1

Chemistry / Re: How do you make a mirror?

« on: 19/10/2018 05:11:47 »

I've used a similar approach to silver-coat the inside-surface of a round-bottomed flask in order to make a scientifically-inspired Christmas baubal. The ammonia solution is very strong and you need good ventilation.

I'm not sure what the tin chloride solution does and why you need that - anyone know?

2

That CAN'T be true! / Re: Do photons, neutrinos and dark matter have a structure?

« on: 15/10/2018 10:46:25 »

Er either I'm really jetlagged or none of this makes any sense whatsoever...

3

Question of the Week / Re: QotW - 18.09.30 - Is second hand smoke more dangerous than smoking a cigarette?

« on: 07/10/2018 15:46:30 »

For many carcinogens and poisons (including cigarette smoke), risk increases with exposure.

Interesting choice of words, @evan_au , begging me to enquire what carcinogens and poisons do not follow a dosage-dependent relationship?

4

Physiology & Medicine / Re: What is the pathophysiology and histopathology of cataract?

« on: 07/10/2018 09:53:32 »

This is a very helpful article about the biochemistry and pathogenesis of cataract formation, which might help you.

5

Physiology & Medicine / Re: Why do people punish themselves sometimes?

« on: 25/09/2018 22:13:20 »

What do you mean by "punish themselves"?

Are you referring to "punishment" in the Max Moseley sense (https://www.dailymail.co.uk/news/article-1033319/Our-kinky-games-Max-Mosley-Girls-tell-sex-session-Grand-Prix-boss--deny-Nazi-orgy.html) or do you mean people self-harming as a means of psychological release, or people who inflict self-deprivation to atone for a perceived failure or expunge feelings of regret?

6

Physics, Astronomy & Cosmology / Re: How do you steer a rocket following take-off?

« on: 08/09/2018 10:55:32 »

Thanks both.

the atmosphere is a real drag, so you want to go vertically to get above it as quickly as possible.

That's a really good point and I should have said that in passing. I'll commit that to memory.

attaining a stable orbit means that you need to be traveling horizontally at about 11km/second.

That sounds a bit fast, @evan_au - I had in my head that orbital velocity is about 7km/s and escape velocity is about 11km/s?

Turning east gives you a useful 1000 mph contribution to speed in that direction

Thanks for that @alancalverd - I did say this on the radio and I was relieved that you agreed with me!

7

General Science / Re: What do nerves do in a human?

« on: 02/09/2018 09:58:15 »

This video we made about how nerves work might be helpful:

8

Physiology & Medicine / Re: How does peritoneal dialysis work?

« on: 02/09/2018 09:54:07 »

Dialysis is indicated when a person's own kidneys fail; in an acute setting, and in chronic kidney conditions where other options may not be suitable, this is usually acheived by placing a tube into a large blood vessel and pumping blood through a partially permeable filter system that uses osmotic and concentration gradients to equilibrate and correct the blood biochemistry.

This sort of process is very invasive, takes a long time and is therefore inconvenient for the patient. Therefore, where the process needs to be carried out in the long term, doctors often elect to do continuous ambulatory peritoneal dialysis (CAPD) as an alternative, at least for a while.

In simple terms, a catheter with a tap on the end is implanted into the abdominal cavity to provide a route between the outside world and the space around the internal organs.

The patient connects this catheter to a large bag of dialysis fluid with the correct biochemical composition to correct their blood chemistry. The fluid runs into the peritoneal cavity and sits there. The patient disconnects the tap and then goes about their business. Meanwhile, the body exchanges ions and water across the membranes of the internal abdominal organs over a period of hours with the infused dialysis fluid.

After a set period of time, the patient re-opens the tap, drains out the spent fluid and then replaces it with fresh. With regular biochemical monitoring, and checks and care to avoid infection, this can be a safe and convenient mode of dialysis for many patients. Yes, the patient walks around with some extra fluid inside them, and they have a tube running into their abdomen so they need to be careful what they do to avoid trauma or infection, but on the whole this is a safe and well-tolerated procedure.

Regrettably, it is not, however, an indefinite option. With time, the peritoneal membranes thicken and develop adhesions in response to the low-grade irritation imparted by the presence of the dialysis fluid. This impairs the effectiveness of the dialysis process, eventually rendering it inadequate. It also carries a risk of other complications such as intestinal obstruction and infection.

At this point, patients normally need to move onto haemodialysis, where blood is piped to a machine for filtering. To facilitate this, a fistula is normally fashioned between an artery and a vein in one arm to provide a high-flow system so that large volumes of blood can be obtained and returned to the body rapidly to minimise the time spent on dialysis.

All of these processes take a heavy toll on a person's health and their well-being. It's also extremely expensive. As such, and where possible, patients are transplanted with a healthy kidney to free them from the burden.

9

General Science / Re: Does using 93 octane petrol rather than 95 octane make a difference?

« on: 31/08/2018 13:48:50 »

The octane rating - known as the RON (research octane number) is a measure of the tendency of a fuel to ignite / detonate under compression. A lower octane fuel, such as 93 RON, will ignite more readily than an 95 RON rated fuel.

This distinction is important because fuels used in petrol engines are mixed with air and added to the cylinder before the piston begins its up-stroke. This means that the fuel and air mixture must be able to withstand being compressed until the spark plug electrically ignites the mix at the desired time.

More powerful engines have a higher compression ratio (because the more air you can pack into the cylinder the more gas there is to do thermal work and the more fuel you can burn from which to extract energy). The downside is that the higher compression produces more adiabatic heating within the cylinder, increasing the chances that the fuel will pre-ignite or begin to burn before it should.

If this does happen, then rather than the fuel burning smoothly and with a "flame-front" originating at the point of ignition (where the spark triggers the burn) and spreading through the fuel air mix, the fuel can begin to burn in a disorganised distribution in multiple places at one; this "pre-ignition" creates pressure waves and resonances within the cylinder that affect the efficiency and speed of the overall burning process, reducing the power development of the engine and also resulting in potentially damaging pressure changes within the cylinder. When this happens it produces a characteristic grating, rattling or banging sound called, appropriately enough, "knocking" or "pinking".

To combat this effect, performance engines use 95 RON fuels that are harder to detonate.

If you put 93 RON fuel into a 95 RON-recommended engine, it will probably pre-ignite and performance will be lower. It might also damage the engine in the long-term.

Most modern engines do have knock / preignition detection built into the engine management system, so the engine can detect when pinking is happening and it will attempt to adjust the timing and mixture to compensate. While this can abolish the knock, it will come at the cost of reduced power, so it amounts to the same thing - poorer output.

10

Chemistry / Re: How is sodium chloride - NaCl - and electrically neutral compound?

« on: 30/08/2018 03:02:11 »

You've already have the correct answer from @Ophiolite above, but to add a further perspective: in a sodium chloride crystal there are equal numbers of sodium ions and chloride ions, because when the sodium and chlorine reacted together, each sodium atom donated one electron to each chlorine atom; as such, no charge has actually been added or taken away, so there is no reason for the constituents to be electrically charged.

Now if we dissolve that sodium chloride crystal in water, although the particles will spread out in solution, there will still be the same number of positively- and negatively-charged ions; hence the solution is also electrically neutral.

11

Chemistry / Re: What is the difference between 'molecule ' and 'compound'?

« on: 22/08/2018 19:19:37 »

Compounds are chemicals formed from mixtures of different elements that are either covalently or ionically bonded. Molecule is a word used to describe a group of atoms, which may be the same or different, chemically bound together.

To be clear, the difference between the two is that a molecule can consist of two or more different or the same atoms joined together - e.g. hydrogen H₂ - whereas a compound is the species formed by the mixing of two or more different atomic species. e.g. magnesium oxide - MgO.

12

Geek Speak / Re: Victim of an Adult Site Blackmail Email Hoax?

« on: 14/08/2018 08:27:40 »

They're back again today:

Hi, victim.
This is my last warning.
I writе yоu bеcаusе I рut a malware оn the web раgе with porn which you havе visited.
My virus grаbbеd аll your personаl infо аnd turned on your саmerа which саpturеd the process of yоur onаnism. Just aftеr thаt thе sоft saved your contаct list.
I will deletе thе соmpromising vidеo аnd infо if you раy mе 600 USD in bitсoin. This is address fоr рaymеnt : 1ML4nLW4tyVwa3dqhbwYRsHw4Tuiqy92W3
 
I givе you 30 hours аfter you ореn my mеssаgе for making thе transаctiоn.
As sооn as you reаd thе mеssagе I'll sеe it right awаy.
It is nоt neсessаry tо tell mе thаt you have sеnt money to me. This аddress is connесted to yоu, my systеm will delеtе everything automatically аfter transfеr соnfirmаtion.
If you nееd 48 h just reрly оn this letter with +.
Yоu cаn visit the роliсe stаtion but nоbоdy can hеlp you.
If you try to decеive mе , I'll see it right аway !
I dоnt livе in yоur сountry. Sо thеy саn nоt trасk my lосatiоn evеn for 9 mоnths.
Goоdbyе. Dоnt forgеt about thе shаmе and tо ignоre, Your life саn be ruined.

This one is from "e" - "admin@warheads2foreheadsproductions.com"

You'll note that the price is now even lower - we're down at US$600 now, so this appears to be bargain bucket porn guilt revenge. Clearly it's worth keeping the spammers waiting - the longer they wait the lower the price. At this rate they will be paying me!

More seriously, this message is almost certainly not written by the same group; it uses shoddy English, contains none of the plausibility of the first wave (that contained passwords for added authenticity) and has a totally different tone.

Amazingly, the "soft" also waited for the (presumably hard) viewer to have an "oanaism" before it saved their contact list. Clever - computer software that can remotely recognise the moment of an "oanism". Shame it still can't implement spellcheck really.

The most likely explanation is that this is a bunch of people piggy-backing off the idea of the first lot, who actually made themselves a reasonable amount of money out of frightened people who paid up.

Please don't fall for this scam. But also watch out for the websites you visit - many are now incorporating all kinds of nefarious code with consequences like cryptojacking...

13

Physiology & Medicine / Re: Can someone develop PTSD after stopping antipsychotic medications?

« on: 09/08/2018 14:08:27 »

I would argue that, in medicine, anything can happen. But in this case, cessation of antipsychotics after long-term use is likely to provoke side effects and other symptoms, at least transiently, and especially if the drugs are not weaned off carefully. These side effects can include anxiety symptoms and mood destabilisation, which might be what you are referring to.

14

Geek Speak / Re: Do you know mobile app for photo editing, if possible, similiar to GIMP?

« on: 04/08/2018 23:20:42 »

There's pixelr, which I've used a few times and seems pretty user friendly.

15

Geek Speak / Re: Why is my Buffalo external HDD creating files that don't exist?

« on: 03/08/2018 23:40:35 »

Sounds like the file allocation table is corrupted. Do you actually need the data on the disk? Otherwise, deletion of the partition data and a reformat would be a good idea, followed by a disk surface scan / SMART test to see what the problem is...

16

Geek Speak / Re: Victim of an Adult Site Blackmail Email Hoax?

« on: 26/07/2018 12:31:30 »

These people have been writing to us for about 2 weeks, each time giving us 24h to pay up before they mail all our contacts with compromising videos of us; in the same breath they counsel that it can take several days to lay your hands on the bitcoins.

No saucy videos sent to our contacts...yet. Do let us know if you receive a video of a naked scientist doing something really naughty, like opening an email, or making a radio programme...

Please don't fall for this anyone.

17

General Science / Re: Why does the inside of my spectacles lenses always get dirtier than the outside?

« on: 23/07/2018 15:20:32 »

Great question!

I think there are several factors - or perhaps (lens) facets, you might say(!) - some of which have been alluded to above.

My own experience of wearing glasses mirrors that of @Mark Grifter with the inside surface of my glasses collecting a healthy coating of debris requiring regular cleaning.

I think that part of this is because volatiles, including sweat and skin oils, get deposited onto the inside of the lens surface from your nearby face. This is splattered into place by eye movements, blinks and other facial contortions.

This splattering of sticky gunk, I speculate, acts as a wallpaper paste to glue dust and other debris in place.

18

Physics, Astronomy & Cosmology / What is the neutrino discovery announced today?

« on: 12/07/2018 22:40:35 »

This is the leader from an article published today by Discover magazine:

Four billion years ago, an immense galaxy with a black hole at its heart spewed forth a jet of particles at nearly the speed of light. One of those particles, a neutrino that is just a fraction of the size of a regular atom, traversed across the universe on a collision course for Earth, finally striking the ice sheet of Antarctica last September. As it hit, a neutrino detector planted by scientists within the ice recorded the neutrino’s charged interaction, causing a blue flash of light that lasted just a moment. The results are published today in the journal Science.

I would appreciate the insights of the learned members of the forum to help me to understand more about this.

1) How do they know where it came from?

2) How do they know how old it is?

3) Why is this important?

19

Just Chat! / Re: Latest Forum Updates and Upgrades

« on: 10/07/2018 11:55:21 »

JULY 2018 UPDATE

  Hello campers! Hi-de-Hi! 

Sorry, forgive the lame 1980s comedic opening. (Some people may remember the TV series I am referencing here)...

A couple of changes to update you about.

1) ANTI-SPAM
Our friends from Korea believe that we need more advertising for their online casinos and other mechanisms to separate your from your money. Unfortunately they've become so over-excited about their ventures that they are accidentally getting carried away and posting hundreds of duplicate threads linking to their nefarious ventures. How nice of them.

Because this sad abuse jeopardises the user experience for everyone else, and the moderators are sick and tired of deleting their pathetic attempts to promote gambling scams, we've adjusted our anti-spam system to employ a re-captcha system instead.

Some users will see this now appearing beneath the reply / posting box. Trusted, senior members will not be troubled, and once a member achieves sufficient seniority or good standing on the forum, this privilege will be awarded so the captcha challenge goes away.

This shouldn't be burdensome for you, and we apologise to newcomers for subjecting them to this additional tick-box, but we hope it will help to keep down our workload so that we have more time to devote to contributing to posts and answering questions rather than deleting rubbish.

If anyone notices that it is causing problems or affecting your user experience, please report this here, preferably accompanied by a screenshot so we can see - and investigate - the problem.


2) GDPR / Data protection / Privacy
In May 2018 the EU rolled out a new set of rules concerning personal data. This is called the GDPR and probably generated the world's largest tide of spam as operators everywhere fired off increasingly desperate email salvos assuring the people they have been spamming for over a decade that their data is safe.

Here are the Naked Scientists we have always been very careful about this sort of thing, and we were largely ahead of the rule changes anyway; nevertheless, we have made some minor alterations to the systems here to ensure that we are compliant with the requirements of the GDPR.

The alerations include:

a) - A clearly-published privacy policy, which you can review here:
https://www.thenakedscientists.com/forum/index.php?action=gpdr;sa=privacypolic

This is in addition to the more general information we provide about privacy and copyright:
https://www.thenakedscientists.com/privacy-and-copyright-policies

...and in addition to the Acceptable User Policy (AUP) that forms part of the registration process and to which everyone signs up to in order to post here:
https://www.thenakedscientists.com/forum/index.php?topic=8535.0

b) - The ability for users to review the data held by the forum about you

c) - The ability to export your data from the forum.

To do either of b or c above, click on the MEMBERS link in the menu at the screen top, and select PROFILE from the drop-down menu

PROFILE.PNG (25.84 kB . 901x370 - viewed 2189 times)

Under the MODIFY PROFILE section, you'll see there's an option to "EXPORT YOUR DATA"

PROFILE-DATA-EXPORT.PNG (20.97 kB . 1178x406 - viewed 2180 times)

This actually provides you with two options: one is to "Export User Data Information" - which you do by clicking the link; the other is to "Export Posts".

d) - Deletion of your user has also been changed slightly.

Previously, a deleted username would remain visible against posts made by that user, although the personal data associated with that user were removed. Now, if you elect to delete your account, as well as the removal of all personally-identifiable data, the username against the posts that you have made will revert to an anonymous "guest" user. This step is irreversible: if you delete your account, we cannot re-associate your earlier posts with a new user that you may create subsequently, so please think carefully before choosing this course.

Thanks, everyone, for making this forum such a splendid place to hang out, and a special thanks to the moderators who work so hard to keep the place looking tidy!!

20

General Science / Re: Can H2O molecules cause an allergic response by binding to immune cells?

« on: 09/07/2018 21:52:10 »

Thanks for that, I was going to include links but when I did I couldn't post.

You need to achieve more seniority before it will permit posting links...