21

That CAN'T be true! / Re: Are home water filtration systems a waste of money?

« on: 07/04/2021 18:54:03 »

probably for now osmotic filters are bargain as quality price and availability, but how any nano filters compare to them I am not sure. probably as new potential technology mxens in time will become cheapest and most useful filters but how soon I am not sure ... what is more intriguing is whether any of these could be DIY doable ...

There are a number of different types of water filters for different situations.  Many could be DIY (or in part DIY).

• The simplest "filter" is simply a sediment trap.  Bring water into a tank, and allow any suspended particles to settle to the bottom.
• A sand filter can be small or large, and consists of running the the water through a container of sand.  In many senses, in low density housing, a well or spring acts like a natural sand filter (as long as it isn't contaminated). 
  I'd be curious if one could augment a sand filter with a layer of carbon.  Perhaps even a DIY carbon source. I'd probably do a layer of gravel then a layer of sand then the carbon then more sand.
• "Hard water" generally has dissolved minerals in it.  And, different minerals act differently. 
  
  Mom has Iron in her water.  The filter system oxidizes the water, then filters out the iron oxide, and flushes it back out.
  
  Ion exchange filters are common for calcium and perhaps magnesium.  Substituting Sodium (Na+) or Potassium (K+) for the Calcium (Ca++) or Magnesium (Mg++).  My grandmother had a sodium ion exchange filter, and I thought I could taste the salt but perhaps they had it adjusted improperly.  They also restricted my grandfather's sodium intake for years while putting bags of salt into the water filter.  I think they had enough salt in the water that while it prevented calcium buildup, it did cause corrosion

Many of the ion exchange type filters are basically a tank with a catalyst medium that you flow water through, then periodically flush.  You should be able to purchase the catalyst, but getting the timers for automatic flushing would be tricky. 

I'm not sure about osmotic and nanofilters.  One trick that will help is to have multiple filters, so if you have a very expensive last filter, you're gone through layers of sand, charcoal,and other filters,so you have very clean water going into the special filter.

22

General Science / Re: Why are Tennis Balls hairy or fluffy?

« on: 04/04/2021 19:09:14 »

I'm pretty sure they're designed that way to be comfortable for dogs to carry around, and to absorb dog slobbers.

23

Guest Book / Re: Mods...May i have a lil of your Attention, Please?

« on: 04/04/2021 12:11:57 »

Moderators are not infallible, and we can fix any mistakes we've made.

However, most forum sites get inundated with SPAM.  So, any first post that appears to be not science related, and blatant self-promotion gets intercepted and removed very quickly.

Hopefully rapid response to SPAM helps let potential spammers know they aren't wanted.

Established users that appear to be problematic for the forum will receive warnings before administrative action is taken.

24

Just Chat! / Re: Do most men believe their penis is most important?

« on: 02/04/2021 07:05:09 »

There are, or course, those moments when the bladder is full...  and everything fades from importance beyond emptying the bladder.

As far as personal attributes, I wouldn't think of that particular body part as being a reflection of me.

25

Technology / Re: Microwave side door gap, is it safe?

« on: 01/04/2021 05:56:35 »

EM radiation falls off by the square of the distance. 

I always take a step or two back whenever I put something in a microwave, and resist the temptation to put the nose up to the glass.

26

Just Chat! / Re: Useless factoid of the day

« on: 01/04/2021 02:23:40 »

If the diameter of a circle equals pi then its circumference equals pi squared and its area equals pi cubed. A cubic area! My lord the world makes no sense!

R=½π
Circumference = 2πR = 2π*½π=π²
Area of Circle = πR² = π*(½π)² = ¼π³

27

Just Chat! / Re: Questions pertaining to Notifications on TheNakedScientists.

« on: 31/03/2021 18:46:36 »

The question has been answered...  letting this fall into posterity.

28

Question of the Week / Re: QotW - 21.03.02 - Difference between rechargeable and normal batteries?

« on: 31/03/2021 18:13:24 »

I have to think the answer is somewhat more complex than simple battery type. 

I'm pretty sure years ago I have recharged alkaline batteries.  One can often get a couple of charge cycles out of them, but they also have a tendency to leak, so I try to avoid using them too long.

Button batteries can be marketed as either rechargeable (for example LIR2032), vs non rechargeable (CR2032).  I think the anodes/cathodes may have slightly different chemistries, but one can often get a couple of charge cycles out of the non-rechargeable button cells.

The non-rechargeable batteries often have many more amp hours. 

I wonder if it is not as much of a chemistry issue, but rather a matrix issue.  So the anode/cathode doesn't get fully reconstituted with each charging cycle. 

This is also the reason why some batteries can last a very long time if light cycled, but can be destroyed quickly if deep cycled.

29

COVID-19 / Re: How best to control coronavirus spread?

« on: 30/03/2021 17:57:28 »

I assume you mean virtually joining hands. 

A year into this, and in many places we're certainly seeing the light at the end of the tunnel.  A lot depends on risk factors.  May countries are making progress on vaccinating vulnerable people, so encourage anybody that is elderly, or has risk factors for an adverse outcome to go ahead and get the vaccine (and continue isolating until a few weeks after all recommended doses).

Also get the vaccine if you might put others at risk.

Then over the next few months, everyone should go ahead and get the vaccine.  If we can knock down community spread, it will help prevent new variants from popping up.

Until then, be safe, and consider the impact of your actions on yourself and others.

30

Just Chat! / Re: Questions pertaining to Notifications on TheNakedScientists.

« on: 29/03/2021 19:24:56 »

Have you updated your notification preferences?
Go to your profile, then "Modify Profile/Notifications".

https://www.thenakedscientists.com/forum/index.php?action=profile;area=notification

Set your notifications as you like.

Ok, I've updated mine to "daily".  I'll see when the notifications roll in.

31

The Environment / Re: What would happen if all of humanity vanishes in one second?

« on: 29/03/2021 18:40:42 »

The survivors obtain it from the millions and millions of metal coins left lying around in the debris of the old, now extinct civilisation.  The old coins - the nickels, dimes and quarters, get "mined". Then hammered and beaten into new arrow-heads.

It's a long time since I read "Earth Abides", and my memory of it has faded .  However I do seem to remember that one of the characters in the book - was it "Ish", raises objections to this method of "mining".  On the grounds that it's not the true creation of new artefacts from raw materials, but more akin to mere "scavenging".

I think Ish gets confuted, but can't remember how.

The "value" of antiquities changes over time.  And, a sustenance society would likely put very low value on them. 

Many of our greatest ancient treasures were mined in one form or another including the metals being stripped from the Roman Pantheon, and limestone taken from Egyptian pyramids and marble removed from other antiquities.

Even today we mine coal which we know is full of fossils, as well as many fossil stones without thought of the life that brought it into existence.

With conservation of matter, everything we have ever dug up out of the earth still exists somewhere in one form or another.  Toxicity aside, our landfills could be full of precious metals for future generations.

Over the next few million years, new mineral veins will be formed or exposed, and much of earth will be reset.

32

General Science / Re: Does pressure in a thermos flask affect the temperature of the water inside?

« on: 29/03/2021 09:43:07 »

Will the release of pressure in the thermos affect the temperature of the water inside it?

Pressure will change the boiling point of water, of course.  So, for example, in your car radiator pure water will boil at about 100°C.  Pressurize it and it will boil at a higher temperature.  Ignoring antifreeze which will impact it further. 

If you heat water up from say 30°C to 100°C, it will also increase volume due to thermal expansion, and cause an increase in pressure in a sealed container.

Even if your container of water isn't experiencing a rigorous boil, it will exert a certain amount of vapor pressure.  Without pressure a seal won't make much difference.  But, with pressure the vapor pressure should be higher.  Lowering that vapor pressure will cause more evaporation, and thus cooling of the liquid.  Replacing the moist air above the liquid with dry air will also cause more evaporation and cooling.

I was wondering if there's a way to introduce a water heater coil without interrupting the vacuum or are there better ways to boil water in a flask with a let on?

I think I've seen travel mugs (sealed?) with 12V heating elements. 

However, if you have a non-metallic container, then you could try a microwave.  There are some cases where metal can also be introduced to a microwave to improve heat transfer.  I'm not sure the limits, but years ago I worked a job that used a RF curing oven with a metalized glue.  Of course, metal without sharp edges can also be used as a shield in a microwave.

33

The Environment / Re: What would happen if all of humanity vanishes in one second?

« on: 29/03/2021 08:29:59 »

If you are talking "replacement species", give it some time.

The first mammal appeared with the dinosaurs a little over 200 million years ago.
The hominid/ape divergence was probably 10 to 20 million years ago.
Homo Sapiens (pretty similar to us) evolved 200 to 300 thousand years ago. 
Homo Sapiens likely had favorable weather similar to our own during the Eemian interglacial period, a little over 100 thousand years ago.
Yet, almost all of our "modern" history (animal domestication, crops, stone construction, etc) dates to around 50 thousand years ago.

It is hard to predict what would replace us.  Some of the more intelligent species may be the elephants and whales, yet they lack opposable thumbs, although the elephant trunk is extremely dexterous.  There are, of course, the apes,that are perhaps 20 million years behind us.  Canines? 

During the next few million years, the earth will evolve significantly.  The current surface will be buried.  New volcanoes.  Surface weathering in some places.  Earthquakes and uplifting in other places.  Rain forests will get buried and begin making new carbon deposits.

Have we used up all the "reduced carbon"?  Not exactly.  Around 3 billion years ago, our planet had a mostly Nitrogen/CO₂ atmosphere.  Then life turned the CO₂ into oxygen and various hydrocarbons, leaving us with almost no CO₂ in the atmosphere, to the point that it was almost too low for plant life during the glacial periods, and thus dangerous for all life on the planet.

There remains the amount of reduced carbon on our planet, somewhere, equivalent to about 20% atmospheric oxygen.  And with all of our burning fossil fuels, we've changed that by about 0.01%.  I.E.  A lot of reduced carbon left somewhere.

Keep in mind that humanity also used sticks and stones for hundreds of thousands of years before finally discovering metals and smelting. 

Aluminum is supposed to be relatively common.  I know where I can find some green rock, probably fairly high in copper and other minerals.  Silicates, of course, are critical for modern life, and extremely common. 

A future society might learn to mine our current society, whether it is hunting for oxidized iron compounds to more long lived copper, brass, bronze,and various rare earth metals.  Fort Knox could be literally a gold mine once it is found. 

Lime is pretty good at preserving reduced iron which could be a big bonus for a developing society.

I.E.  If humans were to disappear (and most animals were to survive, what we leave behind will likely be a huge benefit to a future society. 

Of course, it might take quite a cataclysm to wipe out humanity, which could erase the world back to the mouse evolutionary stage

34

Physiology & Medicine / Re: Is it possible to increase muscle mass by doing endurance training?

« on: 17/07/2018 05:09:19 »

Can't say if you will start speaking with a slur and looking like Sylvester Stallone.

However, the more you exercise, the stronger you will get.

However, you need to incorporate medium and high intensity exercise, including the muscle groups you are interested in.

35

General Science / Re: VACCINES INTERVIEW

« on: 16/07/2018 21:55:34 »

There are some vaccines that cause disease at either a more mild form, or lower incidence rate than the wild disease. 

For example, OPV (one of the primary Polio vaccines) rarely will cause polio. 

However, since beginning a global eradication program, we've gone from about a half million (estimated) cases of polio down to 12 endemic wild type polio cases and 14 circulating vaccine derived polio cases this year.  Yep, a big chunk of the current cases are a result of the vaccine, but the total number of cases are only a tiny fraction of what we had pre-vaccination.

Other vaccines target specific side-effects of the disease.  HPV vaccines appear to be efficacious at preventing long-term development of cervical cancer. 

The Rubella vaccine has been effective at reducing disease associated pregnancy complications.  Obviously men don't get pregnant, but there are benefits of immunizing everyone and reducing the disease incidence in the population as a whole.

36

Question of the Week / Re: QotW - 18.02.11 - How does size affect death from falling?

« on: 30/06/2018 19:57:26 »

I have to wonder if there is also an evolutionary effect. 

So, for example, cats and squirrels climb trees...  and presumably occasionally fall out of trees.  Survival would be of great evolutionary benefit.

A dog (small dog?) doesn't naturally climb trees, and thus might not be expected to fare as well from a fall.

If the theory holds true, then one might expect animals such as mountain goats and mountain sheep to also fare reasonably well with falls.

Monkeys and related animals climbing trees?

37

General Science / Re: Why do women typically have long hair and men short hair?

« on: 09/06/2018 01:14:32 »

Pragmatism? In some traditional-male occupations, long hair might be a liability?
Warfare? In a fight, hair can be used against you.

Evan,

I think you may have just proven the benefit of the bald gene in men (but not women).

Not all cultures cut their hair.  I believe native Americans traditionally kept long hair for both men and women.

I have to wonder if hair might have been part of the divergence between humans and the animal kingdom.  You mention fighting, but some hair may be of benefit in the animal kingdom, as much of the fighting has to do with teeth and claws.  Hair can be slick, but also having the assailant getting a mouth full of hair may be protective.

On the other hand, with humans with the opposable thumbs, letting the assailant get a hand full of hair could be one's downfall. 

It is interesting that human hair seemed to grow shorter and sparcer than other primates except on the scalp, and on Men's faces.

38

Technology / Re: How dangerous are self driving cars?

« on: 21/03/2018 08:49:48 »

Computer vision is a difficult problem, but no doubt getting better. 

In this case, the reports are that the woman stepped out in front of the car.  What was she wearing?  Lights?  Everything seems to indicate that using visible light, she would have been difficult to see, and likely would have been hit be many human drivers.

However, I think there are likely several things that could have been improved.  For example passive IR might be good for night detection of life. 

The car is supposed to also have various types of active imaging that isn't necessarily dependent on visible light.  So, when was the woman first detected?  Could she have been detected earlier?

Part of driving is to anticipate that others will do stupid things.  So, perhaps slow down or move over to create a larger buffer around pedestrians, cyclists, and others that might cross one's path.

A lot of it is basic defensive driving.  Not really a "fault" thing, but rather just rules to be safe on the road.

We'll see what the final report about the incident says.

39

Physics, Astronomy & Cosmology / Re: Which is the Closest Star to Planet Earth ?

« on: 21/03/2018 06:54:08 »

It looks like we need to kick our space program into high gear.  We have about 10,000 years to get to Barnard's Star, otherwise we may never have another chance.  20,000 years to get to Lalande 21185 before it is gone. 

The Centauri cluster of stars will be hanging around a little bit longer, but still, it might not hurt to try to get a rocket out there in 20,000 to 30,000 years. 

And, with our current rocket speeds, we may have to get an early start on some of the trips. 

40

Physiology & Medicine / Re: What would happen if you stabbed yourself through your upper trunk?

« on: 18/03/2018 10:14:47 »

Probably a combination of a lack of anatomical knowledge coupled with an aversion to sticking things into oneself deters most people from trying to kill themselves this way. People aiming to commit suicide "like" the idea of dying (more than they like the idea of being alive) but that doesn't mean that they like the process. As a result, approaches that are very fast with little margin for error or reversing the process tend to be preferred: jumping from a height, medications, hanging and so on.

At least in the US, there are somewhere between 10:1 and 30:1 suicide attempts vs successful suicides, with men choosing more lethal guns more frequently than women, and women tending to choose drugs frequently with less lethal results.

It may well be that some of the attempts are actually cries for help, without consideration of the most lethal method, at least for those that are unsuccessful.

I presume a portion of the choice of methods is what the individual considers least painful.  So, taking drugs and "going to sleep".  Slitting one's wrist may seem to be less painful than trying to cut one's face and neck.

Even a choice of shooting vs cutting may be a choice of what may seem quick, easy, and with the least pain.  Perhaps jumping falls into the same category.

Of course, with the use of guns, people do typically aim for the head, and sometimes miss.