Nov 102013
 

Radiation is a danger to life, but this is a radioactive planet and we have quite a few radioactive elements in our bodies. Let us look at just one, the best known one: uranium. How many atoms of uranium in the human body undergo radioactive decay per minute?

The amount of uranium in the average person is 0.1mg although some may have only 0.01mg while others can have up to 0.4mg.

The chemical unit of 1 mole is the atomic weight in grams and for uranium this is 238 grams, and 1 mole of any element contains 6.02 x 1023 atoms. This means that 0.1 mg of uranium, which is 0.0001 gram, contains 6.02 x 1023 x 10-4 atoms which is 6.20 x 1019 atoms. We have more than a billion billion uranium atoms in our body.

Uranium consists of two isotopes; 99.3% is U-238 (half-life = 4.5 x 109 years) and 0.7% U-235 (half-life 700 x 106 years). Therefore, of the 6.20 x 1019 atoms uranium in the human body, 5.98 x 1019 atoms are U-238 and 0.04 x 1019 atoms are U-235.

Consider U-238

The 5.89 x 1019 atoms will reduce to 2.94 x 1019 atoms in 4.5 x 109 years.

Atoms per year undergoing radioactive decay = 2.94 x 1019/4.5 x 10-9 = 0.65 x 1010.

Minutes in a year = 365 x 24 x 60 = 525,600

Atoms per minute undergoing radioactive decay = 0.65 x 1010 / 525,600 = 12,300

Consider U235

Its 0.04 x 1019 atoms will reduce to 0.02 x 1019 atoms in 700 x 106 years.

Atoms per year undergoing radioactive decay = 0.02 x 1019 / 700 x 106 = 0.286 x 109.

Atoms per minute undergoing radioactive decay = 0.286 x 109/525,600 = 544

Total = 12,800 atoms per minute undergoing radioactive decay.

Which sounds a lot, but is a real threat? However, it is rarely mentioned when others protest about our exposure to other body ‘insults’ from traces of ‘harmful chemicals’ in our food, the implication often being that these are the cause cancer. However, radiation is definitely a cause of cancer but uranium is not the only radioactive element in our body. The others are potassium, carbon-14, thorium, etc.

Does the effect of this natural radioactivity outweigh any impact on the body from chemicals? The body’s repair mechanism obviously evolved to cope with this threat from radiation, as it had to do when dealing with natural materials for which it had no use. The uranium is mainly deposited in the skeleton as uranium phosphate, so it probably does little harm in any case.

Have I got these numbers right? If not then please let me know.

Nov 102013
 

Halloween Quiz 

I devised this quiz for the Twilight Meeting of Ampthill Rotary Club which was held on 30th  October 2013. The winning score was 19 and the prize was a box of Black Magic chocolates.

1 On which day should Halloween really be celebrated?

• 31st October • 31st November• 31st December
 Answer: 31st October

2. What is another name for Halloween?
• Feast of the dead •Feast of the Witches • All Hallows Eve
 Answer: All Hallows Eve (Feast of the Witches is 30th April)

3. What does the word ‘Hallow’ mean?
• Ghost • Goblin • Saint
 Answer: Saint

4. Who first celebrated Halloween?
• Vikings • Druids • Egyptians
 Answer: Druids

5. Who celebrates Halloween by eating sweets shaped like skulls?
• Mexicans • Aboriginal Australians • Croatians
 Answer: Mexico

6. By whom were witches first condemned?

• Emperor Nero • The Old Testament • Pope Innocent VII

Answer: The Old Testament, in the book of Deuteronomy.

7. When was the last witch burnt in Britain?

• 1527 • 1627 • 1727

Answer: Janet Home at Dornoch, Scotland, in 1727.

8. When did the ancient Celts celebrate their new year?
• 1st November • 21st December • 1st January
 Answer: 1st November

9. Where are pumpkins native to?
• Peru • Mexico • USA
 Answer: USA

10. What is a group of witches called?
• Convoy • Commune • Coven
 Answer: Coven

11. Who was burned as a sacrifice on Halloween in the 1973 film The Wicker Man?
• Edward Woodwardd • John Mills  • Herbert Lom
Answer: Edward Woodward

12. What is a male witch called?
• Warlock • Wizard • Sorcerer
 Answer: Warlock

13. Who wrote the book Frankenstein?
• Percy Shelley • Mary Shelly • Bram Stoker
 Answer: Mary Shelley

14. What type of monster was Frankenstein?

• A man who had been hanged • A man who had suddenly died • A murdered lunatic
Answer: None of these. Dr Frankenstein was his master. Deduct 2 points from your score if you Answered this question.

PTO

15. What was Frankenstein’s first name?
• Boris • Victor • Schweitzer
 Answer: Victor
16. Which two colours are associated with Halloween?
• Green and Black • Red and Black • Orange and Black
 Answer: Orange and Black

17. Which animals are associated with Halloween?
• Bats • Black cats • Wolves
 Answer: Black cats
18. The Celts dressed up in strange costumes for Halloween. Why?
• To scare the spirits away • To placate the spirits • To fool the spirits
 Answer: To scare the spirits away
19. What offering did the Druids sacrifice to their gods?
• Goats • Humans • Dogs
 Answer: Human beings

20. Which of these people died at Halloween?

• Houdini in 1926 • Harold Shipman in 2004 • People of Canterbury in 1942
Answer: Houdini and the People of Canterbury (air raid victims).

Give yourself an extra point if you ticked the two correct answers.

21. What is the day following Halloween called?

• Angel Gabriel Day • All Saints Day • Deliverance Day

Answer: All Saints Day

22. Which is said to be the most haunted place in England?

• Tower of London • Pendle Hill in Lancashire • Borley in Essex

Answer: Borley in Essex

23. What is a sure sign that a place is haunted?

• Sudden drop in temperature • dogs are afraid to enter • things move of their own accord

Answer: None of them. There are no ghosts. Deduct 2 points from your score if you ticked one of these answers.

24. Why were fonts in churches sealed when not in use?

• To prevent people adding unholy water • to prevent witches stealing the holy water • to prevent evil spirits defiling the holy water.

Answer: To prevent witches stealing the holy water.

25. How many witches are needed to form a ritualistic assembly?

• 7 • 13 • any number

Answer: Any number.

26. When were Black Magic chocolates first produced?

• 1913 • 1923 • 1933

Answer: 1933 

The tie-breaker question would have been the following: What year did trick-or-treat first begin? The person guessing the nearest year wins.

Answer: 1895 

It started in Scotland as ‘guising’, then spread to Canada in 1911, and then to the USA, where it got the name ‘trick-or-treat’ in 1946.