symmetric. Not "from the inside" because of course there is no "outside" if it is infinite.

Rather than wander off into the barren land of philosophy, we can say that anywhere close to our origin is indeed spherically symmetric because it is homogeneous, and anywhere further away becomes increasingly less significant as we increase r, so as r → ∞  the effect of regions > r cannot become less symmetric. 

18

Physics, Astronomy & Cosmology / Re: Which bit of the Shell theorem is not working?

« on: 13/10/2023 22:04:59 »

We'll have a perfectly uniform distribution of Hydrogen gas spread out over space  AND  we'll also assume that space is infinite.   [NOTE:  It is not necessary or guaranteed that the universe is or was infinite,  that doesn't matter, for this hypothetical situation we are having an infinite space].    For a star to form, some hydrogen has to clump together under gravity and form an overdense region of Hydgrogen.

Eppur si muove (Galileo)

19

Physics, Astronomy & Cosmology / Re: Which bit of the Shell theorem is not working?

« on: 13/10/2023 17:40:42 »

But by definition is isn't locally homgeneous. All the particles are moving at random, so the particle density at any point will vary over time from less than the mean to more than the mean, and if D_loc > D_mean you can get gravitational agglomeration.

20

Physics, Astronomy & Cosmology / Re: Which bit of the Shell theorem is not working?

« on: 13/10/2023 16:50:51 »

BC beat me to it by 30 minutes (I was asleep in the garden).